sewage treatment

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sewage treatment:

see septic tankseptic tank,
underground sedimentation tank in which sewage is retained for a short period while it is decomposed and purified by bacterial action. The organic matter in the sewage settles to the bottom of the tank, a film forms excluding atmospheric oxygen, and anaerobic
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; seweragesewerage,
system for the removal and disposal of chiefly liquid wastes and of rainwater, which are collectively called sewage. The average person in the industrialized world produces between 60 and 140 gallons of sewage per day.
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sewage treatment

[′sü·ij ‚trēt·mənt]
(civil engineering)
A process for the purification of mixtures of human and other domestic wastes; the process can be aerobic or anaerobic.

Sewage treatment

Unit processes used to separate, modify, remove, and destroy objectionable, hazardous, and pathogenic substances carried by wastewater in solution or suspension in order to render the water fit and safe for intended uses. Treatment removes unwanted constituents without affecting or altering the water molecules themselves, so that wastewater containing contaminants can be converted to safe drinking water. Stringent water quality and effluent standards have been developed that require reduction of suspended solids (turbidity), biochemical oxygen demand (related to degradable organics), and coliform organisms (indicators of fecal pollution); control of pH as well as the concentration of certain organic chemicals and heavy metals; and use of bioassays to guarantee safety of treated discharges to the environment.

In all cases, the impurities, contaminants, and solids removed from all wastewater treatment processes must ultimately be collected, handled, and disposed of safely, without damage to humans or the environment.

Treatment processes are chosen on the basis of composition, characteristics, and concentration of materials present in solution or suspension. The processes are classified as pretreatment, preliminary, primary, secondary, or tertiary treatment, depending on type, sequence, and method of removal of the harmful and unacceptable constituents. Pretreatment processes equalize flows and loadings, and precondition wastewaters to neutralize or remove toxics and industrial wastes that could adversely affect sewers or inhibit operations of publicly owned treatment works. Preliminary treatment processes protect plant mechanical equipment; remove extraneous matter such as grit, trash, and debris; reduce odors; and render incoming sewage more amenable to subsequent treatment and handling. Primary treatment employs mechanical and physical unit processes to separate and remove floatables and suspended solids and to prepare wastewater for biological treatment. Secondary treatment utilizes aerobic microorganisms in biological reactors to feed on dissolved and colloidal organic matter. As these microorganisms reduce biochemical oxygen demand and turbidity (suspended solids), they grow, multiply, and form an organic floc, which must be captured and removed in final settling tanks. Tertiary treatment, or advanced treatment, removes specific residual substances, trace organic materials, nutrients, and other constituents that are not removed by biological processes. Most advanced wastewater treatment systems include denitrification and ammonia stripping, carbon adsorption of trace organics, and chemical precipitation. Evaporation, distillation, electrodialysis, ultrafiltration, reverse osmosis, freeze drying, freeze-thaw, floatation, and land application, with particular emphasis on the increased use of natural and constructed wetlands, are being studied and utilized as methods for advanced wastewater treatment to improve the quality of the treated discharge to reduce unwanted effects on the receiving environment. See Absorption, Sewage, Sewage disposal

On-site sewage treatment for individual homes or small institutions uses septic tanks, which provide separation of solids in a closed, buried unit. Effluent is discharged to subsurface absorption systems. See Septic tank, Unit processes, Water treatment

sewage treatment

Any artificial process to which sewage is subjected in order to remove or alter its objectionable constituents and to render it less dangerous from the standpoint of public health.
References in periodicals archive ?
As from 2020, the main sewage plant will use sewage gas to generate autonomously all the energy required for the wastewater treatment.
A spokesman for Severn Trent Water, which runs the sewage plant at Finham, said: "Severn Trent Water takes its environmental responsibilities extremely seriously.
WAFA's correspondent in Gaza said that the 'Israeli aircraft targeted a sewage plant west of the city, which serves the areas of Al-Shati Camp, Tel al-Hawa neighborhood, Sheikh Ajlin and the western areas of Gaza City, and which pumps 25 thousand cubic meters of waste water daily to the public treatment plant '.
The new project is a quantum leap in sewage systems as it will dispense of the need to transport wastewater from Muharraq to Manama, and then to the Tubli Sewage Plant," he said.
Humaid Al Mualla, Director of the Health and Environment Department at the municipality, said the civic body had recently warned the companies to instruct tanker drivers to dump the waste water in the sewage plant.
VANDALISM at a sewage plant could cause an environmental catastrophe, NI Water has warned.
The solid waste management company is proposing a 12-mile pipeline from its American landfill, two miles north of Waynesburg in Sandy Township, to Canton's sewage plant for leachate treatment.
Or possibly right at home as-is on a greeting card for a municipal sewage plant employee, a market that's been woefully underserved by Hallmark.
News that the awful smell from a Dubai sewage plant could be virtually eradicated has been welcomed by people who own property nearby - some of whom said the smell is so bad they moved out.
AN MP will hold crisis talks with water bosses today over a foul stink from a sewage plant that has plagued his constituents for 10 years.
A highly radioactive substance was detected in incinerator ashes at a sewage plant in eastern Tokyo in late March, shortly after the start of the nuclear crisis at the Fukushima Daiichi nuclear power station, metropolitan government sources said Friday.
According to the Yorkshire sewage plant there is a growing trend of people abusing their sewage systems by flushing unwanted items down their drains rather then binning them, which could cause serious problems for residents in the area.