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 ?
Sewage treatment is the process of filtering and purifying municipal wastewater generated by households plus commercial and industrial establishments.
A strategic project for the Saudi region, the Taif Independent Sewage Treatment Plant will have several leading global industry experts in the advisory role.
Consider two successful examples of sewage treatment. The Turkish province Bursa has a population of only three million people.
"Although the sewage treatment works reduce the potential for such problems, it is important that people handle all waste responsibly."
The second phase of the project includes construction of a Thermal Drying Plant (TDP) to process sludge from the sewage treatment plant.
A PUB company has been fined PS150,000 after sewage treatment works at Guisborough's Cross Keys Inn polluted a stream.
("Sound Global" or "the Company") hereby announces that it has won the bid for sewage treatment plant (Phase I) BOT project in five towns of Yangchun City, Guangdong Province, the PRC.
A groundwater monitoring report for the airport sewage treatment system from Stantec, the county's consultant, noted that tile beds had been discharging into the groundwater and producing unacceptable high nitrate levels in three test wells and a neighbour's well for the first half of 2013.
Most of the sewage treatment projects of municipal corporations do not have budget or they are facing the problem of environment clearance from ministry.
Dubai: Municipal officials have rejected claims by residents that the sewage treatment plant near International City has been making them ill, attributing their concerns to the "psychological effects" of living close to the plant.
SEVERN Trent Water is inviting Coventry residents to see its plans for multi-million pound improvements to Finham sewage treatment works today.
Summary: Dubai Municipality announces task force to find ways to contain, control and minimise the odour emissions from the Dubai based Al Aweet Sewage Treatment Plant