Tuesday, 23 October 2018

Wastewater Generation, Treatment and Reuse

In India, wastewater generation from all class-I cities and class-II towns is 38254 MLD and treatment capacity is 11787 MLD, which is about 30 % of total sewage. About 70% of wastewater remain untreated and discharged in water streams like rivers and ocean leaving them polluted.

Average domestic water consumption pattern
In urban India, about 48,000 MLD water is supplied and on average a person uses 165 litres of water per day. The chart and table below show the break up of per capita domestic water use pattern.



Micro STP for Greywater Treatment and Reuse
Greywater is wastewater from non-toilet plumbing fixtures such as showers, basins and taps. Almost 50% of the water supplied for domestic use, comes out as greywater.

         Micro STP is small-scale sewage treatment plant designed for the domestic greywater treatment. Treatment processes, it may employ biological, chemical, mechanical or electrochemical means. The treated water should be free from any kind of harmful bacteria/pathogens, therefore, in addition, disinfection systems may also require with this system, if water is reused indoors.

               Treated greywater can be reused for toilet flushing and laundry which are two of the biggest consumer of the water in an average household. Apart from this,  it can also be reused for other purposes like gardening, car washing, floor mopping etc. Reusing greywater after treatment can reduce per capita water demand by 50 percent or about 80 litres/day.

Environmental Impact
Centralize wastewater treatment is a big challenge as one of the largest issues facing wastewater management facilities is energy consumption. Wastewater treatment consumes almost 3% of the developed nation’s electrical power annually. That is a large expense for the wastewater industry alone. Why not treat the wastewater at a point source and reuse it. Onsite water reuse can not only reduce per capita water requirement but also help in reducing environmental footprint by suppressing the water pollution.

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