Water scarcity in India is a serious worry due to erratic monsoons and depleting groundwater levels. One major strategy is to clean and reuse wastewater, which could possibly meet 10 per cent of our water needs. Currently, large-scale water treatment plants, operated by companies like Va Tech Wabag, Thermax and GE, handle the bulk of wastewater treatment. However, their capacity is limited, with less than 30 per cent of wastewater treated and minimal reuse. There’s an urgent need for smaller sewage treatment plants (STPs) that can treat water where it’s generated. However, these small STPs have not been popular, as they require a lot of land, energy and chemicals and can’t produce water clean enough for anything other than gardening.

A new wave of start-ups is once again taking on the challenge of making decentralised STPs a success. This time a couple of things are in their favour, namely, government polices, rising water shortage and regulatory pressure to treat the water locally. A number of government programmes such as Atal Mission for Rejuvenation and Urban Transformation (AMRUT) are promoting decentralised wastewater treatment and such start-ups are offered a grant of ₹20 lakh and an opportunity to execute pilot projects with urban local bodies. At the same time, there’s a shift in consumer perspective towards purchasing water, and it is routine for apartment complexes and industry to buy water during summer at least, if not all year.

Regulatory mandate

Additionally, regulatory requirements are favouring decentralised water treatment solutions. For instance, in cities like Bengaluru, high-rise apartments are mandated to have their water treatment plants. Moreover, these plants must be located above ground rather than concealed underground. This regulatory mandate has led residents and industries to seek robust and aesthetically pleasing structures that do not emit foul odour.

A new crop of start-ups is addressing the pain points of conventional STPs. Modern sewage treatment plant are good looking, modular and grow vertically instead of occupying land area. However, verticalisation of the structure and replacing civil structure with readymade modules means that STPs are twice as expensive and far less affordable than conventional STPs. Given consumers’ reluctance to pay upfront cost, start-ups are trying to bring in new business models. For example, Indra Water is proposing to offer STP on rent and Tellus Habitat is positioning its product as a consumer non-durable such as washing machine or fridge and has created modular products for independent houses and villas. There are also start-ups such as Boson, which are installing tertiary treatment plant to further purify the water treated by an STP, and are selling it to the industry.

An STP typically relies on bacteria to breakdown the waste and chemicals to disinfect and clean the water. Its operational cost includes cost of bacteria, electricity to blow the air to keep bacterial alive, chemicals to disinfect the water and people to monitor its performance. Some start-ups are trying to reduce this cost through process efficiency by frequently monitoring the quality of input water through IoT-driven systems and reducing required chemicals and electricity, while others such as ECOSTP technologies offer nature driven solutions that do not require electricity and chemicals.

Decentralised water treatment is challenging and there is a reason why large companies are hesitant to enter this segment. The quality of the incoming water can vary by the hour, but the output quality must consistently meet standards, while keeping the STP cost affordable. In no industry, is it necessary to deliver excellent output without having any control over the input. Therefore, start-ups are mostly relying on design changes and automation to solve a tough problem.

This writer is founder of FineTrain, an advisory firm for green businesses