Recovery of Bacillus thuringiensis based biopesticides from fermented sludge by cross-flow microfiltration

Abstract

The recovery of Bacillus thuringiensis (Bt) based biopesticides from fermented sludge broth via cross-flow microfiltration (CFMF) was evaluated. Three types of microfiltration membranes, WX-model cellulose, cellulose acetate, and polyethersulfone, were tested for their permeate flux and restoration capacity. The cellulose acetate membrane with a pore size of 0.8 μm was selected for further process optimization and modeling of CFMF. Under optimal conditions, the permeate flux could be greater than 20 l/m²/h if the retentate contained was less than 100 g/l. The spore and crystal proteins recoveries were found to be 99 and 95%, respectively. The standard hydraulic resistance-in-series model was used to determine the parameters of CFMF of Bt fermented sludge. The results demonstrated that CFMF was effective for Bt based biopesticide recovery from fermented sludge.

Keywords:

• Bacillus thuringiensis
• Permeate flux
• Process optimization
• Membrane
• Modeling

Acknowledgments

This study was supported jointly by Major Projects on Control and Rectification of Water Body Pollution (2009ZX07208-002-001), Agricultural Science and Technology Achievements Transformation Fund Program (2010GB2E000347), and Start-up Fund Programs of Science and Technology Achievements Transformation of Guangdong Province, China (2010B060600010).