Narsi R. Bishnoi

ADSORPTION OF CR(VI) ON ACTIVATED RICE HUSK CARBON AND ACTIVATED ALUMINA

The possible use of activated rice husk and activated alumina as the adsorbents of Cr(VI) from synthetic solutions and the effect of operating parameters were investigated. The activated rice husk carbon was prepared thermally in two sizes 0.3 and 1.0 mm. The maximum removal of Cr(VI) occurred at pH 2 by activated rice husk and at pH 4 by activated alumina. The amounts of Cr(VI) adsorbed increased with increase in dose of both adsorbents and their contact time. The Freundlich isotherm was applied.

Enhanced saccharification of rice straw and hull by microwave–alkali pretreatment and lignocellulolytic enzyme production

In this study, statistical design of experiments was employed to plan experiments and optimize the microwave-alkali pretreatment of rice straw and hulls. Process parameters important in pretreatment of biomass were identified by a Plackett-Burman design and the parameters with significant effects were optimized using a box-behnken design (BBD). Experimental results show that alkali concentration (AC), irradiation time (IT) and substrate concentration (SC) were main factors governing the saccharification of rice straw and hulls. Optimum conditions of pretreatment were AC 2.75%, IT 22.50 min and SC 30 g/L, as optimized by BBD. The growth and production of lignocellulolytic enzymes from Aspergillus heteromorphus, solid state fermentation (SSF) was performed using rice straw and hulls pretreated under optimum conditions. Cellulases and xylanase reached the highest enzyme activity at 6th day of fermentation while maximum manganese peroxidase (MnP) and laccase activity occurred at 12th day.

Biosorption optimization of lead(II), cadmium(II) and copper(II) using response surface methodology and applicability in isotherms and thermodynamics modeling.

The present study was carried out to optimize the various environmental conditions for biosorption of Pb(II), Cd(II) and Cu(II) by investigating as a function of the initial metal ion concentration, temperature, biosorbent loading and pH using Trichoderma viride as adsorbent. Biosorption of ions from aqueous solution was optimized in a batch system using response surface methodology. The values of R(2) 0.9716, 0.9699 and 0.9982 for Pb(II), Cd(II) and Cu(II) ions, respectively, indicated the validity of the model. The thermodynamic properties DeltaG degrees , DeltaH degrees , DeltaE degrees and DeltaS degrees by the metal ions for biosorption were analyzed using the equilibrium constant value obtained from experimental data at different temperatures. The results showed that biosorption of Pb(II) ions by T. viride adsorbent is more endothermic and spontaneous. The study was attempted to offer a better understating of representative biosorption isotherms and thermodynamics with special focuses on binding mechanism for biosorption using the FTIR spectroscopy.

Removal of sulphate, COD and Cr(VI) in simulated and real wastewater by sulphate reducing bacteria enrichment in small bioreactor and FTIR study

The present study was conducted to investigate the chromium(VI), COD and sulphate removal efficiency from aqueous solution and treatment of real effluent (CETP) in a small scale bioreactor using sulphate reducing bacteria consortium. Effect of different hydraulic retention times (HRTs), initial metal concentrations, various carbon sources and temperatures were studied on removal of chromium(VI), COD and sulphate. Maximum chromium(VI) and sulphate removal was found to be 96.0% and 82.0%, respectively, at initial concentration of 50 mg l(-1) using lactate as carbon source. However, highest COD removal was 36.2% in medium containing fructose as the carbon source and electron donor. NADH dependent chromate reductase activity was not observed which indicated the anaerobic consortium. Initially consortium medium with a strong negative oxidation reduction potential indicated the reducing activity. The FTIR spectrum of the sulphate reducing bacteria consortium clearly shows the existence of the sulphate ions and signifies that sulfate reducing bacteria have used sulfate during the growth phase.

Enzymatic hydrolysis optimization of microwave alkali pretreated wheat straw and ethanol production by yeast

Microwave alkali pretreated wheat straw was used for in-house enzyme production by Aspergillusflavus and Trichodermareesei. Produced enzymes were concentrated, pooled and assessed for the hydrolysis of pretreated wheat straw. Factors affecting hydrolysis were screened out by Placket-Burman design (PBD) and most significant factors were further optimized by Box-Behnken design (BBD). Under optimum conditions, 82% efficiency in hydrolysis yield was observed. After the optimization by response surface methodology (RSM), a model was proposed to predict the optimum value confirmed by the experimental results. The concentrated enzymatic hydrolyzate was fermented for ethanol production by Saccharomyces cerevisiae, Pichia stipitis and co-culture of both. The yield of ethanol was found to be 0.48 g(p)/g(s), 0.43 g(p)/g(s) and 0.40 g(p)/g(s) by S. cerevisiae, P. stipitis and by co-culture, respectively, using concentrated enzymatic hydrolyzate. During anaerobic fermentation 42.31 μmol/mL, 36.69 μmol/mL, 43.35 μmol/mL CO(2) was released by S. cerevisiae, P. stipitis and by co-culture, respectively.

Evaluation of Pseudomonas aeruginosa an innovative bioremediation tool in multi metals ions from simulated system using multi response methodology.

Under certain conditions bacteria can act as a good biosorbent towards heavy metals in simultaneous removal from effluents. The present study explores overlay plots of multi response surface methodology for simulated wastewater treatment potential. Pseudomonas aeruginosa was used for bioremediation of metallic ions, where removal of Cd (80-90%), Mn (85-90%), Fe (50-55%), Cr (70-75%) can be achieved by fixing the pH, oxidation reduction potential (mV) and one of the metallic constituent in the simulated effluent. The metal ions Cd and Cr (T), Fe and ORP (mV) are relatively closely located to each other in the loading plot indicating co-variance between these components. However Cr(VI) transformation and Mn removal are distantly placed in the bi-plot indicating the existed significant difference. Elevated reductase enzyme activity (31.75 μg/minmg) observed in the isolate showing the ability to effectively reduce metals ions.

LACCASE PRODUCTION BY ASPERGILLUS HETEROMORPHUS USING DISTILLERY SPENT WASH AND LIGNOCELLULOSIC BIOMASS

Laccase is among the major enzymes which plays an important role in ligninolytic system of fungi. Laccase production by Aspergillus heteromorphus was studied using anaerobically treated distillery spent wash (ADSW) and lignocellulosic biomass. Lignocellulosic biomass (rice straw, wheat straw and sugarcane bagasse) generated during biomass processing leads to solid waste and distillery spent wash is unwanted liquid waste produced by distilleries, both causes environmental pollution. Two mineral media and anaerobically treated distillery spent wash medium was tested for laccase production. Enzyme production in various media and in presence and absence of lignocellulosic biomass supplements showed that anaerobically treated distillery spent wash medium was a better laccase inducer medium than the mineral media. Addition of lignocellulosic biomass enhances laccase production and highest laccase activity was obtained in 5% anaerobically treated distillery spent wash medium with rice straw.

Synergism of Pseudomonas aeruginosa and Fe0 for treatment of heavy metal contaminated effluents using small scale laboratory reactor

In this study Pseudomonas aeruginosa a metal tolerant strain was not only applied for heavy metal removal but also to the solublization performance of the precipitated metal ions during effluent treatment. The synergistic effect of the isolate and Fe(0) enhanced the metal removal potential to 72.97% and 87.63% for Cr(VI) and cadmium, respectively. The decrease in cadmium ion removal to 43.65% (aeration+stirring reactors), 21.33% (aerated reactors), and 18.95% (without aerated+without stirring) with an increase in incubation period not only indicate the presence of soluble less toxic complexes, but also help in exploration of the balancing potential for valuable metal recovery. A relatively best fit and significant values of the correlation coefficient 0.912, 0.959, and 0.9314 for mixed effluent (Paint Industry effluent+CETP Wazirpur, effluent), CETP, Wazirpur, and control effluents, respectively, indicating first-order formulation and provide a reasonable description of COD kinetic data.

Biogenic sulfides for sequestration of Cr (VI), COD and sulfate from synthetic wastewater

Abstract The aim of this work is to explore the possibility of using mixed culture of mesophilic sulfate-reducing bacteria (SRB) for retrieval of toxic and carcinogenic Cr (VI) from synthetic solution. In order to treat Cr (VI) containing wastewater effectively, SRB culture was adapted to 50 mg/L Cr (VI) and maintained through repeated sub-culturing to enhance the growth and activity of SRB. Batch biosorption experiments were carried out in glass serum vials by cultured SRB, accomplishing the removal of 82.1% Cr (VI), 76.9% sulfate, 85.7% COD under the following optimized conditions: pH 7, hydraulic retention time (HRT) 7 days, temperature 37 °C and initial Cr (VI) concentration of 50 mg/L. Further sorption experiments were conducted on synthetic wastewater under optimal operational conditions and resulted in 89.2% Cr (VI), 81.9% COD and 95.3% sulfate reduction from simulated wastewater. The results of this work contributed to a better understanding of metal uptake by biogenic sulfides and would be beneficial in the development of potential biosorbents that possess high capacities for Cr (VI) uptake from aqueous environments.

Physico-chemical pretreatment and enzymatic hydrolysis of cotton stalk for ethanol production by Saccharomyces cerevisiae

The aim of this work was to study the physico-chemical pretreatment and enzymatic hydrolysis of cotton stalk for ethanol production by Saccharomyces cerevisiae. Firstly, factors affecting pretreatment were screened out by Plackett-Burman design (PBD) and most significant factors were further optimized by Box-Behnken design (BBD). As shown by experimental study, most significant factors were FeCl3 concentration (FC), irradiation time (IT) and substrate concentration (SC) affecting pretreatment of cotton stalk among all studied factors. Under optimum conditions of pretreatment FC 0.15mol/l, IT 20min and SC 55g/l, the release of reducing sugar was 6.6g/l. Hydrolysis of pretreated cotton stalk was done by crude on-site produced enzymes and hydrolysate was concentrated. Ethanol production by Saccharomyces cerevisiae using concentrated cotton stalk hydrolysate was 9.8gp/l, with ethanol yield 0.37gp/gs on consumed sugars. The data indicated that microwave FeCl3 pretreated cotton stalk hydrolyses by crude unprocessed enzyme cocktail was good, and ethanol can be produced by fermentation of hydrolysate.