Pilot Scale Studies for Vermifiltration of 1000m3 /day of Sewage Wastewater

Abstract

Vermifiltration is a technology in which the combined action of earthworms’ activity and theabsorption properties of soil, sand and gravel particles on the organic pollutants are applied for wastewater treatment. Vermifiltration was used in sewage wastewater treatment as a cheaper and enviro-friendly technology. 1000m3 /day of sewage wastewater was treated in a four layered vermifilter at an Eisenia fetida earthworm density of 8 000 earthworms/m2 in a 3.6m2 soil bed. The vermifilter bed layers comprised of 4-8mm garden soil particles, 8-12mm mixed sand and gravel particles, 30-50mm small aggregates and 70-80mm large aggregates respectively. A vermifilter bed porosity of 0.96 was used. The vermifilter had a hydraulic retention time of 0.082days and a hydraulic loadingrate of 0.93m3/m2.day. The vermifilter design effectively resulted in over 90% reduction in BOD, COD, TDSS andturbidity as well as neutralized pH in the sewage wastewater. Proper vermifilter design ensures optimum sewage wastewater treatment for potential use in irrigation