B. Inanc*,****, B. Calli*, K. Alp**, F. Ciner***, B. Mertoglu* and I. Ozturk** * Marmara University, Faculty of Engineering, Dept. of Environmental Eng., 81040, Goztepe, Istanbul, Turkey (E-mail:
[email protected]) ** Istanbul Technical University, Faculty of Civil Engineering, Dept. of Environmental Eng., Maslak, Istanbul, Turkey *** Cumhuriyet University, Faculty of Engineering, Dept. of Environmental Eng., Sivas, Turkey **** National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan (E-mail:
[email protected]) Abstract This paper describes the wastewater characterization and aerobic/anaerobic treatability (oxygen uptake rate and biogas production measurement) of chemical-synthesis based pharmaceutical industry effluents in a nearby baker’s yeast industry treatment plant. Preliminary experiments by the industry had indicated strong anaerobic toxicity. On the other hand, aerobic treatability was also uncertain due to complexity and unknown composition of the wastewater. The work in this study has indicated that the effluents of the pharmaceutical industry can be treated without toxicity in the aerobic stage of the treatment plant. Methanogenic activity tests with anaerobic sludge from the anaerobic treatment stage of the wastewater treatment plant and acetate as substrate have confirmed the strong toxicity, while showing that 30 min aeration or coagulation with an alum dose of 300 mg/l is sufficient for reducing the toxicity almost completely. Powdered activated carbon, lime and ferric chloride (100–1,000 mg/l) had no effect on reduction of the toxicity. Consequently, the pharmaceutical industry was recommended to treat its effluents in the anaerobic stage of the nearby baker’s yeast industry wastewater treatment plan at which there will be no VOC emission and toxicity problem, provided that pretreatment is done. Keywords Aerobic, anaerobic; fermentation; pharmaceutical industry; toxicity; treatment; wastewater
Water Science and Technology Vol 45 No 12 pp 135–142 © IWA Publishing 2002
Toxicity assessment on combined biological treatment of pharmaceutical industry effluents
Introduction
Today in the pharmaceutical industry, most drugs are produced by chemical synthesis, and a wide variety of products are produced by so many different types of chemical reactions, recovery processes and chemicals (organic and inorganic reactants, catalysts and solvents) used in both. Waste streams from chemical synthesis operations are complex due to a variety of operations and reactions employed. Sources of wastewater are: (1) process wastes, (2) wet scrubber waters, (3) cleaning and equipment waters, (4) spills and leakage from pumps etc. The waste stream generated in chemical synthesis contains high concentrations of BOD, COD, TSS, and pH may be highly variable in the range of 1.0–11.0 depending on the specific process. The complexity of the structure of the wastewater can cause toxicity and inhibition in biological treatment systems. Also, the highest pollution loading is observed in chemical synthesis processes (EPA, 1991). The industry studied in this study produces mainly active ingredients of antibiotics such as 6-APA, sulbactam, penicillin and amoxillin. Table 1 shows the solvents used for synthesis of three different groups of products in the pharmaceutical industry studied. Total average flow rate of the wastewaters is 22 m3/day at present, but expected to reach 50 m3/day in the future (Ozturk et al., 1996). Preliminary experiments by the industry had indicated strong anaerobic toxicity. On the other hand, aerobic treatability was also uncertain due to complexity and unknown composition of the wastewater. In this study, wastewater characterization and aerobic/anaerobic treatability (oxygen uptake rate and
135
Table 1 The products and solvents
B. Inanc et al.
Product group
Solvent
Group I Group II A B Group III
Methylene Chloride Ethyl acetate + Methylene chloride Ethyl acetate Methylene chloride, Methyl isobutyl ketone, Acetone
biogas production measurement) of a chemical-synthesis based pharmaceutical industry effluents in nearby baker’s yeast industry treatment plant have been investigated. Material and methods Wastewater treatment plant of the fermentation industry
In the plant, baker’s yeast is manufactured by the aerobic fermentation of selected strains of Saccharomyces cerevisiae. Sugar beet molasses which contains about 50% sugar is the primary raw material. High strength wastewaters are originated from yeast separators and rotary vacuum filters. In addition to these effluents medium and low strength wastewaters including floor and equipment cleaning waters and domestic wastewater are also present. Characteristics of the wastewaters and the treatment plant are given in Table 2. The wastewater treatment plant consists of two treatment stages: anaerobic first-stage and aerobic second stage (Inanc et al., 1999). The anaerobic first stage is also a two-phase system: acid production phase and methane production phase. The anaerobic treatment system has several units including a buffer tank, an effluent pumping station, an acid reactor, two methane reactors, vacuum degasifiers, lamella separators, a gas storage tank, a boiler system and a flare for emergency. Anaerobic reactors are constructed as upflow sludge blanket (UASB) reactors. Lamella separators and vacuum degasifiers are added to prevent the washout of the biomass from the system. The aerobic second stage is designed and operated as an extended aeration activated sludge system with a special selector unit at the beginning. The main treatment units of the aerobic stage are the selector compartments, the aeration basin with four equal aerated cells connected in series and a final sedimentation tank with sludge recirculation facility. Surface aerators are used for aeration. Biologically treated wastewater is discharged into municipal sewer system ending with a biological wastewater treatment plant. Aerobic toxicity
Modified OECD method was used for investigating the possible inhibition of oxygen uptake rate. The OECD protocol involves measurement of oxygen uptake rate from a synthetic substrate with activated sludge to which the test compound has been added at Table 2 Operational parameters and efficiency of the treatment plant Parameter
Flow rate, m3/d Temperature, oC pH COD, mg/L OLR*, kgCOD/m3.d F/M, kgCOD/kgMLVSS.d COD removal 136
* Volumetric organic loading rate
Anaerobic first stage influent
Aerobic second stage influent
2,000 20–25 6–6.5 17,000–20,000 8–13 0.20–0.30 70–80
4,000 25–30 7.8–8.6 3,000–4,000 0.5–1.0 0.50–0.80 60–75
B. Inanc et al.
various concentrations. The oxygen uptake rate is measured immediately after addition of the test compound and after 30 minutes of aeration. In modified OECD method, sludge is acclimated to OECD substrate at an F/M of 0.3. The wastewater is added at progressively increasing quantities. Since the sludge is not acclimated to the wastewater, the OUR may be remain the same or increase when no inhibition is present. The presence of inhibition should cause a decrease in the OUR (Ford, 1998). Sludge from the aeration tank of the treatment plant of the baker’s yeast industry (SS = 20,000 mg/l) was brought the laboratory, and was acclimated with OECD substrate solution (F/M = 0.3). The experiments were conducted in 2 litre glass reactors with a working volume of 1 litre. Biomass concentration was adjusted to 2,500 mgSS/l. Anaerobic toxicity
Anaerobic toxicity was investigated with a consideration that there will be a significant VOC emission problem with aerobic treatment of solvent-rich pharmaceutical plant effluents. This problem is minimized in anaerobic treatment system, which is totally closed and all the biogas is burnt for electricity generation on the site. Methanogenic activity tests were conducted in 100 ml batch vial bottles in triplicates. Total volume of anaerobic sludge, dilution solution and pharmaceutical industry wastewater was 50 ml. The vials were flushed with nitrogen gas for 2 minutes before filling. All the transfers were done under continuous nitrogen purging and the vials were sealed with butyl rubber caps and crimped with aluminium crimps (20 mm). Concentration of fermentation industry anaerobic sludge was adjusted to 2,000 mgVSS/l in dilution solution (Valcke and Verstraete, 1983) and the mixture was incubated without substrate overnight at 35°C. Acetate was used as methanogenic substrate at final concentration of 1,000 mg/l, and was added to dilution solution and sludge mixture just before transfer to the vials. An automated transfer apparatus developed during this study was used for transferring sludge-substrate solution under anaerobic conditions and homogenously (Calli et al., 1999). Neutralized pharmaceutical industry wastewater was added to vials with a syringe. All the vials were incubated in a water bath at 35°C. Biogas production was monitored continuously using a new setup based on water displacement. To prevent the dissolution of the gases pH of the solution was adjusted to 2, and 40 g NaCl was added to each litre (Calli et al., 1999). Anaerobic toxicity of each composite sample was investigated at different dilution ratios. Biogas productions were compared with control vials, which were fed with acetate only. Results and discussion Aerobic toxicity experiments
COD, BOD5, TKN and pH values obtained during wastewater characterization studies on weekly composite samples are given in Table 3. A new composite from the mixture of the three weekly composites was prepared, and a portion was subjected to aeration and steam distillation for removing the solvents which were foremost suspected for toxicity (Table 4). Aerobic toxicity was investigated with raw, aerated and steam distilled samples of the mixed-composite, and each composite individually. Table 3 Characteristics of weekly composite wastewater samples Composite
pH
COD mg/l
BOD5 mg/l
TKN mg/l
4.6 1.8 4.0
60,000 56,000 38,000
30,000 17,000 –
7,500 1,100 –
Sample No.
1 2 3
137
Table 4 Characteristics of raw, aerated and distilled mixed-composite Mixed-Composite
Parameter COD pH
Raw 50,000 1.8
Aerated 23,500 7.8
Distilled 48,850 –
B. Inanc et al.
RA W W A S TE W A TE R 140 120
30 min
5 min 30 min
160
OU R m gO 2/hr
OU R m gO 2/hr
COM P OS ITE 1 200
5 min
100 80 60 40 20 0
120 80 40 0
0
2.0 3.3 5.0 10 20 1 2 3 4 5 6 7 8 Pharm aceutical w as tew ater added, m L
9
0
A E RA TE D W A S TE W A TE R 140
30 min
5 min 30 min
160
OU R m gO 2/hr
OU R m gO 2/hr
COM P OS ITE 2 200
5 min
120 100 80 60 40 20 0
120 80 40 0
0
2.0 3.3 5.0 10 20 1 2 3 4 5 6 7 Pharm aceutical w as tew ater added, m L
8
0
DIS TILLE D W A S TE W A TE R 140
0.0 1 2.0 2 2.5 3 3.3 4 5.0 5 10 6 15 7 20 8 50 9 Pharm aceutical w as tew ater added, m L
COM P OS ITE 3 200
5 min
120
30 min
100 80 60 40 20 0
5 min 30 min
160
OU R m gO 2/hr
OU R m gO 2/hr
0.0 2.0 2.5 3.3 5.0 10 15 20 50 1 2 3 4 5 6 7 8 9 Pharm aceutical w as tew ater added, m L
120 80 40 0
0
2.0 3.3 5.0 10 20 1 2 3 4 5 6 7 8 Pharm aceutical w as tew ater added, m L
9
0
0.0 20 50 1 2.0 2 2.5 3 3.3 4 5.0 5 10 6 15 7 8 9 Pharm aceutical w as tew ater added, m L
Figure 1 Oxygen uptake rate (OUR) against addition of aliquots of composite samples
138
Oxygen uptake rates with addition of raw, aerated and distilled mixed-composite sample aliquots show similar behavior in 5 min measurements (Figure 1). OUR decreases with utilization of OECD substrate (F/M = 0.3). Addition of 5 ml wastewater aliquots has not resulted in decreasing OURs, rather significant increase in OUR was observed in all experiments. This indicates the biodegradability of the organics in the wastewater. OUR values after 30 min are comparatively lower than 5 min measurements due to probably existence of some readily biodegradable matter. Aerobic toxicity experiments were repeated with each composite sample individually upon no inhibition in the previous experiments. As it can be seen from Figure 1, no
B. Inanc et al.
inhibition was observed in these experiments, too. The difference in this set of experiments is that composite sample addition has reached to 50 ml which means 1/20 dilution. 5 min OUR values have risen significantly with Composite 1 and 3, after total volumes exceeded 5 ml. 5 min OUR values for Composite 2 was comparatively lower. 30 min OUR values which did not rise after total wastewater volume of 5 ml, except for Composite 1, have also increased and reached the level of 5 min OUR after wastewater volume was raised to 50 ml. Another experiment was conducted where composite wastewater samples were added in large pulses (30 ml each) instead of a series of small aliquots to increase the possibility of toxicity. The results have shown no discernable short-term toxicity, rather higher oxygen uptake rates were observed with increasing amounts of pharmaceutical plant effluents (Figure 2). Continuous flow experiments in 2 litre reactors were conducted in order to investigate the possible long term toxicity (data not shown). Addition of pharmaceutical plant effluents at dilution ratio of 1/100 did not cause any inhibition on COD removal and biomass growth. This was proved by a control reactor fed with only baker’s yeast industry anaerobic reactor effluent. These observations have indicated that the effluents of the pharmaceutical industry can be treated efficiently and will not create toxicity within the aerobic stage of the treatment plant of the baker’s yeast industry. Anaerobic toxicity experiments
30 mL Composite 3
30 mL Composite 2
30 mL Composite 1
The composite samples used in aerobic toxicity experiments were also used in anaerobic toxicity investigation. Preliminary experiments with raw composite samples at all dilution ratios (1/25, 1/50, 1/75, 1/100) have shown strong toxicity (60 to 80%) on biogas production (Figure 3). So, it was decided to investigate pretreatment alternatives. However, it took 4 months to start this work mainly due to construction of a water displacement system and developing automated transfer apparatus. Wastewater samples were kept in closed plastic containers at room temperature during this period. When the setups for toxicity experiments were ready to start, the first effect of aeration was investigated at 1/100, 1/200 and 1/400 dilutions with mixed-composite samples. However, the toxicity was unexpectedly low (Figure 4) for both raw and aerated mixedcomposite (5–10% for raw and 3–6% for aerated). An investigation on COD revealed that COD concentrations had decreased 35.4%, 25.9% and 39.0%, and current COD values
200
OUR mg O 2 /hr
150
100
50
0 -2
0
2
4
6
8
10
12
Time (hour)
Figure 2 Oxygen uptake rate (OUR) against addition of large amounts of composite samples
139
D ilution: 1/25
D ilution: 1/50
25
25 Blank Biogas Production, m l
B. Inanc et al.
Biogas Production, m l
Blank 20
C om p. 1 C om p. 2
15
C om p. 3
10 5 0
20
C om p. 1 C om p. 2
15
C om p. 3
10 5 0
0
50
100 Tim e, hours
150
0
50
D ilution: 1/75
150
D ilution: 1/100
25
25
20
Blank Biogas Production, m l
Blank Biogas Production, m l
100 Tim e, hours
C om p. 1 C om p. 2
15
C om p. 3
10 5 0
20
C om p. 1 C om p. 2
15
C om p. 3
10 5 0
0
50
100 Tim e, hours
150
0
50
100 Tim e, hours
150
Figure 3 Preliminary experiments on anaerobic toxicity of each composite sample
50
50 R aw w as tew ater
Aerated w as tew ater
45
40
Biogas Production, m l
Biogas Production, m l
45
35 30 25 20
Blank
15
D ilution: 1/100
10
D ilution: 1/200
5
D ilution: 1/400
40 35 30 25 20
Blank
15
D ilution: 1/100
10
D ilution: 1/200
5
D ilution: 1/400
0
0 0
50
100 Tim e, hours
150
0
50
100 Tim e, hours
150
Figure 4 Biogas production with four months stored mixed-composite sample
140
were 38,750 mg/l, 41,500 mg/l and 23,200 mg/l, in composite 1, 2 and 3, respectively. It is understood that some solvents have volatilized and escaped even though the plastic containers were well closed. It can also be said that the most toxic solvent is the most volatile, if it is assumed that the toxicity is caused by the solvents. A new composite wastewater sample was obtained from the industry (COD = 35,000 mg /l), and the experiments were repeated. Inhibition levels (80–90%) were similar to those obtained in the preliminary experiments where raw composite samples have caused severe inhibitions on biogas production. On the other hand, 60 min aeration was effective for removing the toxicity, and even resulted in more biogas production than control vials. Another investigation on the duration of aeration indicated that 30 min aeration is also effective for removing the toxicity (Figure 5).
40
45
35
Effect of aeration tim e
35
Biogas Production, m l
40 Blank 1/200 1/100 1/50 A 1/200 A 1/100 A 1/50
30 25 20 15 10
30 25 Blank R aw w w A 1.5hr A 1.0hr A 0.5hr
20 15 10 5
5 0
0 0
50
100 Tim e, hours
150
0
50
100 Tim e, hours
150
200
B. Inanc et al.
Biogas Production, m l
50
Figure 5 Effect of aeration on removal of anaerobic toxicity
Effect of activated carbon, lime, ferric chloride and alum
Activated carbon adsorption was tried as an alternative method for removing the toxicity. Powdered activated carbon (PAC) was added to wastewater sample at 100 mg/l, 500 mg/l and 1,000 mg/l dosages. Parallel experiments were conducted with 1/100 and 1/200 dilutions. As it can be seen from Figure 6, there was almost no reduction in toxicity at doses applied. The effect of lime, ferric chloride and alum was investigated with a consideration that there would be no VOC emission and no need for air pollution. Durations for rapid mixing, slow mixing and sedimentation were 5 min, 20 min and 30 min, respectively. As Figure 7 shows, in first set of experiments lime, ferric chloride and alum were tried at 500 mg/l and 45 PAC: Pow dered activated carbon
Biogas Production, ml
40 35 30 Blank Raw w w 1000mg/l PAC 500mg/l PAC 100mg/l PAC
25 20 15 10 5 0 0
50
100
150
Time, hours
Figure 6 Effect of activated carbon on removal of anaerobic toxicity
60
40 Blank 1000mg/l Lime 500mg/l Lime 1000mg/l FeCl3 500mg/l FeCl3 1000mg/l A lum 500mg/l A lum
30 25 20
Blank 300mg/l A lum, pH=7 500mg/l A lum, pH=7 500mg/l A lum, pH=5.5
50 Biogas Production, m l
Biogas Production, m l
35
15 10 5 0
40 30 20 10 0
0
50
100 Tim e, hours
150
200
0
50
100 150 Tim e, hours
Figure 7 Effect of lime, ferric chloride and alum on removal of anaerobic toxicity
200
250 141
1,000 mg/l dosages. Alum at 500 mg/l only was effective to reduce the toxicity about 70%. In the second set of experiments only alum was used at 300 mg/l and 500 mg/l, and also at pH = 7 and 5.5. Two conditions, namely 300 mg/l at pH = 7 and 500 mg/l at pH = 5.5, have yielded more biogas production than in controls (no toxicity). However, the reason for different biogas production (different inhibition) under different alum dosages and pH values remained unknown. B. Inanc et al.
Conclusions
In this study, wastewater characterization and aerobic/anaerobic treatability of a chemical synthesis based pharmaceutical industry effluents in nearby baker’s yeast industry treatment plant have been investigated. The results of aerobic toxicity experiments have shown no discernable short-term toxicity, rather higher oxygen uptake rates were observed with increasing amounts of pharmaceutical plant effluents, indicating that the effluents can be treated efficiently, and will not create toxicity in the aerobic stage of the baker’s yeast industry treatment plant. However, significant VOC (solvents) emission during aeration process is the main drawback of this alternative. This problem can be minimized in anaerobic stage of the treatment system which is totally closed and all the biogas is burnt for electricity generation on the site, provided that pretreatment is done. Short period aeration around 30 min or coagulation-flocculation with alum (300 mg/l) was found to be effective for removing the toxicity on anaerobic biogas production. Alum treatment would be the method of choice due to almost no VOC emission. Handling the alum sludge as hazardous waste should not be difficult since there is a hazardous waste incineration and landfill facility close to the industry. Therefore, the pharmaceutical industry was recommended to treat its effluents in the anaerobic stage of the nearby baker’s yeast industry wastewater treatment with necessary pretreatment. References Calli, B., Inanc, B. and Akgiray, O. (1999). A Study on Measurement and Reduction of Anaerobic Toxicity for Chemical Synthesis Based Pharmaceutical Industry Wastewaters”, Journal of Water Pollution Control, 9(2), pp. 41–46 (in Turkish). EPA (1991). Guides to Pollution Prevention: The Pharmaceutical Industry, EPA/625/7-91/017. Ford, D.L. (1998). Toxicity Reduction: Evaluation and Control, Vol. III, Technomic Publishing Co. Inc., Lancester, PA, USA. Inanc, B., Ciner, F. and Ozturk, I. (1999). Color Removal from Fermentation Industry Effluents, Water Science and Technology, 40(1), pp. 331–338. Valcke, D. and Verstraete, W. (1983). A Practical Method to Estimate the Acetoclastic Methanogenic Biomass in Anaerobic Sludges, J. Wat. Poll. Control Fed., 55, 1191–1195.
142
