Manteca Wastewater Quality Control Facility
City of Manteca, California
The Manteca Wastewater Quality Control Facility (WQCF) is a 6.5-million gallons per day (mgd) rated
activated sludge plant. The WQCF treats typical municipal wastewater generated in the City of Manteca,
California and the neighboring City of Lathrop. The plant also receives seasonal discharges from a local
food processor. Over the last few years, the Manteca WQCF underwent a $60-million expansion to increase
its capacity from 6.5 to 9.87 mgd. Part of this expansion included the construction of a new influent pump
station with two mechanical screens, and a new dewatering building with two centrifugal dewatering
systems. Because housing developments within the City of Manteca are encroaching upon the plant, and a
new regional softball complex was constructed nearby, an odor control system needed to be designed and
built during the plant expansion to ensure that potential odor complaints from neighbors would be
minimized. Foul air from the influent pump station and the dewatering building is conveyed through large
ducts into a new open bed lava rock-based biofilter near the influent pump station. The biofilter is
composed of five beds, including one used as standby. The four duty beds were designed to treat 33,000
cubic feet per minute of foul air. Approximately 2,100 cubic yards of lava rock were needed for the
biofilter. To the authors’ knowledge, this open bed lava rock biofilter is the first and largest full scale
biofilter of this type in the nation.
Posted: May 3rd, 2011 | Filed under: 50k-100k, Waste Water Treatment | Tags: Biofiltration, Reduced Odor Complaints, Reduced Odors, Signifcantly Reduced Maintenance Requirements | No Comments »
Solid Waste Authority of Palm Beach County
Palm Beach County, Florida
The Solid Waste Authority of Palm Beach County, Florida, operates an in-vessel composting
facility that processes 30 dry tons/day of dewatered biosolids combined with shredded yard
waste. The facility consists of 36 aerated agitated bays in three buildings supplied by
International Processes Systems (Now Siemens Water Technology). All exhaust air from the
buildings is treated in three 60,000 cfm biofilter cells. New biofilter cells were commissioned in
December 2002. Design and construction included some innovative features including: use of
locally available limestone for the support plenum, use of locally available finely ground bark
mulch in the media, a pre-humidification system with air-atomizing nozzles, clean-outs for every
perforated lateral, and a fast-track design-build method of delivery.
After start-up the well water used for humidification caused rapid scaling of the laterals, due to
the high mineral content and high evaporation efficiency. Pre-humidification was discontinued
while a water softening and deionization system was under consideration. Since then the filters
have been operated only with surface irrigation. The most recent rounds of performance testing
have indicated that surface irrigation, combined with rainfall, were sufficient to maintain optimal
moisture content throughout the full depth of media. Without pre-humidification, the irrigation
distribution pattern is critical.
The filters have been periodically tested for odor and ammonia removal, most recently in 2006
and scheduled again for 2007. The filter media in the different cells have been in continuous use
for 2.6 to 3.1 years. Typical inlet conditions were:
Temperature: dry-bulb range 96-105 deg. F. wet-bulb range 86-92 deg F.
Ammonia: 22 – 40 ppm
Hydrogen sulfide and methyl mercaptan: neglible or non-detect
Odor concentration: 1,500 – 2,400 D/T, using the prEN 13725 olfactometry standard.
The biofilters have consistently removed 100 % of ammonia and 93 – 98 % of odor with outlet
odor concentrations in the range of 66 to 86 D/T. Thus, the biofilter is showing highly effective
performance, despite the high temperature and moisture deficit in the inlet air. As a result, the
composting facility is no longer a significant source of off-site odors.
Ammonia is an alkaline gas and there little acid gas present. The media has a pH in the range of
4.8 – 6.8. The acidic pH indicates that alkalinity is being consumed as a result of nitrification. A
nitrogen mass balance indicated that the biofilters are operating in steady state rather than
accumulating nitrogen, and that nitrogen leaves the biofilters by way of leachate and
denitrification. Denitrification was demonstrated by the detection of nitrous oxide. Nitrous oxide
is of increasing interest due to its effect as a greenhouse gases.
Posted: May 3rd, 2011 | Filed under: Uncategorized | Tags: Biofiltration, Reduced Air Pollutants, Reduced Greenhouse Gas Emissions, Reduced Odors | 1 Comment »