With urban Indian population exploding, one of the major civic concerns is the management of sewerage. Although almost all Indian cities and towns have a sewage treatment plant, there is a growing deficit between the requirement and our capabilities. This is worrying because untreated sewage has grave consequences for the quality of human life and the environment in general.
In sewage treatment plants contaminants are removed from wastewater. Contaminants are mostly from household waste mixed with some amount of industrial effluent. Most sewage treatment plants in India use a mix of chemical, physical and biological processes to treat sewage. Much of the sewage that reaches treatment plants in India undergo some sort of pre-treatment.
An Alarming Situation
There is a desperate need for more sewage treatment plants in India. According to government data, urban areas generate approximately 62,000 million liters per day (MLD) sewage. However, treatment capability is limited to 23,277 MLD. This is just 37% of sewage generated, putting our capacities well short of the requirement.
On top of this, not the existing STPs are not functioning. Of the 816 municipal plants, only 522 are working. These numbers indicate that a whopping 70% of the sewage generated is left untreated in India. This is an alarming situation, one that can prove catastrophic if left unresolved.
Untreated sewage usually ends up polluting water sources. Three-fourth of the country’s surface water, about 80%, is possibly heavily polluted. This is a staggering number, indicating that all our water sources are extremely unfit for consumption. Over time, the contaminated water ends up polluting groundwater as well.
Sewage Treatment Plants in India
There is obviously a dire need for a more effective waste management policy. Although sewage treatment is seen as part of wastewater management, given the magnitude of the problem in India, we need a more focused policy in managing our sewage treatment plants. The policy must address some basic requirements:
— Building new sewage treatment plants
— Undertaking repairs for malfunctioning plants
— Ensuring regular maintenance of the plants
— Maintaining the ratio of treatment plants to population
— Creating public-private partnerships
— Ensuring pre-treatment at the source, such as bringing mandatory policies on sewage treatment tools like septic tanks at homes, STPs at hotels etc.
Technologies in Sewage Treatment Plant in India:
A number of methods are used at sewage treatment plants:
Activated sludge process: In this method, water is treated with air and biological flock. It is usually used where organic pollution is high and there are no issues regarding land allocation. However, it does need skilled labor to perform this process. This is quite a flexible method. Many STP manufacturers in India will customize it according to requirements. It is also very effective in removing contaminants. This makes it one of the most popular methods in municipal waste management.
Membrane Bio Reactor: Or MBR uses membrane filtration along with biological treatment. This is an advanced procedure, more effective than activated sludge process. MBR is used in the Industrial sector as well. A microporous membrane is used to purify the water. Where the activated sludge process removes the pollutants, the MBR not only treats the water, it also retains purifying bacteria. Hence, the treated water has high reusability quotient. It is sometimes sent for further RO treatment for further purification. Other advantages include its compact design, Energy efficiency, zero water discharge, efficient energy management, and consistent performance.
Fluidized Bed Bio Reactor: Or FBBR scores in practically every field of other technologies. It utilizes a bio film along with biological carriers for better filtration and treatment. This method has multiple advantages, such as:
— Less labor force to run the plant and no need for skilled manpower.
— Higher removal of contaminants
— Has a self-regulatory system in place, which makes maintenance easier.
— No need for the return of activated sludge stream
— Less power consumption
— Compact design
— Easy to use
Sequential Batch Reactors: This is a kind of wastewater treatment. This is again a highly effective solution that also meets every strict guideline of sewage treatment. With minimum operating costs and low maintenance issues, it also provides consistent high performance. The resultant water is good enough to be discharged from the various process. The method is ideal for industrial effluents, high load municipal plants and places with stringent sewage treatment rules. With its low cost of operation and installation, it is also the recommended method when overhauling old sewage treatment plants in India