EVALUATION OF A PILOT VERMIFILTER FOR THE TREATMENT OF WASTEWATER

Conventional wastewater treatments have high cost for human populations where the construction of sewage drainage is not possible. The vermifiltration is a low-cost, on-site and sustainable technology to solve this problem. The proposals of this study were to design and to install a pilot vermifiler (PV) and to evaluate the efficiency of removal of contaminants by vermifiltration. The PV was packed with organic filter media (vermicompost) and inorganic filter media (Tezontle). On the vermicompost were inoculated earthworms of the genus of Eisenia, sp. With the purpose to feed the worms with fresh solids wastes, it was placed a thin layer with sewage sludge and food wastes, (fruits and vegetables). The PV was fed with continuous flow of sanitary sewage water. The study was divided in three steps, with three rate of filtration and three surface organic loading rates. The influent and effluent were evaluated with conventional methods of water quality. Step 1, which was characterized by a rate of filtration 0.180 m3·m-2·d-1 and surface organic loading of 108 g·m-2·d-1, obtained greater removal of organic matter and suspended solids (92 % COD, 99 % BOD, 97 % TSS), also was efficient in the removal of ammonia (98 %) and in this step the PV obtained a greater removal of fecal coliforms (18.5 x 103 MPN·100 mL-1 to < 3 MPN·100 mL-1). The vermifilter was efficient in the removal of pollutants, and it obtained a significant removal of ammonia. In PV was obtained denitrification, but there was not a continuous process. It is necessary to follow the study to optimize the processes of denitrification, although the effluent can be reuse for agricultural or green areas irrigation. The two filter media proposed (vermicompost and Tezontle) were optimal to removal organic matter (COD and BOD), solids (SST) and ammonia.