Energy Neutral WWTPs
Urban local bodies in emerging economies are not cash rich. To ensure maximum returns on investment in wastewater treatment and increased life of a project, a scientific approach is required for the biological treatment process. This is where “power-neutral” STPs pave the way forward. Sustainability of the treatment process is crucial and it dependent upon constant and assured supply of power.
Green power production from sludge biogas has numerous advantages. First, it not only ensures the plant is self-sustaining but also helps earn carbon credits, a source of revenue. Second, the burden of operating expenditure for the client is substantially reduced by installing a gas engine, which has an attractive payback period of three to four years. Third, the digested sludge is high in organic content and can act as a natural fertilizer high in N, P, K (nitrogen, phosphorus and potassium).
There are time-tested cases proving the viability of power-neutral STPs. Large scale power-neutral installations are present in Xiaohongmen, China, and in Turkey for 600,000 m3/day and 400,000 m3/day WWTP. In India, in 2004, WABAG was entrusted with the turnkey realisation of a new biological sewage treatment plant at Kodungaiyur, Chennai, India. After commissioning in 2006, WABAG also assumed responsibility for operations and maintenance of the plant for a period of 10 years. It is the largest plant of its kind in India – achieving 98% self-sufficiency in terms of power consumption.