Wastewater treatment is the process of transforming wastewater, the water which is no longer suitable for use into bilge water that can be discharged back into the environment.
Here is a step-by-step process of wastewater treatment:
- Step1: Collection of wastewater: This is the very first step of the wastewater treatment process. All the wastewater is collected by the collection systems and directed to a central point. Using underground drainage systems, this water is then directed to a treatment plant.
- Step2: Odour control: At the treatment plant, odour control is crucial. Wastewater contains a number of dirty substances that causes foul smell over time. Odour treatment processes are initiated at the treatment plant to ensure that the surrounding areas are free of the foul smell. All odour sources are contained and treated using chemicals in order to neutralize the foul smell producing elements.
- Step3: Screening: this step involves the removal of large objects such as cotton buds, rags, face wipes, nappies, broken bottles or bottle tops that may damage the equipment. Specially designed equipment is used to get rid of grit that is generally washed down into the sewer lines by rainwater.
- Step4: Primary treatment: In this process, the macrobiotic solid matter is separated from the wastewater. The wastewater is poured into big tanks for the solid matter to settle at the surface of the tanks. The sludge that settles at the surface of the tanks is removed by large scrappers and is pushed to the centre of the cylindrical tanks and later pumped out of the tanks for further treatment. The remaining water is then pumped for secondary treatment.
- Step5: Secondary treatment: This is also known as the activated sludge process. It involves adding seed sludge to the wastewater to ensure that it is broken down further. Air is first pumped into large aeration tanks which mix the wastewater with the seed sludge which is basically small amount of sludge. It fuels the growth of bacteria that uses oxygen and the growth of other smaller microorganisms that consume the remaining organic matter. The wastewater passes through the large tanks for a period of 3-6 hours.
- Step6: Handling of bio-solids: The solid matter that settles out after the primary and secondary treatment stages are directed to digesters. The digesters are heated at room temperature. The solid wastes are then treated for a month where they undergo anaerobic digestion. During this process, methane gases are produced and nutrient rich bio-solids are formed and recycled and dewatered into local firms. The methane gas formed here is generally used as a source of energy at the treatment plants.
- Step7: Tertiary treatment: This stage has the ability to remove up to 99% of the impurities from the wastewater. This produces effluent water that is close to drinking water quality.
- Step8: Disinfection: This process eliminates some of the diseases causing organisms left even after the primary and secondary treatment process. For this, the wastewater must be disinfected for at least 20-25 minutes in tanks containing a mixture of chlorine and sodium hypochlorite. The effluent is later released into the environment through the local water ways.
For more information, you can call on Severn Trent Contact Number and get in touch with its team.