Effectiveness of Some Selected Natural Filter Media for On-Site Small-Scale Treatment of Medium Strength Greywater

Abstract

Greywater represents a potential resource of water that can be recycled to meet the standards for safe discharge or non-potable uses. This study evaluated the performance of sand, charcoal, and saw dust filters in reducing Biochemical Oxygen Demand (BOD₅), Total Dissolved Solids (TDS), pH, Phosphatephosphorus (PO₄-P), and Nitrate-nitrogen (NO₃-N) in greywater. Greywater was fed into a simple filtration system (SFS) with sand, charcoal and saw dust filters each of height 16 cm in three plastic containers of the same size: internal diameter 19 cm and height 22 cm each and operated for two weeks. Sand efficiently reduced the concentrations of BOD₅, phosphate-phosphorus (PO₄-P) and TDS while charcoal and saw dust were less efficient. Sand, charcoal, and saw dust reduced influent BOD₅ by 97.65%, 61.20% and 66.12%; PO₄-P by 99.92%, 83.98% and 20.56%; NO₃-N by 28.30%, 58.80% and 39.21%; and TDS by 47.18%, 7.94% and 29.69%, respectively for the two-week experimental period. Overall, sand appeared to be the most suitable filter for improving greywater quality for discharge or non-potable uses in terms of organic matter reduction. Effective performance of the charcoal and saw dust filters for the treatment of greywater need further investigation.

Keywords: Greywater, daily discharge rate, natural filter media, small-scale treatment.