Filter Media Layers Contribution in Removal of Pollutants from Concentrated Greywater by Vermifiltration.

Abstract

The contribution from each filter medium layer in the removal of pollutants from the concentrated greywater treatment by vermifiltration was studied for 7 months. The two filters were made up of cylindrical DN200-PVC pipes and were filled with 10 cm gravel, 20 cm sand and 30 cm fine sawdust from bottom to top. Two hundred Eudrilus eugeniae earthworms were inoculated to one of the filters and the other was used as a control unit. The sample, first, at the outlet was collected, then the outlet was closed to collect samples from the other sampling ports, which were created at the bottom of each layer. Analysis were done for ammonium (NH₄⁺), nitrate (NO₃^-), nitrite (NO₂^-), orthophosphate (PO₄^3-), Chemical Oxygen Demand (COD), Total suspended solids (TSS), Dissolved Oxygen (DO), pH, and Temperature. The results showed that there were significant differences (<0.05) for removal efficiencies of all parameters among the different layers of the vermifilter and the control unit. However, for concentrations, there were significant differences only for COD, TSS, PO₄^3-, and DO among the layers. When the performances of the respective layers of the vermifilter and control unit were compared, there was no significant differences (>0.05) except for COD and DO concentrations but with a slightly less average effluent concentration of nitrate and orthophosphate in the control unit. To conclude, major removal of NH₄⁺, NO₃^-, NO₂^-, PO₄^3-, COD and TSS were occurred at the fine sawdust layer.

Keywords: Concentrated greywater; Eudrilus eugeniae; Filter materials; Vermifiltration