Abstract
Co-digestion of sewage sludge and regional organic waste, such as kitchen garbage, is a promising energy recovery method for small facilities. Dewatered sludge is effective for transporting sewage sludge to a centralized wastewater treatment plant. Effects of substrate concentration on mesophilic anaerobic digestion performance and characteristics of digested sludge were investigated by a continuously operated experiment fed with dewatered sludge of approximately 20 (undiluted) – 5% total solids (TS). Substrate concentration less than 10% TS resulted in stable operation with methane production of 0.47 NL/ gVS, viscosity less than 5 dPa·s, and ammonia concentration less than 3, 000 mgN/ L. Substrate concentration greater than 15% TS resulted in digested sludge of more than 10% TS and unstable performance with accumulation of volatile fatty acids.
