Comparative Analysis of the use of Citrullus Lanatus and Hibiscus Sabdariffa Seeds Extracts as Natural Coagulant in Greywater Treatment

Abstract

This research seeks to treat high turbid greywater with watermelon and Roselle seed extracts as a natural coagulant, investigate the suitability of the treated water for domestic and agricultural uses (toilet flushing, car wash and irrigation), and also investigate the potentials of combining watermelon and Roselle seed extracts as substitutes for conventional chemicals in greywater treatment, and to compare the two natural coagulants to know which one is more effective in removing the turbidity from the greywater. A stock solution of 5000mg/l of each coagulant was made and used to treat the greywater using a dosage of 50mg/l, 100mg/l, 150mg/l, 200mg/l, and 250mg/l as well as a combined ratio of 80mg/l: 20mg/l, 70mg/l: 30mg/l, 50mg/l: 50mg/l, 30mg/l: 70mg/l and 20mg/l: 80mg/l of watermelon and Roselle seeds were used. The results obtained from the jar test showed that watermelon seeds could effectively remove 89.0% of the 303 NTU turbidity while Roselle seed extracts could remove about 80% of the 303 NTU turbidity all at the same dosage of 100mg/l which is their respective optimum dosage, thus, confirming watermelon seeds to be more effective than Roselle seeds in removing the turbidity from greywater. In the case of the combined use of watermelon and Roselle seed extracts, the result revealed good coagulation properties with turbidity removal of 91% from 303NTU to 26NTU and bacterial count removal of 94.5% at a combined ratio of 70mg/: 30mg/l. It was observed that all the pH is within the recommended value of wastewater used for irrigation. Watermelon and Roselle seed extracts performed reasonably as good disinfectants (anti-microbial agents).