The interacting effects of Focused Pulsed (FP) treatment and solids retention time (SRT) were evaluated in laboratory-scale digesters operated at SRTs of 2-20days. Anaerobic digestion and methanogenesis of waste activated sludge (WAS) were stable for SRT≥5days, but the effluent soluble organic compounds increased significantly for SRT=2days due to a combination of faster hydrolysis kinetics and washout of methanogens. FP treatment increased the CH4 production rate and TCOD removal efficiency by up to 33% and 18%, respectively, at a SRT of 20days. These effects were the result of an increase in the hydrolysis rate, since the concentrations of soluble components remained low for SRT≥5days. Alternately, FP pre-treatment of WAS allowed the same conversion of TCOD to CH4 with a smaller SRT and digester size: e.g., 40% size savings with a CH4 conversion of 0.23g CH4-COD/g CODin.
- Focused Pulsed (FP)
ASJC Scopus subject areas
- Environmental Engineering
- Renewable Energy, Sustainability and the Environment
- Waste Management and Disposal