a composite formulation consisting of agglomerated industrial / residential sewer sludge and recycled high density polyethylene and / or polypropylene materials . the recycled plastic materials act as a binder for the pozzolan industrial / residential sewer sludge . the composite formulation can be produced in a batching process wherein the sieved dried sewer sludge and the recycled plastic in appropriate small cut pieces is fed into a large plastic extruder , heated and extruded into specific structures . the formulation can also be compounded using a compression mold wherein sieved dry sewer sludge are added to heated chopped recycled plastics and heat mixed to produce pellets or directed into a compression mold to create a structural member of predetermined shape .