In the coming years, water is going to be the most debated environmental challenges globally. The global demand for fresh water is increasing rapidly. Water for industrial and residential usage is burgeoning with no signs of abatement.
Due to increasing water scarcity, countries developed technologies to desalinate sea water to compensate for the shortage of fresh water for human consumption. Despite this, today global water scarcity is looming large and worldwide there is an attempt to conserve water. This has resulted in nations looking for ways to reduce the water consumption and also recycle and reuse the waste water. The concept of sewage treatment and industrial effluent treatment was born out of this necessity. The reuse of treated waste water has today become an ecological imperative.
Treatment and recycling of waste water (sewage, sullage, industrial effluent) has been acknowledged as an economical and commercially viable proposition. Recycling of waste water will drastically reduce the rate of depletion of surface and ground water.
As water demand and environmental needs grow, waste water recycling will play a vital role in our overall water supply. Water recycling along with water conservation will help us sustain and manage our vital water resources.
Waste water treatment is the process of removing physical, chemical and biological contaminants from the waste water. These plants operate on the principle of degradation of organic matter achieved through bacterial activity. This bacterial activity can be facilitated through biological processes like aerobic treatment (bacterial growth in oxygenated environment) and anaerobic treatment (bacterial growth in the absence of oxygen).
In the aerobic process, oxygen is generally supplied in diluted form (in the form of air) to oxygenate water. The process of supplying air may be different viz. through fixed or floating aerators or through diffused aeration. This facilitates rapid bacterial growth which eats away the organic matter and cleans up water. As a result, a majority of the biological contaminants found in the waste water is removed.
In the anaerobic process, bacterial digestion is carried out in the absence of oxygen. This process can either be thermophilic in which sludge is fermented in tanks at a temperature of 55 ° C or mesophilic at a temperature of around 36 ° C.