A Common Way Of Treating Wastewater Is By Mechanical Means

water and wastewater is a precious resource. It is important that all of the wastewater produced by humans, whether industrial or domestic, is cleansed of containments and pollutants before it is returned to the natural water cycle for re-use. During treatment wastewater is converted to solids and treated water for reuse. Different processes are used to accomplish this. These can be mechanical, physical or chemical and include such processes as cleaning, iron removal, manganese removal, sterilisation and desalination.

A common way of treating wastewater is by mechanical means. In the first step of this process, the sewage is guided into a screening plant, which removes coarse impurities. This can involve a drum screen, with varying gaps in width, or a sieve. The resulting sludge is then disposed of. This mechanical processing also removes about 20 - 30% of the organic matter load (BOD).

The next stage involves chemical wastewater treatment, where a large amount of an oxidant, such as chlorine, is introduced into the sludge. This breaks down the organic matter and deodorises it. Hydrogen peroxide can also be used as an oxidant. The oxidation process also destroys the bacteria within the sludge.

This sludge can then be further processed in anaerobic digesters. Here, microorganisms in an oxygen-limited environment break down the organic matter, releasing carbon dioxide and producing methane, which can then be used as fuel. The methane is also burnt to produce electricity, which can be used for the pumping and heating of the sludge.

A sludge with a lower BOD level is then produced, which can be used for various purposes, such as gardening or agricultural applications. In general, reusing water for non-potable purposes is a good way of cutting back on the use of freshwater supplies, thereby alleviating pressures on natural water bodies.

Besides the above-mentioned benefits, it is also an environmentally responsible method of wastewater treatment. In arid regions, for example, irrigation using wastewater can reduce the need for other fertilizers. Similarly, in the United States, some cities and towns recycle their treated wastewater for use in agriculture and public green spaces.

All of this is made possible by the sewage system, which conveys sewage and surface runoff into a waste water treatment plant. This includes the sewage pipes, chambers and manholes, as well as a screening plant and a pumping station. This is also known as the sanitary sewerage system, or septic tank system in some jurisdictions.