VERMIFILTRATION OF SEWAGE

Abstract

Rural sewage treatment is now paid more and more attention in India. The high cost of wastewater collection and waste water treatment is not permitting the sewage treatment plant in small areas, so cost effective decentralized and eco-friendly treatments are needed. There is no need of energy in vermifiltration (except pumping), low cost, and no sludge production. Vermifiltration can be very useful for small communities, colonies and villages. The present study was carried out to get optimum HLR for vermi filters to achieve the requisite quality of effluent and to get the hydraulic behaviour of vermi filters. In the present study, there were three reactors T1, T2 and T3. Ti and T2 were inoculated with earthworms (E.fetida) and T3 was without earthworm (control) and waste water was applied to the reactors at four rates: 1.5, 2, 2.5 and 3.5 m3m"2d-' The effluent was analysed for physic-chemical and biological parameters. Maximum removal of organic matters was at 2.5 m3m 2d"'. At this rate, BOD, COD, TSS, TDS removal was 96%, 89%, 90%, 82% respectively. Hydraulic conductivity decreased to 0.002 from 0.005 cm/sec at this HLR. The treated effluent had higher value of nitrate, phosphate which was best suited to reuse for sewage farming or horticulture. There was no sludge production. On the other hand•vermicompost was produced having C/N 28.7, nitrate nitrogen 286.4 mg/g and TP 70.8 mg/g. The effluent and the compost both are useful product. At the end of the experiment hydraulic conductivity was less in vermi-reactors as compared to control while biomass, growth of earthworms were more in vermi-reactors. Based on the materials used in the study, an example vermifilter has been designed for 100 peoples. From this study, it was concluded that the HLR 2.5 m3m 2 d"' is the optimum rate at which better quality of effluent has been found as compare to other HLR in vermi filtration for the test media. Ultimately it has been concluded that vermi filtration has great potential for decentralize wastewater treatment. Keywords: Vermi filter, control, BOD, COD, Hydraulic Loading Rate (HLR), Hydraulic condutivity ii