Sewage is the mainly liquid waste produced by humans. It typically consists of washing water, feces, urine, laundry waste and other material which goes down drains and toilets from households and industry. It is one type of wastewater and is a major actual or potential source of pollution, especially in urban areas. It is estimated that pollution of drinking water due to faeces is by far the biggest cause of death worldwide. Well-organized sewage services prevent pollution of the environment due to sewage by managing the collection, treatment, and recycling or safe disposal of sewage in the environment. As of 2004 in the US, 850 billion gallons of raw sewage were being dumped into waterways every year.
History
The first sanitation systems have been found in the prehistoric Middle East and the surrounding areas. The first time an inverted siphon system was used, along with glass-covered clay pipes, was in the palaces of Crete in Greece. The system is still in working condition, after about 3000 years. Sewage disposal systems did not progress much until the 16th century, when, in England, Sir John Harington invented a device for Queen Elizabeth that released wastes into cesspools.
Sewage Services
Collection and Disposal
A system of sewer pipes (sewers) collects sewage and takes it for treatment or disposal. Where a main sewage system has not been provided, a system of pipes may be used to collect the sewage from homes and transport it to septic tanks or cesspits, where it may be treated or collected in vehicles and taken for treatment or disposal. Properly functioning septic tanks require emptying every 2 to 5 years depending on the load of the system.
Treatment
Sewage treatment is the process of removing the contaminants from sewage to produce liquid and solid sludge suitable for discharge to the environment or for reuse. It is a form of waste management. A septic tank or other on-site wastewater treatment system such as biofilters can be used to treat sewage close to where it is created.
Sewage water is a complex matrix, with many distinctive chemical characteristics. These include high concentrations of ammonium, nitrate, phosphorus, high conductivity (due to high dissolved solids), high alkalinity, with pH typically ranging between 7 and 8. Trihalomethanes are also likely to be present as a result of past disinfection.
In developed countries sewage collection and treatment are typically subject to local, state, and federal regulations and standards.
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