CURRENT RESEARCH Identification of Organic Compounds in Unbleached Treated Kraft Paper Mill Wastewaters Lawrence H. Keith U.S. Environmental Protection Agency, Environmental Research Laboratory, College Station Rd., Athens, Ga. 3060 1
Wastewaters from two kraft paper mills in Georgia were sampled a t various points in the waste treatment systems. Gas chromatography of the organic extracts and identification of many of the specific chemical components by gas chromatography-mass spectrometry provided a “chemical profile” of the effluents. The mills, in different geographical locations, have very similar raw wastewater compositions but different wastewater treatments. In spite of these differences, the treated effluents are qualitatively similar in composition although the quantities of the various components differ. After two years the raw and treated effluents of both mills were resampled. Analyses showed that although concentrations of the organics varied, the same compounds are still present. “The need to know what chemicals may escape into the environment and a t what levels they may be harmful leads rather quickly to a realization that until one can identify these compounds with certainty and measure their presence in selected compartments of the environment, effective control of these chemicals is essentially impossible” ( I ) . Knowledge of the specific chemical composition of treated wastewaters is basic to the evaluation of the environmental impact of these wastewaters and to the problem of analyzing and controlling their discharge. By tracing the chemicals through the treatment system one can identify which compounds are being effectively removed and which are resistant to the treatment in use. Any new chemicals produced during treatment are readily apparent. Once identifications are made, the approximate concentration of each compound can be calculated a t each stage of the treatment. T o our knowledge this study represents the first attempt to characterize a wastewater chemically, trace the dissolved volatile organics through a treatment system, and correlate this information with the
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traditional collective pollution prarameter measurements (BOD, TOC). The results detailed in this paper were gathered over a six-year period and portions of them have been presented previously ( 2 - 4 ) . Paper Mill Treatment Facilities Two mills, having similar processes but different waste treatments, were used in this study. The first, Paper Mill “A”, daily produced about 1400 tons of containerboard in March 1972 when the samples were taken. Approximately 13 million gal of water passed through the treatment system daily. The treatment system is diagrammed in Figure 1. The total BOD reduction through the whole system is reported to be in excess of 70%. The second mill, Interstate Paper Corp., Riceboro, Ga., daily produced about 540 tons of containerboard in March 1972 when the samples were taken. Approximately 5.5 million gal of water passed through the treatment system daily. The treatment system is diagrammed in Figure 2. In the 650-acre stabilization lagoon, the highly alkaline effluent (pH 12) first undergoes partial neutralization to pH 10 by surface absorption of atmospheric carbon dioxide, causing precipitation of nearly all the remaining calcium salts in the inlet section of the stabilization basin. Lime treatment removes about 90% of the color from the effluent. Overall BOD reduction is reported to be 93%, with a concentration of about 6 mg/l. in the lagoon effluent ( 5 , 6). Experimental
Sampling and Materials. Burdick and Jackson “distilled in glass” solvents were used for all extractions. Effluent samples were placed in polyethylene plastic containers and Sample point No. 1 (24-hr composite)
Sample point NO. 1 IGrab sample1
(Retention time about 40 min.)
Sample point NO. 2 (Crab sample 5 h o u r s after Sample No. 1) Sample point No. 3 (Grab sample 3 h o u r s after Sample No. 2)
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2’
I
Sample point No. 3 124-hr composite)
Trickling Blofiiter IRetention tlme &LI 2-4 min)
Secondary Clarifier IRetention time about 3 hours)
I
(9
(Grab sample)
d
” (Retentiontime 3-6 months) (Retention tl me a b u t 2 days)
Figure 1. Waste treatment system diagram of Mill “A”
Figure 2. Waste treatment system diagram of the interstate Paper Corp. mill at Riceboro, Ga.
Volume 10, Number 6, June 1976
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immediately frozen. They were stored a t -10 OC and thawed for use as necessary. Both mills were sampled twice. In 1972, grab samples for chemical characterization were taken a t various stages of the treatment systems and time delays were programmed so that a "slug" of the effluent could be followed through the treatment facilities. However, quantitative analysis indicated that the slug was missed a t the outfall of Mill "A". During the second sampling period, in January 1974, three-day composites were collected from the raw effluent and the outfalls of both mills by automatic sampling devices. Samples were not taken a t intermediate points. A three-day composite composed of equal volumes from the Monday, Tuesday, and Wednesday raw wastewater samples of Mill "A" was prepared. A second three-day composite was composed of equal volumes from the Wednesday, Thursday, and Friday treated wastewater samples of Mill "A". Three-day composities of equal volumes from the Monday, Tuesday, and Wednesday raw wastewater and of the treated wastewater samples of the Interstate Mill a t Riceboro were prepared. Because the stabilization pond retention time is a t least three months, no attempt was made to obtain samples of the same slug of this wastewater. The concentrations in the 1972 grab samples (Table 11) cannot be considered "typical" because the concenpations of the individual components vary significantly with time. Comparison of these values with those obtained in the 1974 sampling period (which are more "typical" because they represent three-day composites) shows that while some compounds varied almost by an order of magnitude, others had very similar values.
I n s t r u m e n t a t ion Both Varian 1400 and Perkin-Elmer 900 gas chromatographs (GC) equipped with flame ionization detectors (FID) were used. Generally, a commercially prepared (PerkinElmer) 50-ft support coated open tubular (SCOT) capillary column coated with Carbowax 20Mherephthalic acid (K 20
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Figure 3. Gas chromatograms of the methyl derivatives from Mill "A" wastewater using (A) dimethyl sulfate, (E) diazomethane, (C) Methyl-8, and (D) MethElute as methylating reagents 556
Environmental Science & Technology
M/TPA) was used for separation. The optfmum carrier gas flow for our GC-MS systems operating under a vacuum and using a Gohlke jet separator (16-18 ml/min) is twice the amount necessary for optimizing conditions with an auxiliary GC (operating under atmospheric pressure). From 1968 to 1971, a Perkin-Elmer/Hitachi RMU-7 double focusing mass spectrometer (MS) connected to a Perkin-Elmer 900 GC through a Watson-Bieman separator was used. Now a computerized Finnigan 1015 quadrupole MS connected to an all-glass, single-stage Gohlke jet separator is used. Complete descriptions of the instrumentation and our techniques for computer matching the mass spectral data are described elsewhere (7, 8).
Analytical Procedures Methylation Techniques. Paper mill wastewater extracts contain two types of extractable volatile compounds: neutrals (predominately terpenes and their derivatives), and acidic compounds converted to their methyl derivatives to facilitate GC separation. The aqueous solution can be methylated directly with dimethyl sulfate and sodium hydroxide, followed by extraction of the methyl derivatives with chloroform, or methyl derivatives of the acid extracts can be made in a separate step using diazomethane, on-column GC methylation techniques, or several other common methylation procedures. Several methods were evaluated-each has its advantages and disadvantages, but their overall effectiveness is best illustrated by Figure 3. A 500-ml portion of the Mill "A" wastewater from sample point 2 (primary clarifier effluent) was made alkaline to pH 11 with sodium hydroxide and extracted with chloroform to remove the neutral compounds. Methylation of the aqueous layer with dimethyl sulfate was followed by re-extraction with chloroform to remove the methylated organics. The procedure we use (9) is a variation of that described by Bicho et al. ( I O , 11). After concentration in a Kuderna-Danish apparatus to 0.5 ml, 1.2 ~1 of the extract was chromatographed on a 50-ft SCOT column coated with Carbowax 20 M/TPA and programmed from 100-200 "C a t 4"/min with an initial 2-min hold a t 100'. The chromatogram is shown in Figure 3-A. A 1-1. portion of the same wastewater was extracted with chloroform a t pH 11to remove neutral compounds and then made acidic to pH
