Development of a Low Cost System for The Removal of Heavy Metals from Polluted Water

Water pollution by heavy metals has become one of the most harmful environmental issues. This study developed a low cost heavy metal (lead and chromium) removal system from polluted water using locally available adsorbents, such as sawdust, pawpaw (Carica papaya) seeds and sand. Heavy metals constitute a serious threat to human health and the entire biological system due to their toxic, mutagenic, and carcinogenic nature even at trace concentrations. The objective of this study was to design and construct a low cost heavy metals removal system, test its performance and do a cost analysis of the system. In this process, a filter column made of a plastic container of height 54 cm and diameter 20.4 cm was constructed. Characteristic properties of the adsorbents were obtained from secondary sources and were found to possess functional groups (hydroxyl, carbonyl, aldehyde and amine) capable of binding to metal ions. Optimization was done with a sawdust and pawpaw seeds/sand height ratios of 10:10, 10:15, 15:10, 20:10 and 10:20 cm respectively in the filter column. Results showed that the best removal efficiencies were 99.88% for lead and 85.57% for chromium with a sawdust to pawpaw seeds/sand mixture ratio of 10:20 cm. Statistical analysis showed a significant difference (p < 0.05) in the final concentrations of lead and chromium using the various adsorbent proportions. Cost per liter of treated water was deduced to be 15.5 FCFA. This cost can be afforded by many households with low incomes and thus, this low cost heavy metals removal technology is highly recommended.