A comparative study for pathogen removal using different filter media during vermifiltration.

The present study focuses on the effect of filter media (riverbed gravel, mud balls, coal and glass balls) for the removal of pathogens during vermifiltration of domestic wastewater. This novel study was conducted for the first time on different vermifilters (VFs) with different media, and pathogen removal was extensively investigated for a period of 3 months. Results indicated that vermifilter with riverbed material (VFR) showed maximum biochemical oxygen demand and chemical oxygen demand removal of 76 and 67%, respectively and vermifilter with mud balls (VFM) showed maximum log removal of total coliforms (2.8), fecal coliforms (2.7), fecal streptococci (2.2), Salmonella (2.1) and Escherichia coli (2.1). The area-based bacterial removal rate constant (k) was found in the range of 2.96-6.68 m/d, which is very high in comparison to the reported values. The population of total heterotrophic bacteria and total fungi was found to be 2-log (99%) higher in VFR and VFM, as compared to other media. The growth rate of Eisenia fetida was higher (42% increase in biomass) in glass balls vermifilter (VFG), and also the abrasions on the body wall of earthworms in VFG showed fewer injuries. Overall, the results of the study described the importance and role of each filter medium.