Development of Low-cost indigenous filtration system for urban sullage: assessment of reusability

Abstract

Treated sullage water could be the answer to urban water scarcity. In this study, urban sullage water was subjected to various tests to determine a number of physiochemical parameters, heavy metal content and coliform count. Obtained results were compared with the Dhaka Water and Sewerage Authority (DWASA) water samples. The sullage water was then treated using a proposed filtration system with indigenous gravel-coal-sand filter. The pH, chlorine (Cl − ) and phosphate (PO 4 3− ) of the sullage water, DWASA water and treated sullage water were found to be within the allowed limit set by Bangladesh Drinking Water Quality Standard. The nitrate (NO 3 1− ), BOD, DO, coliform and phosphate (PO 4 3− ) of the sullage water exceeded both the Bangladesh and WHO standard. The amount of toxic heavy metals, lead, cadmium, chromium, mercury and arsenic, were determined to be below the standards. The results indicated that sullage water is not safe and the treated one is safe from toxic heavy metals for household use. The significant portion of treated water can be reutilized which is equivalent of 29 % savings from the annual DWASA water bill. The quality of the treated sullage water revealed that it can be reused for cleaning, washing, bathing in household activities along with other agricultural and industrial purposes.