How big is the Problem?
Together, India’s largest cities generate more than 38,254 million litres of sewage each day. Of this, it is estimated that less than 20-30% per cent of what is collected undergoes treatment before it is disposed
Although ~30% sewage is treated, but it is also important to note that treatment from a lot of facilities is substandard and the treated water is still not fit to mix into fresh water sources.
As per Central Pollution Control Board (CPCB) rules, a city or town’s municipality or water authority is responsible for collecting and treating 100 percent of the sewage generated within its jurisdiction. The level to which the sewage has to be treated depends on where it will be disposed—treatment standards are higher for disposal into freshwater bodies than the sea.
Is setting up a STP enough?
Typically even where sewage treatment plants (STPs) exist, the underground sewage collection
network is inadequate so only a small portion goes for treatment. The rest flows into nallahs and drains from where it is pumped into surface water bodies. Sometimes wastewater stagnates in pools from where it leaches into the groundwater table and contaminates underground aquifers.
The fact that the required infrastructure is not able to keep pace with the growth in population and city sprawl has been the biggest reason due to all water related problems in the country. The per capita water demand has growing consistently in the urban areas. More and more water from nearby water sources is been pumped into the city due to which several rivers and lakes dry up way before the onset of the monsoon season.
Wastes from all kind of sources like residential, industry, etc are mixed in water bodies. Due to the absence of treatment facilities these water bodies get polluted and no longer remain fit for human use. A significant percentage of people have no other option but to use this polluted water and as a result contract various water borne diseases.
Over exploitation of the available water resources makes the river beds to dry up and the ground-water table to go down. Drying up of groundwater sources causes huge water scarcity in urban areas. At the same time people in rural areas have to walk even greater distances in search of potable water.
What is the government doing about it?
In order to solve the problem of wastewater in urban areas, a centralized approach for treating waste water has been adopted by the Government. Sewerage lines are been laid throughout the cities to collect wastewater and channel it to a single location where the entire sewage is treated.
Laying sewerage lines to establish a centralized wastewater treatment plant is the first and the most important thing to be established in an urban area. Settlements towards the older parts of the city had been established long ago without the proper planning of civic amenities like Sewage Treatment Plant. In such a case, the only solution is to collect the sewage through underground pipelines and treat it at a different location. However there are various shortcomings of a centralized approach:
- High Capital Cost
Centralized approach needs STPs to be setup with the capacity of treating the entire city’s wastewater. Huge capital cost is incurred in this to the Government. (to the tune of 100 Crores and above)
- Additional Cost of Sewer Lines
The cost of laying sewerage lines is far more than setting up of an STP. At an average, the cost of laying supplementary infrastructure is 2-4 times of that of setting up a centralized STP. A lot of pumping stations have to be setup at regular intervals to facilitate centralized collection.
- Insufficient Treatment
The wastewater collected centrally belongs to a variety of sources including non-residential sources as well. The treatment is often improper due to the diversity of pollutants.
- Treated Water Not Reused
Since the treatment facility is generally outside the city, therefore reusing of treated water is not possible in a centralized approach nor can the groundwater throughout the city be recharged with this. All the treated water would be discharged in a single location.
- Keeping up with Urban Growth
The cities are ever expanding and it is impossible for the city administration to lay sewerage lines in the peri-urban areas of the city.
Per Capita Network & Treatment Cost for Sewage
What is the missing part in solving the problem?
For a complete solution to the wastewater related problems of the city, a combination of a decentralized approach and a centralized approach is required. An only centralized approach or an only decentralized approach would not be able to solve the problem entirely. A balanced approach between the two strategies is required.
Decentralized Sewage Treatment Plants and Effluent Treatment Plants have to be setup throughout the city bounds and in peri-urban areas to tackle the problem effectively. Several merits of a decentralized approach are as follows:-
- Lower Capital Cost
Setting up of smaller STPs is easier due to the lower capital cost required.
- Polluters Pay
It sounds fair that whoever is generating the waste should be the one to clean it.
- Correct & Proper Treatment
Appropriate technologies can be implemented based on whether the wastewater is from a residential or an industrial source.
- Lower Electricity Consumption
Application of green technologies is possible in decentralized plants which significantly reduce electricity consumption for treatment. Green technologies STPs can also be integrated beautifully with the surrounding landscape.
- Lesser Sewer Lines
Minimum cost of sewerage lines is incurred in decentralized plants. No pumping stations are required in a decentralized approach.
- Treated Water Reused
Treated water can be reused at the site for gardening, flushing, car wash, cleaning, etc. This can reduce the overall daily freshwater supply by around 50%.
- Cleaner & Perennial Water Bodies
The treated water can be discharged in nearby water bodies thereby reducing water demand on them and making them perennial. These water sources would not get polluted and the water would remain fit for human use.
- Groundwater recharge
The unused treated water can always be used to recharge the groundwater.
- Lower Cost of Water
Several studies have shown that cost of procuring treated water is about 1/4th of the cost of fresh water supplied from the municipalities.
The biggest and the most important thing for the government is that it makes complete economic sense as well. The cost of making fresh water available to people’s doorsteps is 4 times more expensive than providing treated water.
The cost for treated wastewater in Beijing is 1/4th of the cost of fresh tap water.
Several initiatives that can be taken by the Government
In order to setup an extensive network of decentralized STPs, a multipronged approach is required.
The Central Pollution Control Board has already brought in strict guidelines for effluent discharge. Setting up of STPs has been made compulsory for every major polluter within and outside the city bounds. But, due to various reasons PCB is not able to ensure that these STPs are operated on a regular basis. Setting up a STP and not using it is not going to solve any problem. It has to be ensured that not only people operate the STPs but also reuse the treated water.
The followings things should also be done by the Government to promote decentralized waste water treatment:
- Ensure that the STPs that are been setup are used. Ensure that the water is treated according to government guidelines. Defaulters should be fined heavily.
- Ensure “Zero Discharge Policy”. The treated water should be reused internally for gardening, car wash, cleaning, flushing, etc. The remainder of the water can be used to recharge the acquifers.
- The Government can bring in tax concessions for people/settlements which are treating their wastewater and reusing it. Concessions in property tax can be given which is charged for providing water, drainage, roads, electrical supply, etc to the settlements.
- Community STPs can be setup in public gardens by the Government in already established settlements, colonies and nagars. These can be later managed by the residents of the area.
- Promote industries to clean and reuse their waste water.