Biomedical subjects

R D Tyagi

Publications and source records attributed to R D Tyagi.

At least 19 recordsLinked to original sources

PubMed2006

Bacillus thuringiensis fermentation of hydrolyzed sludge--rheology and formulation studies.

Rheology of Bacillus thuringiensis fermentation of hydrolyzed sludge was investigated in bench scale fermenter. Stable liquid formulations were developed and optimized for two-year based studies comprising various physical/chemical (viscosity, particle size, corrosion and suspendibility) and biological (microbial contamination, viable spores and entomotoxicity) parameters at different pHs and temperatures. The hydrolyzed sludge depicted non-Newtonian and pseudoplastic behaviour during fermentation with 90% to 96% confidence of fits into Casson, Power and IPC paste models. Higher values of consistency and flow index during exponential growth and stationary phase, respectively, affected downstream processing. The power law was also followed by stable formulations. Sorbitol, sodium monophosphate and sodium metabisulfite (2.2:1:1) as suspending agents produced suspendibility ranging from 69% to 94%. The stable formulation (FH-4) comprising sorbitol, sodium monophosphate and sodium metabisulfite deteriorated at pHs 6, 6.5 and temperatures, 40 and 50 degrees C, with no signs of corrosion and microbial contamination. The viscosity of FH-4 formulations decreased with shear rate which could improve handling and consequent spraying.

Bacillus thuringiensis↗

PubMed2006

Starch industry wastewater as a substrate for antagonist, Trichoderma viride production.

Starch industry wastewater was investigated to assess and improve its potential as a raw material for the conidia production of biocontrol fungi, Trichoderma viride. The wastewater was tested with and without supplements of glucose, soluble starch, meat peptone and probable conidiation inducer chemicals in shake flask culture. Addition of complex carbon source (soluble starch, 1% and 2% w/v) produced maximum conidia ( approximately 3.02 and 4.2 x 10(10)CFU/mL, respectively). On the other hand, glucose addition as a simpler carbon source was either ineffective or, reduced conidia production (from 1.6 x 10(8) in control to 3.0 x 10(7)CFU/mL in 5% w/v glucose supplement). Supplement of nitrogen source showed a small increase of conidia concentration. Propionic, maleic and humic acids, EDTA, pyridine, glycerol and CaCO(3) were examined as probable conidiation inducers and showed effect only on initial rate of conidiation with no increase in final conidia concentration. Intra and extracellular ATP correlation with spore production showed dependence on growth media used and conidia concentration at the end of fermentation. Addition of carbon and nitrogen sources showed an increase in protease activity (from 0.4985 to 2.43 IU/mL) and entomotoxicity (from 10448 to 12335 spruce budworm unit (SBU)/microL). Entomotoxicity was improved by 11% in fermenter over shake flask when starch industry wastewater was supplemented with meat peptone.

Animals↗

PubMed2006

Dissolved oxygen as principal parameter for conidia production of biocontrol fungi Trichoderma viride in non-Newtonian wastewater.

Dissolved oxygen (DO) concentration was selected as a principal parameter for translating results of shake flask fermentation of Trichoderma viride (biocontrol fungi) to a fermenter scale. All fermentations were carried out in a 7.5 l automated fermenter with a working volume of 4 l. Fermentation performance parameters such as volumetric oxygen transfer coefficient (k (L) a), oxygen uptake rate (OUR), rheology, conidia concentration, glucose consumption, soluble chemical oxygen demand, entomotoxicity and inhibition index were measured. The conidia concentration, entomotoxicity and inhibition index were either stable or improved at lower DO concentration (30%). Variation of OUR aided in assessing the oxygen supply capacity of the fermenter and biomass growth. Meanwhile, rheological profiles demonstrated the variability of wastewater during fermentation due to mycelial growth and conidiation. In order to estimate power consumption, the agitation and the aeration requirements were quantified in terms of area under the curves, agitation vs. time (rpm h), and aeration vs. time (lpm h). This simple and novel strategy of fermenter operation proved to be highly successful which can be adopted to other biocontrol fungi.

Animals↗

PubMed2006

Efficient centrifugal recovery of Bacillus thuringiensis biopesticides from fermented wastewater and wastewater sludge.

Studies were conducted on harvesting of Bacillus thuringiensis (Bt)-based biopesticides from fermented broths of starch industry wastewater (SIW), wastewater sludge (raw and hydrolyzed-NH and TH, respectively) and semi-synthetic soyameal to enhance entomotoxicity (Tx) by centrifugation. Pertinent factors influencing Tx, solids concentration, pH, temperature and centrifugal force were investigated. The centrifugate solids concentration beyond 100 g/l did not enhance Tx, instead caused pellet formation. Centrifugation efficiency (Tx recovery) was higher at pH 4, and temperature 20 degrees C for starch wastewater (98%), wastewater sludge (98% and 97.8% for non-hydrolyzed and hydrolyzed, respectively) and soya broth (83%). For maximum Tx recovery (SIW-95%; NH-90%; TH-98% and soya-78%), the centrifugal force and time required was 48,000 g and 30 min, respectively. Losses in recovery efficiency were lower for SIW and wastewater sludge in comparison to soya on adopting commercially recommended centrifugal force of 9000 g. The settling velocity computations for different fermented broths enabled calculation of Sigma factor for continuous commercial centrifuge of a given capacity and hence simulation of power requirements. It was established that power requirements for a given Tx recovery efficiency were highest for conventional medium (soya) in comparison to other waste-based fermented broths.

Bacillus thuringiensis↗

PubMed2006

Screening of different adjuvants for wastewater/wastewater sludge-based Bacillus thuringiensis formulations.

Screening of different adjuvants, namely, suspending agents, phagostimulants, stickers, antimicrobial agents, and UV screens to develop aqueous biopesticidal suspensions of Bacillus thuringiensis (Bt) variety kurstaki HD-1 fermented broths, specifically, nonhydrolyzed sludge, hydrolyzed sludge, starch industry wastewater, and soya (commercial medium), were investigated. The selected suspending agents [20% (wt:vol)] included sorbitol, sodium monophosphate, and sodium metabisulfite with corresponding suspendibility of 74-92, 69-85, and 71-82%, respectively. Molasses [0.2% (wt:vol)] increased adherence by 84-90% for all fermented broths. The optimal phagostimulants [0.5% (wt:vol)], namely, soya and molasses, caused entomotoxicity increase of 3-13 and 7-13%, respectively. Sorbic and propionic acids showed high antimicrobial action [0.5% (wt:vol)], irrespective of fermentation medium. Sodium lignosulfonate, molasses, and Congo red, when used as UV screens [0.2% (wt:vol)], showed percent corresponding entomotoxicity losses of 3-5, 0.5-5 and 2-16, respectively. The Bt formulations, when exposed to UV radiation, showed higher half-lives (with and without UV screens) than the fermented broths or semisynthetic soya medium and commercial Bt formulation. UV screen-amended nonhydrolyzed, hydrolyzed, and starch industry wastewater formulations showed 1.3-1.5-fold higher half-lives than commercial Bt formulation. Thus, the recommended formulation comprises sorbitol, sodium monophosphate, sodium metabisulfite (suspending agents); molasses, soya flour (phagostimulants); molasses and skimmed milk powder (rainfasteners); sorbic and propionic acids (antimicrobial agents) and sodium lignosulfate; and molasses and Congo red (UV screens). These waste-based Bt formulations offer better UV resistance in comparison with commercial formulation.

Adhesives↗

PubMed2006

Polyhydroxyalkanoates (PHA) production using wastewater as carbon source and activated sludge as microorganisms.

Activated sludge from different full-scale wastewater treatment plants (municipal, pulp and paper industry, starch manufacturing and cheese manufacturing wastewaters) was used as a source of microorganisms to produce biodegradable plastics in shake flask experiments. Acetate, glucose and different wastewaters were used as carbon sources. Pulp and paper wastewater sludge was found to accumulate maximum concentration (43% of dry weight of suspended solids) of polyhydroxy alkanoates (PHA) with acetate as carbon source. Among the different wastewaters tested as a source of carbon, pulp and paper industry and starch industry wastewaters were found to be the best source of carbon while employing pulp and paper activated sludge for maximum accumulation of PHA. High concentration of volatile fatty acids in these wastewaters was the probable reason.

Acetates↗

PubMed2005

Bioconversion of industrial wastewater and wastewater sludge into Bacillus thuringiensis based biopesticides in pilot fermentor.

Starch industry wastewater (SWW), slaughterhouse wastewater (SHWW) and secondary sludges from three different wastewater treatment plants (Jonquière--JQS, Communauté Urbaine de Québec--CUQS and Black lake-BLS) were used as raw materials for the production of Bacillus thuringiensis (Bt) based biopesticides in a pilot scale fermentor (100 L working volume). The slaughterhouse wastewater exhibited the lowest Bt growth and entomotoxcity (Tx) potential (measured against spruce budworm) due to low availability of carbon, nitrogen and other nutrients. Performance variation (growth, sporulation, proteolytic activity and Tx potential) within the three types of sludges was directly related to the availability of nitrogen and carbohydrates, which could change with sludge origin and methods employed for its generation. The Tx potential of Bt obtained in different secondary sludges (JQS: 12 x 10(9) SBU/L; CUQS: 13 x 10(9) SBU/L and BLS: 16 x 10(9) SBU/L) and SWW (18 x 10(9) SBU/L) was higher than the soybean based synthetic medium (10 x 10(9) SBU/L). The maximum protease activity was obtained in CUQ secondary sludge (4.1 IU/mL) due to its high complex protein concentration. Nevertheless, high carbohydrate concentration in SWW repressed enzyme production. The secondary sludges and SWW were found to be suitable raw materials for high potency Bt biopesticide production.

Agriculture↗

PubMed2005

Sludge based Bacillus thuringiensis biopesticides: viscosity impacts.

Viscosity studies were performed on raw, pre-treated (sterilised and thermal alkaline hydrolysed or both types of treatment) and Bacillus thuringiensis (Bt) fermented sludges at different solids concentration (10-40 g/L) for production of biopesticides. Correlations were established among rheological parameter (viscosity), solids (total and dissolved) concentration and entomotoxicity (Tx) of Bt fermented sludges. Exponential and power laws were preferentially followed by hydrolysed fermented compared to raw fermented sludge. Soluble chemical oxygen demand variation corroborated with increase in dissolved solids concentration on pre-treatments, contributing to changes in viscosity. Moreover, Tx was higher for hydrolysed fermented sludge in comparison to raw fermented sludge owing to increased availability of nutrients and lower viscosity that improved oxygen transfer. The shake flask results were reproducible in fermenter. This study will have major impact on selecting fermentation, harvesting and formulation techniques of Bt fermented sludges for biopesticide production.

Animals↗

PubMed2005

Wastewater sludge as a potential raw material for antagonistic fungus (Trichoderma sp.): role of pre-treatment and solids concentration.

Feasibility of production of antagonistic Trichoderma sp. conidial spores using wastewater sludge as a raw material employing different suspended solids concentration (10-50 g/l) was investigated in shake flasks. Maximum conidial spore count obtained for raw sludge was 1.98 x 10(4) CFU/ml, which was enhanced by sludge pre-treatments (alkaline and thermal alkaline). Conidial spore count ranging from 1.3 x 10(6) to 2.8 x 10(7) CFU/ml was observed for alkaline and thermal alkaline treated sludges. Optimal suspended solids concentration was 30 g/l (10(7) CFU/ml) whereas, lower (<20 g/l) and higher (>30 g/l) solids concentration were less efficient. Thermal alkaline pre-treated sludge showed diauxic growth due to multiplicity of sludge biodegradability. A simple, modified CFU filtration technique was also developed for fungal spore assessment in sludge. Bioassay of fermented sludge against spruce budworm larvae showed entomotoxicity (15036 SBU/microl), on par with Bacillus thuringiensis biopesticides. This study successfully demonstrated potential of wastewater sludge as a raw material for production of value added product, aiding in sludge management and proliferation of eco-friendly and economical biocontrol agents.

Animals↗

PubMed2005

Design strategy for a simultaneous nitrification/denitrification of a slaughterhouse wastewater in a Sequencing Batch Reactor: ASM2d modeling and verification.

Sequencing Batch Reactor (SBR) was used to treat slaughterhouse wastewater which contains average Chemical Oxygen Demand (COD) concentration of 5000 mg l(-1) and ammonium of 360 mgN l(-1). Nitrification/denitrification process was conducted for nitrogen removal. The influent wastewater as internal carbon source and sodium acetate as an external one was used for completing denitrification to achieve the simultaneous organic matter removal (95-96%) and nitrogen removal (95-97%). In addition, the dynamic SBR simulation model for biological nitrogen removal based on the Activated Sludge Model No. 2d (ASM2d) and GPS-X software is presented. The experimental study for the calibration and validation of the model was carried out using laboratory SBR. The study showed that the model provides a powerful tool to reduce the experimental expenditure and time to find the optimum strategy.

Abattoirs↗

PubMed2005

Cell agglomeration in acidogenic, mixed, and methanogenic cultures at different loading and mixing conditions.

Cell agglomeration studies were conducted in anaerobic fluidized bed reactors without any external support. Granulation was studied at different combinations of loading and mixing conditions utilizing synthetic wastewater. Both single-stage and two-stage biomethanation processes were studied. Reactors of volume 0.55, 10, and 16 l were operated with height to diameter ratio of 7-8. It was found that the acidogens were more liable to form granules among mixed culture of anaerobes, while the methanogens were capable of forming cell agglomerates in the form of flocs. In acidogenic granules, rod shaped bacteria were dominating, while in case of methanogens, there were more cocci. It was found that for an upflow liquid linear velocity upto 2.0 m h(-1), acidogens showed very good granulation but at relatively higher values of upflow liquid linear velocities granulation was affected adversely, causing breakage and dissociation of granules. In the case of methanogens and mixed process, it was found that upflow liquid linear velocities up to 4.0 m h(-1) were suitable and biomass flocs were actively growing. The maximum organic loadings applied were 39.0 and 54.4 kg COD m(-3) d(-1) (at 27.3 and 35.36 kg COD m(-3) d(-1) degradation respectively) for single-stage and two-stage biomethanation respectively.

Bacteria, Anaerobic↗

PubMed2005

Starch industry wastewater-based stable Bacillus thuringiensis liquid formulations.

Liquid formulations were developed from Bacillus thuringiensis (Bt)-fermented broths of starch industry wastewater (SIW) and of soya medium. Stability studies were carried out for 1 yr. Storage stability was tested by studying various physical and chemical (e.g., viscosity, particle size, corrosion, and suspendibility) and biological (e.g., microbial contamination, viable spores, and entomotoxicity) parameters at different pH levels and temperatures. Three suspending agents, sorbitol, sodium monophosphate, and sodium metabisulfite, were added to fermented broth in different concentrations. Sorbitol and sodium monophosphate in the ratio 3:1 was the best suspending agent combination for both formulations. Starch industry wastewater fermentation yielded cell and viable spore counts 10- and 4-fold greater than those from soya medium, respectively, and a 1.7-fold increase in entomotoxicity. However, both formulations started deteriorating at pH 6 and 6.5 and 40 and 50 degrees C. There were no signs of corrosion and microbial contamination in both types of formulations.

Animals↗

PubMed2004

Scale-up of biopesticide production processes using wastewater sludge as a raw material.

Studies were conducted on the production of Bacillus thuringiensis (Bt)-based biopesticides to ascertain the performance of the process in shake flasks, and in two geometrically similar fermentors (15 and 150 l) utilizing wastewater sludge as a raw material. The results showed that it was possible to achieve better oxygen transfer in the larger capacity fermentor. Viable cell counts increased by 38-55% in the bioreactor compared to shake flasks. As for spore counts, an increase of 25% was observed when changing from shake flask to fermentor experiments. Spore counts were unchanged in bench (15 l) and pilot scale (5.3-5.5 e(+08) cfu/ml; 150 l). An improvement of 30% in the entomotoxicity potential was obtained at pilot scale. Protease activity increased by two to four times at bench and pilot scale, respectively, compared to the maximum activity obtained in shake flasks. The maximum protease activity (4.1 IU/ml) was obtained in pilot scale due to better oxygen transfer. The Bt fermentation process using sludge as raw material was successfully scaled up and resulted in high productivity for toxin protein yield and a high protease activity.

Animals↗

PubMed2004

Treatment of slaughterhouse wastewater in a sequencing batch reactor: simulation vs experimental studies.

In wastewater treatment, the objective of process optimization is primarily to obtain a good treatment efficiency of a specific pollutant. The operational objective of increased productivity has also to be met. This includes a sufficient reduction in the duration of a batch process through batch scheduling. The aim of this paper is thus to find the best cycles for simultaneous carbon, nitrogen and phosphorus (CNP) removal from slaughterhouse wastewater in a sequencing batch reactor (SBR) using GPS-X software and ASM2d model. Simulations with different aeration strategies, residence time, sludge age and feed strategies were carried out to determine the best system performance. The simulation results showed best performance with a system comprised of two equal feeds operated at 48 h hydraulic retention time (HRT) and 20 d solids retention time (SRT). Simulation also showed that addition of metal salts was necessary to reduce the level of phosphorus (P) to meet the requirement (P<1 mg l(-1)). The addition of acetate was also necessary to complete the denitrification process. The simulated results were compared against the experimental results obtained from laboratory SBR. The simulated results of COD, nitrates/nitrites and ammonia removal were very close to the experimental results. A diference of 2-4% between the simulated COD and the experimental COD was observed and that could be attributed to the error in evaluation of the inert COD. For ammonia removal, the simulated (99.9%) and experimental (93-100%) results were practically identical. However, a notable difference in o-PO4 concentration was observed (38% removal by simulation against 78% removal through experiments). After metallic salts addition, P removal efficiency was 98% or 1% less than that observed through experimental results.

Abattoirs↗

PubMed2004

Development of sludge based stable aqueous Bacillus thuringiensis formulations.

This study focuses on development of aqueous flowable (suspension) formulations for Bacillus thuringiensis (Bt) based biopesticides from wastewater sludge. Different inerts like sorbitol, sodium monophosphate, sodium metabisulphite, sorbic acid, propionic acid, Tween-80, Triton X-100 and glycerol were tested for formulations. Five different formulations for non-hydrolyzed (NH) secondary sludges were tried and the best combination selected on the basis of various physical parameters like viscosity, particle size, suspendibility, entomotoxicity, and microbiological purity tests. F5 formulations (for secondary sludge) comprising sorbitol, sodium monophosphate and sodium metabisulphite gave better physical and biological characteristics with a small effect on entomotoxicity and spore concentration after 120 days at pH 6, 6.5 and temperatures 40 and 50 degrees C and viscosity change at 40 and 50 degrees C. The formulations were more stable at pH 4.0 to 5.0 and temperatures 4 to 30 degrees C whereas at pH 6.0 and 6.5 and temperatures 40 and 50 degrees C, there was degeneration of the product. Lower proteolytic activity and physical factors like ionic strength and surface group changes at pH 6 and 6.5 were responsible for the instability of the formulation.

Bacillus thuringiensis↗

PubMed2003

Cocoa shells for heavy metal removal from acidic solutions.

The development of economic and efficient processes for the removal of heavy metals present in acidic effluents from industrial sources or decontamination technologies has become a priority. The purpose of this work was to study the efficiency with which cocoa shells remove heavy metals from acidic solutions (pH 2) and to investigate how the composition of these solutions influences heavy metal uptake efficiency. Adsorption tests were conducted in agitated flasks with single-metal solutions (0.25 mM Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn), multi-metal solution (comprised of 0.25 mM of each of the cations above) and an effluent obtained from chemical leaching of metal-contaminated soil, in the presence of different cocoa shell concentrations (5-40 g/l). Results from the single-metal solution assays indicated that the fixation capacity of heavy metals by cocoa shells followed a specific order: Pb>Cr>Cd=Cu=Fe>Zn=Co>Mn=Ni=Al. Cocoa shells are particularly efficient in the removal of lead from very acidic solutions (q(max)=6.2 mg Pb/g, pH(i)=2.0 and T=22 degrees C). The presence of other metals and cations in solution did not seem to affect the recovery of lead. It was also observed that the maximum metal uptake was reached in less than 2 h. This research has also demonstrated that the removal of metals caused a decline in solution proton concentration (pH increase) and release of calcium, magnesium, potassium and sodium from the cocoa shells.

Cacao↗

PubMed2003

Comparison of natural adsorbents for metal removal from acidic effluent.

Adsorption tests were carried out in acidic synthetic solutions (pH 2.0) using 20 g l(-1) of various natural adsorbents and 0.25 mM of 11 different metals. In decreasing order, the most efficient adsorbents tested were: oyster shells, cedar bark, vermiculite, cocoa shells and peanut shells. In contrast, weak metal adsorption was demonstrated by: red cedar wood, peat moss, pine wood, corn cobs and perlite. Metal adsorption capacities in acidic synthetic solution followed the order: Pb2+> Cr3+> Cu2+> Fe2+> Al3+> Ni2+> Cd2+ > Mn2+ > Zn2+ >> Ca2+, Mg2+. Alkaline treatment (0.75 M NaOH) increased the effectiveness of metal removal for the majority of adsorbents. In contrast, acid treatment (0.75 M H2SO4) either reduced or did not affect the adsorption capacity of the materials tested. Finally, oyster shells, red cedar wood, vermiculite, cocoa shells and peanut shells, were effective natural adsorbents for the selective recovery of lead and trivalent chromium from acidic effluent.

Adsorption↗

PubMed2003

Production of biopesticides using wastewater sludge as a raw material--effect of process parameters.

Production of Bacillus thuringiensis (Bt) based biopesticide was studied using hydrolysed or raw wastewater sludge as a raw material. The sludge hydrolysis was carried out at different pH (2, 4 and 6). The sludge after hydrolysis was sterilised at 121 degrees C for 30 minutes. The effect of temperature, pH and agitation speed on growth and toxin production was also investigated. The pH in the shake flask was controlled by adding 0.1 M TRIS buffer. The progress of the biopesticide production process was monitored by measuring viable cell count (VC), spore count (SC) and entomotoxicity (Tx). The entomotoxicity was measured against spruce budworm. Control of pH substantially increased the entomotoxicity of the final product. Increased agitation speed resulted in higher VC, SC and Tx values.

Animals↗