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Abstract: Dairy wastewater was evaluated for biological hydrogen (H2) production in conjugation with wastewater treatment in a suspended growth sequencing batch reactor (AnSBR) employing sequentially pretreated [heat-shock (100°C, 2h) and acid (pH 3.0, 24h)] mixed consortia. The bioreactor was operated at mesophilic (room) temperature (28±2°C) under acidophilic conditions (pH 6.0) with a total cycle period of 24h consisting of FILL (15min), REACT (23h), SETTLE (30min), and DECANT (15min) phases at three different organic loading rates (OLR) of 2.4, 3.5, and 4.7KgCOD/m3-day, respectively. H2 evolution rate differed significantly with the substrate/OLR of wastewater used as substrate [OLR 2.4KgCOD/m3-day - volumetric H2 production rate: 0.3683mmol H2/m3-min; specific H2 production rate: 0.0184mmol H2/min-gCODL; OLR 3.5KgCOD/m3-day - volumetric H2 production rate: 1.105mmol H2/m3-min; specific H2 production rate: 0.0245mmol H2/min-gCODL and OLR 4.7KgCOD/m3-day - volumetric H2 production rate: 0.7367mmol H2/m3-min; specific H2 production rate: 0.0107mmol H2/min-gCODL]. Substrate (COD) removal efficiency of 64.7 (substrate degradation rate (SDR): 1.577KgCOD/m3-day), 60 (SDR: 3.168KgCOD/m3-day), and 50% (SDR-3.2KgCOD/m3-day), respectively, was observed at operating OLR of 2.4, 3.5, and 4.7KgCOD/m3-day, respectively. The system showed rapid stabilization tendency (2.4KgCOD/m3-day: 39 days; 3.5KgCOD/m3-day: 14 days; 4.7KgCOD/m3-day: 24 days) with respect to H2 generation and COD reduction. A surge in pH values from 5.8 to 4.5 (2.4KgCOD/m3-day), 5.82 to 4.62 (3.5KgCOD/m3-day), and 6.28 to 4.56 (4.7KgCOD/m3-day) was observed during stabilized phase of operation. [Copyright &y& Elsevier]

Molecular hydrogen (H2) production with simultaneous wastewater treatment was studied in biofilm configured periodic discontinuous/sequencing batch reactor using chemical wastewater as substrate. Anaerobic mixed consortia was sequentially pretreated with repeated heat-shock (100°C; 2h) and acid (pH—3.0; 24h) treatment procedures to selectively enrich the H2 producing mixed consortia prior to inoculation of the reactor. The bioreactor was operated at mesophilic (room) temperature (28±2°C) under acidophilic conditions with a total cycle period of 24h consisting of FILL (15min), REACT (23h), SETTLE (30min) and DECANT (15min) phases. Reactor was initially operated with synthetic wastewater (SW) at OLR of 4.8kgCOD/m3-day and subsequently operated using composite chemical wastewater (CW) at OLR of 5.6kgCOD/m3-day by adjusting pH to 6.0 prior to feeding to inhibit the methanogenic activity. H2 evolution rate differed significantly with the nature of wastewater used as substrate [SW—volumetric H2 production rate—12.89mmolH2/m3-min and specific H2 production rate—0.0084mmolH2/min-gCODL (0.026mmolH2/min-gCODR); CW—volumetric H2 production rate—6.076mmolH2/m3-min and specific H2 production rate—0.0089mmolH2/min-gCODL (0.033mmolH2/min-gCODR)]. Relatively rapid progress towards higher H2 yield (2h) was observed with SW compared to the CW (10h). Substrate (COD) reduction of 32.4% (substrate degradation rate (SDR)—1.55kgCOD/m3-day) and 26.7% (SDR-1.49kgCOD/m3-day) was observed with SW and CW, respectively. The system showed rapid stabilization tendency (SW—37 days; CW—40 days) with respect to H2 generation and COD reduction. H2 evolution showed relatively good correlation with VFA concentration in the case of SW (R 2-0.961) compared to CW (R 2-0.912). A surge in pH values from 5.87 to 4.23 (SW) and 5.93 to 4.62 (CW) was observed during the cycle operation. Integration of biofilm configuration with periodic discontinuous batch operation under the defined operating conditions showed potential to influence the microbial system by selectively enriching the specific group of microflora capable of producing H2. [Copyright &y& Elsevier]

Abstract: Polyhydroxyalkanoates (PHA) production using Pseudomonas otitidis, a newly isolated strain from PHA producing bioreactor was investigated using synthetic acids (SA) and acidogenic effluents (AE) from biohydrogen reactor at different organic loading rates (OLRs). P. otitidis showed ability to grow and accumulate PHA, with simultaneous waste remediation. AE showed less PHA production (54%, OLR3), than SA (58%, OLR2). PHA composition showed co-polymer, poly-3(hydroxy butyrate-co-hydroxy valerate), P3(HB-co-HV). Bioprocess evaluation and enzymatic activities showed good correlation with PHA production. Kinetic studies on the growth of bacteria using different models at varying OLR were substantiated with PHA production. High substrate removal was registered at OLR1 (SA, 87%; AE, 82%). AE could be used as an alternative for pure substrates keeping in view of their high cost. [Copyright &y& Elsevier]

Abstract: Distillery wastewater rich in organics is an inexpensive renewable resource for making first generation biofuel. Distillery wastewaters are mostly treated via the biomethanation route; however, in this study the conditions in sequential batch reactor (SBR) are being set to develop and analyze the microbial community that opted for hydrogen production. An optimum performance condition for a bioreactor was achieved after 40 days of operation, which gave substrate degradation rate of 0.72 kg/m3-day with volumetric hydrogen production of 0.32 mol H2/m3-day. Study proposes that the dominant Delftia sp., a hydrogen oxidizing bacterium has been replaced during hydrogen production mode with dominant Anaerofilum sp., an anaerobic Firmicute and the iron dependent hydrogenases dominated as functional gene for hydrogen production. Future studies are required where process-engineering interventions could be applied to improve the hydrogen driving biochemical process. [Copyright &y& Elsevier]

Abstract: The feasibility of bioplastics production as poly(β-OH)butyrate (PHB) was studied with individual volatile fatty acids (VFA) and acid-rich effluents from a biohydrogen producing reactor (HBR) as primary substrates employing aerobic consortia as biocatalyst under anoxic microenvironment. Butyrate as substrate showed higher PHB productivity (33%) followed by acetate (32%), acids mixture (16%) and propionate (11%) among synthetic VFA studied. Acid-rich effluents from HBR yielded higher PHB productivity (25%) especially at lower substrate loading conditions. Decrement observed in PHB production (from 25% to 6%) with increase in substrate load might be due to the presence of high concentration of residual carbon along with acid metabolites. Neutral redox operation showed effective PHB production compared to acidic and basic conditions due to associated higher metabolic activity of the biocatalyst. The integrated approach helped to treat additional COD from acid-rich HBR effluents apart from by-product recovery. [ABSTRACT FROM AUTHOR]

Abstract: This communication provides an insight into the composition of the microbial community survived in the biofilm configured anaerobic reactor operated for biohydrogen (H2) production using wastewater as substrate under diverse conditions for past four years. PCR amplified 16S rDNA product (at variable V3 region using universal primers 341F and 517R) was separated by using denaturing gradient gel electrophoresis (DGGE) to identify the diversity in microbial population survived. The phyologenetic profile of the bioreactor showed significant diversity in the microbial community where major nucleotide sequences were affiliated to Class Clostridia followed by Bacteroidetes, Deltaproteobacteria and Flavobacteria. Clostridium were found to be dominant in the microbial community observed. The controlled growth conditions, application of pre-treatment to biocatalyst, operation with specific pH and variation in substrate composition are reasoned for the robust acidogenic culture identified in the bioreactor. Most of the operational taxonomic units (OTUs) observed in the bioreactor are capable to undergo acetate producing pathway, feasible for effective H2 production. [Copyright &y& Elsevier]

Abstract: An ecologically engineered system (EES) was designed to mimic the natural cleansing functions of wetlands to bring about wastewater treatment. EES consisted of three tanks containing diverse biota viz., aquatic macrophytes, submerged plants, emergent plants and filter feeders connected in series. The designed system was evaluated for 216days by operating in continuous mode (20l/day) to treat both sewage (DS) and fermented-distillery wastewater (FDW, from hydrogen producing bioreactor). Floating macrophyte system (Tank 1) was more effective in removing COD and nitrates. Submerged and emergent integrated macrophyte system (Tank 2) showed an effective removal of volatile fatty acids (VFAs) along with COD. Filter-feeding system (Tank 3) visualized the removal of COD, VFA, turbidity and color. On the whole the system can treat effectively DS (COD, 68.06%; nitrate, 22.41%; turbidity, 59.81%) and FDW (COD, 72.92%; nitrate, 23.15%; color, 46.0%). The designed EES can be considered as an economical approach for the treatment of both sewage and fermented wastewaters. [Copyright &y& Elsevier]

Abstract: Bioslurry phase reactor was used for the degradation of pendimethalin, a pre-emergence herbicide in the contaminated soil under aerobic environment. More than 91% degradation of pendimethalin was observed for 5 days of reactor operation augmented with sewage from effluent treatment plant (ETP). The performance of the reactor was monitored regularly by measuring pH and colony forming units (CFU). The metabolites of pendimethalin formed during degradation were identified using various analytical techniques, viz., thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and liquid chromatography–mass spectroscopy (LC–MS/MS). Four metabolites were formed and identified as N-(1-ethylpropyl)-3,4-dicarboxy 2,6-dinitrobenzenamine-N-oxide, N-(1-ethylpropyl)-3,4-dimethoxy-2,6-dinitrobenzenamine and benezimadazole-7-carboxyaldehyde. The reactions involved were monohydrolysis of 2-methyl groups followed by dihydrolysis. Further oxidation of amine groups and hydroxylation of propyl groups produced the above said metabolites. Degradation pathway of pendimethalin has been proposed in the bioslurry phase reactor. [Copyright &y& Elsevier]

Abstract: Bioremediation of di-n-butyl phthalate (DnBP) in soil was studied with various concentrations in a bioslurry phase batch reactor operated in sequenting batch mode (bioaugmented with effluent treatment plant (ETP) microflora) for a total cycle period of 96h. Process performance during the reactor operation was assessed by monitoring DnBP concentration and biochemical process parameters viz., pH, dissolved oxygen (DO), colony forming units (CFU) and oxygen uptake rate (OUR), during the sequence phase operation. The degradation rate was observed to be rapid at lower substrate concentrations and found to be slow as the substrate concentration increased. The potent bacterial strain was also isolated from the slurry phase reactor. Metabolites formed during the degradation of DnBP in the slurry phase reactor were identified. Studies on the kinetics and half-life of the reaction revealed that the degradation process followed zero-order kinetic model. [Copyright &y& Elsevier]

Abstract: The degradation of DEP contaminated soil was studied in the soil slurry phase sequencing batch reactor (SS-SBR). Experiments were conducted for studying the degradation of DEP using four different reactors. Effect of bioaugmentation using ETP microflora on the degradation of DEP was also investigated and found an enhanced degradation. The reactors were operated with a total cycle period of 48h, comprising one and half hours of fill 45h of react and one and half hours of decant phases. The metabolites for the DEP degradation in slurry phase have been identified. During the operation of bioaugmented reactor, the substrate partition data showed higher desorption of DEP from soil phase to aqueous phase compared to other reactors studied. The degradation of DEP in the slurry phase confirmed to zero order kinetic equation in bioaugmented reactor. The half life period of DEP degradation in the soil phase of bioaugmented reactor was 19 days. Process performance during the investigation was monitored by determining dissolved oxygen (DO), pH, oxygen consumption rate (OCR) and substrate concentration by high performance liquid chromatography (HPLC). [Copyright &y& Elsevier]