Potential use of fruit seeds and plant leaves as coagulation agent in water treatment

Abstract

The treatment of turbid water by coagulation-flocculation was found to be the most common and cost-effective method. Over the years, chemical coagulants have been widely applied to enhance the coagulation process. However, the utilisation of chemical coagulants exhibits several drawbacks, including generation of voluminous sludge and being non-biodegradable as well as toxic compounds to aquatic life. Due to global concerns over the harmful effects, the application of natural coagulants is a promising solution. Therefore, this study was conducted to investigate the potential of plant-based natural coagulants to replace chemical coagulants for water treatment. Fruit seeds (Carica papaya, Nephelium mutabile, and Euphoria malaiense seeds) and plant leaves (Pandanus, Centella asiatica, and Cymbopogon citratus leaves) were selected as natural coagulants in this study. A series of jar tests were performed using raw water from a water treatment plant. The effects of pH and coagulant dosage were evaluated based on the turbidity removal and coagulation activity. Of all the examined plants, the Carica papaya seeds appeared to be the best coagulant for water treatment. An optimum dose of 130 mg/L of this coagulant resulted in a 95.5% turbidity removal and 94% coagulation activity, at optimum pH 7.5. Overall, this study reveals the potential use of fruit seeds and plant leaves as coagulation agents in the water treatment process.