Residuals and Biosolids management Conference 2007 WERF Odor Study Phase III: Impacts of the MicroSludge Process on Odor Causing Compounds

The MicroSludge TM processes is a patented chemical and pressure treatment that liquefies waste activated sludge (WAS) in order to improve the rate and extent of its degradation by anaerobic digestion. The MicroSludge TM processes was operated at full-scale at the Los Angeles County Sanitation District’s Joint Water pollution Control Plant (JWPCP) from October 2005 until August 2006 to evaluate the performance of this technology for enhancing anaerobic digestion. As part of an ongoing WERF research project to evaluate technologies that may enhance odor reduction from anaerobically digested sludge, samples from the anaerobic digester receiving MicroSludge treated WAS were compared to samples from a control digester to determine the effect of the MicroSludge process on odor generation from dewatered sludge cakes. It was found that the MicroSludge process reduced total volatile organic sulfur compounds (TVOSC) by about 50% for most sludges tested, even though the fraction of WAS was only 25% of the digester feed. The mechanism for the reduction is not clear since additional volatile solids reduction was in the range of 3 to 6%.