Considerations of impact of Venturi effect on mesophilic digestion

Abstract

Hydrodynamic cavitation caused by the Venturi effect is one of the most promising methods of sewage sludge pre-treatment. This study has been carried out to investigate the effect of hydrodynamic cavitation on disintegration of activated sludge foam and mesophilic fermentation. Cavitation was generated in standard Venturi tube with the diameter ratio β = d0/d1 = 0.30, working at σ = 0.249. Detailed Computational Fluid Design (CFD) analysis in class of k-ε model of internal flow has been presented. Obtained analytical investigation results confirmed the effect of strong disruption of microorganism cells and release of free organic substance into the liquid phase. After a short (30 minutes) pre-treatment, chemical oxygen demand increased by 8.63 times while Müller's disintegration degree was 50%. Moreover, undertaken mesophilic digestion trials brought significant improvement in biogas production.