Sanitary sewer
Encyclopedia
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
from houses and commercial buildings to treatment
Sewage treatment
Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater
Industrial wastewater treatment
Industrial wastewater treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use....
. The 'system of sewers' is called sewerage
Sewerage
Sewerage refers to the infrastructure that conveys sewage. It encompasses receiving drains, manholes, pumping stations, storm overflows, screening chambers, etc. of the sanitary sewer...
.
Sanitary sewers are operated separately and independently of storm drain
Storm drain
A storm drain, storm sewer , stormwater drain or drainage well system or simply a drain or drain system is designed to drain excess rain and ground water from paved streets, parking lots, sidewalks, and roofs. Storm drains vary in design from small residential dry wells to large municipal systems...
s, which carry the runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
of rain
Stormwater
Stormwater is water that originates during precipitation events. It may also be used to apply to water that originates with snowmelt that enters the stormwater system...
and other water which wash into city streets. Sewers carrying both sewage and stormwater together are called combined sewers.
Nomenclature
In the developed world, sewers are usually pipelines that begin with connecting pipesPipe (material)
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases , slurries, powders, masses of small solids...
from buildings to one or more levels of larger underground trunk mains, which transport the sewage to sewage treatment
Sewage treatment
Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
facilities. Vertical pipes, called manhole
Manhole
A manhole is an opening used to gain access to sewers or other underground structures, usually for maintenance.Manhole may also refer to:* Manhole , a metal band from Los Angeles* The Manhole, a computer game...
s, connect the mains to the surface. The manholes are used for access to the sewer pipes for inspection and maintenance, and as a means to vent sewer gases. They also facilitate vertical and horizontal angles in otherwise straight pipelines. Sewers are generally gravity powered, though pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
s may be used if necessary. The most commonly used sanitary pipe is SDR-35 (standard dimension ratio), with smaller sized laterals interconnected within a larger sized main.
Pipes conveying sewage from an individual building to a common gravity sewer line are called laterals. Branch sewers typically run under streets receiving laterals from buildings along that street and discharge by gravity into trunk sewers at manholes. Larger cities may have sewers called interceptors receiving flow from multiple trunk sewers. A lift station is a gravity sewer sump with a pump to lift accumulated sewage to a higher elevation. The pump may discharge to another gravity sewer at that location or may discharge through a pressurized force main to some distant location.
History
As an outgrowth of the Industrial RevolutionIndustrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...
, many cities in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
grew in the 19th century, frequently leading to crowding and increasing concerns about public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
. As part of a trend of municipal sanitation
Sanitation
Sanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes. Hazards can be either physical, microbiological, biological or chemical agents of disease. Wastes that can cause health problems are human and animal feces, solid wastes, domestic...
programs in the late 19th and 20th centuries, many cities constructed extensive sewer systems to help control outbreaks of disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
such as typhoid and cholera
Cholera
Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...
. Initially these systems discharged sewage directly to surface water
Surface water
Surface water is water collecting on the ground or in a stream, river, lake, wetland, or ocean; it is related to water collecting as groundwater or atmospheric water....
s without treatment. As pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
of water bodies became a concern, cities added sewage treatment plants to their systems. Most cities in the United States underwent their sanitary revolutions between 1900 and 1935, by adding more expensive sewer systems and other technology to rid themselves of bad bacteria by chlorinating water and filtering water and sewage. In areas where there was surface pollution near the shore, such as Cleveland, extended intake systems were put out into the water to reduce contamination in drinking water. In cities during this period, there were reductions in diseases, such as typhoid fever which went from 35 per 10,000 to less than 5 per 10,000 in the population. These early sewer systems can be accredited with a rise in population in cities because life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...
increased and disease went down.
Maintenance
All sewers deteriorate with age; but Infiltration/InflowInfiltration/Inflow
Infiltration/Inflow causes dilution in sanitary sewers. Dilution of sewage decreases the efficiency of treatment, and may cause sewage volumes to exceed design capacity. Although inflow is technically different from infiltration, it may be difficult to determine which is causing dilution problems...
is a problem unique to sanitary sewers; since both combined sewers and storm drains are sized to carry these contributions. Holding infiltration to acceptable levels requires a higher standard of maintenance than necessary for structural integrity considerations of combined sewers. A comprehensive construction inspection program is required to prevent inappropriate connection of cellar, yard, and roof drains to sanitary sewers. The probability of inappropriate connections is higher where combined sewers and sanitary sewers are found in close proximity; because construction personnel may not recognize the difference. Many older cities still use combined sewers while adjacent suburbs were built with separate sanitary sewers.
Simplified sewers
Simplified sanitary sewers consist of small-diameter pipes (typically 100 mm or about 4 inches), often laid at fairly flat gradients (1 in 200). The investment cost for sanitary sewers can be about half the costs of conventional sewers. However, the requirements for operation and maintenance are usually higher. Simplified sewers are most common in BrazilBrazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
and are also used in a number of other developing countries.
See also
- Buchan trapBuchan trapA Buchan Trap is a device made from fireclay located in a domestic sewer pipe to prevent vermin entering the pipe. The trap uses a water seal to prevent rats and mice climbing any further along the pipe. Waste flows from the house through a U-bend in the trap...
- Combined sewer
- Sanitary sewer overflowSanitary sewer overflowSanitary sewer overflow is a condition whereby untreated sewage is discharged into the environment prior to reaching treatment facilities thereby escaping wastewater treatment. When caused by rainfall it is also known as wet weather overflow. It is primarily meaningful in developed countries,...
(SSO) - Sewage treatmentSewage treatmentSewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
- StormwaterStormwaterStormwater is water that originates during precipitation events. It may also be used to apply to water that originates with snowmelt that enters the stormwater system...
- Water pollutionWater pollutionWater pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
- Composting toiletComposting toiletA composting toilet is a dry toilet that using a predominantly aerobic processing system that treats excreta, typically with no water or small volumes of flush water, via composting or managed aerobic decomposition...
External links
- Experiences and Challenges in Sewers: Measurements and Hydrodynamics (2008), International Meeting on Measurements and Hydraulics of Sewers IMMHS'08, Hydraulic Model Report No. CH70/08, University of Queensland, Brisbane, Australia, 114 pages (ISBN 9781864999280)