[New ways to improve volatile fatty acids accumulation in sludge alkaline fermentation system].

To improve the hydrolysis and acidification of activated sludge, two new ways, which were adding fermented sludge or sterilized fermented sludge to batch-mode activated sludge alkaline fermentation system, were investigated in this study. Temperature effect was also studied (10 degrees C and 35 degrees C). Result showed that mesophilic condition greatly enhanced sludge hydrolysis and acidification, which resulted in an obvious volatile fatty acids (VFAs) accumulation in the system.

Effect of temperature on short chain fatty acids (SCFAs) accumulation and microbiological transformation in sludge alkaline fermentation with Ca(OH)₂ adjustment.

The effects of temperatures (15-55 °C) on the alkaline fermentation of sewage sludge were investigated in semi-continuous stirred tank reactors (semi - CSTR) at the pH of 10. The highest soluble chemical oxygen demand (SCOD) yield was obtained at 55 °C (764.2 mg/(gVS L d)), while the highest short chain fatty acids (SCFAs) yield was observed at 35 °C (319.