Production of biopesticides as a novel method of wastewater sludge utilization/disposal

Abstract

Production of Bacillus thuringiensis (Bt) var. kurstaki HD-1, an industrially produced biopesticide source, was tested as a potential method to valorize wastewater treatment sludge. The effects of sludge solids concentration and inoculum size were verified on the production of Bt. Inoculum sizes of 1% and 5% were tested. The cell and spore counts achieved were comparable to those in the industry standard. Sludge with 1% (v/v) inoculum size gave higher entomotoxicity compared to that of 5% inoculum. It was observed that sludge samples with lower solids concentration gave marginally lower cell and spore count but gave considerably higher toxicity. The production time was also comparable to the industrial standard. Results from these experiments and their economical implications are discussed in this paper.