- Not to be confused with overflow combined channels (CSO)
Sewage disposal channel ( SSO ) is a condition in which untreated waste is discharged from sanitation to the environment prior to reaching the sewage treatment facility. When caused by rainfall it is also known as wet weather overflow . This is particularly significant in developed countries, which have extensive treatment facilities. Common causes of SSO spills include:
- Clogged sewer
- Infiltration/Excessive rainfall inflow into sewer during heavy rain
- Pump station failure or power failure
- The channel line is corrupted.
SSO can cause gastrointestinal diseases, beach closures and restrictions on fish and shellfish consumption.
Video Sanitary sewer overflow
The magnitude of the problem
Developed countries like the United States, Canada, most Western European countries (eg Italy and France), Australia, Singapore, South Korea and Japan are struggling with public health problems from SSO prevention. However, the magnitude of the problem is much greater in most developing countries.
United States
The US Environmental Protection Agency (EPA) estimates that at least 23,000 to 75,000 SSO events occur in the United States each year. The EPA estimates that upgrading every municipal care and collection system to reduce the frequency of overflow events to no more than once every five years would cost about $ 88 billion in 2004. This would cost an additional $ 10 billion already invested. Although the volume of untreated waste is discharged to less than 0.01 percent of all waste handled in the United States, its total volume reaches several billion gallons per year and accounts for thousands of cases of digestive diseases each year.
Worldwide perspectives
Developed European countries and Japan have the same or somewhat greater percentage of SSO events compared to the US.
In developing countries, most of the wastewater remains untapped when disposed of into the environment. The People's Republic of China dumps about 55 percent of all waste without any kind of processing, such as in 2001. In a relatively developed Middle Eastern country like Iran, the majority of Tehran's population has completely untreated waste that is injected into the city's groundwater. In Venezuela, a country below the average in South America with respect to wastewater treatment, 97 percent of the country's waste is discharged without care to the environment.
In many countries there is an obligation to measure and report SSO events using real-time telemetry to warn peoples, baths and leather operators.
Maps Sanitary sewer overflow
Cause
Technical aspects
Sewers built in the early stages of urbanization are usually built before sewage treatment takes place. The initial drainage channel is a simple drainage system to remove surface runoff with any waste material that it may contain. This drainage system becomes a combined sewer when the waste from the kitchen, bath and toilet is added; and discharge becomes offensive. An initial sewage treatment plant is built to handle waste during dry weather; but it is unfeasible to handle larger volumes of mixed wastes and rainfall deposition from the combined sewer during the wet season. Sanitary disposal channels are built to keep dirt from mixing with surface runoff so that waste can be efficiently treated during wet and dry weather.
Blockage
Decentralized failure in dry weather mainly occurs from the collection of blocked drains, which can arise from blockage of debris or the intrusion of tree roots into the path itself. About half of SSOs in the United States are caused by a blockage. Greases are blocking agents in about half the US SSOs attributed to clogging, and solid debris is an inhibitor agent for the other 25 percent. Roots are a contributing factor in about a quarter of US SSOs associated with blockage. Fat deposition is caused by cooking fats that are melted with hot water to be discharged into the sanitary sewer. This fat freezes as a solid precipitate in the cooling conduit. Solid debris includes dirty clothes, diapers, and sanitary napkins that are flushing to the toilet.
One of the main problems of decentralized path failure is the difficulty of locating overflow, because typical urban systems contain thousands of miles of collection pipes, and the processing center has no way of communicating with all channels except expensive. monitoring equipment has been installed. Companies in the UK have used bulk dielectric transducers suspended in sewers to detect high levels and report back events through fixed wireless data networks. In certain locations, this practice has enabled a reduction in pollution by up to 60 percent.
Dry weather clogging is less likely in the combined culverts; since the combined sewer designed for additional surface runoff volumes is much larger than the sanitary sewer. Combined wastewater regulators may be vulnerable to clogging by debris, but overflow from such blockages typically enters outbound diversions to avoid personal flooding or public property.
Infiltration/inflow
About a quarter of US SSOs occur during heavy rainfall events, which can lead to the entry of rainwater into the sewer through damage, improper connections, or flooded buildings and lifting stations in the lowlands of the collection system. The combined flow of waste and rainwater exceeds the capacity of sanitary and waste disposal systems discharged into homes, businesses and roads. This situation is most prevalent in old towns whose underwater infrastructure is quite old; Paris, London, Stockholm, New York City, Washington, DC, and Oakland, California are typical examples of these locations. Incoming currents into the sanitary canal may be caused by tree roots that rupture in the subsurface or by mechanical fracture due to age and excess pressure of trucks and buildings.
Malfunction
Other modes of system failure may include a power outage, which can disable the lift station pump and cause overflowing of dirt from the wet lift station properly. Electric lift stations or power outages cause about ten percent of US SSO. This type of discharge is not common from the combined sewer, since the combined volume of waste and rainwater precludes the use of lift stations. The damaged sewer channel is responsible for about ten percent of the US SSO.
Failure of power, human error, or mechanical damage may result in the discharge of untreated or partially treated sewage from the waste treatment plant; but this is usually regarded as a malfunction of a sewage treatment plant rather than a sanitary sewer. Waste treatment plants can be designed to capture an abundance of non-functioning units and dispose of them into alternative treatment facilities. Flooding from private or public property is usually avoided by disposing of overflow into sewer discharges designed for the disposal of treated waste.
Human health and ecological consequences
The human health impact includes a large number of gastrointestinal diseases each year, although death from one overflow event is rare. Additional human impacts include beach closures, swimming restrictions and certain animal aquifers (especially certain mollusks) after the incident overflows. Ecological consequences include killing fish, endangering plankton and other aquatic microflora and microfauna. Increased turbidity and decreased oxygen dissolved in the receiving water may cause accelerated effects beyond pathogens caused by apparent damage to aquatic ecosystems. It is possible that higher life forms such as marine mammals can be affected because certain seals and sea lions are known to experience a peak in the danger of pathogens.
Mitigation techniques
The concept of the SSO containment valve has been pioneered in the UK and they are installed to reduce the dry spillage, by linking rainfall data to the SSO spill activity.
History
Since the Middle Ages rulers have been aware of the impact of raw waste being thrown into the environment incorrectly. Before the treatment system existed in 16th-century England, King Henry VIII decided that the waste trough should continue to flow so they would not stagnate in London before reaching the Thames River (London's sewer system).
In the 19th century, sewage treatment plants were first developed and installed in the US and parts of Europe, and the concept of SSO was identified. However, SSO was not recognized as a widespread environmental problem until the emergence of environmental awareness in the 1960s. Around that time government agencies in the US began to identify the location and frequency of SSO systematically. The local government hears citizens' complaints, and systematic coastal closing protocols to reduce risks to public health.
After part of the Clean Water Act in 1972, the United States spent billions of dollars to upgrade to a sewage treatment plant, with some related improvements and improvements to the associated collection system, where there was an overflow. EPA continues to provide funding for low-interest loans to communities to address SSO issues, through the Clean Water Country Rolling Fund.
In the 1990s Japan, Britain, and a number of other European countries began to make a genuine investigation into some of their country's overflowing problems.
See also
- Water pollution
References
External links
- Additional SSO technical and resource reports - EPA
Source of the article : Wikipedia
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