Assessing the Efficacy of Bio-Coagulants in Water Treatment

Abstract

The study was designed to investigate the efficacy of Bio-Coagulants in water treatment settling tanks using alum (the commercially available coagulant) as a control for comparison. The study employed the preparation of synthetic turbid water using clay as a source of turbidity, jar tests and settling columns to construct settling curves for evaluating removal efficiencies of the biocoagulants, using standard procedures. The findings of the study revealed significant linear correlation (R2 = 0.9967) between clay suspension dosage (x) and turbidity (y), which enabled the replication of synthetic turbid water of the desired turbidity using clay. The equation representing the relationship was found to be y = 1.0705x - 9.7131. From the jar tests, the optimum dosages of the coagulants were 3mg/l, and 8mg/l for M. Oleifera seed extract and watermelon seed extract respectively as coagulants. These dosages resulted in 97 and 91.6% turbidity removal for the respective coagulants. Also, the optimum removal efficiencies observed from the settling column tests were 97%, 84.5% and 70.8% using alum, Moringa oleifera and watermelon seeds, respectively. The study concluded that the plant dimensions designed using alum as coagulant were the most economical followed closely by the one designed using M. Oleifera seed extract (3m width by 37.2m length by 2.5m depth; and 3m wide by 37.8m length by 2.5m depth, respectively). The researcher therefore, recommends that M. Oleifera seed extract could be a viable alternative to alum as a coagulant for use in water treatment settling tanks.