biodegradable pollution - pollution that is rendered harmless by natural processes and so causes no permanent harm

waste, waste material, waste matter, waste product - any materials unused and rejected as worthless or unwanted; "they collect the waste once a week"; "much of the waste material is carried off in the sewers"

effluent, sewer water, wastewater - water mixed with waste matter

drainpipe, waste pipe, drain - a pipe through which liquid is carried away

sewage system, sewage works, sewer system - facility consisting of a system of sewers for carrying off liquid and solid sewage