Wastewater Wastewater Sekaninaite Category="Environmental engineering"Category="Sewerage"Wastewater is any water that has been adversely affected in quality by any anthropogenic influence. It therefore includes liquid waste discharged from domestic houses, industrial, agricultural or commercial processes. It does not include rain-water uncontaminated by human activities.

There is a wide range of wastewaters and an equally wide range of technologies and techniques for mitigating the impacts of wastewaters on the receiving environment.

Wastewater types

Industrial

Organic - bio-degradable - includes abattoirs, creameries, ice-cream manufacture
Organic - non bio-degradable or difficult to treat - for example Pharmaceutical or Pesticide manufacturing
Inorganic - for example metal working industry
extreme pH - acid/alkali manufacturing, metal plating
Toxic - e.g. metal plating, cyanide production, pesticide manufaturing
Solids and Emulsions - e.g. Paper manufacturing, food stuffs, lubricating and hydraulic Oil manufacture
agricultural drainage - direct and diffuse

surface runoff

Highway drainage
Storm drains
industrial site drainage
Black water - surface water contaminated by sewage

Domestic drainage

Sewage
Cesspit leakage
Septic tank discharge
Sewage treatment plant discharge
Grey water also known as sullage water - water from household functions such as washing dishes, laundry or bath water

Treatment

There are numerous processes that can be used to clean up waste waters depending on the type and extent of contamination. Most wastewater is treated in industrial-scale wastewater treatment plants (WWTPs) which may include physical, chemical and biological treament processes. However, the use of septic tanks is widespread in rural areas, serving up to one quarter of the homes in the U.S. The most important aerobic treatment system is the activated sludge process, based on the maintenance and recirculation of a complex biomass composed by micro-organisms able to degrade the organic matter carried in the wastewater. Anaerobic processes are widely applied in the treatment of industrial wastewaters and biological sludge. Some wastewater may be highly treated and reused as Reclaimed water. For some waste waters ecological approaches using reed bed systems such as constructed wetlands may be appropriate. Modern systems include tertiary treatment by micro filtration or synthetic membranes. After membrane filtration, the treated wastewater is indistinguishable from waters of natural origin of drinking quality.

Reuse