Ensuring water security by utilizing roof-harvested rainwater and lake water treated with a low-cost integrated adsorption-filtration system

Drinking water is supplied through a centralized water supply system and may not be accessed by communities in rural areas of Malaysia. This study investigated the performance of a low-cost, self-prepared combined activated carbon and sand filtration (CACSF) system for roof-harvested rainwater and lake water for potable use. Activated carbon was self-prepared using locally sourced coconut shell and was activated using commonly available salt rather than a high-tech procedure that requires a chemical reagent. The filtration chamber was comprised of local, readily available sand. The experiments were conducted with varying antecedent dry intervals (ADIs) of up to 15 d and lake water with varying initial chemical oxygen demand (COD) concentration. The CACSF system managed to produce effluents complying with the drinking water standards for the parameters pH, dissolved oxygen (DO), biochemical oxygen demand (BOD5), COD, total suspended solids (TSS), and ammonia nitrogen (NH3-N). The CACSF system successfully decreased the population of Escherichia coli (E. coli) in the influents to less than 30 CFU/mL. Samples with a higher population of E. coli (that is, greater than 30 CFU/mL) did not show 100% removal. The system also showed high potential as an alternative for treated drinking water for roof-harvested rainwater and class II lake water.