Water vs. salt extraction of bio-coagulant from Leucaena leucocephala pods for removing turbidity from aquaculture effluent

The aquaculture industry is one of the biggest industries in the world and generates a high quantity of contaminated effluent. Coagulation-flocculation is currently the best practice for aquaculture effluent treatment. This study compared water extraction solutions (WE) and salt extraction solutions (NaCl, KCl, and KNO3) with concentrations (0.5, 1, and 2 M) of plant-based coagulant from Leucaena leucocephala pods for the treatment of aquaculture effluent. The concentration of the pods in all extraction solutions and the dosage concentration before running the jar test were fixed at 20 g/L and 120 mg/L, respectively. The coagulation activity of WE was 3.78 % while KCl (2 M) and KNO3 (1 M) have the highest coagulation activities 86.52 % and 86 %, respectively and increased the zeta potential from −17.33 mV into −10.11 mV and −13.37 mV respectively and particle size from 4216 d nm into 14260.5 d nm and 14850 d nm respectively after slow mixing time. Moreover, protein in KCl (2 M) and KNO3 (1 M) solutions was 1192 mg/L and 1023.80 mg/L, respectively, and polysaccharides were 2391.59 mg/L and 2473.30 mg/L, respectively. The effects of salt extracted L. leucocephala pods solutions on zeta potential and particle size indicated the utilization of charge utilization and bridging mechanisms in the treatment process, and they have high potential to be used in the treatment of other kinds of wastewater.