The Relevance of Phosphorus and Iron Chemistry to the Recovery

Environmental Science & Technology 2018 52 (3), 1183-1190 ... degradation using ultrasound/peroxymonosulfate/nanoscale zero valent iron: Reusability, ...
0 downloads 0 Views 1MB Size
Subscriber access provided by CARLETON UNIVERSITY

Critical Review

The relevance of phosphorus and iron chemistry to the recovery of phosphorus from wastewater: a review Philipp Wilfert, Prashanth Suresh Kumar, Leon Korving, Geert-Jan Witkamp, and Mark C.M. Van Loosdrecht Environ. Sci. Technol., Just Accepted Manuscript • Publication Date (Web): 07 May 2015 Downloaded from http://pubs.acs.org on May 7, 2015

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 44

Environmental Science & Technology

1

The relevance of phosphorus and iron chemistry to

2

the recovery of phosphorus from wastewater: a

3

review

4

Philipp Wilfert‡,a,b, Prashanth Suresh Kumar‡,a,b, Leon Korvinga,*, Geert-Jan Witkampa,b, Mark C.

5

M. van Loosdrechtb

6

a

7

8911 MA, Leeuwarden, The Netherlands

8

b

9

Netherlands

Wetsus, European Centre Of Excellence for Sustainable Water Technology, Oostergoweg 7,

Dept. Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The

10



11

*Corresponding author: [email protected]; +31-58-2843160; Wetsus, European Centre

12

Of Excellence for Sustainable Water Technology, Oostergoweg 7, 8911 MA, Leeuwarden, The

13

Netherlands

These authors contributed equally to this work

14

15

ACS Paragon Plus Environment

1

Environmental Science & Technology

Page 2 of 44

16 17

KEYWORDS: Phosphorus recovery, wastewater, iron phosphate, chemical phosphorus removal,

18

adsorption.

19

ABSTRACT

20

21

The addition of iron is a convenient way for removing phosphorus from wastewater, but this is

22

often considered to limit phosphorus recovery. Struvite precipitation is currently used to recover

23

phosphorus, and this approach has attracted much interest. However, it requires the use of

24

enhanced biological phosphorus removal (EBPR). EBPR is not yet widely applied and the

25

recovery potential is low. Other phosphorus recovery methods, including sludge application to

26

agricultural land or recovering phosphorus from sludge ash, also have limitations. Energy-

27

producing wastewater treatment plants increasingly rely on phosphorus removal using iron, but

28

the problem (as in current processes) is the subsequent recovery of phosphorus from the iron. In

29

contrast, phosphorus is efficiently mobilized from iron by natural processes in sediments and

30

soils. Iron–phosphorus chemistry is diverse, and many parameters influence the binding and

31

release of phosphorus, including redox conditions, pH, presence of organic substances, and

32

particle morphology. We suggest that the current poor understanding of iron and phosphorus

33

chemistry in wastewater systems is preventing processes being developed to recover phosphorus

ACS Paragon Plus Environment

2

Page 3 of 44

Environmental Science & Technology

34

from iron–phosphorus rich wastes like municipal wastewater sludge. Parameters that affect

35

phosphorus recovery are reviewed here, and methods are suggested for manipulating iron–

36

phosphorus chemistry in wastewater treatment processes to allow phosphorus to be recovered.

37

1

38 39

1.1 Background Phosphorus (P) is an essential nutrient and is very important for global food production. In

40

2000, 19.7 Mt of P was mined as phosphate rock. The major part, 15.3 Mt P, was used to produce

41

fertilizers.1 The demand for P will further increase in future due to a growing global population,

42

dietary changes and a rising share of biofuels.2 Apart from partial recycling of P by applying

43

manure to agricultural land, the usage of P around the world is linear, with very few recycling

44

routes and huge inefficiencies in its production and use.1–3 Ecological, geopolitical and economic

45

concerns demand P recovery.1–5 Hence, a cyclic use of P and thus development of technologies

46

that allow the recovery of P from secondary sources is required. Globally, about 1.3 Mt P/year is

47

treated in municipal wastewater treatment plants (WWTPs).1 We focus in this review on

48

municipal wastewater as a major secondary source of P. The implications of the interactions

49

described for P and iron (Fe) are also relevant to other wastewaters and even surface water.

Introduction

50

Phosphorus is removed from wastewater to prevent eutrophication in effluent receiving surface

51

waters.6,7 The most popular P removal techniques are enhanced biological phosphorus removal

52

(EBPR) and the more widely used chemical phosphorus removal (CPR) using Fe or aluminum

53

salts (table S1 in supporting information).8–13 Iron salts are usually preferred. They are cheaper

54

than aluminum salts.11,14 Also in EBPR plants, Fe is often dosed to support P removal (table S1 in

55

supporting information). Apart from P removal, Fe plays an important role in modern wastewater

56

treatment in general. It is used to prevent hydrogen sulfide emissions during anaerobic digestion

ACS Paragon Plus Environment

3

Environmental Science & Technology

Page 4 of 44

57

and acts as a coagulant to improve sludge dewatering.15–17 Wastewater pumping stations dose Fe

58

to control odors and corrosion18 and this practice may even aid the removal of P in WWTPs.19

59

Furthermore, significant amounts of Fe (typically: 0.5–1.5 mg Fe/L)20 can already be present in

60

the influent of WWTPs. For instance, data from 19 WWTPs in the Waterschap Vechtstromen in

61

The Netherlands showed influent Fe concentrations between 1 and 10 mg/L resulting in an

62

average Fe/P molar ratio of about 0.26 (unpublished data). These examples illustrate that Fe is

63

omnipresent in modern WWTPs (Table S2 in supporting information) and thus, that significant

64

amounts of P can be Fe bound, also in WWTPs that do not rely on Fe based CPR.

65

The presence of Fe is often perceived as negative when evaluating P recovery options.12,21–26

66

However, we will show that P is efficiently mobilized from various iron–phosphorus compounds

67

(FePs) in environmental systems. This apparent mismatch can be explained by the current lack of

68

understanding of the Fe and P chemistry. We will evaluate the literature that we believe is

69

important to help understanding Fe and P interactions in WWTPs. We will also present possible

70

directions that research and technology related to P recycling from wastewater could take, as

71

inspired by the science of environmental mobilization mechanisms.

72 73

1.2 Critical evaluation of current phosphorus recovery options

74

use of sludge, production of struvite in EBPR plants and recovery of P from sludge ash. After

75

hygienization, sludge (often termed biosolids) can be applied to agricultural land. This practice is

76

a widespread, low cost option for P recycling. About 50% of all sludge in the USA27 and about

77

40% of all sludge in the 27 EU countries28 was applied in agriculture in 2004 and 2005

78

respectively. Public concerns about pathogens, heavy metals, and organic micro-pollutants in

79

biosolids are widespread.29–32 But several studies showed that associated risks are low.33,34

80

Increasing regulations may further reduce concentrations of certain compounds35,36 but at the

Currently, P recovery methods from wastewater, applied on practical scales, include agricultural

ACS Paragon Plus Environment

4

Page 5 of 44

Environmental Science & Technology

81

same time emerging contaminants create new concerns.37 The presence of Fe in biosolids lowers

82

the water soluble P fraction.38–41 This can be considered positive, because it may prevent P loss by

83

surface runoff.34,42 Some authors perceive the presence of Fe in biosolids as negative as it resulted

84

in a reduced plant availability of P.21,22,40,43 However, other studies show Fe bound P can still be

85

plant available.44–46 The biggest problem of biosolid application is perhaps the fact that there are

86

areas with surpluses of P on agricultural land due to manure surpluses.47,48 Transporting sludge

87

from such areas to areas with P deficits is problematic because of the transport costs and logistics

88

involved. Thus, a pure and high value P recovery product is preferred over a complex product like

89

sludge.

90

Several options exist for P recovery to produce high value products.12,49–52 Currently, struvite

91

precipitation is attracting the most interest despite of limited P recovery potential. This technique

92

requires a combination of EBPR and sludge digestion, ideally in combination with a P stripping

93

process.53 But in many countries Fe based CPR plants dominate (Table S1 in supporting

94

information). Furthermore, the efficiency to recover P as struvite is typically only 10–50 % of the

95

total influent P load.51,52,54 This is due to the presence of P fractions that are not extracted during

96

anaerobic digestion (P fixed in biomass or bound to metals like Fe).

97

In a few countries, a significant proportion of the sludge is incinerated in mono-incinerators.28

98

Recovery of P from sludge ash has advantages: (1) economies of scale due to centralized

99

incinerators, (2) nearly all P removed can be recovered, (3) destruction of unwanted compounds

100

and (4) P is present in a concentrated form. Various promising thermo- and wet-chemical

101

technologies have been developed to recover P from sludge ash.26,50–52,55–58

102

technologies Fe plays a role too. It is influencing the extractability of P58 or the water solubility of

For these

ACS Paragon Plus Environment

5

Environmental Science & Technology

Page 6 of 44

103

P in the final product.56 These techniques depend on expensive infrastructure for incineration.

104

Phosphorus recovery alone will not be a sufficient reason to build sludge incinerators.

105

2 Iron is key to wastewater treatment plants of the future

106 107

2.1 A future treatment plant

108

an even more important role in WWTPs (Figure 1). Adding Fe is a key step in upcoming WWTPs

109

as energy and P factories. Energy-producing WWTPs already exist.59 Such plants often apply the

110

A-B process, using a very high loaded biological treatment (adsorption or A-stage) followed by a

111

bio-oxidation process or B-stage to remove nitrogen.60 During the A-stage, soluble chemical

112

oxygen demand (COD) in the wastewater is used for microbial growth and (bio)flocculation

113

removes the biomass, and colloidal and particulate COD from the wastewater. Iron addition is the

114

cheapest option for the required coagulation and flocculation of the COD and for P elimination in

115

the A-stage.60,61 Anaerobic digestion of A-stage sludge produces a large amount of biogas.60

116

Meanwhile, the A-B process has been further improved by using anaerobic ammonium oxidation

117

(anammox) to remove nitrogen in the side streams of several WWTPs at elevated temperatures

118

(25–40 °C).62–65 The anammox process does not need COD for nitrogen removal, while reducing

119

the energy demand simultaneously. The use of anammox at lower temperatures of 10-20 °C (cold

120

anammox) in the main treatment lines of WWTPs is being researched.66 Using anammox in the

121

main line could potentially allow a WWTP to produce energy at a net rate of 86 J/(person d). A

122

typical WWTP, using a classical activated sludge process, consumes 158 J/(person d).67

The presence of Fe is important in wastewater treatment already today. In future, Fe could play

123

In the future WWTP (Figure 1), P and COD removal can be achieved by adding Fe in the A-

124

stage. Nitrogen is removed using cold anammox. The settled sludge would be digested to produce

125

biogas and subsequently, P could be recovered from the digested sludge. Phosphorus recovery

126

could be done by selectively bringing iron-bound P into solution using a chemical or

ACS Paragon Plus Environment

6

Page 7 of 44

Environmental Science & Technology

127

biotechnological P recovery process that is yet to be developed. The sludge would then be

128

dewatered and the P precipitated and recovered as struvite or apatite.

129

Alternatively, P could be removed using an adsorption stage after the cold anammox. Owing to

130

environmental concerns like eutrophication, more stringent regulations on P discharge limits68,69

131

may anyway require P polishing of the effluent. To achieve low P concentrations in the effluent,

132

iron based adsorbents have already been used70,71 due to the high affinity of iron oxides for ortho-

133

phosphate (Portho).72–74 Adsorption also offers the possibility of P recovery and the re-use of the

134

adsorbents.75

135

Most of the wastewater treatment techniques described above are already being used or tested at

136

the pilot scale. Currently, the only missing process (as in current treatment processes) is

137

economically feasible P recovery from FePs-containing sludge. We envisage to develop a P

138

recovery process which is inspired by environmental mechanisms.

139 140

Figure 1: Proposed processes for an energy-producing wastewater treatment plant in which P is

141

recovered.

142 143

2.2 Environmental cycling: inspiration for recovering phosphorus?

144

potential for using sludge in agriculture21,22 or P recovery.12,23,24,26,76 Current processes for

145

recovering P from FePs-containing sludge and ash require large changes in pH, pressure, or

146

temperature (e.g., the Krepro, Seaborne, Mephrec, Ashdec, and Ecophos processes).25,52,56–58,77

A combination of Fe and P is often considered to have a negative impact when evaluating the

ACS Paragon Plus Environment

7

Environmental Science & Technology

Page 8 of 44

147

Usually, it is not economically feasible to use these processes. In contrast, P is mobilized very

148

efficiently from FePs in aquatic and terrestrial ecosystems.78–81 A biomimetic process could

149

therefore be a more attractive alternative.

150

Fungi, bacteria, and plants are able to mobilize Fe bound P and allow P cycling. The

151

mobilization of P can be so efficient that it results in environmental damage by causing

152

eutrophication in freshwater systems.82 Phosphorus can be released from FePs by iron-

153

reducing78,79 or sulfate reducing bacteria.78,79,82 Plants and fungi have developed a wide variety of

154

strategies to access Fe and P in FePs.80,83 For example, excretion of carboxylate anions (such as

155

oxalate or citrate) that chelate Fe and release P,84,85 exudations of anions (e.g., bicarbonate or

156

hydroxide) to desorb P from iron oxides,86,87 or reduction of FePs88 and inducing pH changes to

157

release P from FePs.80 Mechanisms presumed to be predominantly related to the mobilization of

158

Fe (e.g., excretion of siderophores or iron reduction)89 may also play a role in mobilizing P.88,90

159

Dissolved organic matter can assist in the mobilization of P from FePs by chelating Fe91 or by

160

facilitating the microbial reduction of Fe.91–94

161

Iron plays an important role in controlling the mobilization of P in soil and sediment systems.

162

Therefore, a great deal of research has been performed on the role of Fe in the P cycle. The

163

results, show that Fe and P cycling is possible, and this implies that recovering P from FePs is

164

achievable as well. Insufficient understanding of the Fe and P chemistry in WWTPs has prevented

165

the environmental mechanisms responsible for mobilizing P from being transferred to industrial

166

processes.

167

In section 3, we highlight the need for distinguishing between the different kinds of FePs to

168

better understand the binding and release of P. In section 4, we will show that various FePs are

169

formed and transformed during wastewater treatment processes but that little information is

ACS Paragon Plus Environment

8

Page 9 of 44

Environmental Science & Technology

170

available on the occurrence and behavior of these FePs. In Section 5, we will describe the findings

171

on the mobilization of P from FePs that could offer inspiration for the development of new P

172

recovery technologies.

173

3

174 175 176

3.1 Diversity of iron–phosphorus compounds

177

states varying between -2 to +6 although +2 (ferrous) and +3 (ferric) are the most common

178

oxidation states encountered. The solubility of ferrous and ferric ions vary with pH and oxidation

179

reduction potential (ORP) (Figure 2). Depending on the pH, the ferrous and ferric ions can get

180

hydrolyzed and form various insoluble oxides, oxyhydroxides and hydroxides, collectively termed

181

iron oxides.95

Iron and phosphorus interactions

3.1.1 Introduction to iron–phosphorus compounds Iron is a transition metal and its chemistry is very diverse.95 It can exist in several oxidation

182 183

Fig 2: Simplified Pourbaix diagram showing the stable iron species under different conditions

184

The FePs found in WWTPs can be either iron phosphate minerals or adsorption complexes

185

which involve adsorption of Portho to iron oxides (different methods to characterize FeP

186

interactions are listed in table S3).97–100 These FePs have often not been well described. This has

ACS Paragon Plus Environment

9

Environmental Science & Technology

Page 10 of 44

187

led to publications on the removal of P using Fe or on the recovery of P from FePs often

188

containing unspecific expressions such as “insoluble iron phosphates”, “metal phosphates”, and

189

“iron III phosphates”. We will give examples which illustrate that P can be bound to Fe in various

190

ways and that the amount and strength of P bound to the Fe differ. This suggests that there is a

191

range of mechanisms through which FePs can be altered resulting in P release, underlining the

192

importance to differentiate between various FeP.

193 194

3.1.2 Iron oxides and their interaction with Portho At least 16 iron oxides exist.95 Prominent examples of ferric iron oxides are goethite,

195

ferrihydrite, lepidocrocite, akaganeite, and hematite. Green rust iron oxides and magnetite are

196

examples of iron oxides that contain both ferrous and ferric iron. The different iron oxides have

197

different crystalline structures or are amorphous, and these structures largely determine properties

198

such as porosity, specific surface area, the number of exposed surface sites, solubility, and

199

reducibility. These properties in turn affect the Portho binding properties of the iron oxides and the

200

bioavailability of adsorbed Portho.101–105 The surface area of the iron oxide usually correlates with

201

its capacity to adsorb Portho (Figure S1 in supporting information). Amorphous or less crystalline

202

iron oxides have higher Portho adsorption capacities than more crystalline iron oxides, and this is

203

attributed to amorphous iron oxides having higher surface areas.101,103,106 Portho adsorption to iron

204

oxides can also differ due to the type and density of surface hydroxyl groups present on the crystal

205

faces, which are the functional groups where Portho adsorption occurs.95 Hematites showed Portho

206

adsorption capacities varying from 0.19 to 3.33 µmol/m2 due to the differences in their crystal

207

faces.104 In contrast, goethites showed a narrower range of Portho adsorption capacities between

208

2.16 to 2.83 µmol/m2 owing to their relatively constant crystal face distribution.107 Figure 3 shows

209

the Portho adsorption capacities in different iron oxides. The Portho adsorption capacity varies within

ACS Paragon Plus Environment

10

Page 11 of 44

Environmental Science & Technology

210

the same type of iron oxides based on the conditions under which they are synthesized and

211

used.104,105,108

212 213 214 215

Figure 3. Portho adsorption capacities of different iron oxides. Details of conditions used for adsorption are presented in Table S4 in supporting information.

216 217 218

Figure 4: Anion binding onto iron oxides as: Portho adsorbed as innersphere complexes109–111 a)

219

mononuclear monodentate b) mononuclear bidentate c) binuclear bidentate; d) sulfate adsorption

220

is shown as an example for outersphere complex in which water molecules are present between

221

the iron oxide surface and the sulfate112 e) example of surface precipitation in which dissolved Fe

ACS Paragon Plus Environment

11

Environmental Science & Technology

Page 12 of 44

222

from the iron oxide surface contributes to the formation of multiple layers of FeP precipitates113

223

on the surface of the iron oxide.

224

Portho adsorption onto iron oxides occurs since the Fe beneath the surface hydroxyl acts as a

225

Lewis acid and exchanges the surface OH groups for other ligands.95 When Portho is bound directly

226

to an iron oxide surface through a ligand exchange mechanism, without any water molecules

227

between the Portho and the surface, (Figure 4 a,b,c) the resulting complex is called an innersphere

228

complex.114 An innersphere complex can comprise of a single Portho molecule attached through

229

one or two oxygen bonds (mono or bidentate respectively) with either one or two Fe atoms (mono

230

or binuclear, respectively).115 The type of complex formed determines the relative strength at

231

which the Portho is bound. Bidentate complexes have more stable structures than monodentate

232

complexes, which implies that it could be easier to release Portho from monodentate than from

233

bidentate complexes.110 The types of innersphere complexes differ based on the type of iron

234

oxides and the conditions (such as the pH and the initial Portho concentration).109,110,114 Thus, Portho

235

adsorption and desorption properties vary for different iron oxides and for the conditions where

236

the iron oxides are produced and used. This make adsorption a very versatile process and offers

237

the possibility of engineering specific adsorbents based on iron oxides.

238

Adsorption is not the only interaction that occurs between Portho and iron oxides. It is possible to

239

have surface precipitation (Fig 4 e), which is the formation of three-dimensional entities as

240

opposed to the two-dimensional monolayer coverage during adsorption.115,116 Surface

241

precipitation can lead to the formation of a solid phase from which P is less readily desorbed

242

because the P buried in the surface precipitate is no longer in equilibrium with the solution.113 The

243

dissolution of Fe from the iron oxide contributes to the formation of the surface precipitate.113,117

244

For instance, nano zero-valent iron (nZVI) particles were shown to have very high Portho

ACS Paragon Plus Environment

12

Page 13 of 44

Environmental Science & Technology

245

adsorption capacities (245 mg P/g) even though their surface area (27.6 m2/g) were not very high

246

.118 This high capacity to remove Portho was explained as being partly caused by the occurrence of

247

precipitation, which was facilitated by the dissolution of Fe from the nZVI particles. The initial

248

Portho concentration in the solution influences the type of binding with iron oxide by determining

249

the surface coverage of Portho. Surface complexation tends to dominate at low surface coverages,

250

and surface precipitation becomes dominant as the surface loading increases.113,115 At a high

251

surface coverage with Portho, goethite and strengite (an iron phosphate mineral) have similar points

252

of zero charge (PZC), suggesting that surface precipitation occurred on goethite.113

253 254

3.1.3 Iron phosphate minerals Iron phosphate minerals are polyatomic complexes of iron and phosphate.119–121 Unlike

255

adsorption complexes where Portho is removed from solution by binding on the surface of a solid

256

(e.g. iron oxide),115 iron phosphate minerals are usually formed in the presence of Portho and

257

dissolved iron.122–124 However, the exact mechanisms involved in formation of iron phosphate

258

precipitates

259

(Fe(III)[PO4]·2H2O) are the common examples of iron phosphate minerals, although there exist

260

several

261

(Fe(II)(Fe(III))5[(PO4)4|(OH)5]·6H2O) and rockbridgeite (Fe(II)(Fe(III))4(PO4)3(OH)5.119 The

262

stability of different iron phosphate minerals vary in terms of their formation and solubility with

263

respect to pH and redox conditions126 which in turn might have implications on the P release from

264

these compounds. Vivianite has been found in WWTPs and its formation and role in recovering P

265

from wastewater will be discussed in detail in sections 3.2.3 and 4.1.4.

266 267 268

3.2 Iron–phosphorus compounds in wastewater treatment processes

269

efficiency at which P is removed in a WWTP by adding Fe is influenced by the oxygen

can

others

be

complex.98,125

like

Vivianite

lipscombite

(Fe3(II)[PO4]2·8H2O)

and

(Fe(II)(Fe(III))2(PO4)2(OH)2),

strengite

beraunite

3.2.1 Introduction to chemical phosphorus removal using iron salts Amongst other reasons, iron salts are added to wastewater to also remove P.127,128 The

ACS Paragon Plus Environment

13

Environmental Science & Technology

Page 14 of 44

270

concentration (for ferrous salts), the concentrations of competing ions, the presence of organic

271

matter, the pH, the alkalinity, mixing, the age of the Fe or iron oxide flocs, the type of P present,

272

and whether ferric or ferrous iron salts are used.127 FePs are exposed to dramatic changes in ORP

273

and temperature over a period of about one month in a WWTP with an anaerobic digestion

274

process. The following examples will show that adsorption, mineral formation, and

275

recrystallization may occur at different stages in a WWTP (figure 5).

276 277

Figure 5: WWTP schematic highlighting possible Fe and P interactions at different stages. Iron

278

can be dosed at various stages for reasons like sulfide removal, P removal, flocculation and to

279

facilitate dewatering of sludge.

280 281

3.2.2 Dosing ferric versus ferrous iron salts The exact mechanisms through which ferric or ferrous iron salts initially remove P are not yet

282

understood. The hydrolysis of ferric iron in an aqueous solution is usually very rapid.129 It has

283

been suggested that the adsorption of Portho onto iron oxides is an important98,130 or even the major

284

mechanism97,131 involved in the removal of Portho from wastewater when ferric iron salts are dosed.

285

The situation is even more complex when ferrous iron is added because this can be partly or

286

fully oxidized to ferric iron. The ferrous salts are usually added to aerated stages of the WWTP to

ACS Paragon Plus Environment

14

Page 15 of 44

Environmental Science & Technology

287

allow oxidation to ferric iron. The kinetics of ferrous iron oxidation strongly depend on the

288

oxygen concentration and particularly on the pH.132 Half of the ferrous iron in water containing

289

dissolved oxygen at 5 mg/L has been found to be oxidized to ferric iron within 45 minutes at pH 7

290

and within 0.5 minutes at pH 8.133,134 The presence of other ions (e.g., sulfate or Portho) or

291

dissolved organic matter can considerably influence the oxidation kinetics.132,135,136 The kinetics

292

of ferrous iron oxidation and hydrolysis in wastewater are not well established. In a WWTP, about

293

40 % of the ferrous iron that was added was found to be rapidly oxidized to ferric iron (at

294

relatively high pH 8.2 and dissolved oxygen concentration of 4.6 mg/L).137 Similarly, half of the

295

ferrous iron in activated sludge matrix could be oxidized within hours but about 10 % of the

296

ferrous iron fraction was not oxidized even after 6 days of aeration.138 Measurements on sludge

297

taken from the aeration tank of a WWTP in which ferrous iron was used to remove P suggest that

298

most of the Fe in the sludge was ferric iron.139 In contrast, 43 % of the total Fe in activated sludge

299

before anaerobic digestion was found in the form of the ferrous iron phosphate mineral

300

vivianite.100 This data indicates either extensive reduction of ferric iron during wastewater

301

treatment or incomplete oxidation of the ferrous iron that has been added to the aerated tanks.

302

However, also in the absence of oxygen, Portho could be removed with a ferrous Fe:P molar ratio

303

of 1.5 in batch tests using secondary effluents, a maximum Portho removal efficiency (98 %) was

304

found at pH 8.134 It has been suggested that the removal of P can be made more efficient if ferrous

305

iron is slowly oxidized in situ.134,140,141

306 307

3.2.3 Vivianite formation in wastewater treatment plants During wastewater treatment, initially formed FePs may change because of exposure to

308

different ORPs and, therefore, to different microbial and chemical processes.18,100,138,139,142

309

Vivianite can be formed when ferrous iron is added to remove P.100,134,143 Mössbauer

310

spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses,

ACS Paragon Plus Environment

15

Environmental Science & Technology

Page 16 of 44

311

showed that 43 % of the Fe in activated sludge from a WWTP in which ferrous sulfate was used

312

to remove P, and 60–67 % of the Fe in the digested sludge was bound in vivianite.100 Vivianite is

313

sparingly soluble in water (Ksp = 10−36), and it is stable in the absence of oxygen, at pH 6–9, under

314

non-sulfidic conditions, and in the presence of high ferrous Fe and Portho concentrations.144 In

315

WWTPs in which ferric salts are used to remove P or in WWTPs which apply different treatment

316

strategies (e.g., the A-B process), it is not known whether vivianite forms or not and if so to what

317

degree. The microbial reduction of ferric iron in anaerobic treatment stages could initially lead to

318

P release from FePs.138,139 However, the reduced Fe could ultimately act as a P sink by forming

319

vivianite, which has a higher P content (Fe:P molar ratio of 1.5) than ferric FeP precipitates found

320

in experiments with wastewater (Fe:P molar ratio of 2.5).98 The formation of ferric phosphate

321

minerals like strengite (Fe:P molar ratio of 1) does not seem to play a significant role in WWTPs.

322

In WWTPs strengite and lipscombite in Fe stabilized digested sludge were found after high Fe

323

dosing (Fe:P of 6.15) only.99 Hence, the formation of vivianite could be the final mechanism for

324

the retention of P in WWTPs.

325

4 Transforming iron–phosphorus compounds

326 327 328

4.1 Oxidizing and reducing conditions

329

FePs (Figure 6).95,145–147 The mobilization and retention of P from FePs in these systems, in

330

response to changes of ORPs, is well documented.78,82,148 Similar processes could also occur in

331

WWTPs.

4.1.1 Introduction Iron plays an important role in retaining P in soil and sediments because of the formation of

332

WWTPs require a large range of ORPs to allow different microbial processes to take place. The

333

ORPs in a WWTP will range from less than −300 mV, during anaerobic digestion or the anaerobic

334

period of an EBPR process, to more than +200 mV during the nitrification process. Here,

ACS Paragon Plus Environment

16

Page 17 of 44

Environmental Science & Technology

335

microbial and chemical processes can take place that alter FePs by oxidizing or reducing the Fe or

336

by replacing the P with sulfide or other ions. These modifications can affect the P removal

337

performance and other parameters, such as the dewaterability of the sludge.138 Nevertheless, Fe

338

speciation in response to varying ORPs in WWTPs has not received much attention. In a potential

339

P recovery process, exposing FePs to ORPs that anyway occur in WWTP, could assist in P

340

mobilization. For instance, at low ORPs iron reducing or sulfate reducing bacteria could mobilize

341

Fe bound P. On the other hand, oxidation can mobilize P bound in vivianite. The chemical or

342

biological processes that could mobilize P from FePs could be facilitated by the presence of

343

dissolved organic matter. In this section, we give a short overview on how ORPs can influence P

344

binding to Fe. We will show that changes in the ORPs in both, positive and negative ranges and

345

subsequent changes in microbial processes can assist in either retaining or mobilizing P from

346

FePs.

347 348

4.1.2 Iron reduction and iron oxidation The chemical or biological reductive dissolution of ferric iron can cause iron-bound P to be

349

released. In general, dissimilatory iron-reducing bacteria are widespread in soil and sediment

350

systems.149–151 These organisms reduce ferric iron in iron oxides or iron phosphate minerals,

351

thereby mobilizing P.94,152,153 However, in the absence of sulfate, ferrous iron compounds were

352

formed that bound most of the released P.78,154 The reducibility of an iron oxide depends on its

353

crystal structure, solubility, and surface area.155,156 Crystalline iron oxides with low surface area

354

(e.g., goethite and hematite) and low solubility are usually less accessible to iron-reducing

355

organisms than amorphous iron oxides (e.g., lepidocrocite and ferrihydrite).156–158

356

Once formed, ferrous iron can precipitate as secondary iron oxides (e.g., magnetite or green

357

rust) or as ferrous iron phosphate minerals (e.g., vivianite).151 In the presence of electron acceptors

358

(e.g., oxygen or nitrate), dissolved or solid ferrous iron compounds may be oxidized. Biogenic

ACS Paragon Plus Environment

17

Environmental Science & Technology

Page 18 of 44

359

iron oxides that can be formed in the presence of iron-oxidizing bacteria include goethite,

360

magnetite, ferrihydrite, and green rust.151 Biogenic iron oxides are often amorphous and

361

nanocrystalline,159 and thus showed high Portho binding capacities.160 Biologically formed iron

362

oxides can contain organic matter, which disrupts the crystallization process95,161 and makes the

363

Fe more accessible and therefore more easily reduced. This reduction process might be assisted by

364

humic substances.162,163

365

It has been shown that iron-reducing and iron-oxidizing bacteria are very active in

366

WWTPs.138,139,142 Reduction (presumably enzymatic) of Fe has been measured in activated sludge

367

immediately after storage under anaerobic conditions. The ferrous iron produced stayed mainly

368

within the organic matrix of the sludge despite of humic substances showing lower affinity to

369

ferrous than ferric iron.139,164 The authors hypothesized that the reduction of Fe can cause

370

significant P release from sludge under anaerobic conditions in WWTPs. However, the formation

371

of secondary ferrous iron oxides or vivianite that can bind P was not taken into account. It has also

372

been shown that the microbial oxidation of ferrous iron in activated sludge using nitrate as an

373

electron acceptor plays a significant role in the denitrification stage in WWTPs.138 The authors

374

hypothesized that this anoxic oxidation of ferrous iron could improve sludge dewatering and P

375

retention. The kinetics of iron oxidation and reduction and the transformation of Fe, that is cycled

376

through treatment stages with high and low ORPs, have not been determined yet. Thus, it is not

377

known whether ferrous or ferric, crystalline or amorphous, biogenic or chemogenic Fe compounds

378

dominate at different stages of a WWTP. Humic substances also play a role in the redox chemistry

379

of Fe. This will be discussed in section 4.2.

380 381

4.1.3 Sulfide and iron–phosphorus compounds Sulfide can reduce ferric iron compounds165 and can further react to form various iron sulfide

382

compounds (FeSs).166 It has been hypothesized that this could be the main mechanism through

ACS Paragon Plus Environment

18

Page 19 of 44

Environmental Science & Technology

383

which Fe bound P is released from sediments.78,82,148 The reactivity of an iron oxide toward

384

sulfide (as for iron-reducing bacteria) depends on the crystallinity of the iron oxide. Reaction

385

times have been found to range from minutes for poorly crystalline iron oxides (e.g., hydrous

386

ferric oxide, ferrihydrite, and lepidocrocite) to days or years for more crystalline iron oxides (e.g.,

387

hematite and goethite).165,167 The presence of Portho can decrease the reductive dissolution of

388

different iron oxides by sulfide via formation of binculear innersphere complexes.168–170

389

Sulfide has already been used to solubilize P selectively from FePs sludge for P recovery.

390

Sulfide released 75 % of the solid P into solution at pH 4 from sludge collected at a water

391

production plant.171 Similarly, 43 % of the total solid P was found to be released from sludge pre-

392

coagulated with Fe by adding sulfide.172 In another study, iron sulfate was added to precipitate P

393

in sludge liquor and the microbial reduction of the added sulfate produced sulfide.173

394

Subsequently, P was released (1.5 moles of sulfide released about one mol Portho) over a timescale

395

of days, without gaseous hydrogen sulfide formation.

396

To our knowledge, it is not known if sulfide induced P release is influenced by the type of FeP.

397

However, analogous to the difference in reactivity of sulfide to iron oxides, it is likely that the

398

amount of sulfide required to release P from FePs with different crystal structure varies.

399 400

4.1.4 Transforming vivianite Vivianite could be an important ferrous iron phosphate compound in WWTPs (see section

401

3.2.3). Transformation of vivianite by oxidation or by exposing it to sulfide can induce P release.

402

Chemically, about 5–10 % of the ferrous iron in freshly synthesized vivianite has been found to

403

oxidize within minutes when exposed to air and about two thirds of the ferrous iron was oxidized

404

after air bubbling for 53 days.123 In this study, oxidation occurred in the presence of a P sink (an

405

anion exchange membrane). The initial Fe:P ratio (determined by energy dispersive X-ray

406

spectrometry (EDX)) was 1.4 and the final Fe:P ratio was around 6.2. The complete oxidation of

ACS Paragon Plus Environment

19

Environmental Science & Technology

Page 20 of 44

407

vivianite and the formation of an amorphous iron phosphorus compound was much faster (16

408

days) when the oxidation was microbially induced.174 No P sink was present, but the Fe:P ratio

409

(determined by EDX) decreased from 1.3 (vivianite) to 2.8. Due to these properties vivianite has

410

been used as a slow release Fe and P fertilizer.123,175,176 Accordingly, vivianite may recrystallize

411

when sludge is exposed to air resulting in P release.

412

During anaerobic digestion, substantial sulfide formation by sulfate reducing bacteria would

413

most likely result in the release of significant amounts of iron-bound P, as reported for anoxic

414

sediments.82 The formation of vivianite during anaerobic digestion is not hampered by FeSs

415

formation since the supply of sulfate is limited in digesters.177,178 When considering the recovery

416

of P from sludge by sulfide, the crystallinity of vivianite should be taken into account. Vivianite

417

could be rather insensitive to sulfide, similar to more crystalline iron oxides.165,167

418

419 420 421

Figure 6: Redox processes and the cycling of P. The arrow keys represent the effect on soluble P: implies P release,

implies P sink,

implies not clear.

ACS Paragon Plus Environment

20

Page 21 of 44

Environmental Science & Technology

422 423 424

4.2 Humic substances

425

humic substances, plays an important role in Fe and P cycling in soil and aquatic systems. Humic

426

substances have received attention because of their omnipresence and relevance to Fe and P

427

chemistry. Humic substances include humic acids, fulvic acids, and humins.164 These are

428

relatively large, refractory and complex molecules that are products of organic matter degradation.

429

Humic substances lack well-defined compositions but usually contain large numbers of oxygen-

430

containing functional groups, such as carboxyl and hydroxyl groups.164 This characteristic

431

explains some of their interactions with Fe and P. Humic substances contributed about 20 % of the

432

total dissolved organic carbon in secondary effluent180 and 10–20 % of the total organic carbon in

433

sludge dry matter.181 It has been estimated that 22 % of the Fe in activated sludge could be bound

434

to organic matter.139 Accordingly, pyrophosphate extractions showed that approximately 30 % of

435

Fe in digested sludge could be bound to organic matter.182,183 Since humic substances are present

436

in abundance in WWTPs, they can considerably effect Fe and P speciation. Hence, their effects

437

need to be considered during research on P recovery processes from wastewater. Especially, since

438

the effect of humic substances on FePs has shown controversial results. In the next section, we

439

will briefly discuss how humic substances interact with Fe and the various ways in which they can

440

affect Fe and P interaction.

441 442

4.2.2 Humic substances interaction with iron and phosphorus The bond between Fe and humic molecules is relatively strong and can prevent the hydrolysis

443

and polymerization of Fe.184 Mössbauer spectroscopy185 and synchrotron-based spectroscopy184

444

have indicated that ferric iron can occur as oxides and non-oxides together with OM. It has also

445

been shown that different bonds between Fe and humic substances have different strengths186 and

446

that mononuclear and polymeric iron humic complexes occur.184,187,188 The type of complex

4.2.1 Introduction Organic matter contributes 40–80 wt. % of the total solids in sludge.179 Organic matter, like

ACS Paragon Plus Environment

21

Environmental Science & Technology

Page 22 of 44

447

formed influences Fe speciation, and the processes that lead to the different species being formed

448

include Fe hydrolysis, polymerization, and the binding of arsenate, which has similar structure

449

and reactivity as Portho.184,189–191

450

The presence of humic substances decreased the Portho adsorption capacity of goethite.192–194 It

451

has also been suggested that humic substances have either limited or positive effects on the

452

binding of Portho to Fe.195–197 It has been hypothesized that the Portho adsorption capacity of Fe

453

could increase because of the formation of iron–humic–phosphorus complexes.196,198 Such

454

complexes have been found to have about eight times higher Portho adsorption capacities than pure

455

iron oxide phases.195 This could be due to the Fe being finely distributed on the organic

456

surfaces.195 In studies using Mössbauer spectroscopy, it has been confirmed that iron oxides can

457

be evenly distributed over the surfaces of humic compounds.199 Yet, to the best of our knowledge,

458

there is no direct proof for the existence of such iron–humic–phosphorus complexes. However,

459

the binding of arsenic by humic–iron compounds has been proven using extended X-ray

460

absorption fine structure analyses. 189

461

The presence of humic substances could increase the Portho adsorption capacity of iron oxides by

462

preventing crystallization of amorphous iron oxides.185,200–202 However, it has also been shown

463

that organic matter does not have a significant influence on the crystallization of iron oxides and

464

does not affect the adsorption of P.203 Ferrous iron can be bound by humic substances, influencing

465

oxidation properties of ferrous iron, the crystallization of iron oxides, and the bioavailability of

466

ferrous iron.204,205 It has been found that humic substances can dissolve P by chelating Fe from

467

ferric FePs.91 Ferric iron can be kept in solution when it has been complexed with humic acids and

468

may, in that state, bind Portho.184,196,198

ACS Paragon Plus Environment

22

Page 23 of 44

Environmental Science & Technology

469

Iron-reducing bacteria can use humic substances as electron acceptors during the oxidation of

470

organic compounds.92 The rate at which Fe is reduced may be increased by the presence of humic

471

substances and usually inaccessible iron oxides may be made available.93 The ability of humic

472

substances to transfer or shuttle electrons to ferric iron has led to the hypothesis that even

473

fermenting bacteria, sulfate-reducing bacteria, or methanogens could reduce ferric iron.162,163,206

474

When humic substances act as electron acceptors, they can be restored after exposure to

475

oxygen.207 Fig 7 summarizes the possible effect of humics on Fe and P interactions.

476

477 478

Fig 7: Effect of humic substances on Fe and P interaction

479 480 481

4.3 The effect of pH

482

the speciation of Portho, the surface charge of iron oxides and the solubility of iron oxides and iron

483

phosphate minerals. We will discuss the effect of pH on Fe and P interactions in two contexts.

484

Firstly, the effect of pH on adsorption of Portho on and the desorption of Portho from iron oxides

485

respectively. This will be followed by a short discussion on existing techniques to recover P from

486

FePs in sludge to show controversial experiences that have been made in these studies.

4.3.1 Introduction The pH can have a considerable effect on Fe and P interactions since it affects several factors like

ACS Paragon Plus Environment

23

Environmental Science & Technology

Page 24 of 44

487 488

4.3.2 Desorption of Portho from iron oxides The surface potential of the adsorbent as well as the Portho becomes more negative as the pH

489

increases.208 Beyond the PZC of the iron oxide, electrostatic repulsion leads to a decrease in Portho

490

adsorption.209 Furthermore, an increase in pH increases the hydroxide ion concentration, which

491

results in Portho desorption. The hydroxide ion is the hardest Lewis base among the common

492

inorganic ions, so it is an effective reagent for desorption.210 Desorption of Portho from iron oxides

493

has been studied somewhat less than adsorption. Not all of the adsorbed Portho is easily released by

494

competing ions.107,108 The proportion of the adsorbate ion that is not easily desorbed could be

495

explained by the formation of surface precipitates, the slow restructuring of the solid, or diffusion

496

limitations related to the porosities of the iron oxides.108,113,116,211 XRD measurements have shown

497

that the crystallinity of goethite increased after one adsorption-desorption cycle (with NaOH), and

498

this affected Portho adsorption negatively.211 However, no change in crystallinity and reusability

499

(after 10 cycles) was observed after desorption using akaganeite.211

500 501

4.3.3 Inducing pH changes to recover phosphorus Wastewater and sludge is usually at pH 6–8 in WWTPs179 but much higher or lower pH are

502

applied in some processes to recover P. It has been suggested that at pH 13, P may be released

503

from FePs sludge using a microbial electrolysis cell.212,213 Phosphorus extraction from FePs

504

containing sludge, taken from a WWTP using Fe electrolysis for P removal, was more selective

505

and greater in alkaline compared to acidic conditions (92 compared to 70 % of total P

506

extracted).214 In other studies, relatively little P was released under alkaline extraction conditions

507

from FePs sludge215 (13 % extracted at pH 13) and iron-rich sludge ash216 (3–28 % extracted

508

using 1 M NaOH). These contradictory results further underline the importance of characterizing

509

FePs. The re-precipitation of released P (as calcium or magnesium phosphorus compounds) could

510

influence its net release. Strong acidification will dissolve and release P from iron oxides and iron

ACS Paragon Plus Environment

24

Page 25 of 44

Environmental Science & Technology

511

phosphate minerals thereby mobilizing most of the P in sludge and ash samples.215,217–220

512

Acidification is part of current P recovery techniques (such as Ecophos, ICL, PHONAX,

513

Seaborne, and Recophos) but can also bring heavy metals and other metals into solution.

514

5 Approaches to recover phosphorus from iron

515

Future energy producing WWTPs will rely on the removal of P and COD by Fe addition. An

516

economically feasible process for recovering P from FePs does not yet exist. Many different FePs

517

may be formed in WWTPs because of the wide range of microbial and chemical processes that

518

occur. The development of processes for recovering P from FePs demands more research,

519

especially on Fe and P interactions in WWTPs. The generated knowledge will help to identify the

520

best stages for introducing P recovery processes and will prepare a base for additional focused

521

research. Furthermore, this research will help to better understand and to improve wastewater

522

treatment processes, in general. For instance, it may be possible to induce formation of a specific

523

FeP from which P is easily extractable. A wide range of processes for releasing P from FePs in

524

nature exist, these processes depend also on the types of FePs present. The most relevant

525

mechanisms are summarized below:

526

-

The reduction of Fe may trigger initial P release from ferric FePs, but the vivianite

527

subsequently formed can act as a net P sink. In contrast, the oxidation of Fe may cause net

528

release of P bound in vivianite. Biological and chemical oxidation and reduction of FePs

529

occur in WWTPs. The use of these processes to develop a P recovery process remains to be

530

addressed.

531

-

Microbial reduction and oxidation of Fe plays an important role in the binding and release of

532

P. Different Fe compounds have different availabilities to the microbes that are responsible

533

for the oxidation or reduction of the Fe. These processes may be facilitated (e.g., by the

ACS Paragon Plus Environment

25

Environmental Science & Technology

Page 26 of 44

534

presence of humic substances) or hampered (e.g., by the crystal structure of the ferric FePs)

535

by other parameters.

536

-

Sulfide selectively releases P bound to ferric and ferrous FePs. Sulfide is formed to a limited

537

extent during anaerobic digestion of sludge. However, further stimulation of sulfate

538

reducing activity (e.g. after anaerobic digestion) would require COD input and would reduce

539

the net energy yield of the WWTP. Additionally, sulfide is corrosive and toxic. Therefore,

540

although sulfide addition could be useful to recover P, the dosing of sulfide needs to be

541

optimized and economic feasibility needs to be considered as well. The reaction

542

mechanisms between sulfide and FePs and the type of FeP in WWTPs have to be

543

investigated in detail to evaluate the potential of sulfide for P recovery from FePs.

544

-

Under very alkaline or acidic conditions P is released from most FePs. However,

545

contradictory results have been found under alkaline conditions, suggesting that the release

546

depends on the types of FePs that are present in sludge.

547

-

The presence of high concentrations of OM in WWTPs complicates the Fe and P chemistry

548

involved. The role of OM in the Fe and P biogeochemistry is not clear. It can, however, be

549

assumed that OM significantly influence Fe and P speciation in WWTPs. Thus, OM should

550

be included in future research on the development of a biomimetic process to recover P from

551

FePs.

552

-

Another approach to recovering P is to simplify the complex FePs interactions by

553

engineering iron-based adsorbents. Iron-based adsorbents are already used to remove P from

554

WWTP effluent. The regeneration of these adsorbents could be an effective approach to

555

recovering P. Currently, this aspect receives insufficient attention. The diversity of FePs

556

chemistry can be used to influence the binding and release characteristics of P, for example,

ACS Paragon Plus Environment

26

Page 27 of 44

Environmental Science & Technology

557

by varying the crystallinity, pore size distribution or surface area of the iron oxide based

558

adsorbent.

559

We believe that a process for recovering P using Fe should be developed in two steps. First,

560

suitable FePs should be identified and characterized. Second, specific tools for mobilizing P

561

from these compounds should be identified. Developing a biomimetic process to recover P from

562

FePs would be an important step towards WWTPs acting as energy and nutrient factories.

563

6 Acknowledgements

564

This work was performed in the TTIW-cooperation framework of Wetsus, European Centre Of

565

Excellence For Sustainable Water Technology (www.wetsus.nl). Wetsus is funded by the Dutch

566

Ministry of Economic Affairs, the European Union Regional Development Fund, the Province of

567

Fryslân, the City of Leeuwarden and the EZ/Kompas program of the ‘Samenwerkingsverband

568

Noord-Nederland’. The authors would like to thank the participants of the research theme

569

“Phosphate Recovery” for their financial support and helpful discussions.

570

7 Supporting Information Available

571

Tables S1 to S4 and figure S1 are included in the supporting information. The supporting

572

information is available free of charge.

573

ACS Paragon Plus Environment

27

Environmental Science & Technology

Page 28 of 44

574

References

575 576 577

(1) van Vuuren, D. P.; A.F. Bouwman; A.H.W. Beusen. Phosphorus demand for the 1970–2100 period: A scenario analysis of resource depletion. Global Environmental Change 2010, 20 (3), 428–439; DOI 10.1016/j.gloenvcha.2010.04.004.

578 579 580

(2) Cordell, D.; Drangert, J.-O.; White, S. The story of phosphorus: Global food security and food for thought. Global Environmental Change 2009, 19 (2), 292–305; DOI 10.1016/j.gloenvcha.2008.10.009.

581 582

(3) Reijnders, L. Phosphorus resources, their depletion and conservation, a review. Resources, Conservation and Recycling 2014, 93, 32–49; DOI 10.1016/j.resconrec.2014.09.006.

583 584 585

(4) De Ridder, M.; De Jong, S.; Polchar, J.; Lingemann, S. Risks and opportunities in the global phosphate rock market: Robust strategies in times of uncertainty; Rapport / Centre for Strategic Studies no. 17 | 12 | 12; The Hague Centre for Strategic Studies: Den Haag, 2012.

586 587 588

(5) Cooper, J.; Lombardi, R.; Boardman, D.; Carliell-Marquet, C. The future distribution and production of global phosphate rock reserves. Resources, Conservation and Recycling 2011, 57 (January), 78–86; DOI 10.1016/j.resconrec.2011.09.009.

589 590 591

(6) Conley, D. J.; Paerl, H. W.; Howarth, R. W.; Boesch, D. F.; Seitzinger, S. P.; Havens, K. E.; Lancelot, C.; Likens, G. E. Ecology. Controlling eutrophication: nitrogen and phosphorus. Science (New York, N.Y.) 2009, 323 (5917), 1014–1015; DOI 10.1126/science.1167755.

592 593 594

(7) Jarvie, H. P.; N., C.; Withers, P. J. Sewage-effluent phosphorus: a greater risk to river eutrophication than agricultural phosphorus? The Science of the total environment 2006, 360 (13), 246–253; DOI 10.1016/j.scitotenv.2005.08.038.

595 596

(8) Carliell-Marquet, C.; Cooper, J. Towards closed-loop phosphorus management for the UK Water Industry. In Sustainable Phosphorus Summit, 2014.

597

(9) DWA. Stand der Klarschlammbehandlung und Entsorgung in Deutschland, 2005.

598

(10) Korving, L. Trends in slibontwatering; STOWA, 2012.

599 600

(11) Paul, E.; Laval, M. L.; Sperandio, M. Excess sludge production and costs due to phosphorus removal. Environmental technology 2001, 22, 1363–1371.

601 602 603

(12) Morse, G.; Brett, S.; Guy, J.; Lester, J. Review: Phosphorus removal and recovery technologies. The Science of the total environment 1998, 212 (1), 69–81; DOI 10.1016/S00489697(97)00332-X.

604 605 606

(13) De-Bashan, L. E.; Bashan, Y. Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003). Water research 2004, 38 (19), 4222–4246; DOI 10.1016/j.watres.2004.07.014.

607 608

(14) Geraarts, B.; Koetse, E.; Loeffen, P.; Reitsma, B.; Gaillard, A. Fosfaatterugwinning uit ijzerarm slib van rioolwaterzuiveringsinrichtingen; STOWA, 2007.

ACS Paragon Plus Environment

28

Page 29 of 44

Environmental Science & Technology

609 610 611

(15) Charles, W.; Cord-Ruwisch, R.; Ho, G.; Costa, M.; Spencer, P. Solutions to a combined problem of excessive hydrogen sulfide in biogas and struvite scaling. Water Science & Technology 2006, 53 (6), 203; DOI 10.2166/wst.2006.198.

612 613 614

(16) Ge, H.; Zhang, L.; Batstone, D. J.; Keller, J.; Yuan, Z. Impact of Iron Salt Dosage to Sewers on Downstream Anaerobic Sludge Digesters: Sulfide Control and Methane Production. J. Environ. Eng. 2013, 139 (4), 594–601; DOI 10.1061/(ASCE)EE.1943-7870.0000650.

615 616 617

(17) Higgins, M.; Murthy, S. Understanding factors affecting polymer demand for thickening and dewatering; Water Environment Research Foundation; IWA Publishing: Alexandria, Va, London, 2006.

618 619 620

(18) Nielsen, A. H.; Lens, P.; Vollertsen, J.; Hvitved-Jacobsen, T. Sulfide–iron interactions in domestic wastewater from a gravity sewer. Water research 2005, 39 (12), 2747–2755; DOI 10.1016/j.watres.2005.04.048.

621 622 623

(19) Gutierrez, O.; Park, D.; Sharma, K. R.; Yuan, Z. Iron salts dosage for sulfide control in sewers induces chemical phosphorus removal during wastewater treatment. Water research 2010, 44 (11), 3467–3475; DOI 10.1016/j.watres.2010.03.023.

624 625

(20) Hvitved-Jacobsen, T.; Vollertsen, J.; Nielsen, A. H. Sewer processes: Microbial and chemical process engineering of sewer networks, 2nd ed.; CRC Press: Boca Raton, 2013.

626 627 628 629 630

(21) Samie, I. F.; Römer, W. Phosphorus availability to maize plants from sewage sludge treated with Fe compounds. In Plant Nutrition; Horst, W. J., Schenk, M. K., Bürkert, A., Claassen, N., Flessa, H., Frommer, W. B., Goldbach, H., Olfs, H.-W., Römheld, V., Sattelmacher, B., Schmidhalter, U., Schubert, S., Wirén, N. v., Wittenmayer, L., Eds.; Springer Netherlands: Dordrecht, 2001; pp 846–847.

631 632 633

(22) Römer, W. Vergleichende Untersuchungen zur Pflanzenverfügbarkeit von Phosphat aus verschiedenen P-Recycling-Produkten im Keimpflanzenversuch. J. Plant Nutr. Soil Sci. 2006, 169 (6), 826–832; DOI 10.1002/jpln.200520587.

634 635

(23) Egle, L.; Rechberger, H.; Zessner, M. Endbericht Phosphorrückgewinnung aus dem Abwasser: Wien, 2014.

636 637

(24) ACHS. Review of the Feasibility of Recycling Phosphates at Sewage Treatment Plants in The UK - Executive Summary; Department for Environment, Food and Rural Affairs, 2009.

638 639

(25) Schipper, W. J.; Korving, L., Eds. Full-scale plant test using sewage sludge ash as raw material for phosphorus production, 2009.

640 641 642

(26) Schipper, W. J.; Klapwijk, A.; Potjer, B.; Rulkens, W. H.; Temmink, B. G.; Kiestra, F. D.; Lijmbach, A. C. Phosphate recycling in the phosphorus industry. Environmental technology 2001, 22 (11), 1337–1345; DOI 10.1080/09593330.2001.9619173.

643 644 645

(27) Moss, L.; Donovan, J. F.; Carr, S.; Stone, L.; Polo, C.; Khunjar, W.; Latimer, R.; Jeyanayagam, S.; Beecher, N.; McFadden, L. Enabling the future-Advancing Resource Recovery from Biosolids, 2013.

ACS Paragon Plus Environment

29

Environmental Science & Technology

Page 30 of 44

646 647 648

(28) Kelessidis, A.; Stasinakis, A. S. Comparative study of the methods used for treatment and final disposal of sewage sludge in European countries. Waste management (New York, N.Y.) 2012, 32 (6), 1186–1195; DOI 10.1016/j.wasman.2012.01.012.

649 650

(29) Aubain, P.; Gazzo, A.; Le Mous, J.; Mugnier, E.; Brunet, H.; Landrea, B. Disposal and Recycling Routes for Sewage Sludge February; European Commission DG Environment, 2002.

651 652

(30) Beecher, N.; Harrison, E. Risk perception, risk communication, and stakeholder involvement for biosolids management and research. Journal of łdots 2005, 122–128.

653 654 655

(31) Robinson, K. G.; Robinson, C. H.; Raup, L. A.; Markum, T. R. Public attitudes and risk perception toward land application of biosolids within the south-eastern United States. Journal of Environmental Management 2012, 98, 29–36; DOI 10.1016/j.jenvman.2011.12.012.

656 657 658

(32) Langenkamp, H.; Part, P.; Erhardt, W.; Prüe\ss, A. Organic contaminants in sewage sludge for agricultural use October 2001; European Commission, Joint Research Centre, Insitiute for Environment and Sustainability, 2001.

659 660 661

(33) Smith, S. R. Organic contaminants in sewage sludge (biosolids) and their significance for agricultural recycling. Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 2009, 367 (1904), 4005–4041; DOI 10.1098/rsta.2009.0154.

662 663

(34) Lu, Q.; He, Z. L.; Stoffella, P. J. Land Application of Biosolids in the USA: A Review. Applied and Environmental Soil Science 2012, 2012, 1–11; DOI 10.1155/2012/201462.

664 665

(35) Olofsson, U.; Bignert, A.; Haglund, P. Time-trends of metals and organic contaminants in sewage sludge. Water research 2012, 46 (15), 4841–4851; DOI 10.1016/j.watres.2012.05.048.

666 667 668 669

(36) Oliver, I. W.; McLaughlin, M. J.; Merrington, G. Temporal trends of total and potentially available element concentrations in sewage biosolids: a comparison of biosolid surveys conducted 18 years apart. The Science of the total environment 2005, 337 (1-3), 139–145; DOI 10.1016/j.scitotenv.2004.07.003.

670 671 672

(37) Clarke, B. O.; Smith, S. R. Review of 'emerging' organic contaminants in biosolids and assessment of international research priorities for the agricultural use of biosolids. Environment International 2011, 37 (1), 226–247; DOI 10.1016/j.envint.2010.06.004.

673 674 675

(38) Brandt, R. C.; Elliott, H. A.; O'Connor, G. A. Water-Extractable Phosphorus in Biosolids: Implications for Land-Based Recycling. water environ res 2004, 76 (2), 121–129; DOI 10.2175/106143004X141645.

676 677 678

(39) O'Connor, G. A.; Sarkar, D.; Brinton, S. R.; Elliott, H. A.; Martin, F. G. Phytoavailability of Biosolids Phosphorus. Journal of Environment Quality 2004, 33 (2), 703; DOI 10.2134/jeq2004.7030.

679 680 681

(40) Krogstad, T.; Sogn, T. a.; Asdal, \. s.; S\ae b\o, A. Influence of chemically and biologically stabilized sewage sludge on plant-available phosphorous in soil. Ecological Engineering 2005, 25 (1), 51–60; DOI 10.1016/j.ecoleng.2005.02.009.

ACS Paragon Plus Environment

30

Page 31 of 44

Environmental Science & Technology

682 683

(41) Miller, M.; O'Connor, G. A. The Longer-Term Phytoavailability of Biosolids-Phosphorus. Agronomy Journal 2009, 101 (4), 889; DOI 10.2134/agronj2008.0197x.

684 685 686

(42) Elliott, H.; O’Connor, G. Phosphorus management for sustainable biosolids recycling in the United States. Soil Biology and Biochemistry 2007, 39 (6), 1318–1327; DOI 10.1016/j.soilbio.2006.12.007.

687 688 689 690

(43) Kidd, P. S.; Dominguez-Rodriguez, M. J.; Diaz, J.; Monterroso, C. Bioavailability and plant accumulation of heavy metals and phosphorus in agricultural soils amended by long-term application of sewage sludge. Chemosphere 2007, 66 (8), 1458–1467; DOI 10.1016/j.chemosphere.2006.09.007.

691 692 693 694

(44) Prochnow, L. I.; Chien, S. H.; Carmona, G.; Dillard, E. F.; Henao, J.; Austin, E. R. Plant Availability of Phosphorus in Four Superphosphate Fertilizers Varying in Water-Insoluble Phosphate Compounds. Soil Science Society of America Journal 2008, 72 (2), 462; DOI 10.2136/sssaj2006.0421.

695 696 697

(45) Nanzer, S.; Oberson, A.; Berger, L.; Berset, E.; Hermann, L.; Frossard, E. The plant availability of phosphorus from thermo-chemically treated sewage sludge ashes as studied by 33P labeling techniques. Plant Soil 2014, 377 (1-2), 439–456; DOI 10.1007/s11104-013-1968-6.

698 699 700

(46) Kahiluoto, H.; Kuisma, M.; Ketoja, E.; Salo, T.; Heikkinen, J. Phosphorus in manure and sewage sludge more recyclable than in soluble inorganic fertiliser. in revision 2015, 49 (4), 2115– 2122.

701 702 703

(47) Schröder, J. J.; Smit, A. L.; Cordell, D.; Rosemarin, A. Improved phosphorus use efficiency in agriculture: a key requirement for its sustainable use. Chemosphere 2011, 84 (6), 822–831; DOI 10.1016/j.chemosphere.2011.01.065.

704 705 706

(48) Macdonald, G. K.; Bennett, E. M.; Potter, P. A.; Ramankutty, N. Agronomic phosphorus imbalances across the world’s croplands 2011, 108 (7), 3086–3091; DOI 10.1073/pnas.1010808108.

707 708

(49) Petzet, S.; Cornel, P. Towards a complete recycling of phosphorus in wastewater treatment – options in Germany. Water Science & Technology 2011, 64 (1), 29; DOI 10.2166/wst.2011.540.

709 710 711 712

(50) Desmidt, E.; Ghyselbrecht, K.; Zhang, Y.; Pinoy, L.; Van der Bruggen, Bart; Verstraete, W.; Rabaey, K.; Meesschaert, B. Global Phosphorus Scarcity and Full-Scale P-Recovery Techniques: A Review. Critical Reviews in Environmental Science and Technology 2015, 45 (4), 336–384; DOI 10.1080/10643389.2013.866531.

713 714 715

(51) Cornel, P.; Schaum, C. Phosphorus recovery from wastewater: needs, technologies and costs. Water science and technology : a journal of the International Association on Water Pollution Research 2009, 59 (6), 1069–1076; DOI 10.2166/wst.2009.045.

716 717

(52) Hermann, L. Rückgewinnung von Phosphor aus der Abwasserreinigung. Eine Bestandsaufnahme.; Umwelt Wissen No. 0929, 2009.

718 719

(53) Cullen, N.; Baur, R.; Schauer, P. Three years of operation of North America’s first nutrient recovery facility. Water Science & Technology 2013, 68 (4), 763–768.

ACS Paragon Plus Environment

31

Environmental Science & Technology

Page 32 of 44

720 721

(54) Lodder, R.; Meulenkamp, R.; Notenboom, G. Fosfaatterugwinning in communale afvalwaterzuiveringsinstallaties; STOWA, 2011.

722 723 724

(55) Donatello, S.; Cheeseman, C. R. Recycling and recovery routes for incinerated sewage sludge ash (ISSA): a review. Waste management (New York, N.Y.) 2013, 33 (11), 2328–2340; DOI 10.1016/j.wasman.2013.05.024.

725 726 727

(56) Adam, C.; Peplinski, B.; Michaelis, M.; Kley, G.; Simon, F.-G. Thermochemical treatment of sewage sludge ashes for phosphorus recovery. Waste management (New York, N.Y.) 2009, 29 (3), 1122–1128; DOI 10.1016/j.wasman.2008.09.011.

728 729

(57) Hermann, L. A review of innovations in mineral fertilizer production. In 16th World Fertilizer Congress of CIEC, 2014; pp 105–108.

730 731

(58) Langeveld, C. P.; Wolde, K. W. Phosphate recycling in mineral fertiliser production. In Proceedings International Fertiliser Society 717; International Fertiliser Society, UK, 2013; p 24.

732 733

(59) Nowak, O.; Keil, S.; Fimml, C. Examples of energy self-sufficient municipal nutrient removal plants. Water Science & Technology 2011, 64 (1), 1; DOI 10.2166/wst.2011.625.

734 735

(60) Böhnke, B.; Diering, B.; Zuckut, S. W. Cost-effective wastewater treatment process for removal of organics and nutrients. Water Eng. Manag. 1997, 144 (7), 18–21.

736 737

(61) Li, J. Effects of Fe(III) on floc characteristics of activated sludge. J. Chem. Technol. Biotechnol. 2005, 80 (3), 313–319; DOI 10.1002/jctb.1169.

738 739 740

(62) Abma, W. R.; Schultz, C. E.; Mulder, J. W.; van der Star, W.R.L.; Strous, M.; Tokutomi, T.; van Loosdrecht, M. Full-scale granular sludge Anammox process. Water Science & Technology 2007, 55 (8-9), 27; DOI 10.2166/wst.2007.238.

741 742 743

(63) Lackner, S.; Gilbert, E. M.; Vlaeminck, S. E.; Joss, A.; Horn, H.; van Loosdrecht, M. C. M. Full-scale partial nitritation/anammox experiences-an application survey. Water research 2014, 55, 292–303; DOI 10.1016/j.watres.2014.02.032.

744 745 746

(64) Nowak, O.; Enderle, P.; Varbanov, P. Ways to optimize the energy balance of municipal wastewater systems: lessons learned from Austrian applications. Journal of Cleaner Production 2015, 88, 125–131; DOI 10.1016/j.jclepro.2014.08.068.

747 748 749

(65) Jetten, M.; Horn, S.; van Loosdrecht, M. C. M. Towards a more sustainable municipal wastewater treatment system. Water Science and Technology 1997, 35 (9), 171–180; DOI 10.1016/S0273-1223(97)00195-9.

750 751 752

(66) Lotti, T.; Kleerebezem, R.; Kip, C.; Hendrickx, T. L. G.; Kruit, J.; Hoekstra, M.; van Loosdrecht, M. C. M. Anammox growth on pretreated municipal wastewater. Environ. Sci. Technol. 2014, 48 (14), 7874–7880; DOI 10.1021/es500632k.

753 754

(67) Kartal, B.; Kuenen, J. G.; van Loosdrecht, M. C. M. Sewage Treatment with Anammox. Science 2010, 328 (5979), 702–703; DOI 10.1126/science.1185941.

ACS Paragon Plus Environment

32

Page 33 of 44

Environmental Science & Technology

755 756

(68) Oleszkiewicz, J. A.; James L. B. Nutrient removal technology in North America and the European Union: A review. Water Qual.Res.J. Canada 2006, 41 (4), 449–462.

757 758

(69) UK technical advisory group. UK environmental standards and conditions (Phase 1): Water Framework Directive 2008.

759 760 761

(70) Pratt, C.; Parsons, S. A.; Soares, A.; Martin, B. D. Biologically and chemically mediated adsorption and precipitation of phosphorus from wastewater. Current opinion in łdots 2012, 23 (6), 890–896; DOI 10.1016/j.copbio.2012.07.003.

762 763

(71) Ragsdale, D. Advanced Wastewater Advanced Wastewater Treatment to Achieve Low Concentration of Phosphorus, 2007.

764 765 766

(72) Blaney, L. M.; Cinar, S.; SenGupta, A. K. Hybrid anion exchanger for trace phosphate removal from water and wastewater. Water research 2007, 41 (7), 1603–1613; DOI 10.1016/j.watres.2007.01.008.

767 768 769

(73) Genz, A.; Kornmüller, A.; Jekel, M. Advanced phosphorus removal from membrane filtrates by adsorption on activated aluminium oxide and granulated ferric hydroxide. Water research 2004, 38 (16), 3523–3530; DOI 10.1016/j.watres.2004.06.006.

770 771 772 773

(74) Martin, B. D.; Parsons, S. A.; Jefferson, B. Removal and recovery of phosphate from municipal wastewaters using a polymeric anion exchanger bound with hydrated ferric oxide nanoparticles. Water science and technology : a journal of the International Association on Water Pollution Research 2009, 60 (10), 2637–2645; DOI 10.2166/wst.2009.686.

774 775 776

(75) Loganathan, P.; Vigneswaran, S.; Kandasamy, J.; Bolan, N. S. Removal and Recovery of Phosphate From Water Using Sorption. Critical Reviews in Environmental Science and Technology 2014, 44 (8), 847–907; DOI 10.1080/10643389.2012.741311.

777 778

(76) Schröder, J. J.; Cordell, D.; Smit, A. L.; Rosemarin, A. Sustainable use of phosphorus.; Wageningen University and Research Centre, 2010.

779 780

(77) Levlin, E.; Lowen, M.; Stark, K.; Hultman, B. Effects of phosphorus recovery requirements on Swedish sludge management. Water Science and Technology 2002, 46 (4-5), 435–440.

781 782 783

(78) Roden, E. E.; Edmonds, J. W. Phosphate mobilization in iron-rich anaerobic sediments: Microbial Fe(III) oxide reduction versus iron-sulfide formation. Archiv für Hydrobiologie 1997, 139 (3), 347–378.

784 785 786 787

(79) Chacon, N.; Silver, W. L.; Dubinsky, E. A.; Cusack, D. F. Iron Reduction and Soil Phosphorus Solubilization in Humid Tropical Forests Soils: The Roles of Labile Carbon Pools and an Electron Shuttle Compound. Biogeochemistry 2006, 78 (1), 67–84; DOI 10.1007/s10533-0052343-3.

788 789 790

(80) Hinsinger, P. Bioavailability of soil inorganic P in the rhizosphere as affected by rootinduced chemical changes: a review. Plant Soil 2001, 237 (2), 173–195; DOI 10.1023/A:1013351617532.

ACS Paragon Plus Environment

33

Environmental Science & Technology

Page 34 of 44

791 792 793

(81) Bolan, N. S.; Robson, A. D.; Barrow, N. J. Effects of vesicular-arbuscular mycorrhiza on the availability of iron phosphates to plants. Plant Soil 1987, 99 (2-3), 401–410; DOI 10.1007/BF02370885.

794 795 796

(82) Smolders, A. J. P.; Lamers, L. P. M.; Lucassen, E. C. H. E. T.; Van Der Velde, G.; Roelofs, J. G. M. Internal eutrophication: How it works and what to do about it—a review. Chemistry and Ecology 2006, 22 (2), 93–111; DOI 10.1080/02757540600579730.

797 798

(83) Cardoso, I.; Kuyper, T. Mycorrhizas and tropical soil fertility. Agriculture, Ecosystems & Environment 2006, 116 (1-2), 72–84; DOI 10.1016/j.agee.2006.03.011.

799 800 801

(84) Geelhoed, J. S.; Van Riemsdijk, W. H.; Findenegg, G. R. Simulation of the effect of citrate exudation from roots on the plant availability of phosphate adsorbed on goethite. Eur J Soil Science 1999, 50 (3), 379–390; DOI 10.1046/j.1365-2389.1999.00251.x.

802 803 804

(85) Gerke, J.; Römer, W.; Beissner, L. The quantitative effect of chemical phosphate mobilization by carboxylate anions on P uptake by a single root. II. The importance of soil and plant parameters for uptake of mobilized P. J. Plant Nutr. Soil Sci. 2000, 163 (2), 213–219.

805 806 807

(86) Gahoonia, T. S.; Claassen, N.; Jungk, A. Mobilization of phosphate in different soils by ryegrass supplied with ammonium or nitrate. Plant Soil 1992, 140 (2), 241–248; DOI 10.1007/BF00010600.

808 809

(87) Dakora, F. D.; Phillips, D. A. Root exudates as mediators of mineral acquisition in lownutrient environments. Plant Soil 2002, 245 (1), 35–47; DOI 10.1023/A:1020809400075.

810 811

(88) Gardner, W. K.; Barber, D. A.; Parbery, D. G. The acquisition of phosphorus byLupinus albus L. Plant Soil 1983, 70 (1), 107–124; DOI 10.1007/BF02374754.

812 813 814

(89) Altomare, C.; Norvell, W. A.; Bjorkman, T.; Harman, G. E. Solubilization of phosphates and micronutrients by the plant-growth-promoting and biocontrol fungus Trichoderma harzianum Rifai 1295-22. Applied and Environmental Microbiology 1999, 65 (7), 2926–2933.

815 816 817

(90) Reid, R. K.; Reid, C. P. P.; Szaniszlo, P. J. Effects of synthetic and microbially produced chelates on the diffusion of iron and phosphorus to a simulated root in soil. Biol Fert Soils 1985, 1 (1), 45–52; DOI 10.1007/BF00710970.

818 819 820

(91) Lobartini, J. C.; Tan, K. H.; Pape, C. Dissolution of aluminum and iron phosphate by humic acids. Communications in Soil Science and Plant Analysis 1998, 29 (5-6), 535–544; DOI 10.1080/00103629809369965.

821 822 823

(92) Lovley, D. R.; Coates, J. D.; Blunt-Harris, E. L.; Phillips, E. J. P.; Woodward, J. C. Humic substances as electron acceptors for microbial respiration. Nature 1996, 382 (6590), 445–448; DOI 10.1038/382445a0.

824 825 826 827

(93) Lovley, D. R.; Fraga, J. L.; Blunt-Harris, E. L.; La Hayes; Phillips, E. J.; Coates, J. D. Humic substances as a mediator for microbially catalyzed metal reduction. Acta Hydrochemica et Hydrobiologica 1998, 26 (3), 152–157; DOI 10.1002/(SICI)1521-401X(199805)26:33.0.CO;2-D.

ACS Paragon Plus Environment

34

Page 35 of 44

Environmental Science & Technology

828 829 830

(94) Peretyazhko, T.; Sposito, G. Iron(III) reduction and phosphorous solubilization in humid tropical forest soils. Geochimica et Cosmochimica Acta 2005, 69 (14), 3643–3652; DOI 10.1016/j.gca.2005.03.045.

831 832

(95) Cornell, R. M.; Schwertmann, U. The iron oxides: Structure, properties, reactions, occurrences, and uses, 2nd ed.; Wiley-VCH: Weinheim, 2003.

833 834 835

(96) Peña-Méndez, E. M.; Havel, J.; Patočka, J. Humic substances–compounds of still unknown structure: applications in agriculture, industry, environment, and biomedicine. J. Appl. Biomed 2005, 3 (1), 13–24.

836 837

(97) Smith, S.; Takacs, I.; Murthy, S.; Daigger, G. T.; Szabo, A. Phosphate complexation model and its implications for chemical phosphorus removal. water environ res 2008, 80 (5), 428–438.

838 839 840

(98) Luedecke, C.; Hermanowicz, S. W.; Jenkins, D. Precipitation of ferric phosphate in activated-sludge - A chemical model and its verification. Water Science and Technology 1989, 21 (4-5), 325–337.

841 842 843

(99) Huang, X. L.; Shenker, M. Water-Soluble and Solid-State Speciation of Phosphorus in Stabilized Sewage Sludge. Journal of Environment Quality 2004, 33 (5), 1895; DOI 10.2134/jeq2004.1895.

844 845

(100) Frossard, E.; Bauer, J. P.; Lothe, F. Evidence of vivianite in FeSO4-flocculated sludges. Water research 1997, 31 (10), 2449–2454; DOI 10.1016/S0043-1354(97)00101-2.

846 847 848

(101) Parfitt, R. L.; Atkinson, R. J.; Smart, R. S. The Mechanism of Phosphate Fixation by Iron Oxides1. Soil Science Society of America Journal 1975, 39 (5), 837; DOI 10.2136/sssaj1975.03615995003900050017x.

849 850

(102) McLaughlin, J. R.; Ryden, J. C.; Syers, J. K. Sorption of inorganic-phosphate by iron containing and aluminum containing components. Journal of Soil Science 1981, 32 (3), 365–377.

851 852 853

(103) Wang, X.; Liu, F.; Tan, W.; Li, W.; Feng, X.; Sparks, D. L. Characteristics of Phosphate Adsorption-Desorption Onto Ferrihydrite. Soil Science 2013, 178 (1), 1–11; DOI 10.1097/SS.0b013e31828683f8.

854 855 856

(104) Barron, V.; Herruzo, M.; Torrent, J. Phosphate Adsorption by Aluminous Hematites of Different Shapes. Soil Science Society of America Journal 1988, 52 (3), 647; DOI 10.2136/sssaj1988.03615995005200030009x.

857 858 859

(105) Guzman, G.; Alcantara, E.; Barron, V.; Torrent, J. Phytoavailability of phosphate adsorbed on ferrihydrite, hematite, and goethite. Plant Soil 1994, 159 (2), 219–225; DOI 10.1007/BF00009284.

860 861 862

(106) Borggaard, O. K. Effect of Surface Area and Mineralogy of Iron Oxides on Their Surface Charge and Anion-Adsorption Properties. Clays and Clay Minerals 1983, 31 (3), 230–232; DOI 10.1346/CCMN.1983.0310309.

ACS Paragon Plus Environment

35

Environmental Science & Technology

Page 36 of 44

863 864 865

(107) Torrent, J.; Barrón, V.; Schwertmann, U. Phosphate Adsorption and Desorption by Goethites Differing in Crystal Morphology. Soil Science Society of America Journal 1990, 54 (4), 1007; DOI 10.2136/sssaj1990.03615995005400040012x.

866 867 868

(108) Cabrera, F.; Arambarri, P. d.; Madrid, L.; Toga, C. G. Desorption of phosphate from iron oxides in relation to equilibrium pH and porosity. Geoderma 1981, 26 (3), 203–216; DOI 10.1016/0016-7061(81)90016-1.

869 870 871

(109) Arai, Y.; Sparks, D. L. ATR‐FTIR Spectroscopic Investigation on Phosphate Adsorption Mechanisms at the Ferrihydrite‐Water Interface. Journal of Colloid and Interface Science 2001, 241 (2), 317–326; DOI 10.1006/jcis.2001.7773.

872 873 874 875

(110) Abdala, D. B.; Northrup, P. A.; Arai, Y.; Sparks, D. L. Surface loading effects on orthophosphate surface complexation at the goethite/water interface as examined by extended Xray Absorption Fine Structure (EXAFS) spectroscopy. Journal of Colloid and Interface Science 2015, 437, 297–303; DOI 10.1016/j.jcis.2014.09.057.

876 877

(111) Parfitt, R. L.; Atkinson, R. J. Phosphate adsorption on goethite (α-FeOOOH). Nature 1976, 264 (5588), 740–742; DOI 10.1038/264740a0.

878 879 880

(112) Peak; F.; Sparks. An in Situ ATR-FTIR Investigation of Sulfate Bonding Mechanisms on Goethite. Journal of Colloid and Interface Science 1999, 218 (1), 289–299; DOI 10.1006/jcis.1999.6405.

881 882 883

(113) Li, S. Distinguishing Adsorption and Surface Precipitation of Phosphate on Goethite (alpha-FeOOH). Journal of Colloid and Interface Science 2000, 230 (1), 12–21; DOI 10.1006/jcis.2000.7072.

884 885 886

(114) Goldberg, S.; Sposito, G. On the mechanism of specific phosphate adsorption by hydroxylated mineral surfaces: A review. Communications in Soil Science and Plant Analysis 1985, 16 (8), 801–821; DOI 10.1080/00103628509367646.

887 888

(115) Sparks, D. L. Sorption Phenomena on Soils. Environmental Soil Chemistry; Elsevier, 2003; pp 133–186.

889 890

(116) Davis, J. A.; Hayes, K. F., Eds. Geochemical Processes at Mineral Surfaces; ACS symposium series; American Chemical Society: Washington D.C., 1987.

891 892 893

(117) Jonasson, R. G.; M., R. R.; Giuliacci, M. E.; Tazaki, K. Surface reactions of goethite with phosphate. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 1988, 84 (7), 2311; DOI 10.1039/F19888402311.

894 895 896

(118) Wen, Z.; Zhang, Y.; Dai, C. Removal of phosphate from aqueous solution using nanoscale zerovalent iron (nZVI). Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014, 457, 433–440; DOI 10.1016/j.colsurfa.2014.06.017.

897 898

(119) Moore, P. B. Crystal chemistry of the basic iron phosphates. The American Mineralogist 1970, 55.

ACS Paragon Plus Environment

36

Page 37 of 44

Environmental Science & Technology

899 900 901

(120) Stoch, P.; Szczerba, W.; Bodnar, W.; Ciecinska, M.; Stoch, A.; Burkel, E. Structural properties of iron-phosphate glasses: spectroscopic studies and ab initio simulations. Physical chemistry chemical physics : PCCP 2014, 16 (37), 19917–19927; DOI 10.1039/C4CP03113J.

902 903

(121) Moore, P. B. Basic ferric phosphates: a crystallochemical principle. Science (New York, N.Y.) 1969, 164 (3883), 1063–1064; DOI 10.1126/science.164.3883.1063.

904 905

(122) Bache, B. W. Aluminum And Iron Phosphate Studies Relating To Soils. Journal of Soil Science 1964, 15 (1), 110–116; DOI 10.1111/j.1365-2389.1964.tb00250.x.

906 907

(123) Roldan, R.; Barron, V.; Torrent, J. Experimental alteration of vivianite to lepidocrocite in a calcareous medium. clay miner 2002, 37 (4), 709–718; DOI 10.1180/0009855023740072.

908 909 910

(124) Ming, H.; Yu, H.; Wei, H.; Liu, Y.; Li, H.; He, X.; Huang, H.; Kang, Z. Composition and morphology control of Fex(PO4)y(OH)z·nH2O microcrystals. Crystal Research and Technology 2011, 46 (7), 711–717; DOI 10.1002/crat.201100100.

911 912 913

(125) Lente, G.; Magalhães, M. E. A.; Fábián, I. Kinetics and Mechanism of Complex Formation Reactions in the Iron(III)−Phosphate Ion System at Large Iron(III) Excess. Formation of a Tetranuclear Complex. Inorganic Chemistry 2000, 39 (9), 1950–1954; DOI 10.1021/ic991017p.

914 915

(126) Nriagu, J. O.; Dell, C. I. Diagenetic formation of iron phosphates in recent lake sediments. American Mineralogist 1974, 59, 934–946.

916 917

(127) WEF. Nutrient removal; WEF manual of practice no. 34; McGraw-Hill; WEF Press: New York, Alexandria, Va., 2011.

918 919 920

(128) Thomas, A. E. Phosphat-Elimination in der Belebtschlammanlage von Männedorf und Phosphat-Fixation in See- und Klärschlamm. Vierteljahrschr. Naturforsch. Ges. Zürich 1965, 110, 419–434.

921 922

(129) Wendt von, H. Die Kinetik typischer Hydrolysereaktionen von mehrwertigen Kationen. Chimia 1973 (27), 575–588.

923 924 925

(130) Recht, H. L.; Ghassemi, M. Kinetics and mechanism of precipitation and nature of the precipitate obtained in phosphate removal from wastewater using aluminum (III) and iron (III) salts; Water Pollution Control Research Series; University of Michigan, 1970.

926 927 928

(131) Szabó, A.; Takács, I.; Murthy, S.; Daigger, G. T.; Licskó, I.; Smith, S. Significance of Design and Operational Variables in Chemical Phosphorus Removal. water environ res 2008, 80 (5), 407–416; DOI 10.2175/106143008X268498.

929 930

(132) Stumm, W.; Morgan, J. J. Aquatic chemistry: Chemical equilibria and rates in natural waters, 3rd ed.; Environmental science and technology; Wiley: New York, 1996.

931 932

(133) Singer, P. C.; Stumm, W. Oxygenation of ferrous iron: The rate determining step in the formation of acidic mine drainage; Water Pollution Control Research Series, 1969.

933 934

(134) Ghassemi, M.; Recht, H. L. Phosphate Precipitation with Ferrous Iron; Water Pollution Control Research Series, 1971.

ACS Paragon Plus Environment

37

Environmental Science & Technology

Page 38 of 44

935 936

(135) Theis, T. L.; Singer, P. C. Complexation of iron(II) by organic matter and its effect on iron(II) oxygenation. Environ. Sci. Technol. 1974, 8 (6), 569–573; DOI 10.1021/es60091a008.

937 938 939 940

(136) Pham, A. N.; Rose, A. L.; Feltz, A. J.; Waite, T. D. The effect of dissolved natural organic matter on the rate of removal of ferrous iron in fresh waters. In Natural Organic Material Research: Innovations and Applications for Drinking Water; Newcombe, G., Ho, L., Eds.; IWA Publishing, 2004; pp 213–219.

941 942 943

(137) Thistleton, J.; Clark, T.; Pearce, P.; Parsons, S. A. Mechanisms of Chemical Phosphorus Removal. Process Safety and Environmental Protection 2001, 79 (6), 339–344; DOI 10.1205/095758201753373104.

944 945

(138) Nielsen, P. The significance of microbial Fe(III) reduction in the activated sludge process. Water Science and Technology 1996, 34 (5-6), 129–136; DOI 10.1016/0273-1223(96)00638-5.

946 947 948

(139) Rasmussen, H.; Nielsen, P. Iron reduction in activated sludge measured with different extraction techniques. Water research 1996, 30 (3), 551–558; DOI 10.1016/0043-1354(95)002030.

949 950 951

(140) Leckie, J.; Stumm, W. Phosphate precipitation. In Water Quality Improvement By Physical and Chemical Processes; Gloyna, E. F., Eckenfelder, W. W., Eds.; University of Texas Press: Austin, 1970; pp 237–249.

952 953

(141) Svanks, K. Precipitation of Phosphates from Water with Ferrous Salts; United States. Office of Water Resources Research; Ohio State University. Water Resources Center, 1971.

954 955 956 957

(142) Rasmussen, H.; Bruus, J. H.; Keiding, K.; Nielsen, P. H. Observations on dewaterability and physical, chemical and microbiological changes in anaerobically stored activated sludge from a nutrient removal plant. Water research 1994, 28 (2), 417–425; DOI 10.1016/00431354(94)90279-8.

958 959

(143) Singer, P. C. Anaerobic control of phosphate by ferrous iron: Anaerobic control of phosphate by ferrous iron. Journal Water Pollution Control Federation 1972, 44 (4), 663-&.

960 961 962

(144) Nriagu, J. O. Stability of vivianite and ion-pair formation in the system fe3(PO4)2H3PO4H3PO4-H2o. Geochimica et Cosmochimica Acta 1972, 36 (4), 459–470; DOI 10.1016/0016-7037(72)90035-X.

963 964

(145) Froelich, P. N. Kinetic control of dissolved phosphate in natural rivers and estuaries - a primer on the phosphate buffer mechanism. Limnol. Oceangr. 1988, 33 (4, 2), 649–668.

965 966

(146) Sundareshwar, P. V.; Morris, J. T. Phosphorus sorption characteristics of intertidal marsh sediments along an estuarine salinity gradient. Limnol. Oceangr. 1999, 44 (7), 1693–1701.

967 968

(147) Schulz, H. D.; Zabel, M. Marine geochemistry, 2nd rev., updated and extended ed.; Springer: Berlin, New York, 2006.

969 970

(148) Caraco, N. F.; Cole, J. J.; Likens, G. E. Evidence for sulphate-controlled phosphate release from sediments of aquatic systems. Nature 1989 (341), 316–318.

ACS Paragon Plus Environment

38

Page 39 of 44

Environmental Science & Technology

971 972

(149) Lovley, D. R. Microbial Fe(III) reduction in subsurface environments. FEMS Microbiology Reviews 1997, 20 (3-4), 305–313; DOI 10.1016/S0168-6445(97)00013-2.

973 974

(150) Lovley, D. R.; Holmes, D. E.; Nevin, K. P. Dissimilatory Fe(III) and Mn(IV) Reduction. Microbiol Reviews 1991, 49, 219–286; DOI 10.1016/S0065-2911(04)49005-5.

975 976 977

(151) Weber, K. A.; Achenbach, L. A.; Coates, J. D. Microorganisms pumping iron: anaerobic microbial iron oxidation and reduction. Nature reviews. Microbiology 2006, 4 (10), 752–764; DOI 10.1038/nrmicro1490.

978 979 980

(152) Patrick, W. H.; Gotoh, S.; Williams, B. G. Strengite dissolution in flooded soils and sediments. Science (New York, N.Y.) 1973, 179 (4073), 564–565; DOI 10.1126/science.179.4073.564.

981 982 983

(153) Heiberg, L.; Koch, C.B. Kjaergaard, Charlotte; J. Henning S.; Hansen, H. B. C. Vivianite precipitation and phosphate sorption following iron reduction in anoxic soils. J. Environ. Qual. 2012, 41 (3), 938–949; DOI 10.2134/jeq2011.0067.

984 985 986 987

(154) Borch, T.; Fendorf, S. Phosphate Interactions with Iron (Hydr)oxides: Mineralization Pathways and Phosphorus Retention upon Bioreduction. Adsorption of Metals by Geomedia II: Variables, Mechanisms, and Model Applications; Developments in Earth and Environmental Sciences; Elsevier, 2007; pp 321–348.

988 989 990

(155) Larsen, O.; Postma, D. Kinetics of reductive bulk dissolution of lepidocrocite, ferrihydrite, and goethite. Geochimica et Cosmochimica Acta 2001, 65 (9), 1367–1379; DOI 10.1016/S00167037(00)00623-2.

991 992 993

(156) Bonneville, S.; Behrends, T.; van Cappellen, P. Solubility and dissimilatory reduction kinetics of iron(III) oxyhydroxides: A linear free energy relationship. Geochimica et Cosmochimica Acta 2009, 73 (18), 5273–5282; DOI 10.1016/j.gca.2009.06.006.

994 995

(157) Munch, J. C.; Ottow, J. C. G. Reductive transformation mechanism of ferric oxides in hydromorphic soils. Ecological Bulletins 1983, 383–394.

996 997 998

(158) Cheng, X.; Chen, B.; Cui, Y.; Sun, D.; Wang, X. Iron(III) reduction-induced phosphate precipitation during anaerobic digestion of waste activated sludge. Separation and Purification Technology 2015, 143, 6–11; DOI 10.1016/j.seppur.2015.01.002.

999 1000

(159) Fortin, D.; Langley, S. Formation and occurrence of biogenic iron-rich minerals. EarthScience Reviews 2005, 72 (1-2), 1–19; DOI 10.1016/j.earscirev.2005.03.002.

1001 1002 1003

(160) Rentz, J. A.; Turner, I. P.; Ullman, J. L. Removal of phosphorus from solution using biogenic iron oxides. Water research 2009, 43 (7), 2029–2035; DOI 10.1016/j.watres.2009.02.021.

1004 1005 1006

(161) Posth, N. R.; Canfield, D. E.; Kappler, A. Biogenic Fe(III) minerals: From formation to diagenesis and preservation in the rock record. Earth-Science Reviews 2014, 135, 103–121; DOI 10.1016/j.earscirev.2014.03.012.

ACS Paragon Plus Environment

39

Environmental Science & Technology

Page 40 of 44

1007 1008 1009

(162) Piepenbrock, A.; Behrens, S.; Kappler, A. Comparison of Humic Substance- and Fe(III)Reducing Microbial Communities in Anoxic Aquifers. Geomicrobiology Journal 2014, 31 (10), 917–928; DOI 10.1080/01490451.2014.911994.

1010 1011 1012

(163) Piepenbrock, A.; Schröder, C.; Kappler, A. Electron transfer from humic substances to biogenic and abiogenic Fe(III) oxyhydroxide minerals. Environ. Sci. Technol. 2014, 48 (3), 1656– 1664; DOI 10.1021/es404497h.

1013 1014

(164) Stevenson, F. J. Humus chemistry: Genesis, composition, reactions, 2nd ed; Wiley: New York, 1994.

1015 1016 1017

(165) Poulton, S. W.; Krom, M. D.; Raiswell, R. A revised scheme for the reactivity of iron (oxyhydr)oxide minerals towards dissolved sulfide. Geochimica et Cosmochimica Acta 2004, 68 (18), 3703–3715; DOI 10.1016/j.gca.2004.03.012.

1018 1019 1020

(166) Morse, J.; Millero, F. J.; Cornwell, J.; Rickard, D. The chemistry of the hydrogen sulfide and iron sulfide systems in natural waters. Earth-Science Reviews 1987, 24 (1), 1–42; DOI 10.1016/0012-8252(87)90046-8.

1021 1022

(167) Canfield, D. E. Reactive iron in marine sediments. Geochimica et Cosmochimica Acta 1989, 53 (3), 619–632; DOI 10.1016/0016-7037(89)90005-7.

1023 1024 1025

(168) Biber, M. V.; dos Santos Afonso, M.; Stumm, W. The coordination chemistry of weathering: IV. Inhibition of the dissolution of oxide minerals. Geochimica et Cosmochimica Acta 1994, 58 (9), 1999–2010; DOI 10.1016/0016-7037(94)90280-1.

1026 1027 1028

(169) Stumm, W. Reactivity at the mineral-water interface: dissolution and inhibition. Colloids and Surfaces A: Physicochemical and Engineering Aspects 1997, 120 (1-3), 143–166; DOI 10.1016/S0927-7757(96)03866-6.

1029 1030

(170) Yao, W.; Millero, F. J. Oxidation of hydrogen sulfide by hydrous Fe(III) oxides in seawater. Marine Chemistry 1996, 52 (1), 1–16; DOI 10.1016/0304-4203(95)00072-0.

1031 1032 1033 1034

(171) Mejia Likosova, E.; Keller, J.; Rozendal, R. A.; Poussade, Y.; Freguia, S. Understanding colloidal FeSx formation from iron phosphate precipitation sludge for optimal phosphorus recovery. Journal of Colloid and Interface Science 2013, 403, 16–21; DOI 10.1016/j.jcis.2013.04.001.

1035 1036 1037

(172) Kato, F.; Kitakoji, H.; Oshita, K.; Takaoka, M.; Takeda, N.; Matsumoto, T. Extraction efficiency of phosphate from pre-coagulated sludge with NaHS. Water Science and Technology 2006, 54 (5), 119; DOI 10.2166/wst.2006.554.

1038 1039

(173) Suschka, J.; Machnicka, A.; Poplawski, S. Phosphate recovery from iron phosphate sludge. Environmental technology 2001, 22, 1295–1301.

1040 1041 1042

(174) Miot, J.; Benzerara, K.; Morin, G.; Bernard, S.; Beyssac, O.; Larquet, E.; Kappler, A.; Guyot, F. Transformation of vivianite by anaerobic nitrate-reducing iron-oxidizing bacteria. Geobiology 2009, 7 (3), 373–384; DOI 10.1111/j.1472-4669.2009.00203.x.

ACS Paragon Plus Environment

40

Page 41 of 44

Environmental Science & Technology

1043 1044 1045

(175) Eynard, A.; Campillo, M. C.; Barron, V.; Torrent, J. Use of vivianite (Fe3(PO4)2.8H2O) to prevent iron chlorosis in calcareous soils. Fertilizer Research 1992, 31 (1), 61–67; DOI 10.1007/BF01064228.

1046 1047

(176) Diaz, I.; Barron, V.; Del Campillo, M. C.; Torrent, J. Vivianite (ferrous phosphate) alleviates iron chlorosis in grapevine. VITIS 2009, 48 (3), 107–113.

1048 1049 1050

(177) van den Brand, T. P. H.; Roest, K.; Brdjanovic, D.; Chen, G. H.; van Loosdrecht, M. C. M. Influence of acetate and propionate on sulphate-reducing bacteria activity. Journal of applied microbiology 2014, 117 (6), 1839–1847; DOI 10.1111/jam.12661.

1051 1052

(178) Chen, Y.; Cheng, J. J.; Creamer, K. S. Inhibition of anaerobic digestion process: A review. Bioresour. Technol. 2008, 99 (10), 4044–4064; DOI 10.1016/j.biortech.2007.01.057.

1053 1054 1055

(179) Tchobanoglous, G.; Burton, F. L.; Stensel, H. D. Wastewater engineering: Treatment and reuse, 5th ed.; McGraw-Hill Higher Education; McGraw-Hill [distributor]: New York, London, 2013.

1056 1057 1058

(180) Frimmel, F. Basic characterization of reference NOM from Central Europe - Similarities and differences. Environment International 1999, 25 (2-3), 191–207; DOI 10.1016/S01604120(98)00116-0.

1059 1060

(181) Riffaldi, R.; Sartori, F.; Levi-Minzi, R. Humic substances in sewage sludges. Environmental Pollution 1982, 3 (2), 139–146; DOI 10.1016/0143-148X(82)90048-9.

1061 1062 1063

(182) Carliell-Marquet, C.; Oikonomidis, I.; Wheatley, A.; Smith, J. Inorganic profiles of chemical phosphorus removal sludge. Proceedings of the ICE - Water Management 2010, 163 (2), 65–77; DOI 10.1680/wama.2010.163.2.65.

1064 1065 1066

(183) Ito, A., Umita, T., Aizawa, J., Takachi, T., & Morinaga, K. Removal of heavy metals from anaerobically digested sewage sludge by a new chemical method using ferric sulfate. Water research 2000, 34 (3), 751–758; DOI 10.1016/S0043-1354(99)00215-8.

1067 1068 1069

(184) Karlsson, T.; Persson, P. Complexes with aquatic organic matter suppress hydrolysis and precipitation of Fe(III). Chemical Geology 2012, 322-323, 19–27; DOI 10.1016/j.chemgeo.2012.06.003.

1070 1071 1072

(185) Schwertmann, U.; Wagner, F.; Knicker, H. Ferrihydrite–Humic Associations: Magnetic Hyperfine Interactions. Soil Science Society of America Journal 2005, 69 (4), 1009; DOI 10.2136/sssaj2004.0274.

1073 1074 1075

(186) Senesi, N.; Sposito, G.; Holtzclaw, K. M.; Bradford, G. R. Chemical Properties of MetalHumic Acid Fractions of a Sewage Sludge-Amended Aridisol. Journal of Environment Quality 1989, 18 (2), 186; DOI 10.2134/jeq1989.00472425001800020010x.

1076 1077 1078

(187) Karlsson, T.; Persson, P. Coordination chemistry and hydrolysis of Fe(III) in a peat humic acid studied by X-ray absorption spectroscopy. Geochimica et Cosmochimica Acta 2010, 74 (1), 30–40; DOI 10.1016/j.gca.2009.09.023.

ACS Paragon Plus Environment

41

Environmental Science & Technology

Page 42 of 44

1079 1080 1081

(188) Morris, A. J.; Hesterberg, D. L. Iron(III) Coordination and Phosphate Sorption in Peat Reacted with Ferric or Ferrous Iron. Soil Science Society of America Journal 2012, 76 (1), 101; DOI 10.2136/sssaj2011.0097.

1082 1083 1084

(189) Mikutta, C.; Kretzschmar, R. Spectroscopic Evidence for Ternary Complex Formation between Arsenate and Ferric Iron Complexes of Humic Substances. Environ. Sci. Technol. 2011, 45 (22), 9550–9557; DOI 10.1021/es202300w.

1085 1086 1087 1088

(190) Sjöstedt, C.; Persson, I.; Hesterberg, D.; Kleja, D. B.; Borg, H.; Gustafsson, J. P. Iron speciation in soft-water lakes and soils as determined by EXAFS spectroscopy and geochemical modelling. Geochimica et Cosmochimica Acta 2013, 105, 172–186; DOI 10.1016/j.gca.2012.11.035.

1089 1090 1091

(191) Puccia, V.; Luengo, C.; Avena, M. Phosphate desorption kinetics from goethite as induced by arsenate. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009, 348 (1-3), 221–227; DOI 10.1016/j.colsurfa.2009.07.026.

1092 1093 1094

(192) Antelo, J.; Arce, F.; Avena, M.; Fiol, S.; López, R.; Macías, F. Adsorption of a soil humic acid at the surface of goethite and its competitive interaction with phosphate. Geoderma 2007, 138 (1-2), 12–19; DOI 10.1016/j.geoderma.2006.10.011.

1095 1096 1097

(193) Fu, Z.; Wu, F.; Song, K.; Lin, Y.; Bai, Y.; Zhu, Y.; Giesy, J. P. Competitive interaction between soil-derived humic acid and phosphate on goethite. Applied Geochemistry 2013, 36, 125– 131; DOI 10.1016/j.apgeochem.2013.05.015.

1098 1099

(194) Sibanda, H. M.; Young, S. D. Competitive Adsorption of Humus Acids and Phosphate on Goethite, Gibbsite and 2 Tropical Soils. Journal of Soil Science 1986, 37 (2), 197–204.

1100 1101 1102

(195) Gerke, J.; Hermann, R. Adsorption of Orthophosphate to Humic-Fe-Complexes and to Amorphous Fe-Oxide. Zeitschrift für Pflanzenernährung und Bodenkunde 1992, 155 (3), 233– 236; DOI 10.1002/jpln.19921550313.

1103 1104 1105

(196) Gerke, J. Humic (Organic Matter)-Al(Fe)-Phosphate Complexes: An Underestimated Phosphate Form in Soils and Source of Plant-Available Phosphate. Soil Science 2010, 175 (9), 417–425; DOI 10.1097/SS.0b013e3181f1b4dd.

1106 1107 1108

(197) Borggaard, O. K.; Raben-Lange, B.; Gimsing, A. L.; Strobel, B. W. Influence of humic substances on phosphate adsorption by aluminium and iron oxides. Geoderma 2005, 127 (3-4), 270–279; DOI 10.1016/j.geoderma.2004.12.011.

1109 1110

(198) Weir, C. C.; Soper, R. J. Interaction of phosphates with ferric organic complexes. Can. J. Soil. Sci. 1963, 43 (2), 393–399; DOI 10.4141/cjss63-046.

1111 1112 1113 1114

(199) Sorkina, T. A.; Polyakov, A. Y.; Kulikova, N. A.; Goldt, A. E.; Philippova, O. I.; Aseeva, A. A.; Veligzhanin, A. A.; Zubavichus, Y. V.; Pankratov, D. A.; Goodilin, E. A.; Perminova, I. V. Nature-inspired soluble iron-rich humic compounds: new look at the structure and properties. J Soils Sediments 2014, 14 (2), 261–268; DOI 10.1007/s11368-013-0688-0.

1115 1116

(200) Schwertmann, U. Inhibitory Effect of Soil Organic Matter on the Crystallization of Amorphous Ferric Hydroxide. Nature 1966, 212 (5062), 645–646; DOI 10.1038/212645b0.

ACS Paragon Plus Environment

42

Page 43 of 44

Environmental Science & Technology

1117 1118 1119

(201) Schwertmann, U. Influence of various simple organic anions on formation of goethite and hematite from amorphous ferric hydroxide. Geoderma 1970, 3 (3), 207–214; DOI 10.1016/00167061(70)90020-0.

1120 1121 1122

(202) Gerke, J. Phosphate adsorption by humic/Fe-oxide mixtures aged at pH 4 and 7 and by poorly ordered Fe-oxide. Geoderma 1993, 59 (1-4), 279–288; DOI 10.1016/0016-7061(93)90074U.

1123 1124 1125

(203) Borggaard, O. K.; Jorgensen, S. S.; Moberg, J. P.; Rabenlange, B. Influence of Organic Matter on Phosphate Adsorption by Aluminum and Iron Oxides in Sandy Soils. Journal of Soil Science 1990, 41 (3), 443–449.

1126 1127 1128

(204) Pédrot, M.; Le Boudec, A.; Davranche, M.; Dia, A.; Henin, O. How does organic matter constrain the nature, size and availability of Fe nanoparticles for biological reduction? Journal of Colloid and Interface Science 2011, 359 (1), 75–85; DOI 10.1016/j.jcis.2011.03.067.

1129 1130 1131

(205) Catrouillet, C.; Davranche, M.; Dia, A.; Bouhnik-Le Coz, M.; Marsac, R.; Pourret, O.; Gruau, G. Geochemical modeling of Fe(II) binding to humic and fulvic acids. Chemical Geology 2014, 372, 109–118; DOI 10.1016/j.chemgeo.2014.02.019.

1132 1133 1134

(206) Kappler, A.; Benz, M.; Schink, B.; Brune, A. Electron shuttling via humic acids in microbial iron(III) reduction in a freshwater sediment. FEMS Microbiology Ecology 2004, 47 (1), 85–92; DOI 10.1016/S0168-6496(03)00245-9.

1135 1136 1137

(207) Klüpfel, L.; Piepenbrock, A.; Kappler, A.; Sander, M. Humic substances as fully regenerable electron acceptors in recurrently anoxic environments. Nature Geosci 2014, 7 (3), 195–200; DOI 10.1038/ngeo2084.

1138 1139 1140

(208) Stumm, W.; Sigg, L.; Sulzberger, B. Chemistry of the solid-water interface: processes at the mineral-water and particle-water in natural systems; A Wiley-Intersciece publication; Wiley: New York, 1992.

1141 1142 1143 1144

(209) Yoon, S. Y.; Lee, C. G.; Park, J. A.; Kim, J. H.; Kim, S. B.; Lee, S. H.; Choi, J. W. Kinetic, equilibrium and thermodynamic studies for phosphate adsorption to magnetic iron oxide nanoparticles. Chemical Engineering Journal 2014, 236, 341–347; DOI 10.1016/j.cej.2013.09.053.

1145 1146 1147

(210) Awual, M. R.; Jyo, A.; Ihara, T.; Seko, N.; Tamada, M.; Lim, K. T. Enhanced trace phosphate removal from water by zirconium(IV) loaded fibrous adsorbent. Water research 2011, 45 (15), 4592–4600; DOI 10.1016/j.watres.2011.06.009.

1148 1149 1150

(211) Chitrakar, R.; Tezuka, S.; Sonoda, A.; Sakane, K.; Ooi, K.; Hirotsu, T. Phosphate adsorption on synthetic goethite and akaganeite. Journal of Colloid and Interface Science 2006, 298 (2), 602–608; DOI 10.1016/j.jcis.2005.12.054.

1151 1152 1153

(212) Fischer, F.; Bastian, C.; Happe, M.; Mabillard, E.; Schmidt, N. Microbial fuel cell enables phosphate recovery from digested sewage sludge as struvite. Bioresour. Technol. 2011, 102 (10), 5824–5830; DOI 10.1016/j.biortech.2011.02.089.

ACS Paragon Plus Environment

43

Environmental Science & Technology

Page 44 of 44

1154 1155 1156

(213) Fischer, F.; Zufferey, G.; Sugnaux, M.; Happe, M. Microbial electrolysis cell accelerates phosphate remobilisation from iron phosphate contained in sewage sludge. Environmental science: Processes & impacts 2015, 17 (1), 90–97; DOI 10.1039/c4em00536h.

1157 1158 1159

(214) Sano, A.; Kanomata, M.; Inoue, H.; Sugiura, N.; Xu, K.-Q.; Inamori, Y. Extraction of raw sewage sludge containing iron phosphate for phosphorus recovery. Chemosphere 2012, 89 (10), 1243–1247; DOI 10.1016/j.chemosphere.2012.07.043.

1160 1161 1162 1163

(215) Maier, W.; Weidelener, A.; Krampe, J.; Rott, I. Entwicklung eines Verfahrens zur Phosphat-Rückgewinnung aus ausgefaultem Nassschlam oder entwässertem Faulschlamm als gut pflanzenverfügbares Magnesium-Ammonium-Phosphat (MAP): Schlussbericht: Teil 1: Zusammenfassung und Wertung der Ergebnisse, 2005.

1164 1165 1166

(216) Cornel, P.; Jardin, N.; Schaum, C. Möglichkeiten einer Rückgewinnung von Phosphor aus Klärschlammasche: Teil 1: Ergebnisse von Laborversuchen zur Extraktion von Phosphor. GWF Wasser 2004, 145 (9), 627–632.

1167 1168 1169 1170

(217) Biswas, B. K.; Inoue, K.; Harada, H.; Ohto, K.; Kawakita, H. Leaching of phosphorus from incinerated sewage sludge ash by means of acid extraction followed by adsorption on orange waste gel. Journal of Environmental Sciences 2009, 21 (12), 1753–1760; DOI 10.1016/S10010742(08)62484-5.

1171 1172 1173

(218) Petzet, S.; Peplinski, B.; Cornel, P. On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both. Water research 2012, 46 (12), 3769–3780; DOI 10.1016/j.watres.2012.03.068.

1174 1175 1176

(219) Atienza–Martínez, M.; Gea, G.; Arauzo, J.; Kersten, S. R.; Kootstra, A. Maarten J. Phosphorus recovery from sewage sludge char ash. Biomass and Bioenergy 2014, 65, 42–50; DOI 10.1016/j.biombioe.2014.03.058.

1177 1178 1179 1180

(220) Pinnekamp, J.; Everding, W.; Gethke, K.; Montag, D.; Weinfurtner, K.; Sartorius, C.; Horn, J. von; Tettenborn; F.; Gäth, S.; Waida, C.; Fehrenbach, H.; Reinhardt, J. Phosphorrecycling – Ökologische und wirtschaftliche Bewertung verschiedener Verfahren und Entwicklung eines strategischen Verwertungskonzepts für Deutschland, 2011.

ACS Paragon Plus Environment

44