ABSTRACT
Feasibility of integrating Microbial electrolysis cell (MEC) process with dark-fermentation process for additional hydrogen recovery as well as substrate degradation was demonstrated in the present study. MEC was employed in order to utilize the residual organic fraction present in the acidogenic effluents of dark fermentation process as substrate for hydrogen production with input of small electric current. MEC was operated at volatile fatty acids (VFA) concentration of 3000 mg/l under different poised potentials (0.2, 0.5, 0.6, 0.8 and 1.0 V) using anaerobic consortia as biocatalyst. Maximum hydrogen production rate (HPR), cumulative hydrogen production (CHP) (0.53 mmol/h and 3.6 mmol), dehydrogenase activity (1.65 µg/ml) and VFA utilization (49.8%) was recorded at 0.6 V. Bio-electrochemical behavior of mixed consortia was evaluated using cyclic voltammetry and by Tafel slope analysis. Microbial diversity analysis using denaturing gradient gel electrophoresis confirmed the presence of γ-proteobacteria (50%), Bacilli (25%) and Clostridia (25%).
Subject(s)
Acids/metabolism , Biofuels/microbiology , Electrolysis/methods , Wastewater/microbiology , Water Purification/methods , Bacteria/enzymology , Bacteria/genetics , Base Sequence , Biodegradation, Environmental , DNA, Ribosomal/genetics , Denaturing Gradient Gel Electrophoresis , Electrochemical Techniques , Fatty Acids, Volatile/analysis , Hydrogen , Hydrogen-Ion Concentration , Oxidoreductases/metabolism , PhylogenyABSTRACT
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.
Subject(s)
Acids/metabolism , Biocatalysis , Polyhydroxyalkanoates/biosynthesis , Pseudomonas/metabolism , Waste Disposal, Fluid , Wastewater/microbiology , Base Sequence , Biological Oxygen Demand Analysis , Fatty Acids, Volatile/analysis , Hydrogen-Ion Concentration , Kinetics , Models, Biological , Molecular Sequence Data , Phylogeny , Pseudomonas/enzymology , Pseudomonas/genetics , Pseudomonas/growth & development , RNA, Ribosomal, 16S/genetics , Sequence Analysis, RNA , Substrate Specificity , Water PurificationABSTRACT
AIMS: To study the bioelectrochemical behaviour of Pseudomonas aeruginosa (MTCC 17702) and Escherichia coli (MTCC 10436) and to assess their potential to act as anodic biocatalyst with the function of anaerobic consortia for microbial (bio) fuel cell (BFC) application. METHODS AND RESULTS: Three BFCs (single chamber; open-air cathode; noncatalysed electrodes) were operated simultaneously in acidophilic microenvironments. Pseudomonas aeruginosa (BFC(P)) showed higher current density (264 mA m(-2) ) followed by mixed culture (BFC(M); 166 mA m(-2)) and E. coli (BFC(E); 147 mA m(-2)). However, total operating period and substrate degradation were relatively found to be effective with mixed culture (58%; 72 h) followed by BFC(P) (39%; 60 h) and BFC(E) (31%; 48 h). Higher electron discharge (ED) was observed with Ps. aeruginosa while mixed culture showed the involvement of redox mediators in the ED process. CONCLUSIONS: Mixed culture showed to sustain biopotential for longer periods along with a stable ED. The presence of redox signals and high substrate degradation was also evidencing its performance compared to the pure strains studied. This supports the practical utility of mixed culture over the pure cultures for real-field BFC applications especially while operating with wastewater. SIGNIFICANCE AND IMPACT OF THE STUDY: This study revealed the efficiency and viability of mixed consortia in comparison with pure strains for microbial (bio) fuel cell applications.
Subject(s)
Bacteria, Anaerobic/metabolism , Bioelectric Energy Sources , Electrodes , Enzymes/metabolism , Escherichia coli/physiology , Pseudomonas aeruginosa/physiology , Electrochemistry , Electrons , Oxidation-ReductionABSTRACT
Bio (microbial) fuel cell (microbial fuel cell) with Saccharomyces cerevisiae as anodic biocatalyst was evaluated in terms of power generation and substrate degradation at three redox conditions (5.0, 6.0 and 7.0). Fuel cell was operated in single chamber (open-air cathode) configuration without mediators using non-catalyzed graphite as electrodes. The performance was further studied with increasing loading rate (OLRI, 0.91 kg COD/m(3)-day; OLRII, 1.43 kg COD/m(3)). Higher current density was observed at pH6.0 [160.36 mA/m(2) (OLRI); 282.83 mA/m(2) (OLRII)] than pH5.0 (137.24 mA/m(2)) and pH 7.0 (129.25 mA/m(2)). Bio-electrochemical behavior of fuel cell was evaluated using cyclic voltammetry which showed the presence of redox mediators (NADH/NAD(+); FADH/FAD(+)). Higher electron discharge was observed at pH6.0, suggesting higher proton shuttling through the involvement of different redox mediators. The application of yeast based fuel cell can be extended to treat high strength wastewaters with simultaneous power generation.
Subject(s)
Bioelectric Energy Sources/microbiology , Electrodes/microbiology , Saccharomyces cerevisiae/physiology , Catalysis , Energy Transfer , Equipment Design , Equipment Failure Analysis , Oxidation-ReductionABSTRACT
A multi stage high rate biomethanation process with novel self mixed anaerobic digester (SMAD) was developed in the present study to reduce the hydraulic residence time (HRT), increase the volatile solids (VS) loading rate, improve the VS destruction efficiency and enhance the methane yield. Specific design features of SMAD were useful in mixing the digester contents without consuming power and de-alienated the problem of scum formation. In the first phase, poultry litter having 10% total solids (TS) was subjected to high rate biomethanation in multi stage configuration (SMAD-I and II in series with UASB reactor). It was observed that gross VS reduction of 58%, gross methane yield of 0.16 m3 kg(-1) (VS reduced) and VS loading rate of 3.5 kg VS m(-3) day(-1) at HRT of 13 days was obtained. In the second phase SMAD-II was bypassed from the process scheme keeping the other parameters same as in the first phase. The results obtained were not as encouraging as in the first phase. The study showed that multi stage configuration with SMAD design improved the anaerobic digestion process efficiency of poultry litter.
Subject(s)
Bacteria/metabolism , Bioreactors/microbiology , Methane/analysis , Poultry , Refuse Disposal/instrumentation , Refuse Disposal/methods , Waste Products/analysis , Anaerobiosis , Animals , Biodegradation, Environmental , Time Factors , Water Pollutants, Chemical/isolation & purificationABSTRACT
Biodiesel as an eco-friendly fuel is gaining much acceptance in recent years. This communication provides an overview on the possibility of using mixed microalgae existing in ecological water-bodies for harnessing biodiesel. Microalgal cultures from five water-bodies are cultivated in domestic wastewater in open-ponds and the harvested algal-biomass was processed through acid-catalyzed transesterification. Experiments evidenced the potential of using mixed microalgae for harnessing biodiesel. Presence of palmitic acid (C16:0) in higher fraction and physical properties of algal oil correlated well with the biodiesel properties. Functional characteristics of water-bodies showed to influence both species diversity and lipid accumulation. Microalgae from stagnant water-bodies receiving domestic discharges documented higher lipid accumulation. Algal-oil showed to consist 33 types of saturated and unsaturated fatty acids having wide food and fuel characteristics. Simultaneous wastewater treatment was also noticed due to the syntrophic association in the water-body microenvironment. Diversity studies visualized the composition of algae species known to accumulate higher lipids.
Subject(s)
Biofuels/analysis , Biofuels/microbiology , Biotechnology/methods , Ecosystem , Microalgae/metabolism , Rivers/microbiology , Biodiversity , Culture Media/chemistry , Fatty Acids/analysis , Flame Ionization , Gas Chromatography-Mass Spectrometry , Hydrogen-Ion Concentration , Microalgae/cytology , Microalgae/growth & developmentABSTRACT
The feasibility of bioplastics production as poly(beta-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.
Subject(s)
Bioreactors , Biotechnology/methods , Fermentation/physiology , Hydrogen/metabolism , Hydroxybutyrates/metabolism , Polyesters/metabolism , Waste Disposal, Fluid , Biofuels/analysis , Fatty Acids, Volatile/isolation & purification , Hydrogen-Ion Concentration , Oxygen/isolation & purification , Substrate Specificity , Water PurificationABSTRACT
Positive influence of poised potential on microbial fuel cell (MFC) performance was observed with increase in the applied potential up to 600 mV and decreased thereafter. Higher power output (79.33 mW/m(2)) was observed at 600 mV poised potential under open circuit operation (OC). Closed circuit operation (CC) showed almost negligible power output due to continuous electron discharge against an external load (100 Omega). However, CC operation resulted in the higher substrate (chemical oxygen demand (COD)) degradation [61.23% (control); 70.46% (OC; 600 mV); 74.15% (CC; 600 mV)] and total dissolved solids (TDS) removal [29.17% (control); 43.75% (OC; 600 mV); 72.92% (CC; 600 mV)] efficiencies compared to OC. Electron discharge and energy conversion efficiency was also observed to be higher with 600 mV poised potential. Poising potential showed additional redox couples (-0.29+/-0.05 mV) on cyclic voltammetry. Application of poised potential during startup phase will help to enrich electrochemically active consortia on anode resulting in improved performance of MFC.
Subject(s)
Bioelectric Energy Sources , Electrochemistry/methods , Catalysis , Electricity , Electrodes , Electrons , Equipment Design , Oxidation-Reduction , Oxygen/chemistry , Time Factors , Water Purification/methodsABSTRACT
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.
Subject(s)
Acids , Fermentation , Sewage , Animals , Hydrogen-Ion ConcentrationABSTRACT
Microbial fuel cell (MFC; open-air cathode) was evaluated as bio-electrochemical treatment system for distillery wastewater during bioelectricity generation. MFC was operated at three substrate loading conditions in fed-batch mode under acidophilic (pH 6) condition using anaerobic consortia as anodic-biocatalyst. Current visualized marked improvement with increase in substrate load without any process inhibition (2.12-2.48mA). Apart from electricity generation, MFC documented efficient treatment of distillery wastewater and illustrated its function as an integrated wastewater treatment system by simultaneously removing multiple pollutants. Fuel cell operation yielded enhanced substrate degradation (COD, 72.84%) compared to the fermentation process ( approximately 29.5% improvement). Interestingly due to treatment in MFC, considerable reduction in color (31.67%) of distillery wastewater was also observed as against color intensification normally observed due to re-polymerization in corresponding anaerobic process. Good reduction in total dissolved solids (TDS, 23.96%) was also noticed due to fuel cell operation, which is generally not amenable in biological treatment. The simultaneous removal of multiple pollutants observed in distillery wastewater might be attributed to the biologically catalyzed electrochemical reactions occurring in the anodic chamber of MFC mediated by anaerobic substrate metabolism.
Subject(s)
Biodegradation, Environmental , Bioelectric Energy Sources , Electrochemical Techniques/methods , Industrial Waste/prevention & control , Water Pollutants, Chemical/chemistry , Anaerobiosis , Color , ElectricityABSTRACT
Performance of microbial fuel cell (MFC) was evaluated with the function of phosphatase and dehydrogenase activities at increasing organic loading rate (OLR) (0.195kg chemical oxygen demand (COD)/m(3)-day; 0.458kg COD/m(3)-day; 0.911kg COD/m(3)-day; 1.589kg COD/m(3)-day). Variation in enzyme activities along with power generation and substrate degradation was observed during MFC operation with the function of organic loading rate (OLR). Phosphatase activity showed a decreasing trend with time from 24 to 36th hour depending on OLR which is a good sign of substrate utilization. Dehydrogenase activity was observed to be high at the 12th hour irrespective of the OLR. However, the activity was increased with increasing OLR. Higher dehydrogenase activity was observed at 1.589kg COD/m(3)-day representing the possibility of higher redox reactions. Higher power output was recorded at the 12th hour with 53.58mW/m(2) (0.195kg COD/m(3)-day) and 24th hour with 60.29mW/m(2) (0.458kg COD/m(3)-day) and 76.17mW/m(2) (0.911kg COD/m(3)-day). At higher OLR studied (1.589kg COD/m(3)-day), maximum power generation (49.86mW/m(2)) was observed at 12th hour indicating decreased performance. Electron discharge and recovery properties observed during MFC operation were supporting higher performance at 0.911kg COD/m(3)-day. Increase in OLR showed improvement in substrate degradation [OLR1, 56.32% (0.11kg COD/m(3)-day); OLR2, 56.42% (0.26kg COD/m(3)-day); OLR3, 59.53% (0.54kg COD/m(3)-day); OLR4, 64.40% (1.78kg COD/m(3)-day)].
Subject(s)
Bioelectric Energy Sources , Oxidoreductases/metabolism , Phosphoric Monoester Hydrolases/metabolism , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/metabolism , Water Purification/methods , Anaerobiosis , Electricity , Electrodes , Oxygen/chemistry , Oxygen/metabolism , Time FactorsABSTRACT
L-Asparaginase is an important component in the treatment of acute lymphoblastic leukemia in children. Its antineoplastic activity toward malignant cells is due to their characteristic nature in slow synthesis of L-asparagine (Asn), which causes starvation for this amino acid, while normal cells are protected from Asn starvation due to their ability to produce this amino acid. The relative selectivity with regard to the metabolism of malignant cells forces to look for novel asparaginase with little glutaminase-producing systems compared to existing enzyme. In this investigation, the role of the extracellular asparaginase enzyme produced by an isolated bacterial strain was studied. Biochemical characterization denoted that this isolated bacterial strain belongs to the Bacillus circulans species. The strain was tested for L-asparaginase production, and it was observed that, under an optimized environment, this isolate produces a maximum of 85 IU ml(-1) within 24-h incubation. This enzyme showed less (60%) glutaminase activity compared to commercial Erwinia sp. L-asparaginase. The partially purified enzyme showed an approximate molecular weight of 140 kDa. This enzyme potency in terms of antineoplastic activity was analyzed against the cancer cells, CCRF-CEM. Flow cytometry experiments indicated an increase of sub-G1 cell population when the cells were treated with L-asparaginase.
Subject(s)
Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Asparaginase/biosynthesis , Asparaginase/pharmacology , Bacillus/isolation & purification , Bacillus/metabolism , Extracellular Space/enzymology , Antineoplastic Agents/therapeutic use , Asparaginase/therapeutic use , Bacillus/cytology , Cell Line, Tumor , Cell Proliferation/drug effects , Humans , Leukemia/drug therapyABSTRACT
Dehydrogenase (DH) activity associated with bio-electrochemical behavior was analyzed for the first time to understand the redox reactions involved in fermentative hydrogen (H(2)) production process in concurrence with proton (H(+)) shuttling and electron (e(-)) discharge (ED) pattern. DH facilitates the availability of H(+) through redox reactions to make H(2). We have designed a comprehensive experimental study to evaluate the DH activity (H(+) shuttling) and ED to understand the biochemical process with the function of pH (5, 6, 7 and 8) and metabolic microenvironment [anaerobic, anoxic and aerobic (control)]. DH activity was observed to be higher during anaerobic operation suggesting the higher availability of H(+) and e(-) due to the inter-conversion of metabolites and the same was reflected in the voltammetry analysis. Higher H(2) production under anaerobic operation corroborated well with these findings. The DH activity associated with H(+) shuttling and ED was also correlated with the substrate degradation pattern.
Subject(s)
Hydrogen/chemistry , Oxidation-Reduction , Oxidoreductases/chemistry , Bioreactors , Biotechnology/methods , Electrochemistry/methods , Electrons , Equipment Design , Fermentation , Glucose/chemistry , Hydrogen-Ion Concentration , Oxygen/chemistry , Protons , Water Pollutants, Chemical/chemistry , Water Purification/methodsABSTRACT
Single chambered mediatorless microbial fuel cell (MFC; non-catalyzed electrodes) was operated to evaluate the potential of bioelectricity generation from the treatment of composite waste vegetables (EWV) extract under anaerobic microenvironment using mixed consortia as anodic biocatalyst. The system was operated with designed synthetic wastewater (DSW; 0.98 kg COD/m(3)-day) during adaptation phase and later shifted to EWV and operated at three substrate load conditions (2.08, 1.39 and 0.70 kg COD/m(3)-day). Experimental data illustrated the feasibility of bioelectricity generation through the utilization of EWV as substrate in MFC. Higher power output (57.38 mW/m(2)) was observed especially at lower substrate load. The performance of MFC was characterized based on the polarization behavior, cell potentials, cyclic voltammetric analysis and sustainable resistance. MFC operation also documented to stabilize the waste by effective removal of COD (62.86%), carbohydrates (79.84%) and turbidity (55.12%).
Subject(s)
Bioelectric Energy Sources , Bioreactors , Conservation of Energy Resources , Electrodes , Waste Disposal, Fluid/methods , Water Purification , Biodegradation, Environmental , Carbohydrates/isolation & purification , Catalysis , Electricity , Electrochemistry/methods , Nephelometry and Turbidimetry/methods , Oxygen/isolation & purificationABSTRACT
In the present investigation, impact of nickel-impregnated silica paramagnetic particles (NSP) as biocatalyst immobilization matrices was investigated. These nanoparticles were synthesized by sol-gel route using a nonionic surfactant block co polymer [poly (ethylene glycol)-block-poly-(propylene glycol)-block-poly (ethylene glycol)]. Diastase enzyme was immobilized on these particles (enzyme-impregnated NSP) as model enzyme and characterized using Fourier-transform infrared spectroscopy and X-ray crystallography. Analysis of enzyme-binding nature with these nanoparticles at different physiological conditions revealed that binding pattern and activity profile varied with the pH of the reaction mixture. The immobilized enzyme was further characterized for its biocatalytic activity with respect to kinetic properties such as Km and Vmax and compared with free enzyme. Paramagnetic nanoparticle-immobilized enzyme showed more affinity for substrate compared to free one. The nature of silica and nickel varied from amorphous to crystalline nature and vice versa upon immobilization of enzyme. To the best of our knowledge, this is the first report of its kind for change of nature from one form to other under normal temperatures upon diastase interaction with NSP.
Subject(s)
Amylases/chemistry , Enzymes, Immobilized/chemistry , Nanoparticles/chemistry , Nickel/chemistry , Silicon Dioxide/chemistry , Silicon Dioxide/chemical synthesis , Amylases/metabolism , Binding Sites , Biocatalysis , Crystallography, X-Ray , Enzyme Activation , Enzymes, Immobilized/metabolism , Hydrogen-Ion Concentration , Hydrolysis , Maltose/chemical synthesis , Maltose/chemistry , Models, Molecular , Polyethylene Glycols/chemistry , Propylene Glycols/chemistry , Starch/chemistry , Surface Properties , Surface-Active Agents/chemistryABSTRACT
In the present investigation, performance of various laccase-membrane reactor configurations including direct enzyme contact, enzyme impregnated, immobilized enzyme and a reactor system based on laccase immobilization in chitosan membranes for decolorization of azo dye (acid black 10 BX) were examined using laccase enzyme purified from white rot fungi Pleurotus ostreatus 1804. A five-step laccase purification procedure was employed, which improved the enzymatic activity by 8.27 folds. Laccase was confirmed by comparing with the standard marker using SDS-PAGE electrophoresis, which showed molecular weight of 63 kDa. Experimental data showed that laccase has great potential for color removal without addition of external redox mediators. Various process parameters viz. aqueous phase of pH 6.0, enzyme concentration of 1.75 U/ml, dye concentration of 20 mg/L, temperature of 30 degrees C and reaction time of 120 min were optimized to achieve maximum decolorization efficiencies. Moreover, different laccase-membrane reactor configurations were tested to determine the efficacy of repeated application of laccase on dye decolorization process. Among the different reactor configurations employed, laccase encapsulated in chitosan membrane showed advantages such as short-term contact period and reusability of enzyme for a number of cycles.
Subject(s)
Azo Compounds/metabolism , Bioreactors , Coloring Agents/metabolism , Laccase/metabolism , Azo Compounds/analysis , Catalysis , Chitosan/metabolism , Color , Coloring Agents/analysis , Enzymes, Immobilized/metabolism , Fermentation , Hydrogen-Ion Concentration , Laccase/isolation & purification , Pleurotus/enzymology , Polyvinyls/metabolism , TemperatureABSTRACT
Single chambered mediatorless microbial fuel cell (MFC Nafion-117 membrane) fabricated with non-catalyzed electrodes was operated with open-air cathode to evaluate bioelectricity generation from domestic wastewater under acidogenic conditions (pH, 6) using anaerobic mixed consortia as anodic biocatalyst. Experimental data illustrated the feasibility of bioelectricity generation from domestic wastewater treatment. A steady increase in MFC performance was observed from the first cycle (0.248 V; 27.3 mW/m(2); 1.06 W/kg COD(R)) during the startup phase prior to stabilization on fourth cycle (0.449 V; 144.6 mW/m(2); 4.64 W/kg COD(R)). Sharp increase in power generation was observed after the fourth hour (125.4 mW/m(2); 289.61 mA/m(2)) which continued up to the sixth hour (155.92 mW/m(2); 325.51 mA/m(2)) and gradually decreased thereafter. Voltammogram evidenced clear redox peaks (E(0)', -0.334 V) related to redox mediator NAD(+)/NADH (E(0)', -0.32 V) suggesting a strong reducing phase. Higher energy (1.33 J) was observed at the fourth hour in concurrence with the effective electron discharge and higher substrate degradation.
Subject(s)
Bacteria, Anaerobic/metabolism , Bioelectric Energy Sources/microbiology , Electrochemistry/methods , Water Purification , Acids/chemistry , Biodegradation, Environmental , Electrochemistry/instrumentation , Electrodes , Equipment Design , FermentationABSTRACT
Vegetable based market waste was evaluated as a fermentable substrate for hydrogen (H(2)) production with simultaneous stabilization by dark-fermentation process using selectively enriched acidogenic mixed consortia under acidophilic microenvironment. Experiments were performed at different substrate/organic loading conditions in concurrence with two types of feed compositions (with and without pulp). Study depicted the feasibility of H(2) production from vegetable waste stabilization process. H(2) production was found to be dependent on the concentration of the substrate and composition. Higher H(2) production and substrate degradation were observed in experiments performed without pulp (23.96 mmol/day (30.0 kg COD/m(3)); 13.96 mol/kg COD(R) (4.8 kg COD/m(3))) than with pulp (22.46 mmol/day (32.0 kg COD/m(3)); 12.24 mol/kg COD(R) (4.4 kg COD/m(3))). Generation of higher concentrations of acetic acid and butyric acid was observed in experiments performed without pulp. Data enveloping analysis (DEA) was employed to study the combined process efficiency of system by integrating H(2) production and substrate degradation.
Subject(s)
Bacteria, Anaerobic/metabolism , Bioreactors/microbiology , Garbage , Models, Biological , Sewage/microbiology , Vegetables/microbiology , Computer Simulation , Hydrogen , Industrial WasteABSTRACT
Endocrine disruptive compounds (EDC) are a wide variety of chemicals which typically exert effects, either directly or indirectly, through receptor-mediated processes. They mimic endogenous hormones by influencing the activities of hormone activities even at nanogram concentrations and reported to disrupt the vital systems (e.g., the endocrine system) in aquatic organisms. The EDC are present in aquatic water bodies and sediments mainly due to the release of human and animal excreted waste. Estriol (E3) removal by adsorption process was investigated in this study to evaluate the potential of activated charcoal as adsorbent. Agitated non-flow batch sorption studies showed good E3 removal efficiency. Sorption kinetic data illustrated good fit with pseudo-first-order rate equation. Experimental data confirmed to linear Langmuir's isotherm model. Neutral pH condition showed comparatively good sorption of E3. Adsorption capacity showed a consistent increasing trend with increase in the operating temperature [DeltaH degrees , -9.189 kJ/mol); DeltaS degrees , 0.492 J/mol K) suggesting exothermic nature of E3 sorption process. Free energy (DeltaG degrees ) increased from 2.51 to 2.97 kJ/mol with increase in temperature from 0 to 50 degrees C. Further, E3 spiked distilled water, untreated domestic sewage and treated domestic sewage were studied in fixed bed column to assesses the potential of sorption process as tertiary unit operation in the ETP system. Total E3 concentration was determined quantitatively by employing direct competitive enzymatic-immuno assay (EIA) procedure.
Subject(s)
Endocrine Disruptors/isolation & purification , Water Pollutants, Chemical/isolation & purification , Water Purification/methods , Adsorption , Animals , Charcoal , Endocrine Disruptors/analysis , Enzyme-Linked Immunosorbent Assay , Estriol/isolation & purification , Humans , Thermodynamics , Water Pollutants, Chemical/analysisABSTRACT
Six different types of ecological water bodies were evaluated to assess their potential to generate bioelectricity using benthic type fuel cell assemblies. Experiments were designed with various combinations of electrode assemblies, surface area of anode and anodic materials. Among the 32 experiments conducted, nine combinations evidenced stable electron-discharge/current. Nature, flow conditions and characteristics of water bodies showed significant influence on the power generation apart from electrode assemblies, surface area of anode and anodic material. Stagnant water bodies showed comparatively higher power output than the running water bodies. Placement of cathode on algal mat (as bio-cathode) documented several folds increment in power output. Electron-discharge started at 1000 Omega resistance in polluted water bodies (Nacaharam cheruvu, Hussain Sagar lake Musi river), whereas, in relatively less polluted water bodies (Uppal pond/stream, Godavari river) electron-discharge was observed at low resistances (500/750 Omega).