Removal Characteristics of Dissolved Organic Nitrogen and Its

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Removal characteristics of dissolved organic nitrogen and its bioavailable portion in post-denitrifying biofilter: effect of C/N ratio Haidong Hu, Kewei Liao, Jinju Geng, Ke Xu, Hui Huang, Jinfeng Wang, and Hong-qiang Ren Environ. Sci. Technol., Just Accepted Manuscript • Publication Date (Web): 19 Dec 2017 Downloaded from http://pubs.acs.org on December 19, 2017

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Environmental Science & Technology

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Removal Characteristics of Dissolved Organic Nitrogen and its Bioavailable

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Portion in Post-denitrifying Biofilter: Effect of C/N Ratio

3 4 5 6 7

Haidong Hu, Kewei Liao, Jinju Geng, Ke Xu, Hui Huang, Jinfeng Wang, Hongqiang Ren*

8 9 10 11 12 13

State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment,

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Nanjing University, Nanjing 210023, Jiangsu, PR China

15 16 17 18

*Corresponding author.

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Tel.: +86 25 89680512; fax: +86 25 89680569.

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E-mail address: [email protected] (H. Hu); [email protected] (H. Ren).

21

Notes

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The authors declare no competing financial interest.

1

ACS Paragon Plus Environment


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ABSTRACT: Addition of external carbon sources to post-denitrification biofilters (DNFs) is

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frequently used in municipal wastewater treatment plants to enhance dissolved inorganic nitrogen

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removal. However, little is known about its influence on the removal of dissolved organic nitrogen

26

(DON). This study investigated the effect of the carbon-to-nitrogen (C/N) ratio (3, 4, 5 and 6) on

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the removal characteristics of DON and bioavailable DON (ABDON) in the pilot-scale DNFs

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treating real secondary effluent. Results showed that DNFs effluent DON accounted for 31.2−39.8%

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of the effluent total nitrogen. The maximum effluent DON and ABDON concentrations were both

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occurred in DNF operated at a C/N ratio of 3. There was no significant difference in effluent DON

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concentrations in DNFs at C/N ratios of 4, 5, and 6; however, effluent ABDON and DON

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bioavailability significantly decreased with C/N ratios (p ˂ 0.05, t-test). According to the chemical

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composition analysis, effluent DON at high C/N ratios tend to contain less %molecular weight ˂1

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kDa nitrogenous organic compounds and proteins/amino sugars-like nitrogenous organic formulas,

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which is likely responsible for its low bioavailability. Overall, this study indicates the benefit of a

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high C/N ratio during the DNF process in terms of controlling the DON forms that readily stimulate

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algal growth.

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INTRODUCTION

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The effluent discharged from municipal wastewater treatment plants (MWWTPs) is an

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important source of nitrogen loading to aquatic environments and thus contributes to

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eutrophication.1 With stricter effluent total nitrogen permit limits becoming more common, many

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existing MWWTPs are facing the need to upgrade.2 Due to the benefits of the small footprint and

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high efficiency, post-denitrification biofilters (DNFs) are widely used as a practical technology for

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tertiary nitrogen removal in MWWTPs.3,4 In this process, oxidized nitrogen is denitrified to

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nitrogen gas under anoxic conditions, with organic substrates as the electron donor.5

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Effluent nitrogen includes both inorganic and organic nitrogen. Dissolved organic nitrogen

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(DON) has become more important as it can account for 52% and even up to 80% of the effluent

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total nitrogen in low effluent total nitrogen MWWTPs.6,7 Moreover, recent research has shown

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that a portion of DON in treated effluent can be bioavailable to natural phytoplankton and hence

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can play an important role in nitrogen cycling.8-11 Bioavailable DON (ABDON) is the component

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of DON which supports the growth of bacteria and algae.12 Because of the importance of DON in

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MWWTPs addressing low effluent total nitrogen concentration goals, understanding the removal

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characteristics of DON and ABDON in the DNF is of great interest. So far, most research has

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focused on the performance of DNF for the removal of dissolved inorganic nitrogen, whereas little

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is known about the DON and ABDON.13-17

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Previous research suggests that the bioavailability of DON (ABDON/DON) is related to the

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chemical composition of DON.12,18 Eom et al.19 fractionated the effluent-derived DON into

3



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high-molecular-weight DON (>1 kDa) and low-molecular-weight DON (˂1 kDa) by ultrafiltration

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and found that low-molecular-weight DON is highly bioavailable and stimulates phytoplankton

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growth. Recently, ultra-high-resolution Fourier−transform ion cyclotron resonance mass

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spectrometry (FTICR-MS) has been used to characterize wastewater-derived DON.20,21 FTICR-MS

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can provide an unprecedented resolution of thousands of molecular formulas and, therefore, is

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capable of distinguishing between new production and degradative loss of compounds during DON

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transformation.21 Hence, this technique could possibly reveal a potential relationship between DON

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chemical molecular composition and bioavailability.22

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The availability of an electron donor, conveniently expressed in terms of the

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carbon-to-nitrogen (C/N) ratio, is the main control parameter for the DNF process.23 It has been

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observed that nitrate and/or nitrite accumulates because of insufficient carbon dosage; however, an

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overdose of the carbon source results in a waste of expensive electron sources and increases the

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effluent chemical oxygen demand (COD).15,24 Recent studies found that the C/N ratio plays an

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important role in the removal of nitrogenous organic micropollutants,25 and the production of

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soluble microbial products (SMPs)26 under anoxic conditions. SMPs, produced as a result of

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substrate metabolism and biomass decay, is an important fraction of DON.8,27 Consequently, it is

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expected that the C/N ratio affects the removal characteristics of both inorganic and organic

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nitrogen in the DNF.

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In this study, we investigated the effect of C/N ratio on the removal characteristics of DON

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and ABDON in the pilot-scale DNFs treating real secondary effluent. The chemical composition

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of DON in DNF effluent was also investigated with the purpose of facilitating a better 4


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understanding of the impact of C/N ratio on DON bioavailability (ABDON/DON). To our

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knowledge, this is the first study focusing on organic nitrogen removal during the DNF process,

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and the efforts would allow for optimization of the DNF process for both inorganic and organic

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nitrogen removal.

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MATERIALS AND METHODS

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Description of the Pilot−scale DNF. Four pilot-scale DNFs were operated in parallel at four

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different C/N ratios (3, 4, 5, and 6). Each pilot-scale DNF system consisted of three parts: a

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denitrification bed, a raw water feeding subsystem, and a backwashing subsystem (Figure S1). The

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denitrification bed was constructed as a cylinder with an inner diameter of 0.35 m and height of 3.4

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m. The bed was filled with a 0.3 m layer of pebbles and then further filled with sea sand up to 2.0 m

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in height. The media size and density of the sand were 2−3 mm and 2.54 g/cm3, respectively. DNF

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influent collected in a storage tank was pumped to the top of the filter bed. The influent used in this

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study was secondary effluent taken from the secondary settling tank of a MWWTP (an

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anaerobic-anoxic-oxic process) in Wuxi, China. The secondary effluent quality is included in Table

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1.

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Experimental Procedures and Sample Collection. The overall experiment consisted of a

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start-up period (0−70 days) followed by an operation period (71−197 days). By continuously

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operating the DNFs for two months, each DNF effluent nitrate (NO3-) became stable (Figure 1).

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Acclimatized denitrifying bacteria were thus obtained.24 The system was then maintained at the

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same operational conditions for a few more days to verify and ensure the full accomplishment of 5



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the start-up. After start-up, the influent C/N ratio was changed by changing the amount of external

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carbon source, whereas other variables were maintained as the experiment proceeded: DNF І (C/N

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= 3); DNF II (C/N = 4); DNF III (C/N = 5); and DNF IV (C/N = 6) (Table 2). Due to its high

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denitrification rate, acetate (i.e., sodium acetate) was commonly used as the external carbon

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source for DNF.13,23 Therefore, acetate was selected as the external carbon source in this study.

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After 50 days of operation, stable NO3-, total nitrogen (TN), chemical oxygen demand (COD), and

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suspended solids (SS) removal was achieved in each DNF (Figure 1 and Figures S2−S4), which

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determined the acclimation of the DNFs to be complete.28 It was maintained for another 20 days of

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operation to ensure each DNF achieved steady state. Detailed operating conditions of the DNFs

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including the filtration velocity and backwash operation are shown in Table 2.

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Throughout the experiment, samples were collected at the inlet and outlet of the DNF every

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two to seven days and analyzed for ammonium (NH4+), NO3-, nitrite (NO2-), TN, SS, and COD. To

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investigate the effect of C/N ratio on DON removal characteristics, DON samples were collected

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weekly and analyzed for DON and DON bioavailability after each DNF became stable. Among

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them, triplicate DON samples were also used for DON size fractionation and DON molecular

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composition analysis. A peristaltic pump (average flow rate < 4 mL/min) was used for continuous,

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flow-proportional sampling of the DNF effluent. Within 20−24 h after each sampling day, the

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wastewater samples were filtered through 0.45 mm cellulose acetate membranes (ANPEL, China).

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The samples were then stored in the dark, kept at 4 °C prior to the experiments, and analyzed

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within one week after collection.

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DON, ABDON, and DON Bioavailability Determination. To minimize the impact of 6


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inorganic nitrogen on the accuracy of DON measurements, the DON was measured after a dialysis

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pretreatment using cellulose ester dialysis membranes (SPECTRUM LABORATORIES, 100−500

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Da molecular weight cutoff).29,30 After the dialysis pretreatment, the concentration of DON was

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calculated as the difference between total dissolved nitrogen (TDN) and the sum of inorganic

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nitrogen species (i.e., NH4+, NO3-, and NO2-).31-33 The concentration of ABDON was determined

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by a 14−day algal growth bioassay.12 Nitrate-free wastewater was obtained by using an

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ion-exchange (Dowex 1×8 chloride form resin, Sigma-Aldrich, USA) pretreatment method.8 To

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start the bioassay, 1.5 mL of algal seeds (Selenastrum capricornutum, obtained from the

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FACHB-collection, Chinese Academy of Sciences, China) and 1 mL mixed culture bacteria

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collected from the MWWTP were added to 100 mL DON samples in a 250 mL Erlenmeyer flask.

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Each bioassay was incubated in a temperature-controlled shaker (22−25 °C) with a 12-h light/dark

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cycle. The fate of background DON introduced by inoculation was evaluated with the deionized

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water control. The ABDON concentrations relied on the change of DON in the sample before and

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after the incubation period (eq. 1),12 where DONi and DONf represent DON before and after

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incubation for test samples and DONbi and DONbf represent DON before and after incubation for

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deionized water samples. DON bioavailability was calculated according to eq. 2.34

136

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ABDON (mg/L) = (DONi – DONf) – (DONbi – DONbf)

DON bioavailability (%) =

୅୆ୈ୓୒ ୈ୓୒

×100%

(1)

(2)

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Chemical Composition of DON. a) DON size fractionation. DON was classified into four

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groups on the basis of its molecular weight (MW): 10 kDa DON.

7



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MW fractionations were conducted in a 400-mL commercial stirred cell unit (Model 8400,

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Millipore Corp. USA), employing filters with MW cutoffs of 10, 3, and 1 kDa (Millipore Corp.

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USA) which were rinsed with Milli-Q water prior to filtration. The percentages of DON in each size

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range were calculated using the method described by Lee and Westerhoff.35

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b) DON molecular composition measurement. DON molecular composition was analyzed

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using a 9.4 T Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS, Bruker,

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Germany). A standard Bruker electrospray ionization (ESI) source was used to generate negatively

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charged molecular ions. The DON in wastewater samples was concentrated and extracted for

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FTICR-MS analysis using 1 g, 6 mL functionalized styrene-divinyl-benzene polymer resin (PPL,

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Supelco, USA) solid phase extraction (SPE) cartridges. The SPE-extracted DON sample was

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dissolved in 100% LC-MS methanol (Merck Lichrosolv, Germany) and was injected into the ESI

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source at 180 µL/h using a syringe pump. An LC−MS methanol blank was injected before and after

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each sample to ensure no cross-contamination between samples.36 Masses within the mass range of

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200−700 Da were considered.37 Methodologies for FTICR-MS mass calibration and processing can

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be found elsewhere.38 The van Krevelen diagram plots molar H/C vs O/C of each distinct empirical

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formula, aligning formulas in regions that can be attributed to lipids (O/C = 0−0.2, H/C = 1.7−2.2),

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proteins/amino sugars (O/C = 0.2−0.6, H/C = 1.5−2.2), carbohydrates (O/C = 0.6−1.2, H/C =

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1.5−2.2), lignin (O/C = 0.1−0.6, H/C = 0.6−1.7), tannins (O/C = 0.6−1.2, H/C = 0.5−1.5),

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unsaturated hydrocarbons (O/C = 0−0.1, H/C = 0.7−1.5), and condensed aromatics-like organic

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matter (O/C = 0−1, H/C = 0.3−0.7).39 Regions in which compounds share common elemental ratios

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were distinguished by N/C or the modified aromaticity index.39 8


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Wastewater Analysis. NO3- and NO2- were analyzed by ion chromatography (Dionex

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ICS-1100, USA). To measure TDN, samples were oxidized to NO3− using persulfate digestion. The

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NO3− concentration in the digested solution was then quantified by ion chromatography. NH4+ was

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determined by the salicylate method.40 Detection limits for all inorganic nitrogen species in

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wastewater samples were below 0.06 mg N/L. SS, COD, total phosphorus (TP), and UV254

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absorbance were measured according to Standard Method.40 Temperature and pH were measured

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on site using an HQ40d portable multiparameter tester (HACH, USA).

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Statistical Analyses. Student's t test (t-test) and analysis of variance (ANOVA) were

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conducted by the SPSS 19.0 (IBM, Armonk, New York). A p-value of 0.05, t-test), significant

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differences in the effluent ABDON were observed between C/N ratios of 4 and 5, 4 and 6, and 5

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and 6 (p < 0.05, t-test, Figure 3b). The concentration of effluent ABDON is an important issue

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because bioavailable nitrogen-containing organic compounds can be bioavailable to natural algae,

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which can lead to oxygen consumption and support eutrophication in waters.9,41-43 One of the

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important findings of the pilot-scale DNF tests was that effluent ABDON generally decreased with

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C/N ratios (Figure 3).

10


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The bioavailability of DON (ABDON/DON) in DNF effluent ranged from 38% to 55%

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(Figure 3). The range of effluent DON biodegradability observed in this study is agreeable with

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the values (18−61%) previously reported in low total nitrogen wastewater effluent.8,44 The

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bioavailability of effluent DON reached to a peak of 55 ± 4% at the C/N ratio of 4 (Figure 3a).

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After increasing C/N ratio in the feed, the bioavailability of effluent DON presented a significant

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decreasing trend for other two conditions (p < 0.05, Figure 3). These decreases in bioavailability

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indicate that the chemical composition of the effluent DON changed.12,45 This hypothesis will be

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further confirmed in the following section. Taken together, the results illustrate that DNF operating

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at high C/N ratio produce effluent DON with less bioavailability leading to relatively low nutrient

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support in receiving waters.

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Effect of C/N Ratio on Effluent DON Chemical Composition. To better understand the

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effect of C/N ratio on effluent DON bioavailability (ABDON/DON), the molecular weight (MW)

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distribution and molecular composition of DON in DNF effluent at different C/N ratios were

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investigated.

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a) Molecular weight distribution. The MW distribution of effluent DON from DNFs at

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different C/N ratios is shown in Figure 4. MW˂3 kDa DON made up the greatest portion in all

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DNF effluent (62−92%), which is consistent with previous studies,46-48 implying that most DON

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consists of low MW compounds. The %MW˂1 kDa content of DON in DNF effluent at a C/N ratio

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of 6 (average: 44%) was lower than that at C/N ratios of 3, 4, and 5 (average: 58%, 68% and 45%,

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respectively). Notice that DON substances with MW˂1 kDa property are likely to have a greater

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potential for phytoplankton production than MW˃1 kDa DON.19 This is likely the reason why the 11



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bioavailability of effluent DON at the C/N ratio of 6 was less than that at C/N ratios of 3, 4, and 5

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(Figure 3). Indeed, previous research has reported that the bioavailability of DON in wastewater

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positively correlated with low MW DON.48 In this study, the general tendency of DON

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bioavailability also increased with an increase in the %MW˂1 kDa DON, although no statistical

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significance was observed (R2 = 0.283, p > 0.05, ANOVA, Figure S6).

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b) Molecular composition. The molecular composition of DON in DNF effluent at different

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C/N ratios was analyzed by an ultra-high-resolution FTICR-MS. The mass spectra was analyzed

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to determine molecular formulas containing nitrogen, which was presented using a van Krevelen

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diagram (Figure 5a). A van Krevelen diagram is a useful way to visualize a large number of

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formulas because different regions correspond to different compound classes,49 which typically

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includes lipids, proteins/amino sugars, lignin, tannins, carbohydrates, condensed aromatics, and

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unsaturated hydrocarbons.39,50 A principal component analysis (PCA) based on the classes of

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effluent DON molecular composition was conducted, as shown in Figure 5b. Variable lignin and

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proteins/amino sugars had the highest loadings on PC1 (0.81 and -0.50, respectively, Figure S7).

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The compound type of proteins/amino sugars is aliphatic and typically represents the bulk of the

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labile DON pool.22 In contrast to the proteins/amino sugars-like compounds, the lignin-like

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compounds presumably have an aromatic nature limiting their degradability.51 The possible

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refractory nature of the lignin-like materials suggests that these compounds are presumably the

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organic residues remaining after degradation of the labile fraction of influent DON in DNF.36

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According to the PCA analysis, effluent DON from DNFs at different C/N ratios differed in

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its molecular composition. PC1, indicative of a refractory (positive PC1) vs. labile (negative PC1) 12


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character of the DON, explained 97.4% of the variance, whereas PC2 only accounted for 1.8% of

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the variance. The general trend observed for PC1 was that effluent DON at a C/N ratio of 4

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featured negative PC1 values (ranging from -9.25 to -8.30) and effluent DON at C/N ratios of 3, 5,

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and 6 had positive PC1 values (ranging from 0.96 to 5.96, Figure S8). This corresponds to the

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findings which showed that the maximum effluent DON bioavailability was reached at a C/N ratio

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of 4 (Figure 3). Furthermore, compared with the effluent DON at a C/N ratio of 5 (ranging from

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0.96 to 2.28), those at a C/N ratio of 6 were more positive on the PC1 axis (ranging from 5.36 to

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5.96, Figure S8), which suggest that effluent DON at a C/N ratio of 6 contain an important pool of

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nitrogen-containing compounds that are likely refractory or only semilabile.22,36 This data is also

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consistent with our earlier results on the bioassay tests (Figure 3).

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In summary, there were compositional differences in the DON in DNF effluent at different

254

C/N ratios. For the effluent DON at C/N ratios of 4, 5, and 6, those at high C/N ratios tend to

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contain less %MW˂1 kDa nitrogenous organic compounds and proteins/amino sugars-like

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nitrogenous organic formulas, which is likely responsible for its low bioavailability.

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Implication. Researchers and engineers working on DNFs have primarily focused on whether

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treated wastewater meets the total nitrogen discharge requirements and how to optimize the

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operation of DNFs to decrease the dissolved inorganic nitrogen.23,52,53 Concern is rarely paid to the

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removal of DON during the DNF process and its impact on the receiving water systems. Optimizing

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external carbon addition not only improves the NDF process efficiency but also saves chemical

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costs and reduces secondary pollution (e.g., COD).4,54 Considering the relatively high proportion of

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DON in total nitrogen in DNF effluent (31.2−39.8%, Figure 2) and the great potential of DON to 13



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stimulate phytoplankton biomass (DON bioavailability: 38−55%, Figure 3), knowing the effect of

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C/N ratio on the removal characteristics of DON and ABDON in the DNF is critical for the

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strategies to balance eutrophication risk from wastewater effluents with secondary factors such as

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cost, energy consumption, and secondary pollution. Our results showed the maximum effluent

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DON and ABDON both occurred in DNF operated at a C/N ratio of 3. The effluent DON from

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DNFs did not significantly differ when the C/N increased from 4 to 6 (p > 0.05); however, effluent

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ABDON and DON bioavailability significantly decreased with the C/N ratio (p ˂ 0.05, t-test,

271

Figure 3). In addition, results of DON size fractionation analysis suggest that the effluent DON

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from the DNF with C/N 4 and 5 contain more low-WM DON, compared with that from the DNF

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with C/N 6 (Figure 4). Low-MW DON are difficult to remove by conventional tertiary treatment,

274

e.g., coagulation, and tend to enter receiving waters.35 Overall, this study indicates the benefit of

275

high C/N ratios during the DNF process in terms of controlling the DON forms that readily

276

stimulate algal growth.

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Although acetate has been the widely used carbon source for enhancing heterotrophic

278

denitrification,13,23,55 many alternatives, e.g., methanol,56 ethanol,5 and natural and synthetic

279

biopolymers (woodchips, polycaprolactone, etc.),57 are also applied. Thus, determining if different

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external carbon sources would show similar results could also be important for future research on

281

this topic.

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ASSOCIATED CONTENTS

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Supporting Information

14


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The Supporting Information is available free of charge on the ACS Publications website.

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Schematic of the DNF system (Figure S1); removal of TN, COD, and SS (Figures S2−S4);

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concentration of effluent NO2- (Figure S5); relationship between DON bioavailability and %MW˂1

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kDa DON (Figure S6); PC1 and PC2 loadings and scores of the PCA (Figure S7 and S8) (PDF)

288

ACKNOWLEDGMENTS

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This study was supported by the Jiangsu Natural Science Foundation (BK20160655), the

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National Science and Technology Major Project (2017ZX07204001), and the Project of Jiangsu

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Provincial Six Talent Peaks (2015−JNHB−002).

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REFERENCES

293

(1) Price, J. R.; Ledford, S. H.; Ryan, M. O.; Toran, L.; Sales, C. M. Wastewater treatment plant

294

effluent introduces recoverable shifts in microbial community composition in receiving streams. Sci.

295

Total Environ. 2018, 613, 1104−1116.

296

(2) Sun, Y.; Chen, Z.; Wu, G.; Wu, Q.; Zhang, F.; Niu, Z.; Hu, H. Y. Characteristics of water

297

quality of municipal wastewater treatment plants in China: implications for resources utilization and

298

management. J. Clean. Prod. 2016, 131, 1−9.

299 300

(3) Bollon, J.; Filali, A.; Fayolle, Y.; Guerin, S.; Rocher, V.; Gillot, S. Full-scale post denitrifying biofilters: sinks of dissolved N2O? Sci. Total Environ. 2016, 563, 320−328.

301

(4) Li, P.; Zuo, J.; Wang, Y.; Zhao, J.; Tang, L.; Li, Z. Tertiary nitrogen removal for municipal

302

wastewater using a solid-phase denitrifying biofilter with polycaprolactone as the carbon source and

303

filtration medium. Water Res. 2016, 93, 74−83.

304

(5) Shi, Y.; Wu, G.; Wei, N.; Hu, H. Denitrification and biofilm growth in a pilot-scale

305

biofilter packed with suspended carriers for biological nitrogen removal from secondary effluent. J.

306

Environ. Sci. 2015, 32, 35−41.

307

(6) Pehlivanoglu-Mantas, E.; Sedlak, D. L. Wastewater-derived dissolved organic nitrogen:

308

analytical methods, characterization, and effects—a review. Crit. Rev. Env. Sci. Tec. 2006, 36 (3),

309

261−285.

310 311

(7) Chen, B.; Kim, Y.; Westerhoff, P. Occurrence and treatment of wastewater-derived organic nitrogen. Water Res. 2011, 45 (15), 4641−4650.

312

(8) Sattayatewa, C.; Pagilla, K.; Pitt, P.; Selock, K.; Bruton, T. Organic nitrogen

313

transformations in a 4-stage Bardenpho nitrogen removal plant and bioavailability/biodegradability 15



314

of effluent DON. Water Res. 2009, 43 (18), 4507−4516.

315

(9) Simsek, H.; Kasi, M.; Ohm, J. B.; Blonigen, M.; Khan, E. Bioavailable and

316

biodegradable dissolved organic nitrogen in activated sludge and trickling filter wastewater

317

treatment plants. Water Res. 2013, 47 (9), 3201−3210.

318

(10) Vaquer-Sunyer, R.; Conley, D. J.; Muthusamy, S.; Lindh, M. V.; Pinhassi, J.;

319

Kritzberg, E. S. Dissolved organic nitrogen inputs from wastewater treatment plant effluents

320

increase responses of planktonic metabolic rates to warming. Environ. Sci. Technol. 2015, 49

321

(19), 11411−11420.

322

(11) Reader, H. E.; Lindh, M. V.; Conley, D. J.; Kritzberg, E. S. Effects of wastewater

323

treatment plant effluent inputs on planktonic metabolic rates and microbial community

324

composition in the Baltic Sea. Biogeosciences 2016, 13 (16), 4751–4765.

325

(12) Liu, H.; Jeong, J.; Gray, H.; Smith, S.; Sedlak, D. L. Algal uptake of hydrophobic

326

and hydrophilic dissolved organic nitrogen in effluent from biological nutrient removal

327

municipal wastewater treatment systems. Environ. Sci. Technol. 2012, 46 (2), 713−721.

328

(13) Mokhayeri, Y.; Riffat, R.; Murthy, S.; Bailey, W.; Takacs, I.; Bott, C. Balancing yield,

329

kinetics and cost for three external carbon sources used for suspended growth

330

post-denitrification. Water Sci. Technol. 2009, 60 (10), 2485−2491.

331 332

(14) Samie, G.; Bernier, J.; Rocher, V.; Lessard, P. Modeling nitrogen removal for a denitrification biofilter. Bioprocess Biosyst. Eng. 2011, 34 (6), 747−755.

333

(15) Rocher, V.; Laverman, A. M.; Gasperi, J.; Azimi, S.; Guerin, S.; Mottelet, S.;

334

Villieres, T.; Pauss, A. Nitrite accumulation during denitrification depends on the carbon

335

quality and quantity in wastewater treatment with biofilters. Environ. Sci. Pollut. Res. Int. 2015,

336

22 (13), 10179−10188.

337

(16) Liu, X.; Wang, H.; Long, F.; Qi, L.; Fan, H. Optimizing and real-time control of

338

biofilm formation, growth and renewal in denitrifying biofilter. Bioresour. Technol. 2016, 209,

339

326−332.

340

(17) Rissanen, A. J.; Ojala, A.; Fred, T.; Toivonen, J.; Tiirola, M. Methylophilaceae and

341

Hyphomicrobium as target taxonomic groups in monitoring the function of methanol-fed

342

denitrification biofilters in municipal wastewater treatment plants. J. Ind. Microbiol.

343

Biotechnol. 2017, 44 (1), 35−47.

344 345

(18) Bolyard, S. C.; Reinhart, D. R. Evaluation of leachate dissolved organic nitrogen discharge effect on wastewater effluent quality. Waste Manage. 2017, 65, 47−53.

346

(19) Eom, H.; Borgatti, D.; Paerl, H. W.; Park, C. Formation of low-molecular-weight

347

dissolved organic nitrogen in predenitrification biological nutrient removal systems and its

348

impact on eutrophication in coastal waters. Environ. Sci. Technol. 2017, 51 (7), 3776−3783.

349

(20) Mesfioui, R.; Love, N. G.; Bronk, D. A.; Mulholland, M. R.; Hatcher, P. G.

350

Reactivity and chemical characterization of effluent organic nitrogen from wastewater

351

treatment plants determined by Fourier transform ion cyclotron resonance mass spectrometry.

352

Water Res. 2012, 46 (3), 622−634.

353

(21) Hu, H.; Jiang, C.; Ma, H.; Ding, L.; Geng, J.; Xu, K.; Huang, H.; Ren, H. Removal

354

characteristics of DON in pharmaceutical wastewater and its influence on the

355

N-nitrosodimethylamine formation potential and acute toxicity of DOM. Water Res. 2017, 109, 16


Page 16 of 26

Page 17 of 26


356 357 358

114−121. (22) Lusk, M. G.; Toor, G. S. Dissolved organic nitrogen in urban streams: Biodegradability and molecular composition studies. Water Res. 2016, 96, 225−235.

359

(23) Shi, Y.; Wei, N.; Wu, G. Tertiary denitrification of the secondary effluent in biofilters

360

packed with composite carriers under different carbon to nitrogen ratios. Environ. Eng. Res. 2016,

361

21 (3), 311−317.

362 363

(24) Her, J. J.; Huang, J. S. Influences of carbon source and C/N ratio on nitrate/nitrite denitrification and carbon breakthrough. Bioresour. Technol. 1995, 54, 45−51.

364

(25) Torresi, E.; Escola Casas, M.; Polesel, F.; Plosz, B. G.; Christensson, M.; Bester, K.

365

Impact of external carbon dose on the removal of micropollutants using methanol and ethanol in

366

post-denitrifying moving bed biofilm reactors. Water Res. 2017, 108, 95−105.

367

(26) Xie, W. M.; Ni, B. J.; Zeng, R. J.; Sheng, G. P.; Yu, H. Q.; Song, J.; Le, D. Z.; Bi, X. J.; Liu,

368

C. Q.; Yang, M. Formation of soluble microbial products by activated sludge under anoxic

369

conditions. Appl. Microbiol. Biotechnol. 2010, 87 (1), 373−382.

370

(27) Zhang, H.; Zhang, K.; Jin, H.; Gu, L.; Yu, X. Variations in dissolved organic nitrogen

371

concentration in biofilters with different media during drinking water treatment. Chemosphere 2015,

372

139, 652−658.

373 374 375 376

(28) Zhang, Y.; Ji, G.; Wang, R. Drivers of nitrous oxide accumulation in denitrification biofilters with low carbon:nitrogen ratios. Water Res. 2016, 106, 79−85. (29) Lee, W.; Westerhoff, P. Dissolved organic nitrogen measurement using dialysis pretreatment. Environ. Sci. Technol. 2005, 39 (3), 879−884.

377

(30) de Vera, G. A.; Gernjak, W.; Weinberg, H.; Farré, M. J.; Keller, J.; von Gunten, U.

378

Kinetics and mechanisms of nitrate and ammonium formation during ozonation of dissolved

379

organic nitrogen. Water Res. 2017, 108, 451−461.

380 381

(31) Simsek, H.; Kasi, M.; Wadhawan, T.; Bye, C.; Blonigen, M.; Khan, E. Fate of dissolved organic nitrogen in two stage trickling filter process. Water Res. 2012, 46 (16), 5115−5126.

382

(32) Simsek, H.; Kasi, M.; Ohm, J. B.; Murthy, S.; Khan, E. Impact of solids retention time on

383

dissolved organic nitrogen and its biodegradability in treated wastewater. Water Res. 2016, 92,

384

44−51.

385

(33) Zhu, G.; Wang, Q.; Yin, J.; Li, Z.; Zhang, P.; Ren, B.; Fan, G.; Wan, P. Toward a better

386

understanding of coagulation for dissolved organic nitrogen using polymeric zinc-iron-phosphate

387

coagulant. Water Res. 2016, 100, 201−210.

388

(34)

Hu, H.; Ma, H.; Ding, L.; Geng, J.; Xu, K.; Huang, H.; Zhang, Y.; Ren, H.

389

Concentration, composition, bioavailability, and N-nitrosodimethylamine formation potential of

390

particulate and dissolved organic nitrogen in wastewater effluents: A comparative study. Sci. Total

391

Environ. 2016, 569, 1359−1368.

392 393

(35) Lee, W.; Westerhoff, P. Dissolved organic nitrogen removal during water treatment by aluminum sulfate and cationic polymer coagulation. Water Res. 2006, 40 (20), 3767−3774.

394

(36) Yekta, S. S.; Gonsior, M.; Schmitt-Kopplin, P.; Svensson, B. H. Characterization of

395

dissolved organic matter in full scale continuous stirred tank biogas reactors using ultrahigh

396

resolution mass spectrometry: a qualitative overview. Environ. Sci. Technol. 2012, 46 (22),

397

12711−12719. 17



398

(37) Mesfioui, R.; Abdulla, H. A.; Hatcher, P. G. Photochemical alterations of natural and

399

anthropogenic dissolved organic nitrogen in the York River. Environ. Sci. Technol. 2014, 49 (1),

400

159−167.

401

(38) Chen, H.; Stubbins, A.; Perdue, E. M.; Green, N. W.; Helms, J. R.; Mopper, K.;

402

Hatcher, P. G. Ultrahigh resolution mass spectrometric differentiation of dissolved organic

403

matter isolated by coupled reverse osmosis-electrodialysis from various major oceanic water

404

masses. Mar. Chem. 2014, 164, 48−59.

405

(39) Antony, R.; Grannas, A. M.; Willoughby, A. S.; Sleighter, R. L.; Thamban, M.;

406

Hatcher, P. G. Origin and sources of dissolved organic matter in snow on the East Antarctic ice

407

sheet. Environ. Sci. Technol. 2014, 48 (11), 6151−6159.

408 409 410 411

(40) EPA of China. Water and Wastewater Monitoring Analysis Method, fourth ed. Chinese Environment Science Publisher, 2002, Beijing. (41)

Pehlivanoglu, E.; Sedlak, D. L. Bioavailability of wastewater-derived organic

nitrogen to the alga Selenastrum Capricornutum. Water Res. 2004, 38 (14), 3189−3196.

412

(42) Qin, C.; Liu, H.; Liu, L.; Smith, S.; Sedlak, D. L.; Gu, A. Z. Bioavailability and

413

characterization of dissolved organic nitrogen and dissolved organic phosphorus in wastewater

414

effluents. Sci. Total Environ. 2015, 511, 47−53.

415

(43) Fan, L.; Brett, M. T.; Jiang, W.; Li, B. Dissolved organic nitrogen recalcitrance and

416

bioavailable nitrogen quantification for effluents from advanced nitrogen removal wastewater

417

treatment facilities. Environ. Pollut. 2017, 229, 255−263.

418 419

(44) Urgun-Demirtas, M.; Sattayatewa, C.; Pagilla, K. R. Bioavailability of dissolved organic nitrogen in treated effluents. Water Environ. Res. 2008, 80 (5), 397−406.

420

(45) Pisani, O.; Boyer, J. N.; Podgorski, D. C.; Thomas, C. R.; Coley, T.; Jaffé, R.

421

Molecular composition and bioavailability of dissolved organic nitrogen in a lake

422

flow-influenced river in south Florida, USA. Aquat. Sci. 2017, 1−18.

423

(46) Pehlivanoglu-Mantas, E.; Sedlak, D. L. Measurement of dissolved organic nitrogen

424

forms in wastewater effluents: concentrations, size distribution and NDMA formation potential.

425

Water Res. 2008, 42 (14), 3890−3898.

426

(47) Huo, S.; Xi, B.; Yu, H.; Qin, Y.; Zan, F.; Zhang, J. Characteristics and

427

transformations of dissolved organic nitrogen in municipal biological nitrogen removal

428

wastewater treatment plants. Environ. Res. Lett. 2013, 8 (4), 044005.

429

(48) Hu, H.; Ding, L.; Geng, J.; Huang, H.; Xu, K.; Ren, H. Effect of coagulation on

430

dissolved organic nitrogen (DON) bioavailability in municipal wastewater effluents. J.

431

Environ. Chem. Eng. 2016, 4 (2), 2536−2544.

432

(49) Kim, S.; Kramer, R. W.; Hatcher, P. G. Graphical method for analysis of

433

ultrahigh-resolution broadband mass spectra of natural organic matter, the van Krevelen

434

diagram. Anal. Chem. 2003, 75 (20), 5336−5344.

435

(50) Ohno, T.; Parr, T. B.; Gruselle, M. C.; Fernandez, I. J.; Sleighter, R. L.; Hatcher, P. G.

436

Molecular composition and biodegradability of soil organic matter: a case study comparing

437

two new England forest types. Environ. Sci. Technol. 2014, 48 (13), 7229−7236.

438

(51) Maizel, A. C.; Remucal, C. K. The effect of advanced secondary municipal

439

wastewater treatment on the molecular composition of dissolved organic matter. Water Res. 18


Page 18 of 26

Page 19 of 26


440

2017, 122, 42−52.

441

(52) Wei, N.; Shi, Y.; Wu, G.; Hu, H.; Wu, Y.; Wen, H. Tertiary denitrification of the secondary

442

effluent by denitrifying biofilters packed with different sizes of quartz sand. Water 2014, 6 (5),

443

1300−1311.

444

(53) Liu, X.; Wang, H.; Yang, Q.; Li, J.; Zhang, Y.; Peng, Y. Online control of biofilm and

445

reducing carbon dosage in denitrifying biofilter: pilot and full-scale application. Front. Environ. Sci.

446

Eng. 2017, 11 (1), 4.

447

(54) Mohan, T. V. K.; Nancharaiah, Y. V.; Venugopalan, V. P.; Sai, P. M. S. Effect of C/N ratio

448

on denitrification of high-strength nitrate wastewater in anoxic granular sludge sequencing batch

449

reactors. Ecol. Eng. 2016, 91, 441−448.

450

(55) Shahabi, Z. A., Naeimpoor, F. Enhanced heterotrophic denitrification: effect of dairy

451

industry sludge acclimatization and operating conditions. Appl. Biochem. Biotechnol. 2014, 173 (3),

452

741−752.

453

(56) Hagman, M.; Nielsen, J. L.; Nielsen, P. H.; Jansen, J. Mixed carbon sources for nitrate

454

reduction in activated sludge-identification of bacteria and process activity studies. Water Res. 2008,

455

42 (6), 1539−1546.

456 457

(57) Wang, J.; Chu, L. Biological nitrate removal from water and wastewater by solid-phase denitrification process. Biotechnol. Adv. 2016, 34 (6), 1103−1112.

19



458

Page 20 of 26

Table 1. The quality of secondary effluent, which was used as the influent for NDFs. Average

Range

P(25th, 75th)a

nb

NO3- (mg/L)

16.08

13.62−18.41

15.22, 17.34

39

+

0.33

0.10−0.50

0.20, 0.46

39

-

NO2 (mg/L)

0.04

0.00−0.10

0.02, 0.06

39

COD (mg/L)

23.0

17.5−31.4

19.1, 26.0

39

NH4 (mg/L)

c

SS (mg/L)

12.0

9.6−14.7

10.9, 13.1

39

DON (mg/L)

1.91

1.80−2.11

1.82, 2.03

21

TPd (mg/L)

0.94

0.67−1.10

0.88, 1.03

21

UV254

1.15

1.02−1.32

1.07, 1.22

21

pH

7.47

7.33−7.65

7.39, 7.55

21

Temperature (°C)

23.9

20.9−26.5

22.5, 25.4

21

459

a

460

b

the number of measured samples.

461

c

suspended solids.

462

d

total phosphorus.

P

(25th, 75th)

is percentile, 25th and 75th.

463 464

Table 2. Operation parameters of the DNFs. Operation conditions

Start−up periods

Operation periods

(DNF І−IV)

DNF І

DNF II

DNF III

DNF IV

4

3

4

5

6

C/N ratio Filtration velocity (m/h)

7.2

a

Backwash cycle (days)

2 Air (15 L/m2·s) + Water (6 L/m2·s)

Backwash operation modes Backwash operation time (min)

6

465

a

466

accumulation of the denitrifying bacteria.

the NDFs were not backwashed for the first seven days during the start−up periods to allow

20


Page 21 of 26


467 468

Figure 1. Removal of NO3- in DNFs operated at different C/N ratios during the start-up and

469

operation periods.

21



470 471

Figure 2. The proportion of DON to total nitrogen in DNF effluent at different C/N ratios under

472

steady−state conditions (n = 9).

22


Page 22 of 26

Page 23 of 26


(a)

(b)

473

Figure 3. (a) DON, ABDON and DON bioavailability (ABDON/DON) in DNF effluent at

474

different C/N ratios under steady-state conditions (n = 9). (b) Variation of effluent DON, ABDON

475

and DON bioavailability at different C/N ratios under steady-state conditions. A hexagram indicates

476

there is significant differences in the DON, ABDON or DON bioavailability at different C/N ratios

477

(p-value < 0.05, t-test).

23



478 479

Figure 4. Percentage of each size-fractionated DON in DNF effluent at different C/N ratios under

480

steady-state conditions (n = 3).

24


Page 24 of 26

Page 25 of 26


(a)

(b)

481

Figure 5. (a) Representative van Krevelen diagram shows the molecular formulas of DON in

482

DNF effluent. The types of nitrogen-containing molecules include (1) lipids, (2) proteins/amino

483

sugars, (3) carbohydrates, (4) lignin, (5) tannins, (6) unsaturated hydrocarbons, and (7) condensed

484

aromatics.39 (b) Principal component analysis (PCA) plot of the types of effluent DON molecules

485

from DNFs at different C/N ratios under steady-state conditions. The two principal components

486

together explain 99.2% of the variance in the types of data sets. PC1 and PC2 loadings and scores

487

plot are presented in Figure S7 and S8, respectively, in the Supporting Information.

25



488

ABSTRACT ART

489

26


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Removal Characteristics of Dissolved Organic Nitrogen and Its

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