‘Nature-based’ solutions for wastewater treatment in rural Gurugram

Gurugram:

Gurugram:

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The district administration’s Gurujal society has planned to establish at least eight ‘nature-based’ wastewater treatment plants (WWTPs) across eight villages in Gurugram for the benefit of rural clusters that do not have proper facilities to treat household sewage.

Three are already operational in Maujabad, Khentawas and Nawada villages while the rest are under construction.

The purpose of these eco-friendly WWTPs are two-fold, Gurujal officials explained. “They are all part of a larger pond-revival project, where we will use the treated wastewater to recharge underlying groundwater aquifers and to fill up locally available water bodies. The other goal is to provide a sustainable, self-sufficient wastewater solution in villages where household sewage typically collects in some low-lying area outside the village,” Sayani Halder, wastewater consultant, Gurujal, said.

Experts explained that these WWTPs differ from traditional sewage treatment plants (STPs) in that they do not rely on chemical treatment of wastewater, and do not use motors and pumps to transport the water within the plant.

These plants do not have a high operational cost, do not require a constant supply of electricity (making them suitable for rural clusters), and do not require technically trained staff to manage daily operations.

Subhi Kesarwani, chairperson, Gurujal, said Gurugram is the only district in the country implementing these technologies on a large scale. “In other parts of the country, such WWTPs have been built, but at smaller capacities of 25KLD or less. We are building them to treat between 100KLD and 500KLD of wastewater every day. Moreover, each of these will serve as its own pilot project so we can gauge the efficacy of various technological solutions.”

The eight villages in rural Gurugram earmarked for such WWTPs are Maujabad, Hariahera, Dhaula, Tajnagar, Khentawas, Nawada, Budera and Kasan. Of these, the first four plants are based on ‘root bed zone systems’, wherein “wastewater passes through a bed of specialised plants, where treatment takes place by filtration through layers of soil,” explains a methodology brief shared by Gurujal. Various microorganisms present in these root systems of these plants are responsible for “cleaning up” the wastewater, which passes through the root beds.

“These WWTPs are best suited for rural areas as they require a fair bit of land. These are called nature-based solutions because they use the natural topography of the region to channel wastewater from homes to treatment plants, where the water is filtered through biological systems, like root zones, or more sustainable material like gravel and coconut husks. The water may also be treated through biological enzymes. There is none of the chemical treatment that a traditional, electro-mechanical STP in urban areas would use. For the same reason, and because they rely on naturally available materials, they are much cheaper to build and operate,” said Halder.

In Budera village, where the WWTP will operate at a capacity of 500KLD, the plant is based on a technology known as DEWATS (short for decentralised wastewater treatment system).

Halder explained, “This technology is different from root zone systems in that there is no biological agent which oxygenates the water. Instead, the water is passed through multiple physical barriers made up of natural materials that filter out any unwanted biological and chemical agents.”

These barriers are built in the form of ‘constructed wetlands’ and do not require much day-to-day maintenance, or skilled staff to operate it, Halder added.

Variations and combinations of these technologies are being implemented in other villages. In Nawada, for example, biological filtration systems are being combined with the use of biological enzymes, which break down unwanted agents and possible pathogens in sewage. In Kasan, meanwhile, the WWTP will make use of bio-filters, but will also use an ozonation tank to eliminate any bacterial pathogens in treated sewage.

Yet another technological solution, which is being implemented in Khentawas village, involves the use of an ‘advanced eco-reactor’ (AER). According to a brief shared by Gurujal, “This is based on the principle of trickling water, where wastewater is sprayed over numerous layers of gravel and coconut husks, which are initiated with bio-enzymes that provide both biological and physical treatment of water.”

Kesarwani said each of these plants has been carefully planned after considering the local environmental context. “We have realised that it is not enough to simply have a cut-copy-paste solution. These specific technologies have been chosen after thorough investigation of the local situation. Is it more important to ensure groundwater recharge? Or is it more important to ensure availability of water for non-potable purposes? What is the local hydrogeology and what solution would it serve best? Depending on our findings in a given village, we have a range of solutions which can be used, either alone or in combination, depending on the local conditions.”

Advantages of ‘nature-based’ wastewater treatment plants:

1) Preventing pollution of drains, water bodies and groundwater

2) Treated water can be used locally for secondary, non-pot able purposes like agriculture and washing

3) Lower operational and maintenance cost

4) Do not technically trained staff to operate

5) Do not rely on electricity to work, making them ideal for rural clusters where power cuts are frequent

6) Make use of naturally available materials, no chemical treatment of water involved