Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
684300 | Bioresource Technology | 2009 | 9 Pages |
Abstract
This study investigated the production of biopesticides, protease and chitinase activity by Bacillus thuringiensis grown in raw wastewater sludge at high solids concentration (30 g/L). The rheology of wastewater sludge was modified with addition of Tween-80 (0.2% v/v). This addition resulted in 1.6 and 1.3-fold increase in cell and spore count, respectively. The maximum specific growth rate (μmax) augmented from 0.17 to 0.22 hâ1 and entomotoxicity (Tx) increased by 29.7%. Meanwhile, volumetric mass transfer coefficient (kLa) showed marked variations during fermentation, and oxygen uptake rate (OUR) increased 2-fold. The proteolytic activity increased while chitinase decreased for Tween amended wastewater sludge, but the entomotoxicity increased. The specific entomotoxicity followed power law when plotted against spore concentration and the relation between Tx and protease activity was linear. The viscosity varied and volume percent of particles increased in Tween-80 amended wastewater sludge and particle size (D50) decreased at the end of fermentation. Thus, there was an increase in entomotoxicity at higher suspended solids (30 g/L) as Tween addition improved rheology (viscosity, particle size, surface tension); enhanced maximum growth rate and OUR.
Keywords
NAGEPSμmaxN-acetyl glucosamineVIPsKLAParticle sizedissolved oxygenBacillus thuringiensisSuspended solidsMaximum specific growth rateEntomotoxicityVolumetric mass transfer coefficientProtease activityWastewater sludgeOURExtracellular polymeric substancesOxygen uptake rateViscosityVegetative insecticidal proteinsSurface tension
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Process Chemistry and Technology
Authors
Satinder K. Brar, M. Verma, R.D. Tyagi, J.R. Valéro, R.Y. Surampalli,