subject: Waste Water Treatment Plants And How They Work [print this page] Wastewater treatments are used to remove impurities from household or industrial wastewater. These systems use different biological, chemical and physical processes to remove impurities from waster. The water after treatment should be safe for environment and for reuse as fertilizer, garden and lawn watering, or for industrial applications etc. Today there is advanced technology that has made it possible to reuse sewage water as drinking water or for other domestic or household uses.
Impure water from homes usually comes from toilets, showers, bathtubs, sinks and kitchens. Wastewater comes from industries also. Grey water from industries doesn't contain human waste and is treated so that it can be used for landscape irrigation purposes and wetlands that are created for migratory and native birds.
Black water usually has pathogens that should be decomposed before they are safe enough for environment or reuse. This can be achieved by decomposing if the water content is low. The thermophilic microorganisms will create heat that will help to raise the compost to over 60 degrees Celsius. This process will eliminate the hazardous pathogens and the resulting black water will be ready to be used for safe fertilizer after a period of a year.
Waste water systems can be used by companies that have impure or contaminated effluent and would like to filter it for reuse. These systems can be very small so that they can fit in small areas and can be easily transported from one place to another. They can also be large in size so that they can treat huge amount of wastewater every day.
There are different systems for different kinds of wastewater, but the major and fundamental steps for treatment are:
1: Pre-treatment that helps to remove large pieces and debris, such as cans, rags, branches, leaves etc.
2: Screening is used to remove large pieces that are smaller than the impurities removed in the pre-treatment process including plastic packets, cans, rags etc. This is done with both a racking bar but can also be done manually.
3: Grit removal includes removing sand, small stones and broken glass. This can be done in large systems instead of small systems because in small systems the grit can be removed during the screening.
4: In larger systems fat and grease can be removed with skimmers that collect all the impurities floating on the surface. In most water treatment plants this can be done with mechanical surface skimmers.
5: Sludge can be settled through sedimentation by primary treatment. These systems have scrapers that push the settled sludge to a container for further treatment.
6: All the biological content from sewage that comes with human or food wastes is degraded by secondary treatment. Secondary treatment systems are of different types.
If the water is supposed to be discharged into coral reefs or estuaries, then there is tertiary water treatment after secondary treatment to treat the water chemically or physically. If the water is treated and purified according to desired level, it can be reuse to recharge groundwater or for irrigation.
