Water pollution has reached an alarming height today. The first step to curb this pollution is to treat the water before it is set out in waterbodies. The process by which the wastewater is treated is called wastewater treatment plant. Wastewater treatment plant is also called sewage treatment plant.
Wastewater treatment means merely removing the impurities from waste or sewage water before they are thrown out in water bodies like; lakes, rivers, oceans or aquifers. In this process first wastewater is converted into the effluent, this effluent can be returned into water cycle, and it will cause less damage to the environment. This treatment is carried out at water treatment plant or sewage treatment plant. Here, mainly wastewater from municipalities, i.e., household waste and waste from small industries are treated here. In India, there is separate water treatment plant to clean the polluted water of river Ganges.
This treatment of waste is part of sanitation. In sanitation process, there is the treatment of even human waste, solid waste, as well as drainage management.
In this process of wastewater treatment plant, a lot of by-products like screenings, grit and sewage sludge are formed which is again treated in the treatment plant.
The process of waste treatment:
There is a three-tier process involved in sewage treatment plant;
First or Primary stage:
This natural step includes sedimentation of solid waste within the water. Large contaminants of water are removed from waste. This wastewater is passed through several tanks and filters. This separates water from pollutants. The product that is formed is called sludge. This sludge is then placed into the digester, where the further process is carried out. At this primary stage, the muck that is formed contains about 50% of solid wastewater.
Second or secondary waste:
In the second stage oxidation process is used to purify wastewater. There are three alternative methods to carry out oxidation, they are;
Aeration: Aeration is a long process of oxidation. There is mixing of wastewater into a solution of microorganisms. It is an advantageous process. The product which is then formed is then aerated for about 30hours for a better result.
Oxidation ponds; In this process, natural water bodies are used like lagoons. Wastewater is then passed through this lagoon and is then kept there for about 2 to 3 weeks. This process of oxidation requires warmer place.
In this method, additional sediments are removed from wastewater. There are three kinds of filters used in this process, sand filters, tricking filters and contact filters. The trickling filter is the very effective method used for treating small effluents.
Third or tertiary wastewater treatment:
This is the third and last step for treatment of wastewater. It is also the fundamental step. In this process chemicals like phosphates and nitrites are removed from waste. In this process activated carbon and sands are used in this process to carry out treatment.
There can be more than these three steps as above mentioned, to treat the wastewater. It is an important step to reduce contamination of wastes from water. The first step to curb water pollution.