Mr. Amitabh Kant, CEO of NITI Ayog, said that India’s wastewater treatment market stood at USD 2.4 billion in 2019 and is projected to reach USD 4.3 billion by 2025. The development of Sewage Treatment plants has been a significant objective of various government programs like Namami Gange, Atal Mission of Rejuvenation and Urban Transformation (AMRUT), and Swachh Bharat Abhiyan. The total capacity of Sewage Treatment Plants in India is 6,190 MLD, and another 1742.6 MLD, sewage treatment capacity, is under construction. According to CPCB, states of Maharashtra, Gujarat, Uttar Pradesh, NCT of Delhi, and Karnataka are the top 5 states which have installed significant sewage treatment facilities. With increasing awareness of water scarcity, government and non-government organizations take proactive measures to overcome the considerable generation of wastewater.
Sewage Treatment Plants remove pollutants, contaminants, and hazardous substances from the sewage water and produce clean water. The treated water fulfills various water needs like agricultural, horticultural, and industrial. However, Sewage water treatment Plants come with several advantages and disadvantages.
Advantages of Sewage Treatment Plants
Traditionally sewage was removed and collected manually. Nowadays, sewage is extracted, organized, and transported using technology and can be handled by minimum workers. In addition, modern Sewage Treatment Plants can treat massive amounts of sewage, reducing the long work hours.
- Produce Energy
Sewage contains significant amounts of organic matter, which is used to generate energy. Sludge is pre-treated, and then anaerobic digestion breaks it down. Anaerobic digestion produces methane gas, which provides power to the grid. It can provide energy to run the Sewage Treatment Plant and supply power to the residential areas. Sewage gas can also be configured as a combined heat and power plant (CHP), and CHP mode increases the plant’s overall efficiency.
- Fertilizer Production
The sludge gathered for treatment carries a colossal amount of biodegradable matter, nitrogen, and phosphorous. Therefore, when the sludge is treated with the sludge drying method, it leads to biodegradable fertilizer. This fertilizer is suitable for agricultural and gardening use.
- Reduce public health risk
Less than 50% of the Indian population has access to safe drinking water, and annually about 37.7 million Indians are affected by water-borne diseases. In addition, untreated sewage is released in ponds, lakes, and rivers and directly affects the underprivileged Indian population. Sewage Treatment reduces the health risk of the people as it removes most of the contaminants from wastewater before release in the natural water stream.
- Environment friendly
Sewage Treatment Plants treat water in various steps to remove large solid particles, chemicals, hazardous substances, and microorganisms. As a result, the treated water is safe for re-use and minimizes water needs and pollution.
Disadvantages of Sewage Treatment Plants
- Putrid odor
Sewage Treatment Plants comprise numerous types of waste that have several smells. Foul odor generally originates from organic decomposition. The prominent smell is of sewage, and other aromas include hydrogen sulfide (rotten eggs), ammonia, mercaptans, and other chemicals. Most of the scent is retained in the plant’s boundary, affecting employees, and some smell drifts towards the surrounding area. They are worse during summertime when the temperature is high.
- Bacterial imbalance
An optimum amount of microorganisms can help in sewage treatment. However, the concentration of bacteria may rise in some situations and affects the treatment process. For example, they might slow down the process or stop it completely. In addition, sometimes, the treatment process can create variants of bacteria that are resistant to antibiotics that can kill other microbes. Moreover, they increase rapidly, and sewage provides them with an optimum environment.
- High installation costs
According to CPCB, the estimated conventional cost for a Sewage Treatment Plant comes to rupees 1 crore per million liters daily (MLD). So, for example, a Sewage Treatment Plant with 500 MLD capacity will require 500 crores to be set up.
- More use of power
Sewage Treatment Plants require a continuous power supply to function properly. For example, plants with more than 200 MLD capacity need a 1 megawatt power supply. Therefore, interruption in power supply damages the mechanism of Sewage Treatment Plants.
- Maintenance costs
Annual maintenance costs of Sewage Treatment Plants are high. For example, the yearly maintenance of plants with a minimum capacity of 100 MLD requires rupees 70 lakh to 2 crores.
‘STPs are costly affairs and can only be maintained when a comprehensive financial structure of maintenance is available. An STP needs all its sections to be fully functional in order to treat sewage,” says A.B. Akolkar, Member secretary, CBCP.
- Environmental footprint
Though Sewage Treatment Plats treat water for re-use, they still leave an environmental footprint. The left-over residues after sewage treatments must be eradicated, leading to pollution. Moreover, fumes of Green House Gases, CO2, and N2O are released into the environment and contribute 26% of the carbon footprint.
- Massive land utilization
Sewage Treatment Plants require large land areas for construction, and authorities impose regulations of boundaries which becomes a problem for area selection for plants. Moreover, the direct flow of sewage to sewage treatment plants is a concern mainly in urban areas where drainage systems and old.
Sewage Treatment Plant has its pros and cons. Although it treats water in less time, produces energy, fertilizers, reduces public health risk, and reduces water pollution, it also produces a pungent smell, hybrid bacteria, requires huge capital, land area, and leaves an environmental footprint. However, advancement in technology will reduce the disadvantages of Sewage Treatment Plants and enhance the efficiency of STPs.