Treatment of effluent from a malting processing plant using bio-coagulants

Abstract

Stringent measures by water authorities worldwide on water clarification has resulted in the use of chemical-based coagulants to be a formidable challenge. This has driven the need to find alternative sustainable coagulants such as plant-based bio coagulants which are readily available, abundant and cost effective in developing countries such as Zimbabwe. In this regard, the effectiveness of treating effluent from a brewery malting processing plant using bio-coagulants (Aloe vera, Cactus opuntia and Okra seeds) was investigated compared to that of a chemical coagulant (Alum). The water pollution parameters that were investigated include turbidity, total dissolved solids, electrical conductivity, temperature and pH. The results showed that Alum was the most effective coagulant as it reduced the turbidity from 734 NTU to 68.3 NTU and Total Dissolved Solids (TDS) from 19,800 ppm to 880 ppm at a dosage of 40 mg/L. Okra seeds had an optimum dosage of 35 mg/L with a turbidity and TDS removal of 88.83% and 95.25% respectively. Aloe Vera had an optimum dosage of 40 mg/L with a turbidity and TDS removal of 74.25% and 95.40% respectively. For Cactus opuntia it was 50 mg/L obtaining turbidity and TDS removal of 74.66% and 95% respectively. The best blend of the bio coagulants had a ratio of (0.17, 0.17, and 0.67) for Aloe vera, Cactus opuntia and Okra seeds respectively. At a dosage of 40 mg/L the turbidity removal was 83.92% and TDS removal was 95.12%. The results indicated that blending the plant-based coagulants had a positive synergistic effect. Graphical Abstract