Disingection

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Disinfection
Untreated domestic wastewater contains microorganisms or pathogens that produce human diseases. Processes used to kill or deactivate these harmful organisms are called disinfection.Chlorine is the most widely used disinfectant but ozone and ultraviolet radiation are also frequently used for wastewater effluent disinfection.
Chlorine
Chlorine kills microorganisms by destroyingcellular material. This chemical can be applied to wastewater as a gas, a liquid or in a solid form similar to swimming pool disinfection chemicals. However, any free (uncombined) chlorine remaining inthe water, even at low concentrations, is highly toxic to beneficial aquatic life. Therefore, removal of even trace amounts of free chlorine by dechlorination is often needed to protect fish andaquatic life. Due to emergency response and potential safety concerns, chlorine gas is used less frequently now than in the past.
Ozone
Ozone is produced from oxygen exposed to a high voltage current.Ozone is very effective at destroying viruses and bacteria and decomposes back to oxygen rapidly without leaving harmful by products. Ozone is not very economical due to high energy costs.
UltravioletRadiation
Ultra violet (UV) disinfection occurs when electromagnetic energy in the form of light in the UV spectrum produced by mercury arc lamps penetrates the cell wall of exposed microorganisms.The UV radiation retards the ability of the microorganisms to survive by damaging their genetic material. UV disinfection is a physical treatment process that leaves no chemical traces. Organisms cansometimes repair and reverse the destructive effects of UV when applied at low doses.
Pretreatment
The National Pretreatment Program, a cooperative effort of Federal, state, POTWs and their industrialdischargers, requires industry to control the amount of pollutants discharged into municipal sewer systems. Pretreatment protects the wastewater treatment facilities and its workers from pollutants...
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