Lewiston-Auburn Water Pollution Control Authority-Auburn, Maine
“Agitated Bin”, In-Vessel System—Mike Pelletier, Operator
Maine Compost School—2013 (photos by Mark King, Maine DEP)
The Lewiston/Auburn Water Pollution Control Authority (LAWPCA) serves a population of 90,000 residents and has been successfully re-using its sewage sludge since the early 1980’s.
The facility utilizes an agitated bin, in-vessel system engineered by Longwood Manufacturing Corporation. The system consists of six, 210 foot long by 9 foot wide by 7 foot high composting bins. Each bin floor is porous and supplemental aeration is provided along its entire length, to enhance active, aerobic composting. Compost mixtures are also turned by overhead mixers, which travel on rails located on top of each compost bin sidewall. The LAWPCA facility operates from October through June of each year.
Receiving Area-Municipal Sewage Sludge is dumped onto a “tip-floor” and mixed with sawdust and shavings and some finished compost, using a frontend loader.
Composting Area-Compost mixture is then loaded into one of the facility’s 210 foot-long bins, where it will be turned and aerated daily [moving the material rearward 10 feet at a time] for a total of 21 days. Building air is exchanged regularly and exhausted through an in-ground Biofilter for odor control.
Curing Area-Following the “Active” composting phase, compost drops onto the curing floor where it is formed into windrows over perforated pipe and allowed to condition for an additional 21 days under forced air. Finally, the finished material is sent to long-term storage and made available for sale.