Anaerobic treatment of antibiotic production wastewater and kinetic evaluations

In this study, the anaerobic treatment of high-strength antibiotic production wastewater and the development of a mathematical model for the treatment were attempted. Anaerobic treatability was investigated using synthetic solutions and original wastewater of which the initial chemical oxygen demand (COD) was determined. Initial COD of solutions was increased from 3,000 to 43,000 mg O(2)/liter in an anaerobic bioreactor. The bioreactor pH was maintained at 6.5-7.5. The temperature was kept constant at 37 +/- 1 degrees C. Raw materials and original wastewater containing penicillin antibiotics were obtained from Fako Pharmaceutical Factory (Fako) in Istanbul, Turkey. Anaerobic sludge used for treatment was obtained from Pakmaya Baker's Yeast Producing Factory (Pakmaya) in Izmit, Turkey and the Fako. A mathematical model based on substrate (total COD) concentration was developed assuming that only three consecutive reactions, namely, hydrolysis, acidogenesis and methanogenesis, are significant. From the experimental data, a model that can be used for COD calculation as a function of time was developed using the first- and the second-order kinetic approaches. Making use of the developed model equation, it was proved that the anaerobic treatment of high strength (COD > 25,000 mg O(2)/liter) antibiotic production wastewater fits the second-order kinetics.     

Novel application of oxygen-transferring membranes to improve anaerobic wastewater treatment

Anaerobic biological wastewater treatment has numerous advantages over conventional aerobic processes; anaerobic biotechnologies, however, still have a reputation for low-quality effluents and operational instabilities. In this study, anaerobic bioreactors were augmented with an oxygen-transferring membrane to improve treatment performance. Two anaerobic bioreactors were fed a synthetic high-strength wastewater (chemical oxygen demand, or COD, of 11,000 mg l(-1)) and concurrently operated until biomass concentrations and effluent quality stabilized. Membrane aeration was then initiated in one of these bioreactors, leading to substantially improved COD removal efficiency (> 95%) compared to the unaerated control bioreactor (approximately 65%). The membrane-augmented anaerobic bioreactor required substantially less base addition to maintain circumneutral pH and exhibited 75% lower volatile fatty acid concentrations compared to the unaerated control bioreactor. The membrane-aerated bioreactor, however, failed to improve nitrogenous removal efficiency and produced 80% less biogas than the control bioreactor. A third membrane-augmented anaerobic bioreactor was operated to investigate the impact of start-up procedure on nitrogenous pollutant removal. In this bioreactor, excellent COD (>90%) and nitrogenous (>95%) pollutant removal efficiencies were observed at an intermediate COD concentration (5,500 mg l(-1)). Once the organic content of the influent wastewater was increased to full strength (COD = 11,000 mg l(-1)), however, nitrogenous pollutant removal stopped. This research demonstrates that partial aeration of anaerobic bioreactors using oxygen-transferring membranes is a novel approach to improve treatment performance. Additional research, however, is needed to optimize membrane surface area versus the organic loading rate to achieve the desired effluent quality.     

Effects of cationic polymer on performance of UASB reactors treating low strength wastewater

The effect of cationic polymer additives on biomass granulation and COD removal efficiency had been examined in lab-scale upflow anaerobic sludge blanket (UASB) reactors, treating low strength synthetic wastewater (COD 300-630 mg/l). Under identical conditions, two reactors were operated with and without polymer additives in inoculum under four different organic loading rates (OLRs). The optimum polymer dose was adopted based upon the results of jar test and settling test carried out with inoculum seed sludge. With the use of thick inoculum, SS greater than 110 g/l and VSS/SS ratio less than 0.3, granulation was observed in UASB reactor treating synthetic wastewater as well as actual sewage, when OLR was greater than 1.0 kg COD/m(3) d. Polymer additive with such thick inoculum was observed to deteriorate percentage granules and COD removal efficiency compared to inoculum without polymer additives. At OLR less than 1.0 kg COD/m(3) d, proper granulation could not be achieved in both the reactors inoculated with and without polymer additive. Also, under this low loading, drastic reduction in COD removal efficiency was observed with polymer additives in inoculum. Hence, it is rational to conclude that biomass granulation for treatment of low strength biodegradable wastewater depends on the applied loading rate and selection of thick inoculum sludge.     

Growth and production of biomass of Rhodovulum sulfidophilum in sardine processing wastewater

AIMS: Rhodovulum sulfidophilum was grown in sardine processing wastewater to assess growth characteristics for the production of bacterial biomass with simultaneous reduction of chemical oxygen demand. METHODS AND RESULTS: Growth characteristics were compared in diluted and undiluted, settled and non-settled wastewater growing in anaerobic light and aerobic dark conditions; and also at different agitation speeds. The highest biomass (8.75 g l(-1)) and a reduction in chemical oxygen demand of 71% were obtained in unsettled, undiluted wastewater after 120 h culture with 15% inoculum. In settled wastewater, highest biomass (7.64 g l(-1)) and a COD reduction of 77% was also obtained after 120 h. Total biomass was higher (4.34 g l(-1)) after 120 h culture in anaerobic light compared to (3.23 g l(-1)) in aerobic dark growth. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: Better performance, mean of total biomass (6.97 g l(-1) after 96 h), total carotenoids (4.24 mg g(-1) dry cell from 24 h) and soluble protein (431 microg ml(-1) after 96 h) were obtained from aerobic dark culture at 300 rev min(-1). The COD reduction, however, was lower (69%) after 96 h culture. Thus, the benefits in the production of bacterial biomass in non-sterilized sardine processing wastewater with the reduction of chemical oxygen demand could be achieved.     

Anaerobic hydrogen production with an efficient carrier-induced granular sludge bed bioreactor

A novel bioreactor containing self-flocculated anaerobic granular sludge was developed for high-performance hydrogen production from sucrose-based synthetic wastewater. The reactor achieved an optimal volumetric hydrogen production rate of approximately 7.3 L/h/L (7,150 mmol/d/L) and a maximal hydrogen yield of 3.03 mol H2/mol sucrose when it was operated at a hydraulic retention time (HRT) of 0.5 h with an influent sucrose concentration of 20 g COD/L. The gas-phase hydrogen content and substrate conversion also exceeded 40 and 90%, respectively, under optimal conditions. Packing of a small quantity of carrier matrices on the bottom of the upflow reactor significantly stimulated sludge granulation that can be accomplished within 100 h. Among the four carriers examined, spherical activated carbon was the most effective inducer for granular sludge formation. The carrier-induced granular sludge bed (CIGSB) bioreactor was started up with a low HRT of 4-8 h (corresponding to an organic loading rate of 2.5-5 g COD/h/L) and enabled stable operations at an extremely low HRT (up to 0.5 h) without washout of biomass. The granular sludge was rapidly formed in CIGSB supported with activated carbon and reached a maximal concentration of 26 g/L at HRT = 0.5 h. The ability to maintain high biomass concentration at low HRT (i.e., high organic loading rate) highlights the key factor for the remarkable hydrogen production efficiency of the CIGSB processes.     

Performance of an anaerobic bioreactor with biomass recycling, continuously removing COD and sulphate from industrial wastes

A 30-l anaerobic bioreactor with biomass recycling was used to provide a continuous reduction in sulphate and a continuous COD removal from wastewater, which consisted of the effluent from an industrial pig fattening farm, enriched with technical FeSO(4) x 7H(2)O, a waste product from ferrous metallurgy. The concentrations of sulphate and COD in the wastewater amounted to 2.73 g l(-1) and 3.15 g l(-1), respectively. The HRT (hydraulic retention time) of 10-1.7d produced an extent of sulphate and COD reduction which totalled 98% and 88%, respectively. When the HRT was further shortened, the efficiency of reduction in sulphate and COD decreased. The maximum removal rate constants for both the pollutants, calculated by means of a modified Stover-Kincannon model, were 80.9 g COD l(-1)d(-1) and 41.8 g SO(4)(2-)l(-1)d(-1), the values of the saturation constants being 91.582 g COD l(-1)d(-1) and 42.398 g SO(4)(2-)l(-1)d(-1).     

Characterization of tannery wastewater and biomass in a membrane bioreactor using respirometric analysis

Respirometric techniques and an activated sludge model (ASM) were applied for the characterization of tannery wastewater and biomass in a pilot plant membrane bioreactor (MBR) operating at high sludge age. The traditional respirometric tests and the IWA-ASM1 were modified to take into account the specific operating conditions, the solid-liquid separation technology and the wastewater complexity. As a result the wastewater biodegradable COD was fractionated into four components: readily biodegradable, rapidly hydrolysable, slowly hydrolysable and inorganic (due to the presence of reduced sulphur compounds). The kinetic and stoichiometric parameters of the biomass (heterotrophic and nitrifying) were estimated through the integration of model simulations and respirometric tests results. In particular the ammonium and nitrite-oxidizing biomasses were separately characterized: the growth kinetics of ammonium and nitrite-oxidizing bacteria resulted noticeably lower than the traditional reference values (mu(max,AOB)=0.25d(-1)e mu(max,NOB)=0.23d(-1) at 20 degrees C, respectively). The ASM was finally used to confirm that the results of the wastewater and biomass characterization allow to properly simulate the mixed liquor suspended solids in the MBR pilot plant and the COD concentration in the effluent.     

Biomass retention and performance of anaerobic fixed-film reactors treating acetic acid wastewater

An acetic-acid-based synthetic wastewater of different organic concentrations was successfully treated at 35 degrees C in anaerobic downflow fixed-film reactors operated at high organic loading rates and short hydraulic retention times (HRTs). Substrate removal and methane production rates close to theoretical values of complete volumetric chemical oxygen demand (COD) removal and maximum methane conversion were obtained. A high concentration of biofilm biomass was retained in the reactor. Steady-state biofilm concentration increased with increased organic loading rate and decreased HRTs, reaching a maximum of 8.3 kg VFS/m(3) at a loading rate of 17 kg COD/m(3) day. Biofilm substrate utilization rates of up to 1.6 kg COD/kg VFS day were achieved. Soluble COD utilization rates at various COD concentrations can be described by half-order reaction kinetics.     

2,4-Dichlorophenol (DCP) containing wastewater treatment using a hybrid-loop bioreactor

Synthetic wastewater containing 2,4-dichlorophenol (DCP) was biologically treated using a hybrid-loop bioreactor system consisting of a packed column biofilm reactor (PCBR) and an aerated tank with effluent recycle. Effects of the feed DCP concentration on COD, DCP and toxicity removals were investigated. Biomass concentration in the packed column and in the aeration tank decreased with increasing feed DCP content due to toxic effects of DCP on the microorganisms. Low biomass concentrations at high DCP contents resulted in low COD, DCP and toxicity removals. Therefore, percent DCP, COD and toxicity removals decreased with increasing feed DCP content. Nearly 70% COD removal was achieved with a feed DCP content of 380 mg L(-1). The system should be operated with the feed DCP lower than 100 mg L(-1) in order to obtain DCP, COD and toxicity removals above 90%.     

Effect of COD/N ratio and salinity on the performance of sequencing batch reactors

The effects of COD/N ratio (3-6) and salt concentration (0.5-2%) on organics and nitrogen removal efficiencies in three bench top sequencing batch reactors (SBRs) with synthetic wastewater and one SBR with fish market wastewater were investigated under different operating schedules. The solids retention time (SRT, 20-100 days) and aeration time (4-10h) was also varied to monitor the performance. For synthetic wastewater, chemical oxygen demand (COD) removal efficiencies were consistently greater than 95%, irrespective of changes in COD/N ratio, aeration time and salt concentrations. Increasing the salt concentrations decreased the nitrification efficiency, while high COD/N ratio's favored better nitrogen removal (>90%). The treatment of real saline wastewater ( approximately 3.2%) from a fish market showed high COD (>80%) and nitrogen (>40%) removal efficiencies despite high loading rate and COD/N fluctuations, which is due to the acclimatization of the biomass within the SBR.     

圆红冬孢酵母利用生物乙醇废水-木薯粉水解液发酵产油

【目的】获得能够高效降解生物乙醇废水化学需氧量(COD)的圆红冬孢酵母菌株,评估废水初始COD浓度对驯化菌株生长的影响,将木薯粉生产微生物油脂和高浓度有机废水降解过程整合,以生物乙醇废水为水源制备生物乙醇废水-木薯粉水解液培养基,明确产油效率高、生物乙醇废水COD降解率高的初始还原糖浓度。【方法】采用在高浓度的生物乙醇废水中进行多次驯化的方法,获得能够适应废水环境的圆红冬孢酵母菌株;采用双酶水解法对加入乙醇废水中的木薯粉进行水解;采用重量法监测生物量浓度变化,采用酸热法提取油脂,重铬酸钾法监测COD,DNS法测定废水还原糖浓度,凯氏定氮法测定总氮,钼酸铵比色法测定总磷。【结果】通过驯化筛选得到一株能耐受高浓度生物乙醇废水的优势菌株Rhodosporidium toruloides D5。以未稀释的废水为培养基,驯化菌株的最终生物量浓度和COD降解率分别为3.8 g/L和75.0%。采用生物乙醇废水-木薯粉水解液发酵时,控制初始还原糖浓度低于30 g/L时,生物量浓度和油脂浓度随初始还原糖浓度的升高而升高,均在120 h时达到最高COD降解率,初始还原糖浓度对达到的最大COD降解率无明显影响,废水N、P去除率分别达到99%和92%以上。【结论】在未经稀释的高浓度生物乙醇废水中可获得较高的生物量浓度;采用高浓度生物乙醇废水-木薯粉水解液培养基发酵产油,初始还原糖浓度为30 g/L,可在保证高油脂产量的同时,实现废水COD的高效降解,有效回收利用废水中残余的N、P源,从而降低微生物油脂生产和废水处理成本,研究结果可为开发廉价微生物油脂生产技术提供有用的参考。     

Optimization of a biological process for treating potato chips industry wastewater using a mixed culture of Aspergillus foetidus and Aspergillus niger

Potato chips industry wastewater was collected and analyzed for biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and total carbohydrates. Two Aspergillus species, A. foetidus and A. niger, were evaluated for their ability to grow and produce biomass and reduce the organic load of the wastewater. A. foetidus MTCC 508 and A. niger ITCC 2012 were able to reduce COD by about 60% and produce biomass 2.4 and 2.85 gl(-1), respectively. Co-inoculation of both Aspergillus strains resulted in increased fungal biomass production and higher COD reduction than in individual culture at different culture pH. pH 6 was optimum for biomass production and COD reduction. Amendment of the wastewater with different N and P sources, increased the biomass production and COD reduction substantially. Under standardized conditions of pH 6 and amendment of wastewater with 0.1% KH2PO4 and 0.1% (NH4)2 SO4, a mixed culture gave 90% reduction in COD within 60 h of incubation.     

Performance of a submerged membrane bioreactor for the aerobic treatment of abattoir wastewater

The performance of a submerged membrane bioreactor (SMBR) has been investigated for abattoir wastewater (AW) treatment. The chemical oxygen demand (COD) of permeate has not exceeded 25 mg L⁻¹ providing an average COD removal of 98%. Microbiological analysis showed that the SMBR has allowed a complete removal of fecal coliforms, Listeria and Salmonella. A significant reduction in the excess biomass production was also observed. In fact, the yield of biomass production (Yobs) ranged between 0 and 0.106 g suspended solids/g COD removed.The study of the dynamic of bacterial communities using the single strand conformation polymorphism (SSCP) method showed a significant change in the population structure and revealed a correlation between the sludge production yield and the bacterial communities.     

Biological treatment of a synthetic space mission wastewater using a membrane-aerated,membrane-coupled bioreactor (M2BR)

This paper describes the membrane-aerated, membrane-coupled bioreactor (M2BR), which was developed for wastewater treatment during long-term space missions because it achieves aeration and biomass separation using components that are compatible with microgravity conditions. In the experiments described herein, the M2BR was used to treat a synthetic wastewater formulated by NASA to simulate the wastewater typically collected during space missions. The M2BR was able to achieve more than 90% removal of both chemical oxygen demand (COD) and total nitrogen when it was fed a modified NASA wastewater that had a 4:1 COD to nitrogen ratio. When the full-strength synthetic wastewater was fed to the M2BR (COD:N=1), however, the nitrogenous pollutant removal efficiency was adversely affected because of either insufficient oxygen transfer to support nitrification (an air-fed M2BR) or insufficient electron donor to support denitrification (an oxygen-fed M2BR). In conclusion, the M2BR provides considerable promise for wastewater treatment during long-term space missions, although additional research is needed to identify the best approach to treat the space mission wastewater, which poses a unique challenge because of its low COD:N ratio.     

Statistical modeling and optimization of biomass granulation and COD removal in UASB reactors treating low strength wastewaters

The aim of this work was to study the influence of influent chemical oxygen demand (COD), upflow velocity of wastewater, and cationic polymer additives in inoculum, on biomass granulation and COD removal efficiency in upflow anaerobic sludge blanket (UASB) reactor for treating low strength wastewater. Statistical models were formulated based on these three variables to optimize the biomass granulation and COD removal efficiency in UASB reactors using a two-level, full factorial design. For the thick inoculum used in this study, having suspended solids (SS) >80 g/l and volatile suspended solids (VSS) to SS ratio <0.3, cationic polymer additives in the inoculum showed adverse effect on biomass granulation and COD removal efficiency. It is concluded that for such thick inoculum, granulation can be obtained while treating low strength wastewaters in UASB reactor by selecting proper combination of influent COD and liquid upflow velocity so as to represent the organic loading rate (OLR) greater than 1.0 kg COD/m(3) d. Validation of model predictions for treatment of synthetic wastewater and actual sewage reveals the efficacy of these models for enhancing granulation and COD removal efficiency.     

Industrial wastewater treatment in internal circulation bioreactor followed by wetlands containing emergent plants and algae

Wastewater treatment based on ecological principles is a low cost and highly desirable solution for the developing countries like Pakistan. The present study evaluated the effectiveness of biological treatment systems including Internal Circulation (IC) anaerobic bioreactor and constructed wetlands (CWs) containing macrophytes and mixed algal cultures for industrial wastewater treatment. The IC bioreactor reduced COD (52%), turbidity (89%), EC (24%) of the industrial wastewater. However, the effluents of IC bioreactor did not comply with National Environmental Quality Standards (NEQS) of Pakistan. Post-treatment of IC bioreactor effluents was accomplished in CW containing macrophytes (Arundo donax and Eichhornia crassipes) and mixed algal culture. The CWs planted with macrophytes lowered the concentrations of COD (89%) and turbidity (99%). CWs with algal biomass were not effective in further polishing the effluent. Inhibition of algal biomass growth was observed due to physicochemical characteristics of wastewater. The integrated treatment system consisting of IC bioreactor and macrophytes was found more suitable option for industrial wastewater treatment.     

Assessment of anaerobic wastewater treatment failure using terminal restriction fragment length polymorphism analysis

AIMS: The suitability of genetic fingerprinting to study the microbiological basis of anaerobic bioreactor failure is investigated. METHODS AND RESULTS: Two laboratory-scale anaerobic expanded granular sludge bed bioreactors, R1 and R2, were used for the mesophilic (37 degrees C) treatment of high-strength [10 g chemical oxygen demand (COD) l(-1)] synthetic industrial-like wastewater over a 100-day trial period. A successful start up was achieved by both bioreactors with COD removal over 90%. Both reactors were operated under identical parameters; however, increased organic loading during the trial induced a reduction in the COD removal of R1, while R2 maintained satisfactory performance (COD removal >90%) throughout the experiment. Specific methanogenic activity measurements of biomass from both reactors indicated that the main route of methane production was hydrogenotrophic methanogenesis. Terminal restriction fragment length polymorphism (TRFLP) analysis was applied to the characterization of microbial community dynamics within the system during the trial. The principal differences between the two consortia analysed included an increased abundance of Thiovulum- and Methanococcus-like organisms and uncultured Crenarchaeota in R1. CONCLUSIONS: The results indicated that there was a microbiological basis for the deviation, in terms of operational performance, of R1 and R2. SIGNIFICANCE AND IMPACT OF THE STUDY: High-throughput fingerprinting techniques, such as TRFLP, have been demonstrated as practically relevant for biomonitoring of anaerobic reactor communities.     

Impact of ammonia concentration on Spirulina platensis growth in an airlift photobioreactor

Spirulina platensis was cultivated in a bench-scale airlift photobioreactor using synthetic wastewater (total nitrogen 412 mg L(-1), total phosphorous 90 mg L(-1), pH 9-10) with varying ammonia/total nitrogen ratios (50-100% ammonia with balance nitrate) and hydraulic residence times (15-25 d). High average biomass density (3500-3800 mg L(-1)) and productivity (5.1 g m(-2) d(-1)) were achieved when ammonia was maintained at 50% of the total nitrogen. Both high ammonia concentrations and mutual self-shading, which resulted from the high biomass density in the airlift reactor, were found to partially inhibit the growth of S. platensis. The performance of the airlift bioreactor used in this study compared favorably with other published studies. The system has good potential for treatment of high strength wastewater combined with production of algae for biofuels or other products, such as human and animal food, food supplements or pharmaceuticals.     

Biotechnological production of lactic acid integrated with fishmeal wastewater treatment by <Emphasis Type="Italic">Rhizopus oryzae</Emphasis>

Fishmeal wastewater, a seafood processing waste, was utilized for production of lactic acid and fungal biomass by Rhizopus oryzae AS 3.254 with the addition of sugars. The 30 g/l exogenous glucose in fishmeal wastewater was superior to starch in view of productivities of lactic acid and fungal biomass, and COD reduction. Fishmeal wastewater can be a replacement for peptone which was the most suitable nitrogen source for lactic acid production among the tested organic or inorganic nitrogen sources. Exogenous NaCl (12 g/l) completely inhibited the production of lactic acid and fungal growth. In the medium of COD 5,000 mg/l fishmeal wastewater with the addition of 30 g/l glucose, the maximum productivity of lactic acid was 0.723 g/l h corresponding to productivity of fungal biomass 0.0925 g/l h, COD reduction 84.9% and total nitrogen removal 50.3% at a fermentation time of 30 h.     

Anaerobic treatment of wastewater with high suspended solids from a bulk drug industry using fixed film reactor (AFFR)

Studies are carried out on the treatment of wastewater from a bulk drug industry using an anaerobic fixed film reactor (AFFR) designed and fabricated in the laboratory. The chemical oxygen demand (COD) and total dissolved solids (TDS) of the wastewater are found to be very high with low Biochemical oxygen demand (BOD) to COD ratio and high total suspended solid (TSS) concentration. Acclimatization of seed consortia and start up of the reactor is carried out by directly using the wastewater, which resulted in reducing the period of startup to 30 days. The reactor is studied at different organic loading rates (OLR) and it is found that the optimum OLR is 10 kg COD/m3/day. The wastewater under investigation, which is having considerable quantity of SS, is treated anaerobically without any pretreatment. The COD and BOD of the reactor outlet wastewater are monitored and reduction at steady state and optimum OLR is observed to be 60-70% of COD and 80-90% of BOD. The reactor is subjected to organic shock loads at two different OLR and it is observed that the reactor could withstand shocks and performance could be restored to normalcy at that OLR. The results obtained indicated that AFFR could be used efficiently for the treatment of wastewater from a bulk drug industry having high COD, TDS and TSS.