Wastewater Sludge Pre-treatment for Enhancing Entomotoxicity Produced by Bacillus thuringiensis var. kurstaki |
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Authors: | Abdessalem Yezza Rajeshwar D. Tyagi José R. Valéro Rao Y. Surampalli |
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Affiliation: | (1) Terre et Environnement 490, INRS Eau, rue de la Couronne, Québec, Canada, G1K 9A9;(2) Centre Foresterie des Laurentides, Service Canadien des Forêts, Canada;(3) US Environmental Protection Agency, USA |
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Abstract: | Summary Wastewater sludge is a complex raw material for fermentation and requires pre-treatment in order to transform less biodegradable compounds into more easily degradable ones. In this study, sludge was treated by thermo-alkaline and oxidative pre-treatment methods and subjected to Bacillus thuringiensis fermentation in bench scale fermentors under controlled conditions. Thermo-alkaline treatment was found to be an effective process in order to enhance the entomotoxicity tested against spruce budworm. The total cell and spore counts were improved by 40 and 46%, respectively as compared to that using the untreated sludge. The final entomotoxicity potency increased from 12.3 × 109 SBU/l of the raw sludge to 16.6 × 109 SBU/l of the thermo-alkaline pre-treated sludge. The improvement of the process performance was attributed to a better oxygen transfer due to decrease in media viscosity and an improvement of nutrient availability due to the sludge solubilization and biodegradability. |
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Keywords: | Bacillus thuringiensis var. kurstaki entomotoxicity poly-β -hydroxy butyric acid protease sporulation thermo-alkaline pre-treatment wastewater sludge |
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