Biomedical subjects

R Y Surampalli

Publications and source records attributed to R Y Surampalli.

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

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↗

PubMed2005

Biomass concentration and biofilm characteristics in high-performance fluidized-bed biofilm reactors.

Two laboratory scale fluidized-bed biofilm reactors (FBBRs) were used to investigate the biomass concentration and the biofilm characteristics in a high performance FBBR used for the denitrification of exceptionally high-nitrate wastewater (1000 mg-N/L). Reported correlations by other workers for predicting the biomass concentration in FBBR were examined for their validity in comparison with the experimental results of this study and the best set of applicable correlations was recommended. The effects of the two main operational parameters, the superficial velocity and nitrogen loading rate on the biomass concentration in the FBBR were also studied. Correlations for the drag coefficient and the expansion index from the literature, together with the biofilm dry density correlation produced from this study were found to produce the best prediction of the FBBR biomass concentration compared to other reported correlations. The average biomass concentration in the FBBR decreased with the increase of the superficial velocity in the range of 45 to 65 m/h at all the applied nitrogen loadings (i.e. 6, 8, 12 and 16 kg-N/m3(bed).d).

Biofilms↗

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

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↗

PubMed2002

Studies on the production of B. thuringiensis based biopesticides using wastewater sludge as a raw material.

Growth and delta-endotoxin yield of Bacillus thuringiensis (Bt) subsp kurstaki in tryptic soy yeast extract (TSY) medium, soybean meal based commercial medium and wastewater sludge medium were studied. The viable spores (VS) count in sludge medium was comparable to that obtained in laboratory and commercial media. The entomotoxicity of the fermentation liquid (Bt grown sludge) against Choristoneura fumiferana was comparable to the concentrated commercial Bt formulation available in the market (Foray 48B). A higher entomotoxicity was observed in a sludge medium than in the TSY or soybean meal media. The secondary and mixed (mixture of primary and secondary) sludges from various wastewater treatment plants were also evaluated for spore formation and entomotoxicity yield. The VS count was higher in a mixed sludge compared to the secondary sludge at a similar sludge solids concentration. Both VS count and entomotoxicity yield was found to be a function of sludge solids concentration in the medium. The optimum value of solids concentration for Bt production was found to be 25 g (-1) (dry weight basis). Beyond this concentration, a drop in VS count and entomotoxicity yield was observed. A low C:N ratio in the secondary sludge and a high C:N ratio in the mixed sludge resulted in a higher entomotoxicity. The optimum value of C:N ratio in combined sludge for Bt production was found to be 7.9-9.9. Relationships between entomotoxicity and maximum specific growth as well as with specific sporulation rate were developed.

Animals↗

PubMed2002

Effects of aerobic and anaerobic digestion systems on pathogen and pathogen indicator reduction in municipal sludge.

In this study, the effectiveness of anaerobic treatment systems in reducing pathogenic density levels was evaluated under the US EPA municipal sludge rule (40 CFR Part 503 Rule). Wastewater and sludge samples were analyzed for both pathogens and pathogenic indicator organisms from six different existing wastewater treatment systems. The results indicate that Class B sludge requirements under the US 503 Rule are reasonable and can be achievable by the existing treatment systems while Class A sludge requirements under the same rule may not be easily achieved by the existing treatment systems. The effects of volatile solids loading rates on anaerobic digester performance were investigated. Under anaerobic digestion conditions, it appears that the log reductions in fecal coliform and fecal streptococcus appeared to be dependent on VSS loading rates. On the other hand, Salmonella sp. density reductions did not appear to be dependent on VSS loading rates.

Bacteria, Aerobic↗