The City of Philadelphia is the largest city in the Commonwealth of Pennsylvania and the fifthmost-populous city in the United States with over 1.5 million residents. The City encompasses
approximately 134 square miles of land area. As an operating department of the City, the
Philadelphia Water Department (PWD) provides integrated water, wastewater, and stormwater
retail services to residential, commercial, and industrial customers.
PWD is committed to pursuing economically feasible energy independence and resource recovery
at its facilities. In particular, biogas created from the anaerobic digestion process at the Southwest
and Northeast Water Pollution Control Plants (WPCPs) is recovered and may be utilized onsite for
heat, power generation, and as fuel for other plant processes. In addition, the biosolids created at
the end of the anaerobic digestion process are further processed to create Class A biosolids and
pellets for off-site fertilizer usage. Co-digestion involves the introduction of additional digestible
organic material directly into the anaerobic digesters along with the solids from the wastewater
treatment process, thereby increasing biogas production. For instance, PWD currently co-digests
aircraft deicing fluid (ADF) in partnership with the Philadelphia International Airport. An
additional organic waste that is a viable material for co-digestion is food waste.