Sunday, 29 October 2017
Waste Water Treatment Processes and Benefits
In urban settings, wastewater treatment comes under the authority of the Public Works Department which is entrusted with the management of solid waste, sewage treatment including human waste, storm water drainage etc. Wastewater treatment plants in these areas treat wastewater as well as the byproducts or effluents from the wastewater treatment like sewage sludge, grit and screenings. Here it is mostly wastewater from households and industries and the treatment is referred to as 'sewage treatment' although in many cities the sewer lines also carry large amounts of industrial effluents to the sewage treatment plants in addition to storm water also.
Hence, sewage treatment primarily comprises the process of removing contaminants through a combination of physical, biological and chemical processes and ensure that the end product is environmentally safe treated water that is suitable for land uses. Most wastewater treatment plants are 'centralized systems' with a vast extensive network of aerobic treatment systems, bio-filters and septic tanks.
The term 'wastewater treatment' has in many countries today replaced the term 'sewage treatment'. In the developed world, wastewater treatment plants treat mainly wastewater from residential areas and business places. Wastewater from industrial and manufacturing plants, refineries etc. is treated onsite through infrastructure and facilities to ensure that the effluents are treated before release into local environments. Hence the processes are very complex. The first stages can see the wastewater being used to cool machines and boile
Primary processes of wastewater treatment
Wastewater treatment processes involve several steps, chief among them are the following:
1. Collection of wastewater at a central point or plant
2. Odor control by use of chemicals to neutralize foul smells
3. Screening process, which involves removal of large waste objects - e.g. broken bottles, diapers, nappies, plastics, sanitary items etc. that can cause damage to machinery and cause environmental damage.
4. Primary treatment process which involves separating macrobiotic waste solids from the wastewater. The solids which collect on the surface of large tanks are removed and pumped out for further treatment.
5. Secondary treatment is broadly referred to as the 'activated sludge process' which breaks down the sludge in the wastewater further. Huge aeration tanks into which air is pumped mix the wastewater with the 'seed sludge' enabling the growth of bacteria and other microorganisms which consume the organic residues. Larger particles and residue settle at the bottom of these tanks.
Benefits
After these primary processes, later steps include secondary treatment, bio-solids handling, tertiary treatment, disinfection and sludge treatment. Wastewater treatment provides several benefits such as preventing water pollution, ensuring the environment is clean and free from damage, maximizes usage of natural resource like water, provides an alternate source of water for factory and industrial usage, prevents disease outbreaks and ensures adequate water supply for agriculture and irrigation purposes.
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