Chemical and microbiological characterization of drinking water after filtration with a domestic-size charcoal column and ultraviolet sterilization.

This paper concerns the effect on various parameters of contamination of drinking water following a domestic-size filtration unit. A column containing 500 g of coconut activated charcoal was connected to a stainless steel cylindrical chamber equipped with two 8 W ultraviolet (UV) lamps. The inlet flow was set at 2 l/min to simulate domestic drinking water use. Organic volatile pollutant concentrations were measured by gas chromatography isotopic dilution mass spectrometry (GC/MS-ID), using solid phase micro extraction. Pollutants were measured in the water before and after the charcoal column filtering batches of 600 l tap water, roughly equivalent to 2 months of average domestic use for a family of four, up to 3000 l. The efficiency of column in removing pollutants varied with different chemicals: trichloromethane: 55–90%; trichloroethene: 12–31%; benzene: 8–38%; methylbenzene: 9–21%; 1,2-dimethylbenzene: 20–36%; 1,3-dimethylbenzene: 1–29%. The bacterial concentration in the inlet tap water was negligible, whereas after filtration total bacterial counts were high. However, after water passed through the stainless steel UV chamber, bacterial contamination became negligible. The results show that a low-cost charcoal filtration unit can effectively remove some trace contaminants such as trichloromethane and could be safe for human consumption after UV sterilization.