Neutral organic compounds in biologically treated bleached kraft mill

Neutral organic compounds in biologically treated bleached kraft mill effluents. Ronald H. Voss. Environ. Sci. Technol. , 1984, 18 (12), pp 938–946...
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Envlron. Sci. Technol. 1904, 18, 938-946

Neutral Organic Compounds in Biologically Treated Bleached Kraft Mill Effluents Ronald H. Voss Pulp and Paper Research Institute of Canada, Pointe Claire, Quebec, Canada "3 3J9

About 40 neutral organic compounds were identified by gas chromatography/mass spectrometry from a survey of biologically treated bleached kraft mill effluents sampled from the aerated lagoon discharge at nine bleached kraft pulp mill sites. Several classes of compounds were found including terpenes (such as camphor), organosulfur compounds (such as 2-acetylthiophene), chlorinated dimethyl sulfones, chlorinated p-cymen-8-ols, and a group of methyl-substituted 2-cyclopentenones. Although the terpene content in the various biotreated effluents was quite variable, the methyl-substituted 2-cyclopentenones were observed to be relatively common residual organics in such effluents. W

Introduction According to Keith ( I ) , a new phase of environmental chemistry, namely, the identification and analysis of specific organic pollutants in water, was begun in the early 1970s. A knowledge of the identities and quantities of specific organic compounds in industrial wastewaters is recognized as a valuable basis for pollution treatment and control and, also, for evaluation of the possible environmental impact resulting from the discharge of such wastewaters to the aquatic environment. Environmental effects of concern to society range from the possible impairment of drinking water taste and odor or fish tainting to potential chronic toxic effects on aquatic life and man. The single most important factor contributing to our ability to identify specific organic compounds in water has been the development of combined gas chromatography/mass spectrometry (GC/MS). A treated kraft pulp mill effluent was one of the first industrial wastewaters to which this powerful analytical tool was applied (2). Subsequent results acquired over a 6-year period from studies of treated and untreated unbleached kraft paper mill wastewaters at two mill sites in Georgia were published by Keith in 1976 ( 3 , 4 ) . About the same time, Hrutfiord and co-workers reported the results of a study to determine the organic compounds entering and leaving the aerated lagoon treatment systems at two mill sites located in the U S . Northwest (5-7). Their study included a bleached, as well as an unbleached, kraft mill. Since the completion of these two studies in the early 197Os,little or no new work has been reported on the characterization of the (nonchlorinated) organic constituents and particularly the neutral organics in biologically treated kraft mill effluents. Recently we have undertaken a chemical analysis program to obtain a detailed inventory of the low molecular weight organic compounds, viz., those which are amenable to gas chromatographic analysis, found in bleached kraft mill effluents (BKME), particularly after treatment in aerated lagoons. To obtain information generally applicable to biologically treated BKME, aerated lagoon outlet samples for chemical analysis were taken from nine softwood bleached kraft pulp mills located across Canada. Information pertaining to the chlorinated, neutral organic content of the nine biotreated BKME samples has already been reported (8). In this paper we present the results of a study to determine the unchlorinated neutral organic 930

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constituents present in the same nine samples of biotreated BKME. Experimental Section Effluent Samples. A grab sample of aerated lagoon discharge was collected at each of the nine bleached kraft pulp mill sites during the winter of 1980-1981. The retention time in the aerated lagoons at the various mill sites ranged from 5 to 8 days. Upon receipt of the effluent samples at our laboratory, they were transferred to 1-L polyethylene plastic bottles and stored at -10 "C until analyzed. Preparation of Effluent Samples for GC and GC/ MS Analysis. Figure 1shows a schematic of the procedure used to isolate organic constituents from the lagoon outlet samples and to fractionate the isolated organic compounds into the following three classes for subsequent GC and GC/MS analysis: neutral, pentane solubles (fraction "A"), neutral, methylene chloride solubles (fraction "B"), and methylene chloride soluble phenolics (fraction "C"), Typically, 1 L of effluent acidified to ca. pH 2 with sulfuric acid was passed by gravity flow (-20 mL/min) through a bed (15 cm long X 1.1cm diameter) of XAD-2 resin (-15 mL) held in a glass column. Following the adsorption step, the resin was washed sequentially, first with 10 mL of acetone (Burdick 85 Jackson; distilled in glass) and then 40 mL af methylene chloride (Burdick & Jackson; distilled in glass). The acetone/methylene chloride eluate was collected in a 125-mL separatory funnel, separated from a small upper layer of water, and then evaporated to approximately 1mL under reduced pressure with a rotary evaporator. After addition of 20 mL of pentane (Burdick & Jackson; distilled in glass), the pentane-rich eluate was extracted twice with 20-mL portions of 0.1 M NaOH. The aqueous layer was collected and further extracted twice with 10-mL portions of pentane. To the combined pentane extracts (total volume -40 mL) was added 50 pL of isooctane containing 1.03 pg/pL of n-tridecane (Analabs, Inc.) which served as an internal standard for subsequent GC analysis. The combined pentane extract was concentrated by using a two-step procedure. First, a vacuum rotary evaporator was used to reduce the volume to about 0.8 mL. Second, further concentration to about 0.5 mL in a 1-mL Reacti-Vial (Pierce Chemical Co.) was accomplished by using a gentle stream of nitrogen. This provided fraction A shown in Figure 1. The aqueous alkaline layer (-40 mL) remaining after extraction with pentane was extracted twice with 10-mL portions of methylene chloride to recover the more polar neutral organic compounds not extracted by the pentane. To the combined methylene chloride extract was added 50 pL of a stock solution of n-tridecane internal standard (1.03 pg/pL in isooctane). The volume of the methylene chloride extract was reduced to 0.5 mL (=fraction B) by using the same concentration procedure as described above for the pentane-soluble fraction. The aqueous alkaline solution remaining from the methylene chloride extraction was adjusted to -pH 8 with

0013-936X/84/0918-0938$01.50/0

0 1984 American Chemical Soclety

Scheme I R7

1

NO?

-

R4

Acidify to p H 2

c=l XAD-2

Elute with acetoneICH2CI2

Eluate I

1. Concentrate 2. Add pentane 3. Extract with aq. NaOH

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1:15 split ratio was used (column flow = 1.2 mL/min; split +l vent flow = 18 mL/min). Pentane Layer

1. Extract lpentanel

1. Add Int std. 2. Concentrate

2. Extract Pentane Extract

ri CHzC12 Layer

1. Add int. std. 2. Concentrate

t Aqueous Layer

I 1 Neutralize 2. Add int. std 3. Acetylate 4. Extract with CHzCI2

Figure 1. Schematic of procedure used to prepare samples for and GC/MS analysis.

GC

1N sulfuric acid and transferred to a 125-mL separatory funnel. Internal standard, 4-isopropylphenol (40 fiL of 1.026 fig/fiL solution in acetone), and 2 g of NaHC03 were added to the aqueous sample. Upon addition of 1 mL of acetic anhydride, the separatory funnel was shaken vigorously for 2 min with frequent venting to permit the release of evolved carbon dioxide. After being allowed to stand for 15 min, the acetylated sample was extracted twice with 10-mL portions of methylene chloride. The combined methylene chloride extract was then concentrated to 0.4 mL (=fraction C) by using the same procedure for extract concentration as employed for fractions A and B. Corresponding reagent blanks for each fraction were also prepared. This paper will deal solely with the analysis of the two neutral fractions (A and B). Results from an investigation of the phenolic fraction (C) will be presented in a separate forthcoming report. Instrumentation and Analysis. Gas chromatographyJmass spectrometry was performed on a HewlettPackard Model 5985A GC/MS system. A 30 m X 0.25 mm i.d. fused silica capillary column, wall coated with SE-30 (J & W Scientific, Orangeville, CA), was connected to the quadrupole mass spectrometer via a glass jet separator. Helium makeup gas at a flow rate of 30 mL/min was added a t the capillary column outlet. Electron impact mass spectra were obtained at 70-eV ionizing energy. The temperatures of the jet separator interface and ion source were 250 and 200 "C, respectively. The GC conditions were as follows: column, 110 "C (held for 3 min) and then programmed to 120 "C at 1"C/min followed immediately by a 8 "C/min temperature increase to 210 "C; injector, 250 "C; carrier gas, helium at 90 P a . A split injection with

In many cases preliminary compound identifications were based on computer matching of mass spectra employing the MSSS (Mass Spectral Search System) component of the NIH/EPA Chemical Information System. Wherever possible, the tentative assignments were confirmed by running pure reference compounds through the GC/MS system. Although the main purpose of this study was to obtain qualitative information about the indentity of neutral organics in biotreated BKME, we also determined approximate concentrations for the individual compounds by GC analysis using a Hewlett-Packard Model 5840A gas chromatograph (which was a component of the 5985A GC/MS system) with a flame ionization detector (FID). The GC conditions used were the same as those described above for GC/MS analysis. Compound concentrations were estimated on the basis of (electronically integrated) GC peak areas relative to the tridecane internal standard and an assumed relative response factor of 1.0 in all cases. In addition, it should be mentioned that factors such as recovery and precision were not thoroughly assessed; therefore, the concentration data should be considered as being only semiquantitative. Reference Compounds. The following standards were obtained from commercial suppliers: 2-acetylthiophene, 3-acetylthiophene, a-terpineol, terpinen-4-01, benzyl alcohol, 3-methyl-2-cyclopentenone, and verbenone from Aldrich Chemical Co.; dimethyl trisulfide, fenchyl alcohol, p-isopropylcyclohexanol (mixture of cis and trans), and piperitone from Pfaltz & Bauer; fenchone and borneol from ICN Pharmaceuticals, Inc.; a-phellandrene from Fluka Chemical Corp.; camphor from J.T. Baker Chemical Co.; 2-propionylthiophene from Alfa Products; trans-piperitol from PCR Research Chemicals Inc.; 1,4-dichlorobenzene from RFR Corp. A Grignard synthesis was used to prepare p-cymen-8-01 by reacting p-methylacetophenone (Aldrich) with CH3MgBr. A series of methyl-substituted 2-cyclopentenones were synthesized in our laboratory by alkaline cyclization of 1,4-diketones (9) according to Scheme I. Alkaline Degradation of Bleached Kraft Pulp. A sample of fully bleached softwood kraft pulp was used as a cellulose-rich substrate to investigate the low-molecular-weight organics formed from cellulose during kraft cooking. The kraft pulping process utilizes an aqueous alkaline solution of Na2S at elevated temperatures to reduce the wood feed stock to a fibrous pulp. A kraft "cook of the fully bleached softwood kraft pulp was made in a 250-mL autoclave. The 250-mL bomb was charged with 20.2 g of air-dried pulp plus 200-mL of "cookingn liquor which was an aqueous solution of NaOH (1M) and Na2S (0.2 M). The bomb was then placed in an oil bath wherein Environ. Sci. Technol., Vol. 18, No. 12, 1984

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I

I

I

lMill DI

3

10

20

30

Time (min) Figure 2. Gas chromatograms for pentane-soluble fractions isolated from biologically treated bleached kraft mill effluents from mills A-D (S = internal standard).

the cooking temperature of 170 OC was reached after 90 min. The bomb was held at the cooking tempetature for an additional 85 min. A 100-mL aliquot of the spent cooking liquor was extracted with three 100-mL portions of pentane. The pentane extracts were combined and then concentrated to 1mL by using a vacuum rotary evaporator.

Results and Discussion Pentane-Soluble Neutral Organics. Figures 2 and 3 show the gas chromatograms for the pentane soluble 940

Environ. Sci. Technol., Vol. 18, No. 12, 1984

fractions obtained from the nine effluent extracts. Table I lists the individual neutral organics that were identified in the pentane-soluble fractions by GC/MS analysis. Before the individual organic compounds are considered, some general features of the GC profiles should be noted. On the basis of their content of terpenes (mainly located in the region between peaks 11 and 25 in Figures 2 and 3), the pulp mill effluenta can be grouped into two classes, those effluents (mills A-D) where terpenes were relatively dominant components (Figure 2) and those effluents (mills

IUill GI S

0

10

20

30

Time (min) Flgure 3. Gas chromatograms for pentanasoluble fractions isolated from blologlcally treated bleached kraft mill effluent from mills E-I (S = internal standard).

E-I) where terpenes were much less abundant (Figure 3). Several factors including the type of raw wood furnish, the absence or presence of in-plant pollution control measures (e.@;.,turpentine recovery and condensate stripping), total water usage, and operating efficiency of the aerated lagoon are the likely causes of the observed differences with respect to terpene concentrations. Further investigation is required in order to establish the relative importance of the various factors. Regardless of the terpene content, all of the effluent samples, with the exception of effluent from

mill I, had very similar profiles for the early eluting peaks (1-10 in Figures 2 and 3). Because many of the early eluting peaks were common to most of the effluent samples, our discussion will begin with an examination of the identity of the individual neutral organics found in this region of the gas chromatograms. Of particular interest are the compound peaks 1, 5, 7, 10, 12, and 13 (see Figures 2 and 3 and Table I) which correspond to a homologous series of methyl-substituted 2-cyclopentenones. Two of these compounds, Environ. Sci. Technol., Vol. 18, No. 12, 1984

941

Table I. Pentane-Soluble Neutral Organics Found from a Survey of Nine Biologically Treated Bleached Kraft Mill Effluents peak no."

compd identified

approximate concn, unlL mean range

1 2,5-dimethyl-2-cyclopentenone* 6 (9)' 2 dimethyl trisulfide* NQd (6) 3 a-phcllandrene* 10 (1) 4 1,4-dichlorobenzene NQ 5 2,3-dimethyl-2-cyclopentenone* 10 (6) 6 @-phellandrene 10 (1) 7 2,3,5-trimethyl-2-cyclopentenone* 20 (8) 8 3-acetylthiophene* 4 (7) 9 2-acetylthiophene* 7 (7) 10 2,3,4-trimethyl-2-cyclopentenone* 9 (8) 11 fenchone* 10 (5) 12 2,3,4,5-tetramethyl-2-cyclo4 (9) pentenone* 13 tetramethyl-2-cyclopentenone NQ (7) 14 fenchyl alcohol* 7 (4) 15 cyclohexylidene acetone 30 (4) 16 unidentified terpene 10 (3) 17 camphor* 40 (7) 18 2-methyl-3-isopropylcyclo30 (2) pentanone 19 2-propionylthiophene* 7 (7) 20 unidentified terpene alcohol 30 (7) 21 terpinen-4-01* 50 (4) 22 unidentified terpene alcohol 50 (5) 23 a-terpineol* 200 (2) 24 verbenone* 20 (3) 25 piperitone* 10 (3) 26 unidentified ketone 10 (6) 27 dicyclohexylamine 60 (2) 28 dichloro-p-cymen-8-o1 6 (8) 29 diethyl phthalate 50 (9) 30 p-menthane-1,2-diol 10 (5) 31 unidentified S-bearing compound 10 (8) 32 diisobutyl phthalate NQ (8) 33 dibutyl phthalate 70 (9) 10 (7) 34 juvabione

2-10

5-20 9-40 2-6 3-10 1-20 2-20 2-10 3-10 8-80 2-20 3-100 20-30 2-10 2-80 10-100 2-100 5-300 10-30 10-20 2-20 30-100 2-20 20-100 3-30 3-20 10-100 2-30

"From Figures 2 and 3. *Asterisk denotes that identification was confirmed by comparison with mass spectrum and GC retention time of a pure standard. cNumber in parentheses indicates the number of samples out of nine where the compound was found. Not quantitated.

2,5-dimethyl-2-cyclopentenone (peak 1)and,2,3,4,5-tetramethyl-2-cyclopentenone(peak 12), were found in all nine of the biotreated BKME samples. Eight of the effluent samples contained both 2,3,5-trimethyl-2-cyclopentenone (peak 7 ) and 2,3,4-trimethyl-2-cyclopentenone (peak 10). The GC/MS data also indicated that for several of the effluents a trace amount of acetophenone coeluted with the 2,3,5-trimethyl-2-cyclopentenone (peak 7 ) . Methylsubstituted 2-cyclopentenones have previously been identified in a variety of sources including tobacco and tobacco smoke condensates (10-15) and coffee (16) and in products derived from the aqueous alkaline degradation of pure cellulose (17). The latter observation was made by Molton and co-workers from a study to elucidate the mechanism of conversion of cellulosic wastes to liquid fuels through thermochemical digestion in aqueous sodium carbonate at elevated temperatures (>300 "C) (17). Molton et al. identified 2,5-dimethyl-2-cyclopentenoneas well as several alkyl-substituted cyclopentanones from GC/MS analysis of the low-molecular-weight products obtained from the aqueous alkaline degradation of cellulose. In a similar study Eager et al. (18) identified several alkyl-substituted cyclopentanones in oils derived from the alkaline digestion of aspen poplar wood, cellulose, and an isolated poplar lignin. The relative abundance of the cy942

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No. 12, 1984

10

Time (min)

15 I

Figure 4. Gas chromatogram for pentane-soluble organics in spent liquor derived from a kraft cook of fully bleached softwood kraft pulp. (GC conditions are the same as described under Experimental Section except for modification to oven temperature program: 75 "C (held for 2 min) and then programmed to 140 "C at 5 "C/min.)

clopentanones was observed to decrease from cellulose to wood to lignin. From an analysis of the oils derived from hydrogenation of aspen wood, Boocock and co-workers (19) observed that one-third of the neutral organic fraction consisted of alkyl cyclopentanones and cyclohexanones. The results from such studies on the conversion of biomass to potential liquid fuels suggest that the methyl-substituted 2-cyclopentenones which we found in our effluent samples probably originated from the degradation of the cellulose component of wood during the kraft pulping process. In kraft pulping the wood chips are cooked in an alkaline solution of NazS at a temperature of approximately 170 "C. To test this hypothesis regarding the origin of the methyl-substituted 2-cyclopentenones, a celluloserich substrate (fully bleached softwood kraft pulp) was subjected to a "kraft cook". Subsequent GC/MS analysis of the organic material extracted with pentane from the spent cooking liquor revealed (see Figure 4) that the pentane-soluble neutral organics in the liquor corresponded almost exclusively to methyl-substituted 2-cyclopentenones. This extract contained all of the methylsubstituted 2-cyclopentenones previously found in the effluent extracts (Table I; Figures 2 and 3) plus some additional isomers as well as monomethyl- and pentamethyl-2-cyclopentenones. This study reinforces the assumption that the methyl-substituted 2-cyclopentenones found in kraft combined mill effluents probably originate from the alkaline degradation of the cellulose component of wood during kraft pulping. While the present work was being prepared for publication, Turoski et al. (20) reported the identification of 3-methyl-2-cyclopentenoneand 2,3,4-trimethyl-2-cyclopentenone in a treated (unspecified) paper mill effluent. Otherwise, none of these types of compounds have previously been reported in kraft mill wastewaters. Inasmuch as our study indicated that the methyl-substituted 2cyclopentenones are common constituents of kraft pulp mill wastewaters, it was somewhat surprising that they were not found in the previous studies made by Hrutfiord et al. (5) and Keith ( 1 , 3 , 4 ) . A closer examination of their data, however, suggests that the 2-cyclopentenones were present in their effluent samples as well. For example, in 1969 Keith (2) reported a cluster of three GC peaks whose mass spectra contained dominant ions at masses 110 (parent ion), 95, and 67. He assigned the tentative empirical formula of C,HI00 to these compounds. In all

ii 50. 0

Flgure 6. Mass spectrum for compound (peak 28 in Figures 2 and 3) tentatively Identified as dichloro-p-cymen-8-ol. hrrnrr

120

I

I

Flgure 5. Mass spectra of dlmethyl-2-cyclopentenone standards: (a) 2,5dimethyl-2-cyclopentenone; (b) 2,3dimethyl-2-cyclopentenone.

likelihood these compounds corresponded to dimethyl-2cyclopentenones. Mass spectra for the 2,5- and 2,3-dimethyl-2-cyclopentenoneswhich we have identified in biotreated BKME (compounds 1 and 5 in Table I and Figures 2 and 3) are shown in Figure 5. Note the major fragments at 110, 95 and 67 amu. Similarly, the compounds assigned an empirical formula C8H120and having major ions at masses 124 (parent ion), 109, and 81 probably corresponded to trimethyl-2-cyclopentenones. The “unidentified terpene ketones” reported in a later publication by Keith (e.g., compounds 65,67,68, and 70 in his Table I (3)) are all likely to be methyl-substituted 2cyclopentenones. Computer matching of the mass spectra for these compounds using the mass spectral data base which was available to Keith at that time provided tentative identifications (3) of l-cyclohexenyl methyl ketone and 3-cyclohexen-l-yl methyl ketone for two of the compounds which probably corresponded to trimethyl-2cyclopentenones. Also, the mass spectral fragment ions reported by Hrutfiord et al. (5) for their unknowns 15 and 18 (Table I11 in ref 5 ) are consistent with a dimethyl- and a trimethyl-2-cyclopentenone,respectively. Fortunately the EPA/NIH mass spectral library that we used for our computer-assisted searches contained the spectra for several isomers of trimethyl-2-cyclopentenone.Consequently, searches of the EPA/NIH mass spectral data base alerted us to the possible presence of such compounds in the BKME samples which we studied. Other relatively common compounds found in the early portion of the GC chromatograms for the pentane soluble fractions (Figures 2 and 3) were three organosulfur compounds, dimethyl trisulfide (peak 2), 3-acetylthiophene (peak 8), and 2-acetylthiophene (peak 9). Dimethyl trisulfide was detected in six of the nine effluent samples. Owing to its surprisingly strong response to the electron capture detector (ECD), we had previously (8) detected dimethyl trisulfide from an investigation of the chlorinated neutral organics content of these same nine biotreated BKME samples. The identification of dimethyl trisulfide in treated and untreated kraft mill effluents has been reported earlier by Keith (3,4) and Hrutfiord et al. (5-7). Recently Rogers (21)identified dimethyl trisulfide in a sample of biologically treated BKME taken from a pulp mill located in western Canada. Unlike 2-acetylthiophene which has been reported previously by Keith (3, 4), the

3-acetylthiophene(peak 8) appears to be a newly identified compound in treated kraft mill effluents. The terpene composition of the biologically treated BKME samples was similar in some respects to that found from previous studies of treated kraft mill effluents (3-7). For example, camphor (peak 17 in Table I and Figures 2 and 3) and, less frequently, fenchone (peak 11)were major terpenes in the lagoon outlet samples. In other respects, the terpene composition of our effluent samples was different in that in some cases terpene alcohols were dominant terpene components, e.g., a-terpineol (peak 23) in mill A effluent and terpinen-4-01 (peak 21) in biotreated BKME from mills B and D. Two compounds, peaks 20 and 22, which were tentatively identified as “terpene alcohols” (Table I) were relatively common constituents of the biotreated bleached kraft mill effluents. The mass spectrum for compound 20 was very similar to that for p-cymen-8-01. However, its retention time did not match that for a p-cymen-8-01 standard-compound 20 eluted approximately 0.1 min earlier. Mass spectrum of compound 22 was similar to that for a-terpineol. Verbenone (peak 24) and piperitone (peak 25) appear to be newly identified terpenes in biotreated BKME. An organosulfur compound, 2-propionylthiophene (peak 19), was found in the vicinity of the terpene alcohols in the gas chromatograms for seven of the nine effluents samples. Keith (3,4) had previously reported the identification of this compound in treated kraft paper mill wastewaters. Many of the dominant later eluting peaks in the GC chromatograms (Figures 2 and 3) for the pentane-soluble fractions corresponded to phthalate esters (peaks 29, 32, and 33) which are ubiquitous environmental contaminants. The source of these compounds is not certain. Some may have leached out of the plastic containers used for shipping and storing the effluent samples. Some of the phthalates may have originated from the mill process equipment (pipes, seals, etc.). Although the major emphasis of this study was the identification of non-chlorinated neutral organics, two chlorinated neutral organics were identified in the pentane-soluble fractions: 1,4-dichlorobenzene (peak 4 in Figure 3 and Table I) and dichloro-p-cymen-8-01(peak 28). The identification of the dichloro-p-cymen-8-01was based upon mass spectral interpretation and also upon comparison with the published mass spectrum for chlorocymen-8-01(22). A mass spectrum used for this tentative identification is presented in Figure 6. Lindstrom et al. have previously reported (23,24) the presence of monoand dichloro-p-cymen-8-01sin the spent wash liquors obtained from the chlorination stage of kraft pulp bleaching. We are not aware of any previous reports of chlorinated p-cymen-8-01s in combined bleached kraft mill effluents. To obtain a preliminary assessment of the effect of an aerated lagoon waste treatment system on the pentanesoluble neutral organics, additional samples of BKME entering and leaving mill F’s aerated lagoon were examined by GC and GC/MS analysis. The overall effectiveness of the treatment system can be assessed by visual comparison of the GC profiles for the lagoon inlet and outlet samples Environ. Sci. Technol., Vol. 18, No. 12, 1984

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I LAGOON INLET 1

I LAGOON OUTLETI (29

31

I V

Time (min) Figure 7. GC/FID chromatographicprofiles of pentane-soluble neutral organics through the biological treatment system of bleached kraft pulp mill F (S = internal standard).

shown in Figure 7. Information about the identification of the GC peaks shown in Figure 7 along with semiquantitative concentration data is given in Table 11. A considerable reduction in the (detectable) number and concentration of neutral organics after aerated lagoon treatment is readily apparent from an inspection of the GC profiles for the lagoon inlet and outlet samples (Figure 7). Most of this decrease is related to a relatively efficient removal of the terpene components which are located mainly in the region between compound peaks 8 (fenchone) and 25 (piperitone) in Figure 7. Mill F’s aerated lagoon reduced the concentration of terpenes in the combined bleached kraft mill effluent by about 90%. The GC/MS data for the peak identified as camphor (peak 14 in Figure 7) indicated that this peak corresponded to a mixture of camphor and trans-p-isopropylcyclohexanol for the lagoon inlet sample. Except for 2,3-dimethyl-2cyclopentenone (peak 3 in Figure 7 and Table 11), the methyl-substituted 2-cyclopentenones (peaks 1,4,7,9, and 10 in Figure 7 and Table 11) appeared to pass through the aerated lagoon with little, if any, removal. Ketones 65,67, and 68 from Keith’s study (3, 4 ) , which we suspect correspond to methyl-2-cyclopentenones,were also observed not to decrease in concentration after treatment at one of the mill sites included in his study. The aerated lagoon’s removal efficiency for the acetylthiophenes (compound peaks 5 and 6 in Table 11) was about 50 % . 944

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The chlorinated neutral organic compounds found in the lagoon inlet and outlet samples included 1,4-dichlorobenzene (peak 2 in Figure 7), a,a,a’-trichlorodimethyl sulfone (peak 22), and a series (peaks 27 and 31) of dichloro- and trichloro-p-cymen-8-01s. The presence of chlorinated dimethyl sulfones including a,a,a’-trichlorodimethyl sulfone in biologically treated BKME has been reported and discussed previously (8). To our knowledge the occurrence of chlorinated p-cymen-8-01sin combined bleached kraft mill effluent has not been reported before. The presence of up to five isomers of monochloro- and dichloro-p-cymen-8-o1 in spent liquor from the first (chlorination)stage of kraft pulp bleaching has been noted by Lindstrom and Nordin (23). The location of the chlorinated p-cymen-8-01s in our sample chromatograms was determined from extracted ion current profiles by using masses 43, 203, and 205 to find the dichloro-p-cymen-8-01s and masses 43, 237, and 239 to locate the trichloro-p-cymen-8-01s. Otherwise, many of these compounds, particularly the trichloro-p-cymen-8-ols, would have gone undetected. Distinct peaks for the trichlorop-cymen-8-01s were not observed in the GC/FID chromatograms (Figure 7). The compounds tentatively identified as trichloro-p-cymen-8-01s were estimated to be present in the effluent samples at a concentration less than 1pg/L. The semiquantitative concentration data obtained for one of the dichloro-p-cymen-8-01s(peak 27 in Table 11) suggest that the chlorinated p-cymen-8-01smay not be

~~

Table 11. Pentane-Soluble Neutral Organic Compounds Found Entering and Leaving Mill F's Aerated Lagoon

peak no.' 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

II

approximate concn, pg/L inlet outlet

compd identified 2,5-dimethyl-2-cyclopentenone* 1,4-dichlorobenzene 2,3-dimethyl-2-cyclopentenone* 2,3,5-trimethyl-2-cyclopentenone* 3-acetylthiophene* 2-acetylthiophene* 2,3,4-trimethyl-2-cyclopentenone* fenchone* 2,3,4,5-tetramethyl-2-cyclopentenone* tetramethyl-2-cyclopentenone fenchyl alcohol* cyclohexylidene acetone cis-p-isopropylcyclohexanol* camphor* born eo1* 2-propionylthiophene* unidentified terpene alcohol p-cymen-&ol* terpinen-4-01* unidentified terpene alcohol a-terpineol* a,a,a'-trichlorodimethylsulfone* piperitol* pentamethyl-2-cyclopentenone piperitone* unidentified ketone dichloro-p-cymen-8-o1(4 isomers) diethyl phthalate p-menthane-l,a-diol unidentified S-bearing compound trichloro-p-cymen-8-01(2 isomers) dibutyl phthalate manool total

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20

Time (mid

fractions. Surprisingly, the 2,3 isomer of dimethyl-2cyclopentenone was about equally distributed between the pentane and methylene chloride fractions. A dominant peak (peak 3 in Figure 8) that appeared in the methylene chloride soluble fractions of all nine of the effluent samples corresponds to a,a-dichlorodimethyl sulfone. Chlorinated dimethyl sulfones, including a,a-dichlorodimethyl sulfone, a,a,a'-trichlarodimethylsulfone (peak 6 in Figure 8), and (tentativey) a,a,a,',a',-tetrachlorodimethylsulfone, were identified in a previous investigation (8) of the chlorinated neutral organics content of the same nine samples of biotreated BKME. The results of the previous study (8) revealed that a,a-dichlorodimethyl sulfone with a mean concentration of 223 pg/L is the single most dominant chlorinated organic constituent in biologically treated bleached kr mill effluent. From a closer reexamiantion of the methyle e chloride extract for one of the mill effluents (mill D), we were able to find the monomethyl-2cyclopentenones plus some additional (unidentified) dimethyl-2-cyclopentenones which had been found in the pentane extract from the cellulose cook (Figure 4). An indication of the effect of biological treatment on the methylene chloride soluble organics was obtained by GC and GC/MS examination of a new set of samples for mill F corresponding to BKME entering and leaving this mill's aerated lagoon. As shown in Figure 9 biological treatment (peak had little effect on 2,3,5-trimethyl-2-cyclopentenone 3 in Figure 9) and the chlorinated dimethyl sulfones (peaks 4 and 7). Our previous assessment of the effect of biological treatment on the chlorinated dimethyl sulfones (8) had also indicated that they were relatively resistant to removal by aerated lagoon treatment. The lagoon inlet sample for the methylene chloride fraction of mill F effluent also contained two phenolic compounds: guaiacol (peak 5 in Figure 9) and 4-ethylguaiacol (peak 8). Apparently portions of these compounds were extracted by methylene chloride from the 0.1 M NaOH aqueous solution (see Figure 1). The presence of a trace amount of 2,3,4trimethyl-2-cyclopentenone(peak 6 in Figure 9) which was presumed to be present in the lagoon inlet sample would be obscured by the guaiacol which had a similar retention time. Results from a study of the phenolic fraction ("C"

%

S

2

LAGOON OUTLET

Figure 9. GWFID chromatographic profiles of methylene chloride soluble neutral organics through the biological treatment system of bleached kraft pulp mill F: S, trldecane internal standard; 1, benzyl alcohol; 2, 2,3dlmethyl-2-cyclopentenone; 3, 2,3,5-trlmethyl-2-cyclopentenone; 4, a,adichlorodlmethyIsulfone; 5, guaiacol; 6, 2,3,4trimethyl-2-cyclopentenone; 7, a,a,a'-trlchlorodimethyl sulfone; 8, 4ethylguaiacol.

From Figure 7. bAsterisk denotes that identification was confirmed by comparison with mass spectrum and GC retention time of a pure standard. CNot quantitated. dNot detected. e Approximate concentration for dominant isomer.

I

S

. 20

30

Time (rnin) Figure 8. Gas chromatogram for methylene chlorlde soluble fraction of biologically treated BKME for mill F (S = tridecane Internal standard).

easily removed by aerated lagoon biological treatment systems. Methylene Chloride Soluble Neutral Organics. The GC trace shown for the mill F effluent in Figure 8 is representative of the GC profiles observed for the methylene chloride soluble fractions of the nine biotreated BKME extracts. In comparison to the pentane-soluble fractions (see Figures 2 and 3) the gas chromatograms for the methylene chloride fractions (e.g., Figure 8) contained fewer and smaller peaks. Most of the peaks identified in Figure 8 correspond to compounds (peaks 1-2 and 4-6) which were not completely recovered by the previous pentane extraction. The concentrations of the trimethyl-2-cyclopentenones(peaks 2 and 5 in Figure 8) in the methylene chloride fractions (Table 11) were generally about 10% of the amounts found in the pentane-soluble

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No. 12, 1984 945

in Figure 1)of the nine biotreated BKME samples will be reported separately. Conclusions. About 40 neutral organic compounds were identified from a survey of biologically treated bleached kraft mill effluents sampled from the aerated lagoon discharge at nine bleached kraft pulp mill sites. The mean concentration for the compounds listed in Table I for “typical” biologically treated bleached kraft mill effluent is about 30 pg/L and ranges from 4 to 200 pg/L. Upon discharge of the treated pulp mill effluent to recipient waters and subsequent dilution (typically 1:lOO and greater), the concentrations of the neutral organic compounds identified from this study are expected for the most part to be at the submicrogram per liter level. Information about ecological effects is lacking for most of the compounds identified from this study. Consequently, at this time it is difficult to specify whether such levels of the neutral organic compounds in the pulp mill receiving waters would present an enviromental problem. Should deleterious environmental effects traceable to the discharge of treated bleached kraft mill effluents be observed, then the inventory of neutral organic compounds developed from this study will be valuable in helping to determine which compounds are responsible for what kind of deleterious effect and for developing strategies to control the discharge of such substances to the environment.

Acknowledgments

I am especially grateful to A. Rapsomatiotis for his expert technical assistance. The p-cymen-8-01standard was synthesized by A. Quesnel while on a cooperative work term from the University of Waterloo, Waterloo, Ontario. The assistance of Dr. R. D. Mortimer and P. M. Wong with the “cooking” of kraft pulp is greatly appreciated. Registry No. 2,5-Dimethyl-2-cyclopentenone, 4041-11-6; dimethyl trisulfide, 3658-80-8; a-phellandrene, 99-83-2; 1,4-dichlorobenzene, 106-46-7;2,3-dimethyl-2-cyclopentenone, 1121-057; 6-phellandrene, 555-10-2; 2,3,5-trimethyl-2-cyclopentenone, 54562-24-2; 3-acetylthiophene, 1468-83-3;2-acetylthiophene, 8815-3; 2,3,4-trimethyl-2-cyclopentenone, 28790-86-5; fenchone, 1195-79-5; 2,3,4,5-tetramethyl-2-cyclopentenone, 54458-61-6; tetramethyl-2-cyclopentenone,92366-34-2; fenchyl alcohol, 1632-73-1;cyclohexylidene acetone, 874-68-0; camphor, 76-22-2; 2-methyl-3-isopropylcyclopentanone, 54549-81-4; 2-propionylthiophene, 13679-75-9;terpinen-4-01,562-74-3; a-terpineol, 9855-5; verbenone, 18309-32-5;piperitone, 89-81-6; dicyclohexylamine, 101-83-7; dichloro-p-cymen-8-o1,92366-35-3;diethyl phthalate, 84-66-2;p-menthane-1,2-diol, 33669-76-0; diisobutyl phthalate, 84-69-5;dibutyl phthalate, 84-74-2; juvabione, 17904-27-7; cis-pisopropylcyclohexanol, 22900-089; borneol, 507-70-0;p-cymen-8-01, 64568-19-0; a,a,d-trichlorodimethyl sulfone, 64568-19-0; piperitol, 54983-96-9; pentamethyl-2-cyclopentenone, 92366-36-4; tri-

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chloro-p-cymen-8-ol, 92366-37-5; manool, 596-85-0.

Literature Cited (1) Keith, L. H. In ”Identification and Analysis of Organic Pollutants in Water”; Keith L. H., Ed.; Ann Arbor Science: Ann Arbor, MI, 1976; p iii. (2) Keith, L. H. “Abstracts of Papers”, 157th National Meeting of the American Chemical Society, Division of Water, Air, and Waste Chemistry, Minneapolis, MN, 1969; American Chemical Society: Washington, DC, 1969; p 76. (3) Keith, L. H. Enuiron. Sci. Technol. 1976,10, 555. (4) Keith, L. H. In “Identification and Analysis of Organic Pollutants in Water”; Keith, L. H., Ed.; Ann Arbor Science: Ann Arbor, MI, 1976; p 671. (5) Hrutfiord, B. F.; Friberg, T. S.; Wilson, D. F.; Wilson, J. R. US.Environ. Protect. Agency 1975,EPA-660/2-75-028. (6) Wilson, D.; Hrutfiord, B. Pulp Pap. Can. 1975,76 (No. 6), 91. (7) Hrutfiord, B. F.; Friberg, T. S.; Wilson, D. F.; Wilson, J. R. Tappi 1975,58(No. lo), 98. (8) Voss, R. H. Environ. Sci. Technol. 1983,17, 530. (9) King, G. S. C. Ph.D. Thesis, University of London, London, England, 1974, p 59. (10) Shigematau, H.; Ono, R.; Yamashita, Y.; Kaburaki, Y. Agric. Biol. Chem. 1971,35, 1751. (11) Kim, K.; Kurata, T.; Fujimaki, M. Agric. Biol. Chem. 1974, 38,53. (12) Fujimori, T.; Kasuga, R.; Matsushita, H.; Kaneko, H.; Noguchi, M. Agric. Biol. Chem. 1976,40,303. (13) Ishiguro, S.; Sugawara, S. Agric. Biol. Chem. 1978,42,1527. (14) Newell, M. P.; Heekman, R. A.; Moates, R. F.; Green, C. R.; Best, F. W.; Schumacher, J. N. Tob. Sci. 1978,22,6. (15) Sakuma, H.; Ohsumi, T.; Sugawara, S. Agric. Biol. Chem. 1979,43,2619. (16) Fridel, P.; Krampl, V.; Radford, T.; Renner, J. A.; Shephard, F. W.; Gianturco, M. A. J . Agric. Food Chem. 1971,19,530. (17) Molton, P. M.; Miller, R. KO;Donovan, J. M.; Demmitt, T. F. Carbohydr. Res. 1979,75, 199. (18) Eager, R. L.; Pepper, J. M.; Roy, J. C. Can. J . Chem. 1983, 61, 2010. (19) Boocock, D. G. B.; Kallury, R. K. M. R.; Tidwell, T. T. Am1. Chem. 1983,55,1689. (20) Turoski, V. E.; Woltman, D. L.; Vincent, B. F. Tappi 1983, 66 (No. 4), 89. (21) Rogers, I. H.; Mahood, H. W. Department of Fisheries and Oceans, Vancouver, B.C., 1982, Canadian Technical Report of Fisheries and Aquatic Sciences No. 1135. (22) Eklund, G.; Josefsson, B.;Bjorseth, A. J . Chromatogr. 1978, 150, 161. (23) Lindstrom, K.; Nordin, J. Sven. Papperstidn. 1978,81,55. (24) Lindstrom, K.; Nordin, J.; Osterberg, F. In “Advances in the Identification and Analysis of Organic Pollutants in Water”; Keith, L. H., Ed.; Ann Arbor Science: Ann Arbor, MI, 1981; Vol. 2, p 1039.

Received for review January 11,1984. Revised manuscript received May 3, 1984. Accepted June 5,1984.