Tertiary baptize treatments are the third, or Ending, stages of cleaning imbue after it has been used for farm, tame or industrial purposes. Influential treatment screens particulates and settles sludge in ponds. Secondary treatment is "microbial degradation," bottom line human away or other biological dissipate is decomposed by algae and bacteria. Tertiary treatment passes the douse fini filters to remove biological pollutants that bacteria cannot division down. Tertiary treatment further uses chemicals to remove chemical pollutants such phosphorous and nitrogen.
Primary Treatment
Green sewage or industrial away is screened and pumped into enormous, open-air settling tanks. Screening begins by passing the bathe concluded a course of bars to arrest paper and cloth rags. At this page, all grit must be removed from the drool, so that it Testament not damage the channel. Grit Testament put into the backside of a channel channel whether hose is allowed to sit for one minute. The dilute is passed on ice a series of screens, with meshes that vary in immensity from coarse to also positive. The screens rotate, so that Dregs Testament not clog them. Screened aqua is pumped into the Centre of the settling tanks, where sludge settles to the backside and cleared doctor flows away the tops of the sides.
After the water is filtered, it is treated with chemicals to remove to remove two pollutants: phosphorous and nitrogen. Excess phosphorous or nitrogen acts as a fertilizer in the natural ecosystem. Phosphorous is precipitated from the water as calcium phosphates, aluminum phosphates or iron phosphates. Nitrogen (ammonium compounds) is treated with chlorine to release the nitrogen gas to the atmosphere.
Tertiary Treatment -- Stage Two
Secondary Treatment
Algae and bacteria biodegrade dissolved biological affair in the bathe, pliant a minimal dimensions of minerals and a broad immensity of detachable solids. In an anaerobic receptacle as all the more as 15 feet below, biodegredation Testament part approximately 30 days and make severe odours. Another oftentimes, aerobic algae and anaerobic bacteria are used in sync to degrade the biological matter. This aerobic process requires several months in open-air facultative ponds about 6 feet deep. The pond can be earthen or paved. Algae grow at the top of the pond and bacteria grow at the bottom. Many viruses in the water die during this process, especially as they are exposed to sunlight.Tertiary Treatment -- Stage One
Tertiary treatment starts with pumping water through activated carbon filters. Activated carbon is charcoal that is treated to increase its porosity and its potential for chemical bonding.Some chemical pollutants can only be removed by specialized chemical treatment that will precipitate them into small clumps that can be settled or filtered out of the water. For instance, hexavalent chromium is toxic to the natural environment and can cause cancer, but adding iron sulfate and lime to the water will produce an iron oxide and a harmless trivalent chromium. Also, magnesium and calcium that harden the water can be softened with lime.
Tertiary Treatment -- Zeolite Ion Exchange
If there are still pollutant minerals in the water, an ion exchange filter will remove them. An ion is an atom or molecule that has a positive or negative charge and can bond to another atom or molecule. Ion exchange filters are made of zeolite clay that can exchange a sodium ion in its structure for a pollutant ion in the water. After the filter is used, it can be flooded with salty water to put the sodium back. The filter can then be used again.
Tertiary Treatment -- Ultra-filtration Membrane
Ultra-filtration is a tertiary process for industries that want to reuse their water. Pulp and paper manufacturers, food industries and oil producers are target markets for ultra-filtration systems. The filter membranes are made of tough, durable polyvinylidene fluoride fibers and can be cleaned in place and used again. Beyond ultra-filtration is nano-filtration and reverse-osmosis, which both use pressure to move water through a fine membrane.
