Wastewater, sewage or blackwater is water that has been polluted with human or animal feces/urine. It is different from greywater which is wastewater than has not been polluted with fecal material.
Wastewater management is an important part of sanitation. Creation of wastewater can be limited by separating human and animal feces and urine from the ambient water reserves (e.g., rivers, sea, etc.). This can be done partially accomplished by using composting toilet instead of flush toilets..[1]
The essential components of wastewater management are the sewerage or sewage system (see sewage collection) and the actual wastewater treatment.
Industrial wastewater may also contain toxic or caustic effluent[verification needed].
The stages in wastewater treatment are:
- Primary wastewater treatment - sieving and sedimentation.
- Secondary wastewater treatment - digestion of biological matter, usually through oxidation, although anaerobic digestion is also possible.
- Tertiary wastewater treatmentW - an additional treatment stage to improve effluent quality its discharge into the environment. This covers additional removal of suspended solids, refractory organics, heavy metals and dissolved solids
- "Advanced wastewater treatment" may be considered part of tertiary treatment, or may be considered separately - this is a matter of terminology. It includes nutrient removal - i.e. biological removal of nitrogen and phosphorus to avoid eutrophication of the receiving water body.