Wastewater
Wastewater is any water that exhibits impaired water quality due to anthropogenic influence. It comprises discharges of domestic, residential, commercial, industrial, as well as agricultural origin. Wastewater can contain various constituents and concentrations reflecting the variety of its sources.
Content Table
Wastewater types and terms
Sewage, often incorrectly used as synonym for wastewater is traditionally the subset of wastewater that is contaminated with faeces or urine.
Blackwater is characterised as toilet waste from water closets (faeces, urine, toilet paper, and flush-water).
Greywater is defined as the wastewater from baths, showers, hand basins, laundry machines and kitchen sinks.
Another subset of wastewater is runoff water (manmade or stormwater runoff) from partially impervious surfaces for example from urban areas like roads, roofs, parking lots, etc. Contaminated runoff created at industrial or agricultural sites is also being counted to wastewater.
Industrial process and cooling waters as well as any other resulting water flow contaminated with liquid or solid waste.
Any water that comes into contact with any of the subsets of wastewater is also consequently classified as wastewater due to the uptake of contaminants. For example spills or leakages from septic tanks, cesspits, process waters, etc. into groundwater and surface waters can make treatment thereof inevitable.
Constituents
Wastewater is mainly comprised of more than 95% water and can contain all the Chemistry and Biology that result from anthropogenic life. Its composition strongly depends on its sources.
One significant fraction is any form of solid waste like paper waste, food, plastic bags, etc.
Many constituents are not toxic, but to the least can still cause problems by their pure mass like sand. Others are not toxic per se, but become an environmental impairment when accumulated in nature. Examples are de-icing salts, heavy metals like zinc or copper, fats, etc.
A large spectrum of toxic substances and pathogens are the main reason to make wastewater treatment a public duty to avoid harm for human health. Among these are for example are many inorganic constituents (Cadmium, Lead, Mercury, Arsenic, Ammonia, etc.), organic compounds (pesticides, many polycyclic aromatic hydrocarbons (PAH), MTBE, pharmaceuticals, etc.), and pathogenic organisms (Cryptosporidium parvum, Giardia intestinalis, Toxoplasma gondii, Adeno- and Enteroviruses, Hepatitis A and E viruses, Escherichia coli O157:H7, Salmonella typhi, Vibrio Cholerae, and others)
Numerous incidents are known in human history related with mishandling of anthropogenic created wastewater.
Examples are:
- Minimata disease: release of methyl mercury in the industrial wastewater (Japan).
- Itai-itai disease: release of cadmium by mining processes (Japan).
- Milwaukee outbreak: waterborne Cryprosporidium infection through contamination in public water supply (USA).
- UN report: Sick Water?: "...more people die as a result of polluted water than are killed by all forms of violence including wars”
Wastewater quality parameters
Besides element or molecule specific analyses that are chosen based on the origin of certain wastewaters there are several bulk parameters that are generally tested in wastewater. These are pH, TOC (total organic carbon), DOC (dissolved organic carbon), TSS (total suspended solids), COD (chemical oxygen demand), and BOD (biological oxygen demand).
Related Articles
Wastewater UV disinfection I and II
References
Standard methods of the examination of water and Wastewater
Helena Palmquist, Jorgen Hanaeus, Hazardous substances in separately collected grey- and blackwater from ordinary Swedish households, Science of The Total Environment, Volume 348, Issues 1-3, 15 September 2005, Pages 151-163
Gross A., Kaplan D., Baker K. (2007). Removal of chemical and microbiological contaminants from domestic greywater using recycled vertical flow bioreactor (RVFB). Ecological Engineering, 31(2), 107-114.
MacKenzie WR, Schell WL, Blair KA, Addiss DG, Peterson DE, Hoxie NJ, Kazmierczak JJ, Davis JP. (1995), Massive outbreak of waterborne cryptosporidium infection in Milwaukee, Wisconsin: recurrence of illness and risk of secondary transmission, Clin. Infect. Dis., 21(1):57-62)
Links
European Union: Urban wastewater directive
United States Environmental Protection Agency's Office of Wastewater Management
