Why Sewage Treatment Plant?
One question that many people might ask is, “Why not simply dump this wastewater onto the ground outside the house, or into a nearby stream?” If you release wastewater directly into the environment, things get very smelly very fast. Human waste naturally contains bacteria that can cause disease. Once water becomes infected with these bacteria, it becomes a health hazard. The increased algae, reduced oxygen and murkiness destroy the ability of a stream or lake to support wildlife, and all of the fish, frogs and other life forms quickly die. That’s why communities build wastewater treatment plants and enforce laws against the release of raw sewage into the environment.
Stages in Sewage Treatment Plant
Pre-treatment removes materials that can be easily collected from the raw wastewater before they damage or clog the pumps and skimmers of primary treatment clarifiers. The influent sewage water is strained to remove all large objects carried in the sewage stream. This is most commonly done with an automated mechanically raked bar screen in modern plants serving large populations, whilst in smaller or less modern plants a manually cleaned screen may be used.
Conventional sewage treatment may involve three stages, called primary, secondary and tertiary treatment. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. The settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment.
Secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment. Secondary treatment removes dissolved and suspended biological matter.Tertiary treatment: Tertiary treatment is effected by sand filters, mechanical filtration or by passing the effluent through a constructed wetland such as a reed bed or grass plot. Tertiary treatment is sometimes defined as anything more than primary and secondary treatment. Treated water is sometimes disinfected chemically or physically (for example by lagoons and micro filtration) prior to discharge into a stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf course, green way or park. If it is sufficiently clean, it can also be used for groundwater recharge or agricultural purposes.
Sludge produced by sewage treatment is organic in nature and contain useful amounts of plant nutrients such as nitrogen, phosphorus and essential trace elements. The first objective should be to utilize the sludge as a fertilizer or soil conditioner on agricultural land. Sludge is treated using a variety of digestion techniques, the purpose of which is to reduce the amount of organic matter and the number of disease-causing microorganisms present in the solids. The most common treatment options include anaerobic digestion, aerobic digestion, and composting.Anaerobic digestion generates biogas with a high proportion of methane that may be used to both heat the tank and run engines or microturbines for other on-site processes. In large treatment plants sufficient energy can be generated in this way to produce more electricity than the machines require. Anaerobic digestion is a bacterial process that is carried out in the absence of oxygen.Aerobic digestion is a bacterial process occurring in the presence of oxygen. Under aerobic conditions, bacteria rapidly consume organic matter and convert it into carbon dioxide. Once there is a lack of organic matter, bacteria die and are used as food by other bacteria.
About the Author
Shubham is the leading Indian water and wastewater Treatment Company providing the most comprehensive water and waste water treatment systems and services for industrial, institutional and municipal customers. Through a pioneering approach in water and waste water treatment, Shubham works to service its clients through a holistic approach.
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