Total COD Removal Efficiency Research Articles

Performance of CSTR-EGSB-SBR system for treating sulfate-rich cellulosic ethanol wastewater and microbial community analysis.

Performance and microbial community composition were evaluated in a two-phase anaerobic and aerobic system treating sulfate-rich cellulosic ethanol wastewater (CEW). The system was operated at five different chemical oxygen demand (COD)/SO42- ratios (63.8, 26.3, 17.8, 13.7, and 10.7). Stable performance was obtained for total COD removal efficiency (94.5%), sulfate removal (89.3%), and methane production rate (11.5L/day) at an organic loading rate of 32.4kg COD/(m3·day). The acidogenic reactor made a positive contribution to net VFAs production (2318.1mg/L) and sulfate removal (60.9%). Acidogenic bacteria (Megasphaera, Parabacteroides, unclassified Ruminococcaceae spp., and Prevotella) and sulfate-reducing bacteria (Butyrivibrio, Megasphaera) were rich in the acidogenic reactor. In the methanogenic reactor, high diversity of microorganisms corresponded with a COD removal contribution of 83.2%. Moreover, methanogens (Methanosaeta) were predominant, suggesting that these organisms played an important role in the acetotrophic methanogenesis pathway. The dominant aerobic bacteria (Truepera) appeared to have been responsible for the COD removal of the SBR. These results indicate that dividing the sulfate reduction process could effectively minimize sulfide toxicity, which is important for the successful operation of system treating sulfate-rich CEW.

An investigation of two‐stage thermophilic and mesophilic fermentation process for the production of hydrogen and methane from palm oil mill effluent

The two‐stage process of combined hydrogen and methane production with the recirculation of digestate sludge using palm oil mill effluent as substrate was investigated. During the first stage, an up‐flow anaerobic sludge blanket reactor (UASB) was operated at thermophilic conditions [hydraulic retention time (HRT)−2 days, organic loading rate −75 gCOD L−1d−1] for hydrogen production. The operation performance at short HRT and low pH was useful to separate the acidogenesis from methanogenesis. The effluents from UASB reactor containing mainly acetate and butyrate were fed into a continuous stirred tank reactor (CSTR) for methane production under the mesophilic temperature at two different HRTs (5 and 3 days). Both UASB and CSTR reactors were operated for 120 days continuously and a stable production of the hydrogen and methane was obtained simultaneously. The total hydrogen and methane yields obtained were 215 L H2 kgCOD−1 and 320 L CH4 kgCOD−1, respectively with the total COD removal efficiency of 94% in the two stage process. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 895–902, 2017

Biogas Production from Brewer's Yeast Using an Anaerobic Sequencing Batch Reactor.

Renewable energy sources are becoming increasingly important in the beverage and food industries. In the brewing industry, a significant percentage of the used raw materials finishes the process as secondary resource or waste. The research on the anaerobic digestion of brewer's yeast has been scarce until recent years. One of the reasons for this is its use as a secondary resource in the food industry and as cattle feed. Additionally, market value of brewer's yeast is higher than its energy value. Due to the increase of energy prices, brewer's yeast has become of interest as energy substrate despite its difficult degradability in anaerobic conditions. The anaerobic co-digestion of brewer's yeast and anaerobically treated brewery wastewater was studied using a pilot-scale anaerobic sequencing batch reactor (ASBR) seeded with granular biomass. The experiments showed very good and stable operation with an organic loading rate of up to 8.0 kg/(m3·day), and with a maximum achieved organic loading rate of 13.6 kg/(m3·day) in a single cycle. A specific biogas productivity of over 0.430 m3/kg of the total chemical oxygen demand (COD) inserted, and total COD removal efficiencies of over 90% were achieved. This study suggests that the brewer's yeast can be successfully digested in an ASBR without adverse effects on the biogas production from brewer's yeast/wastewater mixtures of up to 8% (by volume). By using the brewer's yeast in the ASBR process, the biogas production from brewery wastewater could be increased by 50%.

Improvement and prediction of OSA system performance in sludge reduction through integration with thermal and mechanical treatment

The oxic-settling-anoxic (OSA) process is one of the sludge production reduction methods in the activated sludge process. In this method, sludge is stored in an anaerobic tank within the sludge return line before entrance into an aeration tank. Due to this method's flexibility in application to operating treatment plants and not being energy-consuming, its application is developing. In this research, the improvement of the OSA process is investigated via thermal and mechanical treatment in a sequencing batch reactor (SBR). A pilot-scale reactor and domestic wastewater are used. Sludge was subjected to high temperature in an anaerobic tank using a heat transformer and it was subjected to mechanical shear through mechanical mixing in the anaerobic tank. Different temperatures and voltages were tested. The OSA process reduced sludge production by 24% while the chemical oxygen demand (COD) removal rate decreased from 90% to 86%. Thermal treatment combined with the OSA process caused a maximum of 46% sludge production reduction. However temperatures above 90 °C are not recommended due to a high level of decrease in COD removal. Mechanical mixing in combination with the OSA process led to 34% sludge production reduction. The effluent quality is not affected by the OSA process itself but is slightly reduced by thermal treatment and mechanical mixing. Therefore, for reaching the maximum sludge reduction in OSA plus thermal and mechanical treatment it would be necessary to evaluate the effect of different sets of parameters on effluent quality beside the sludge reduction. For this purpose multi-layer perceptron artificial neural network models are developed to predict the effluent total suspended solids and COD removal efficiency as well as sludge production rate. The models perform well and would be useful tools in determining the optimal set of system operation parameters.

Flocculent Settling of Food Wastes.

This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft deep column. A total of eight runs at three different testing conditions involving MWW alone, food waste (FW) alone, and FW in MWW (FW+MWW) were conducted. Total suspended solid (TSS), total BOD (TBOD), total COD (TCOD), total nitrogen (TN), and total phosphorous (TP) removal efficiencies after 3 hours of settling were 62%, 46%, 49%, 46% and 62% for FW, and 50%, 43%, 39%, 37% and 24% for MWW. Removal efficiencies of particulate COD (PCOD) and particulate BOD (PBOD) at the lowest surface overflow rate (SOR) of 1.1 m3/m2/hr corresponding to the longest settling time of 3 hours were 59% and 64% for FW, and 65% and 70% for FW with MWW samples. On the other hand, no significant variation between FW and FW with MWW was observed for PN removal after 3 hours of settling.

Process enhancement of hydrogen and methane production from palm oil mill effluent using two-stage thermophilic and mesophilic fermentation

The present study investigates the technical possibilities of hydrogen and methane production from palm oil mill effluent (POME). The production was carried out in two stage (thermophilic and mesophilic) continuous phase with recirculation of the digestate sludge. The reactors used for the present study, up-flow anaerobic sludge blanket reactor (UASB) and continuous stirred tank reactor (CSTR) were operated under thermophilic and mesophilic conditions, respectively. The UASB reactor was operated at 2 days hydraulic retention time (HRT) and 75 kgCOD m3 d−1 organic loading rate (OLR) for hydrogen production. The effluents from UASB reactor containing mainly with acetate and butyrate were directly fed into CSTR for methane production and 5 days HRT was maintained. Both UASB and CSTR reactors were operated for 120 days continuously, and a stable production of the hydrogen and methane was obtained in the separate reactors. The maximum hydrogen and methane production rate achieved was 1.92 L H2 L−d−1 and 3.2 L CH4 L−1 d−1, respectively. The cumulative hydrogen and methane yields were 215 L H2/kgCOD−1 and 320 L CH4/kgCOD−1, respectively with the total COD removal efficiency of 94%. Thermoanaerobacterium species was dominant in hydrogen reactor, while methane reactor was dominated with Methanobrevibacter sp.

Impact of aluminum chloride on process performance and microbial community structure of granular sludge in an upflow anaerobic sludge blanket reactor for natural rubber processing wastewater treatment

In this study, granular sludge formation was carried out using an aluminum chloride supplement in an upflow anaerobic sludge blanket (UASB) reactor treating natural rubber processing wastewater. Results show that during the first 75 days after the start-up of the UASB reactor with an organic loading rate (OLR) of 2.65 kg-COD·m(-3)·day(-1), it performed stably with a removal of 90% of the total chemical oxygen demand (COD) and sludge still remained in small dispersed flocs. However, after aluminum chloride was added at a concentration of 300 mg·L(-1) and the OLR range was increased up to 5.32 kg-COD·m(-3)·day(-1), the total COD removal efficiency rose to 96.5 ± 2.6%, with a methane recovery rate of 84.9 ± 13.4%, and the flocs began to form granules. Massively parallel 16S rRNA gene sequencing of the sludge retained in the UASB reactor showed that total sequence reads of Methanosaeta sp. and Methanosarcina sp., reported to be the key organisms for granulation, increased after 311 days of operation. This indicates that the microbial community structure of the retained sludge in the UASB reactor at the end of the experiment gave a good account of itself in not only COD removal, but also granule formation.

Biomethane production from vinasse in upflow anaerobic sludge blanket reactors inoculated with granular sludge.

The main objective of this study was to evaluate the anaerobic conversion of vinasse into biomethane with gradual increase in organic loading rate (OLR) in two upflow anaerobic sludge blanket (UASB) reactors, R1 and R2, with volumes of 40.5 and 21.5 L in the mesophilic temperature range. The UASB reactors were operated for 230 days with a hydraulic detection time (HDT) of 2.8 d (R1) and 2.8–1.8 d (R2). The OLR values applied in the reactors were 0.2–7.5 g totalCOD (L d)−1 in R1 and 0.2–11.5 g totalCOD (L d)−1 in R2. The average total chemical oxygen demand (totalCOD) removal efficiencies ranged from 49% to 82% and the average conversion efficiencies of the removed totalCOD into methane were 48–58% in R1 and 39–65% in R2. The effluent recirculation was used for an OLR above 6 g totalCOD (L d)−1 in R1 and 8 g totalCOD (L d)−1 in R2 and was able to maintain the pH of the influent in R1 and R2 in the range from 6.5 to 6.8. However, this caused a decrease for 53–39% in the conversion efficiency of the removed totalCOD into methane in R2 because of the increase in the recalcitrant COD in the influent. The largest methane yield values were 0.181 and 0.185 (L) CH4 (g totalCOD removed)−1 in R1 and R2, respectively. These values were attained after 140 days of operation with an OLR of 5.0–7.5 g totalCOD (L d)−1 and totalCOD removal efficiencies around 70 and 80%.

Performance of an upflow anaerobic filter in the treatment of cold meat industry wastewater

Treatment of cold meat industry wastewater was performed in an upflow anaerobic filter (UAF) analyzing the effect of the physicochemical characteristics of the wastewater, which contains high concentrations of organic matter expressed as total chemical oxygen demand (COD) (3500mgL−1) and total biochemical oxygen demand (BOD) (2035mgL−1), fat oil and grease (FOG) (1114mgL−1), in addition salts (nitrogen and phosphorus), additives, colorings, flavorings and others. The biomass used was previously adapted to the cold meat wastewater in a batch reactor, reducing the total COD and total BOD concentrations by 81% and 87% respectively over a period of 15 days and ensuring to decrease time of staring-up and stabilization of the UAF. Removal efficiencies of total COD and total BOD attained 84% and 88% respectively in the UAF reactor, operating at organic loading rates ranging from 1.17 to 3.5kgCODm−3day−1 at 37°C and pH 7; methane production yield at operating conditions in the stable period of operation reached 422mLCH4(gCODremoved)−1. Physicochemical characteristics of the wastewater, particularly nutrient concentration was determinant in the biomass adaptation and in the self-generated alkalinity, two parameters that greatly contributed to the performance and stabilization of the reactor.

An innovative of aerobic bio-entrapped salt marsh sediment membrane reactor for the treatment of high-saline pharmaceutical wastewater

A novel bio-entrapped salt marsh sediment membrane reactor (BESMSMR) was evaluated for treating high-salinity pharmaceutical wastewater, and membrane fouling behaviour was also assessed. The BESMSMR was operated in parallel with a conventional membrane bioreactor (CMBR), and a salt marsh sediment membrane bioreactor (SMSMBR) as well as an entrapped biomass MBR (bio-entrapped membrane reactor, BEMR) to facilitate a meaningful comparison of performance characteristics obtained in these reactor systems. Two hydraulic retention times (HRTs) of 60 and 40h with organic loading rates (OLRs) varied from 7.0 to 11.9kgCOD/m3d were tested. The pharmaceutical wastewater used has an average total chemical oxygen demand (TCOD) of 17,931±1851mg/L and total dissolved solids (TDS) of 20,881±2030mg/L. The BESMSMR demonstrated the highest removal efficiencies of TCOD (78.4–81.3%), due to the ability of the marine sediment microorganisms seeded from coastal shores to thrive in the hyper-saline environment and degraded recalcitrant organic matter present in the pharmaceutical wastewater. The anoxic zone presented in the inner part of bio-carriers could have triggered the denitrification reaction, and thus improved the TN removal rate by 15–20%. Membrane fouling was reduced with lower concentrations of mixed liquor suspended solids (MLSS), extracellular polymeric substance (EPS), and soluble microbial products (SMP) in the entrapped biomass MBRs. Proteins rather than carbohydrates were the main component of EPS and SMP in the MBR systems. The novel BESMSMR possesses the benefits of salt marsh sediment and an entrapped biomass technique that offered effective organic removal for the high-salinity pharmaceutical wastewater and reduced membrane fouling.

Sequential batch membrane bio-reactor for wastewater treatment: The effect of increased salinity

In this work, a sequential batch membrane bioreactor pilot plant is investigated to analyze the effect of a gradual increase in salinity on carbon and nutrient removal, membrane fouling and biomass kinetic parameters. The salinity was increased by 2gNaClL−1 per week up to 10gNaClL−1. The total COD removal efficiency was quite high (93%) throughout the experiment. A gradual biomass acclimation to the salinity level was observed during the experiment, highlighting the good recovery capabilities of the system. Nitrification was also influenced by the increase in salinity, with a slight decrease in nitrification efficiency (the lowest value was obtained at 10gNaClL−1 due to lower nitrifier activity). Irreversible cake deposition was the predominant fouling mechanism observed during the experiment. Respirometric tests exhibited a stress effect due to salinity, with a reduction in the respiration rates observed (from 8.85mgO2L−1h−1 to 4mgO2L−1h−1).

Stacked-MFC into a typical septic tank used in public housing

ABSTRACTTo test the viability of incorporating a stacked-microbial fuel cell (SMFC) within a typical septic tank, 15 cartridges of MFCs with proton exchange membrane without catalysts were installed in a real system considered with a pretreatment. Both chemical oxygen demand (COD) removal and electricity generation using super capacitors by electricity storage were investigated under continuous flow mode. Three MFCs A1, B4 and C2 with 109.40 ± 34.25 mW/m3, 131.58 ± 27.75 mW/m3 and 124.01 ± 27.57 mW/m3, respectively, were chosen for testing. The organic loading rate was 0.24, 0.52 and 1.05 kg DQO/m3-d corresponding to 200, 500 and 1000 ppm. Total COD removal and total coulombic efficiency were 89.67 ± 5.19% and 48.07 ± 2.33%. The results of this study suggest that MFCs may be suitable for deployment in a septic tank. This research has demonstrated the great challenges in applying a stack of MFC in scale-up. Rint showed that anode resistances are higher than cathode; however, the configuration seems to be indicated for this kind of system depuration in developing countries. An electrochemical model must be developed for scale up which explains performance and electrochemical data. It is necessary to develop experiments in scale up and to test the feasibility of implementation.

Industrial-scale biological treatment of Chinese nutgall processing wastewater by combined expanded granular sludge bed and bio-contact oxidation

The industrial-scale biological treatment of Chinese nutgall processing wastewater was conducted with a 200 m 3 expanded granular sludge bed reactor and a 900 m 3 bio-contact oxidation reactor. The temperature of the two reactors was controlled under mesophilic conditions (32 - 40˚C), through changing the proportion of the dilution water, which was composed of steam condensation water and residual circulating water. The effluent COD, gallic acid, chroma, total nitrogen, total phosphorus levels and pH of both the expanded granular sludge bed and bio-contact oxidation reactors were monitored. In addition, the redox potential in the expanded granular sludge bed was recorded. The total COD removal efficiency was 87.257% when the influent COD concentration was 14 251±3 148 mg/L, and the ratio of wastewater: dilution water was 1:5. The removal efficiencies of gallic acid, chroma, total nitrogen, and total phosphorus were 72.221%, 43.940%, 64.151% and 39.316%, respectively. The effluent pH increased in either the expanded granular sludge bed reactor or the bio-contact oxidation reactor during the operation. The redox potential in the expanded granular sludge bed varied between -367 mV and -435 mV. The results indicate that the combined process was suitable for treating Chinese nutgall processing wastewater.

Qualitative evaluation of small scale municipal Wastewater Treatment Plants (WWTPs) in South India

Decentralized wastewater treatment system (DEWATS) are widely used for the treatment of wastewater originating from residences, institutes and municipalities, specifically in South India. Most of these STPs are denounced owing to failures on several fronts including design, operation and maintenance, installation and monitoring. A comprehensive review and evaluation of STPs was timely, in order to derive sound conclusions and recommendations for future wastewater management strategies. The objective of the present study was to conduct an independent evaluation of already existing decentralized STPs in South India. The technologies assessed were Aerated lagoon (AL), Extended aeration (EA), Anaerobic filter/Vortex put forward by Centre for Scientific Research (CSR VORTEX), Constructed Wetland (DEWATS others), Membrane bioreactor (MBR) and Moving bed Biofilm reactor (MBBR). Among the various technologies evaluated, MBR exhibited the highest total COD, BOD and solids removal efficiency. Pathogen count was lowest in MBR, followed by MBBR and AL. Nutrient removal in terms of ammoniacal nitrogen and nitrate nitrogen was highest in DEWATS. Effective hours of continuous operation enabled improved plant performance. In case of natural treatment technology such as DEWATS, energy requirement is quite low, whereas conventional treatment technologies such as EA necessitate considerably high demand of energy, requiring few personnel to operate the system. Innovative high cell density systems such as MBBR and MBR entail significant power consumption and elaborate maintenance, requiring large number of skilled professionals. The major reasons for failure of STPs were related to mechanical, electrical and labour problems. Regular monitoring and maintenance is required with due diligence in all the treatment technologies for proper functioning.

Pyrosequencing reveals microbial community profile in anaerobic bio-entrapped membrane reactor for pharmaceutical wastewater treatment

In this study, pharmaceutical wastewater with high salinity and total chemical oxygen demand (TCOD) was treated by an anaerobic membrane bioreactor (AnMBR) and an anaerobic bio-entrapped membrane reactor (AnBEMR). The microbial populations and communities were analyzed using the 454 pyrosequencing method. The hydraulic retention time (HRT), membrane flux and mean cell residence time (MCRT) were controlled at 30.6h, 6L/m2h and 100d, respectively. The results showed that the AnBEMR achieved higher TCOD removal efficiency and greater biogas production compared to the AnMBR. Through DNA pyrosequencing analysis, both the anaerobic MBRs showed similar dominant groups of bacteria and archaea. However, phylum Elusimicrobia of bacteria was only detected in the AnBEMR; the higher abundance of dominant archaeal genus Methanimicrococcus found in the AnBEMR could play an important role in degradation of the major organic pollutant (i.e., trimethylamine) present in the pharmaceutical wastewater.

Effect of persulfate and persulfate/H2O2 on biodegradability of an anaerobic stabilized landfill leachate

The current study investigated the effects of S2O82− and S2O82−/H2O2 oxidation processes on the biodegradable characteristics of an anaerobic stabilized leachate. Total COD removal efficiency was found to be 46% after S2O82− oxidation (using 4.2g S2O82−/1g COD0, at pH 7, for 60min reaction time and at 350rpm shaking speed), and improved to 81% following S2O82−/H2O2 oxidation process (using 5.88g S2O82− dosage, 8.63g H2O2 dosage, at pH 11 and for 120min reaction time at 350rpm). Biodegradability in terms of BOD5/COD ratio of the leachate enhanced from 0.09 to 0.1 and to 0.17 following S2O82− and S2O82−/H2O2 oxidation processes, respectively. The fractions of COD were determined before and after each oxidation processes (S2O82− and S2O82−/H2O2). The fraction of biodegradable COD(bi) increased from 36% in raw leachate to 57% and 68% after applying S2O82− and S2O82−/H2O2 oxidation, respectively. As for soluble COD(s), its removal efficiency was 39% and 78% following S2O82− and S2O82−/H2O2 oxidation, respectively. The maximum removal for particulate COD was 94% and was obtained after 120min of S2O82−/H2O2 oxidation. As a conclusion, S2O82−/H2O2 oxidation could be an efficient method for improving the biodegradability of anaerobic stabilized leachate.

Anaerobic Filter에 의한 양돈폐수의 전처리 특성 평가

Anaerobic Filters (AF) packed with porous ceramic floating media were operated at different operational conditions to identify the feasibility of the renewable bioenergy, methane production from swine wastewater and to verify the suitability of effluent from anaerobic filters for the subsequent biological nitrogen and phosphorus removal. Stepwise increase in organic loading rates (OLRs) or decrease in hydraulic retention times (HRTs) with influent TCOD concentration of 14,000 mg/L were utilized at mesophilic temperature. The maximum methane productivity of 1.74 volume of CH4 per volume of reactor per day (v/v-d) was achieved at an hydraulic retention time (HRT) of 0.5 day (OLR 28 g TVS/L-d). Based on the biogas production, the highest total volatile solids (TVS) removal efficiency of 63% was obtained at an HRT of 3 days (OLR 4.67 g TVS/L-d), however based on the result from the effluent total chemical oxygen demand (TCOD) analysis, the highest TCOD removal efficiency of 75% was achieved. The effluent alkalinity concentration over the range of 2,050~2,980 mg/L as CaCO3 at all operational conditions, could compensate the alkalinity destruction caused by nitrification. The effluent from the anaerobic filter operated under the HRT of 2 days showed the COD/TKN ratio of 15~35 and COD/TP ratio of 38~56. Therefore effluent C/N/P ratio is able to satisfy the optimum COD/TKN ratio of greater than 8.0 and COD/TP ratio of 33 for the subsequent biological nutrient removal.

물 부족국가에서 활용가능한 정화조의 최적모형 개발

Abstract This study was carried out to evaluate the performance of a lab-scale novel septic tank system for improving the conventional septic tank in the developing countries of water shortages. The lab-scale novel septic tank system consists of sepetic tank, aeration tank with HBC-ring, and sand filter. Optimum HRT was reguired about 1.5days to get a total COD removal efficiency of 90%, COD, BOD and SS removal efficiency was about 70%, 60%, and 85% in sepetic tank only. The structure of sepetic tank with two stages results in the high removal efficiency of organic matter. When sepetic tank, aeration tank, and sand filter were more than HRT 1.5days, 18hrs, and 12hrs, respectively, final effluent was less than 20 mg/L of BOD, 14 mg/L of SS, so that there is a high potential of its use for reusing water in flush toilet. There is no significant effect of HRT change on nu trient removal. Total nitrogen removal efficiency was about 40%, final effluent was 30~40 mg/L of TN, total phosphorus removal efficiency was about 11~25%, final effluent was 9~12 mg/L of TP. Because there is very small amounts of organic nitrogen and phosphorus in effluent, it was possible to reuse water for agricultural use.

Evaluation of system performance and microbial communities of a bioaugmented anaerobic membrane bioreactor treating pharmaceutical wastewater

In this study, a control anaerobic membrane bioreactor (C-AnMBR) and a bioaugmented anaerobic membrane bioreactor (B-AnMBR) were operated for 210 d to treat pharmaceutical wastewater. Both the bioreactors were fed with the pharmaceutical wastewater containing TCOD of 16,249 ± 714 mg/L and total dissolved solids (TDS) of 29,450 ± 2209 mg/L with an organic loading rate (OLR) of 13.0 ± 0.6 kgCOD/m3d. Under steady-state condition, an average total chemical oxygen demand (TCOD) removal efficiency of 46.1 ± 2.9% and 60.3 ± 2.8% was achieved by the C-AnMBR and the B-AnMBR, respectively. The conventional anaerobes in the C-AnMBR cannot tolerate the hypersaline conditions well, resulting in lower TCOD removal efficiency, biogas production and methane yield than the B-AnMBR seeded from the coastal shore. Pyrosequencing analysis indicated that marine bacterial species (Oliephilus sp.) and halophilic bacterial species (Thermohalobacter sp.) were only present in the B-AnMBR; these species could possibly degrade complex and recalcitrant organic matter and withstand hypersaline environments. Two different dominant archaeal communities, genus Methanosaeta (43.4%) and Methanolobus (61.7%), were identified as the dominant methanogens in the C-AnMBR and the B-AnMBR, respectively. The species of genus Methanolobus was reported resistant to penicillin and required sodium and magnesium for growth, which could enable it to thrive in the hypersaline environment.

Two-stage electrochemical treatment of bio-digested distillery spent wash using stainless steel and aluminum electrodes

The objective of this study was to determine the effectiveness of two-stage electro-coagulation (EC) process using multi-parameter optimization for treating bio-digested distillery spent wash by stainless steel (SS) and aluminum (Al) electrodes. Operating parameters have been optimized and treatment efficiency of SS and Al electrodes have been compared by central composite design of response surface analysis in terms of COD, color and total organic carbon (TOC) removal. Individual and interactive effects of four independent parameters namely initial pH (pHo: 2–10 and 4–10 for SS and Al electrodes, respectively), current density (j: 30.86–154.32 A m−2), inter-electrode distance (g: 0.5–2.5 cm) and electrolysis time (t: 30–150 min) on the COD, color and TOC removal efficiency were evaluated for both the electrodes. SS electrode was found to be more effective for the removal of COD, color and TOC with removal efficiencies of 70%, 93% and 72%, respectively, as compared to Al electrode, which showed respective removal efficiencies of 59%, 80% and 55%. A two-stage EC process was also conducted to study the predominance of different types of electrodes, and to increase the efficiency of EC process. Results shows that SS followed by Al electrode (with total COD, color and TOC removal efficiency of 81%, 94% and 78%, respectively) was found to be more effective than Al followed by SS electrode combination (with total COD, color and TOC removal efficiency of 78%, 89% and 76%, respectively). Present study shows that EC process can be used as an additional step to bio-methanation process so as to meet effluent discharge standards in distilleries.