Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. In the most common usage, it refers to the municipal wastewater that contains a broad spectrum of contaminants resulting from the mixing of wastewaters from different sources. Sewage is correctly the subset of wastewater that is contaminated with feces or urine, but is often used to mean any waste water. "Sewage" includes domestic, municipal, or industrial liquid waste products disposed of, usually via a pipe or sewer or similar structure, sometimes in a cesspool emptier. The physical infrastructure, including pipes, pumps, screens, channels etc. used to convey sewage from its origin to the point of eventual treatment or disposal is termed sewerage. Origin
Wastewater or sewage can come from (text in brackets indicates likely inclusions or contaminants): • Human waste (fæces, used toilet paper or wipes, urine, or other bodily fluids), also known as blackwater, usually from lavatories; • Cesspit leakage;
• Septic tank discharge;
• Sewage treatment plant discharge;
• Washing water (personal, clothes, floors, dishes, etc.), also known as greywater or sullage; • Rainfall collected on roofs, yards, hard-standings, etc. (generally clean with traces of oils and fuel); • Groundwater infiltrated into sewage;
• Surplus manufactured liquids from domestic sources (drinks, cooking oil, pesticides, lubricating oil, paint, cleaning liquids, etc.); • Urban rainfall runoff from roads, carparks, roofs, sidewalks, or pavements (contains oils, animal fæces, litter, fuel or rubber residues, metals from vehicle exhausts, etc.); • Seawater ingress (high volumes of salt and micro-biota); • Direct ingress of river water (high volumes of micro-biota); • Direct ingress of manmade liquids (illegal disposal of pesticides, used oils, etc.); • Highway drainage (oil, de-icing agents, rubber residues); • Storm drains (almost anything, including cars, shopping trolleys, trees, cattle, etc.); • Blackwater (surface water contaminated by sewage);
• Industrial waste
• industrial site drainage (silt, sand, alkali, oil, chemical residues); o Industrial cooling waters (biocides, heat, slimes, silt); o Industrial process waters;
o Organic or bio-degradable waste, including waste from abattoirs, creameries, and ice cream manufacture; o Organic or non bio-degradable/difficult-to-treat waste (pharmaceutical or pesticide manufacturing); o extreme pH waste (from acid/alkali manufacturing, metal plating); o Toxic waste (metal plating, cyanide production, pesticide manufacturing, etc.); o Solids and Emulsions (paper manufacturing, foodstuffs, lubricating and hydraulic oil manufacturing, etc.); o agricultural drainage, direct and diffuse.
The composition of wastewater varies widely. This is a partial list of what it may contain: • Water ( > 95%) which is often added during flushing to carry waste down a drain; • Pathogens such as bacteria, viruses, prions and parasitic worms; • Non-pathogenic bacteria;
• Organic particles such as faeces, hairs, food, vomit, paper fibers, plant material, humus, etc.; • Soluble organic material such as urea, fruit sugars, soluble proteins, drugs, pharmaceuticals, etc.; • Inorganic particles such as sand, grit, metal particles, ceramics, etc.; • Soluble inorganic material such as ammonia, road-salt, sea-salt, cyanide, hydrogen sulfide, thiocyanates, thiosulfates, etc.; • Animals such as protozoa, insects, arthropods, small fish, etc.; • Macro-solids such as sanitary napkins, nappies/diapers, condoms, needles, children's toys, dead animals or...