Replacing drinking water in blended concrete with processed waste water from STP

With only a small fraction—about 0.5 %—of the Earth’s total water being drinkable, and with the rapid rise in demand caused by urban growth and ongoing construction activities, identifying sustainable alternatives to freshwater in concrete manufacturing has become critical. This research explores the potential of using 10 million liters of treated wastewater generated daily by a sewage treatment facility located in Patna, Bihar, which operates on consecutive batch reactor device (SBR) equipment, as a replacement for common water in tangible production. A comprehensive investigation was carried out over a span of three years (2021 – 2023) to assess the appropriateness of the purified wastewater for concrete mixing. The study analyzed key water quality indicators such as pH, temperature, TSS (total suspended solids), COD, BOD, coliform count, and total Kjeldahl nitrogen. Concrete blocks were molded using three different types of water: pure common water, a 60:40 mix of drinkable water and principal processed wastewater, as well as a 60: 40 mixture of intermediate processed wastewater and drinkable water. Following a 28-day cure time, the concrete samples produced with the 60:40 secondary treated water mixture attained a compressive strength of 23.5 N/mm², compared to 24.56 N/mm² attained using just potable water. Conversely, cube blocks prepared with the basic processed water mix recorded a lower strength of 18.57 N/mm². The results suggest that subordinate processed sewage water can be effectively utilized as a partial auxiliary for drinkable water in concrete production, although the compression power of the concrete might differ based on the degree of water purification.