Results From the Trial of Microsludge® at the Joint Water Pollution Control Plant at Los Angeles County
Stephenson, R., Laliberte, S., Hoy, P., Drew, A., and Britch, D.
Paradigm Environmental Technologies Inc., Canada
(free)
MicroSludge® is a patented chemical and pressure pre-treatment process that liquefies secondary activated sludge (SAS, or
waste activated sludge, WAS) to increase both the rate and extent that SAS is degraded in a conventional anaerobic digester.
The process uses chemical pre-treatment to weaken cell membranes and a high-pressure homogenizer, or “cell disrupter”, to
provide an enormous and sudden pressure change to burst the cells in SAS. The resulting liquefied SAS is more readily
converted to biogas.
Following the demonstration of the first full-scale MicroSludge unit near Vancouver, Canada in 2004, a second full-scale unit
was commissioned at the Los Angeles County Sanitation Districts’ (LACSD’s) Joint Water Pollution Control Plant (JWPCP) in
October 2005. The JWPCP is located in Carson, California, and treats 400 MGD of wastewater, serving a population of
approximately 3.5 million. The JWPCP services a large industrial base: approximately 20% of the total organic load to the
WWTP is contributed by seven oil refineries in Los Angeles County. Additionally, the JWPCP also treats solids from the
LACSD’s upstream water reclamation facilities for a solids loading population equivalent of approximately 5 million.
A MicroSludge system with two 4,000 L/h cell disruption modules were continuously operated for 24 hours per day to process
approximately 192 m3/day (50,000 GPD) of thickened SAS at 5 to 6% total solids (TS) concentration. The processed SAS
was co-digested with primary sludge (PS) in a 75:25 by volume (approximately 68:32 by mass) PS:SAS mix at an HRT of
approximately 19 days. The digester performance was compared with the performance of one of the other 23 digesters that
was operated under similar conditions at the JWPCP, except that the SAS feed was not pre-treated.
This paper outlines the results obtained to date of the January 2006 to October 2006 testing program.
KEY WORDS
anaerobic digestion, cell lysis, digester foaming, high pressure homogenization, MicroSludge, odour reduction, secondary
activated sludge, sludge pre-treatment
