Table IV. Analysis of Detergent Formulations Using Bismuth Method Amount added Amount found NTA found, Detergent no. mg 1, 1 .o 1 .o 2.0 2.0 5.0 5.1
z
I . .
2
15.2'
1.0 2.0 5.0
1. o 2.1 5.1
3
...
1.o 2.0 5.0
1. o 2.1
1. o 2.0 5.0
1.o 2.1 4.9
1.o 2.0 5.0
1. o 2.1 5.1
4
...
5
(L
10-6M NTA using lead and bismuth are shown in Figure 8. The identical curves were obtained on synthetic lake water. A series of experiments with various concentrations of NTA showed that peak heights were reproducible to within a graticule division irrespective of the number of scans o n the solutions. The precision of the methods was calculated by determining the percentage standard deviation from the multiple analyses of a series of solutions, each containing 50 pg/ liter of NTA. The coefficient of variation was 5.4 and 3.8 for the lead and bismuth methods. Analysis of Lake Water Samples and Detergents. Tables 111 and IV show the results obtained for lake water samples from the Winnipeg area and NTA content of different detergent formulations.
5.1
6
12.4a
1.0 2.0 5.0
1 .o 2.0 5.1
7
5.6'
1 .o 2.0 5.0
1. o 2.1 5.0
Nitrilotriacetic acid is expressed as HsX. In detergent formulation
NassTA, H20 is added; therefore, above values should be multiplied
Literature Cited
Clinckemaille, G. G., Anal. Chin2 Acta 43,520 (1968). Daniel, R. L., LeBlanc, R. B., Anal Chirn. Acta 31,1221 (1959). Davis, H . M., Shalgosky, H. I . , J . Polarogr. SOC.6,12 (1960). Farrow, R. N. P., Hill, A. G . ,Analyst 90,241 (1965). Horacek, J., Pribii, R., Talunfa16,1495 (1969). Hoyle, W., Sanderson, I. P., West, T. S., J . Electronal. Chetn. 2, 166 (1961). Hoyle, W., West, T. S., Talantn 2,158 (1959). LeBlanc, R. B., Anal. Clrern. 31,1840 (1959). SCI.TECHNOL. 2, 543 (1968). Pfiel, B. H., Lee, G. F., ENVIRON. Pickering, Q. H., Henderson, C., Air W a f . Pollut. Znt. J . 10,453 (1966). Sprague, J. B., Nuture220,1345 (1968). Swisher. R. D.. Crutchfield. M. M.. Caldwell. D. W.. ENVIRON. SCI.TECHSOL. 1, 820 (1967).
by 1.44 t o get correct values.
Receiced for reciew July 16, 1970. Accepted Dec. 24, 1970.
Classification of Organics in Secondary Effluents Menahem Rebhun and Josepha Manka
Technion-Israel Institute of Technology, Sanitary Engineering Laboratories, Haifa, Israel
w The composition of soluble organics in secondary effluents was investigated. A fractionation procedure was applied enabling recovery and quantitative determination of humic substances as well as other chemical groupings present in secondary effluents. This procedure made possible the classification of the total organic content of secondary effluents. Forty to 5 0 z of the organics was classified as humic substances (humic, fulvic, and hymathomelanic acids), the fulvic acid being the major fraction of this class. The remainder of the organic matter consisted of (in percent): ether extractables, -8.3; anionic detergents, -13.9; carbohydrates, -11.5; proteins, -22.4; and tannins, -1.7.
T
he permanent increase of pollution in existing freshwater sources and the need to reuse waste water in many parts of the world are focusing attention on more efficient methods of contaminant removal. Effluents from the common biological treatment processes contain considerable 606 Environmental Science & Technology
amounts of organics. These organics are responsible for taste, odor, and color in contaminated water supplies; some of them may have toxic effects on the biota of freshwater bodies. In the case of waste water reuse for human consumption, attention has been given to the aesthetic as well as physiological effects of the organic residuals (McCallum, 1959; Ottoboni and Greenberg, 1970). Improvement of effluent (waste water) quality is planned mainly by application of physicochemical treatment processes. Since existing treatment plants apply biological methods, it is mostly their effluent that will be subjected to chemical and physical treatment, in this case tertiary treatment. Residual organics affect and are affected by many of the tertiary physicochemical processes (Dean, 1969). Better understanding of the composition and characteristics of the residual organics in secondary effluents, as well as in effluents after various stages of tertiary chemical treatment, would aid better design and operation of physicochemical treatment processes and the assessment of the significance of the organics in water quality. Little has been reported on the composition of secondary effluents, the most comprehensive reports available are those
of Painter et al. (1960) and Bunch et al. (1961). Both investigators a priori divided the soluble organic content of the effluents into specific classes which they afterward tried to identify and determine quantitatively. The main classes under investigation were: ether extractable proteins, carbohydrates, tannins and lignins, and detergents. They classified about 35 of the organics present in domestic secondary effluents, leaving, however, 65 % unidentified. There are few indications as to the nature of these unidentified compounds, (Bunch et al., 1961). One suggestion is that about 40% of the organic matter is of high molecular weight, since it was not dialyzable. Philips (1938) stated that the aerobic biological treatment leaves in the effluent “some inert humus matter which is highly carbonaceous and apparently does not serve as bacterial food.” The appearance of biologically resistent organic material in soil and surface waters has been widely reported and described under the general name “humic substances” and various attempts have been made to characterize these substances (Black and Christman, 1963; Ghassemi and Christman, 1968, Gjessing, 1965; Kononova, 1961 ; Packham, 1964). They are formed by microbial action in a complex, two-phase process, including: decomposition of original plant and animal residues to simpler compounds and subsequent synthesis of specific, high molecular weight substances, so-called humic substances (Kononova and Aleksandrova, 1959). About 20% of manure applied to the soil is fixed in the form of humus, mainly humic acids, the rest being mineralized (Kononova, 1961). Rebhun and Kaufman (1967) assumed that the unidentified part of organics from Painter’s and Bunch’s classification systems mainly comprised high-molecularweight compounds. Sorption behavior of the bulk of effluent organics was indeed similar to that of humic substances (Abrams and Breslin, 1965; Rebhun and Kaufman, 1967). The effect and behavior of organic matter from secondary effluents in chemical treatment processes were found to be similar to that of humic compounds in natural water and soil (Rebhun et al., 1969). The objective of this study was to investigate, more comprehensively, the organic content of secondary effluents. By leaving the classification system of Bunch and Painter unchanged, a new class has been added, the class of so-called humic substances. The analogy between the conditions of humus formation in soil and those of biological waste water treatment and the similarity in behavior toward chemical treatment of humic substances from natural water and of organics in secondary effluents seemed to justify the assumption that a considerable part of residual soluble organics in secondary effluents consists of humic-type compounds. Experimental The effluent used for this investigation was collected from the Haifa municipal waste water treatment plant which uses high-rate trickling filters preceded and followed by settling. The raw waste water consists of 80% domestic and 20% industrial origin, mostly light industries. Large petrochemical and chemical plants are not connected to the municipal system. The collected samples were centrifuged for 30 min at 8000 rpm (10,400 g) and the supernatant was concentrated twentyfold in an evaporator operating under vacuum of about 75 mm Hg between a 40’ to 50” C. Concentrating the effluent resulted in the increase of p H from about 8.0 to 9.4, and formation of a precipitate. The concentrate was filtered through a Millipore membrane filter
Filtrate, pH = 9.4 extraction with diethyl ether
+
Water layer HCI, to pH = 1.0
Ether layer ether extractable, pH = 9.4
precipitate appears
Aprecipitate
filtrate extraction with diethyl ether
extraction with ethyl alcohol
n ether laver
water layer extraction with n-but= water layer (F)
Asoluble
insoluble humic acid
ethei extractable = 1.0
hymathomelanic acid
buthanol layer evaporated to dryness, extracted with acetone
n
inso1;ble residue (traces) discarded
soiuble fulvic acid
Figure 1. Fractionation of the filtrate
Precipitate dissolved in HCl at pH = 1
/\
soluble extraction with diethyl ether
insoluble extraction with ethyl alcohol
n
A ether layer
water layer extraction with n-buthanol water layer (P)
insoluble humic acid
ether extractable
soluble hymathomelanic acid
buthanol layer evaporated to dryness, extracted. with acetone
A
solid residue (traces) discarded
soluble fulvic acid
Figure 2. Fractionation of the precipitate
0.45 1.1. The filtrate as well as the precipitate was subjected to a fractionation procedure developed during this investigation. It is a combination of the scheme proposed by Bunch et al. (1961) and Painter et al. (1960) and of reported methods of fractionation of humic substances in soil and water (Black and Christman, 1963; Kononova, 1961 ; Packham, 1964). The fractionation schemes are presented in Figures 1 and 2. The fractions obtained were: ether extractable (at p H = 1.0 and p H = 9.4) humic, fulvic, and hymathomelanic acids. Each fraction was examined for its COD value and for the content of the following groups: detergents, proteins, carbohydrates, and tannins. The same determinations were carried out for the water layers F and P (Figures 1 and 2). Volume 5, Number 7, July 1971 607
The methods of analyses applied in this study were as follows: COD, anionic detergents, tannins, and lignins were determined according to “Standard Methods” (Amer. Pub. Health Ass., 1965); the concentration of carbohydrates was determined by the anthrone procedure (Colowick and Kaplan, 1957) and that of soluble proteins by the Folin phenol method (Lowry et al., 1951).
Results and Discussion I n Table I are given typical results of several analyses of secondary effluents of the Haifa treatment plant. The color and soluble organic content (as determined by COD)of this effluent are much higher than that usually encountered in the U S . This is a result of the low per capita water use in Israel and a high COD (1200 mg/liter) in the raw waste water. Eckhoff and Jenkins (1966) have shown that the residual soluble COD is a function of the COD of the raw waste water. However, the soluble BOD can be reduced to low values by biological treatment. This explains the high COD to BOD ratio (coD/BoD),~~,,,~~ g 3 0 in secondary effluents in Israel as compared to ( c o D / B o D ) , ~ ~ ,g~ ~8 ~typical for secondary effluents in the U S . The results of determinations of organic compositions of three different samples are summarized in Table 11. The different groups and fractions of soluble organics separated and determined in this study are expressed as percent of COD in relation to total COD of the effluent. While the COD of each fraction was determined analytically, the
Table I. Typical Results of the Analysis of the Secondary Effluent (After Centrifugation) PH 8.1 Color (at p H = 8.4) in Hazen units 214 Conductivity, pmho/cm 2300 Turbidity traces COD, mg/liter as 0 2 185,O BOD, mg/liter as O2 6.0 60.0 Total nitrogen, mg/liter as N Organic nitrogen, mg/liter as N 18.0 Ca, mg/liter as Ca 110.0 49 0 Mg, mg/liter as Mg Alkalinity, mg/liter as C a C 0 3 480,O Anionic detergents, mg/liter as alkyl benzene sulfonate 12.0 Chlorides, mg/liter as C1 450,O Sodium, mg/liter as Na 250,O
COD’S of each group, such as detergents, carbohydrates, proteins, and lignins were calculated, on the basis of their concentration in the effluent under investigation. F o r COD calculation purposes, each group was described by one representative, Le., detergents by alkyl benzene sulfonate, proteins by bovine albumin, carbohydrates by glucose, and tannins by tannic acid. The calculated COD values of the individual groups were subsequently subtracted from the originally determined COD of each fraction, thus providing the “net COD value” of each fraction. The meaning of the term “net COD value” may be explained by an example calculation of this value for the humic acid fraction. The humic acid fraction in Sample 2 has been separated and its COD value was found to be 14.373 of the total effluent’s COD.
The separated fraction was then examined for the presence of detergents, carbohydrates, proteins, and tannins and the results expressed as percent of the total effluent’s COD value. It was found that humic acid fraction contained: As
COD
Detergents Carbohydrates Proteins Tannins Total
% Of total effluents COD 0.8 0.9 0.5 0.1
3.373
This value has been substracted from the experimentally found 14.373 thus giving a “net COD value” of 11.0% for the humic acid fraction. The values of detergents, carbohydrates, tannins, and proteins given in Table I1 are the totals of their respective content in each fraction. The classification of the organic constituents (Table 11) is similar to that used by Bunch et al. (1961), with fractionation to humic substances added. The so-called “humic substances,” isolated in this work by the fractionation procedure applied, correspond to the “unidentified” part of the organic substances in the classification systems of the previous investigators. In the effluents investigated, humic substances constituted approximately 40 to 50% of the total COD. By including the humus fractions in the scheme, it was possible to classify almost 100% of the soluble organic matter. The precipitate formed during concentration of the effluent contained about 40% of the total organic matter of the effluent. The major part of the humic acid was found in the precipitate, which is in accordance with the low solubility of its calcium
Table 11. Composition of Soluble Organics in Secondary Effluent as Percent of Total COD Sample 1 (3/26/69) Sample 2 (5/20/69) Sample 3 (7/24/69) Total Total Total Constituent effluent Filtrate Precipitate effluent Filtrate Precipitate effluent Filtrate Precipitate Ether extractable 10.6 6.4 4.2 6.6 4.2 2.4 7.8 4.7 3.1 Anionic detergents 12.8 6.6 6.2 13.3 6.2 7.1 15.6 7.7 7.9 Carbohydrates 10.9 8.1 2.8 12.7 8.1 4.6 11 . o 8.3 2.7 Tannins 1.5 0.9 0.6 1.4 0.7 0.7 2.2 1. o 1.2 Proteins 21 . o 16.9 4.1 22 0 16.8 5.2 24.1 17.3 6.8 Fulvic acid 22.5 19.2 3.3 18.8 15.4 3.4 25.8 20.4 5.4 Humic acid 10.4 2.9 7.5 11 . o 1.7 9.3 11.9 2.9 9.0 Hymathomelanic acid 7.4 0.9 6.5 9.5 1.0 8.5 7.5 1.3 6.2 Total 97.1 61.9 35.2 95.3 54.1 41.2 105.9 63.6 42.3 608 Environmental Science & Technology
salts. Most of the fulvic acid remained in the filtrate, where it constituted about 75 % of the total humic substances. Fulvic acid was also the major class (more than 50%) of the total humic substances present in the whole effluent. Further examination of the data presented in Table I1 shows that the results obtained from three samples collected a t different periods of time are quite close. While the percent of “ether extractable” and “tannins” was in good agreement with that reported by Bunch et al. (1961), the content of “proteins” and “carbohydrates” was about twice as high in our samples: approximately 20% vs. 10% in the case of proteins and 10% vs. 5 % in the case of carbohydrates. It should be mentioned that, in this work, the term “humic substances” applies t o the organic constituents on the basis of their behavior toward various solvents in a fractionation method, applied both in the soil and surface water. The exact structure of these substances is still under dispute even in soil and surface water. To obtain more knowledge about the so-called humic substances and other organics isolated from secondary effluents, further studies are under way t o determine the structure of these substances as well as their fate in physicochemical treatment processes. Literature Cited
Abrams, I . , Breslin, R., “Recent Studies on the Removal of Organics from Water,” 26th Annual Meeting International Water Conference of the Engineers Society of Western Pennsylvania, Pittsburgh, Pa., October 1965. American Public Health Association, “Standard Methods for the Examination of Water and Wastewater,” 12th ed., New York, N.Y., 1965, pp 296, 303, 510.
Black, A. P., Christman, R. F., J . Amer. Water Works. Ass. 55 (6), 753 (1963). Bunch, R. L., Barth, E. F., Ettinger, M. B., J . Water Pollut. Contr. Fed. 33 (2), 122 (1961). Colowick, S. P., Kaplan, N. D., “Methods in Enzymology,” Academic Press, New York, N.Y., 1957, p 84. Dean, R. B., ENVIRON. Scr. TECHNOL. 3 (9), 820 (1969). Eckhoff, D. U., Jenkins, D. J., “Transient Loading Effects in the Activated Sludge Process,” Proceedings of the Third International Conference of Water Pollution Research, Munich, 1966, p 309. Ghassemi, M., Christman, R. F., Lirnnol. Oceanogr. 13 (4), 583 (1968). Gjessing, E. T., Nature 208 (5015), 1091 (1965). Kononova, M. M., “Soil Organic Matter,” Pergamon Press, Oxford, England, 1961, pp 49, 51, 295. Kononova, M. M., Aleksandrova, I. V., Soils Fert. 22, 77 (1 959)I ’ \-- - _
Lowry, 0. H., Rosebrough, N . J., Farr, A. L., Randall, R . J., J . Biol. Chern. 193. 265 (1951). McCallum, G. E., Proc. Znd: Waste Con/:, Purdue University, Series no. 104, 1959, p 669. Ottoboni. A.. Greenbern. -, A. E. J . Water PoIIut. Contr. Fed. 42, 493 (1970). Packham, R. F., Proc. SOC.for Water Treat. Exariz. 13, 316 (1964). Painter,’ H. A , , Viney, M., Bywaters, A., “Composition of Sewage and Sewage Effluents,” presented at a meeting of the Metropolitan and Southern Branch, The Institute of Sewage Purification, London, Dec. 8, 1960. Philips, E. B., “Biochemistry in Sewage Treatment Modern Sewage Disoosal.” Chao. - Works . 14.,Federation of Sewane AssoFiatioi, 1938. Rebhun, M. Kaufman, W. J., SERL Rept. no. 67-9, University of California. Berkeley. Calif.. December 1967. Rebhun, M., Narkis, N:,’ Wachs, A. M., Water Res. 3, 345 (1969). Receiced for reciew August 3, 1970. Accepted March 26, 1971.
Method for Macrodetermination of Carbon and Hydrogen in Solid Wastes Donald L. Wilson Environmental Protection Agency, Solid Waste Management Office, Cincinnati, Ohio 4521 3
Present methods for determining carbon in solid waste samples are not feasible because the material is too heterogeneous and contains too many interfering substances. The modified macroanalytical technique described here employs a dry combustion-purification-gravimetric approach and precisely and accurately analyzes 1 to 10 grams of prepared solid waste. All samples must be thoroughly dried and generally uniform with a particle size of less than 2 mm and with most of the glass, ceramics, and metals removed.
T
he carbon and hydrogen contents of various solid waste materials are important to some of the volume reduction processes used for waste disposal. I n the incineration process, for example, the operating efficiency of an incinerator can be measured by material balance techniques, and analyzing carbon and hydrogen contents of the solid wastes to be incinerated is essential. Performing these same analyses o n incinerator residue and compost used for landfill is also essen-
tial because the stability of these waste products is a function of their carbon and hydrogen contents. Conventional methods to determine carbon and hydrogen contents require either a n extremely homogeneous sample because of the small amount of material analyzed (usually 50 mg) or a low carbon content sample (less than 6%) that contains no impurities to affect the carbon-hydrogen analyses. Solid waste samples are too heterogeneous and contain too many interfering substances for these conventional methods. Of the six basic means to analyze samples for their carbon content, five were unsatisfactory. The volumetric manner (Treadwell, 1930) involves adsorption solutions that may not be capable of absorbing large amounts of carbon dioxide emitted from solid waste materials. The percent ash relationship technique (Bell, 1963), although sometimes used for compost samples, has not shown a consistent relationship between the percent ash (or volatile) and the carbon content of the samples. The alkalimetric system (Hamilton and Simpson, 1958) relies on an acid-catalyst-heat combination that cannot handle heterogeneous solid waste samples. The manometric method (AOAC, 1965a) relies o n acids that cannot react with all the carbon in solid waste materials and on an Volume 5, Number 7, July 1971 609
