Investigating calcined filter backwash solids as supplementary cementitious material for recycling in construction practices

Backwashing of filter beds in the water treatment plant produces a large volume of spent filter backwash water containing finer solid particles as waste/residue. In this study, solids present in the spent filter backwash water have been collected, processed, and calcined at 800 °C to prepare calcined filter backwash solids (CFBS) and investigated for its potential utilization as supplementary cementitious material in construction industry. Up to 20% replacement of 43 grade ordinary Portland cement, the cement-CFBS mixture complies the Indian standard specification required for construction. The study concludes that WTS obtained from filtration units in the form of CFBS is one of the best sustainable and beneficial reuse options.