The treatment of domestic wastewater using small-scale vermicompost filter beds

The aim of this study is to quantity the effect of filter bed depth and solid waste inputs on the performance of small-scale vermicompost filter beds that treat the soluble contaminants within domestic wastewater. The study also aims to identify environmental conditions within the filters by quantifying the oxygen content and pH of wastewater held within it. Vermicompost is being utilised within commercially available on-site domestic waste treatment systems however, there are few reported studies that have examined this medium for the purpose of wastewater treatment. Three replicate small-scale reactors were designed to enable wastewater sampling at five reactor depths in 10-cm intervals. The surface of each reactor received household solid organic waste and 1301 m(-2) per day of raw domestic wastewater. The solid waste at the filter bed surface leached oxygen demand into the wastewater flowing through it. The oxygen demand was subsequently removed in lower reactor sections. Both nitrification and denitrification occurred in the bed. The extent of denitrification was a function of BOD leached from the solid waste. The environmental conditions measured within the bed were found to be suitable for earthworms living within them. The study identified factors that will affect the performance and application of the vermicompost filtration technology. (C) 2004 Elsevier B.V. All rights reserved.