Impacts of Filter Media on Enzymatic Activities in Earthworm Biofilter

Abstract:

Vermifiltration is an ecological technology that is applied to decentralized wastewater and excess sludge treatment. Filter media significantly influence physiological and ecological functions of earthworms and microbes. At the organic loading (mass concentration of volatile suspended solids) of 2.11 kg?(m3?d)-1, the effects of the three filter media (wooden bead, porcelain ball and pall ring) on excess sludge treatment performance were investigated by exploring the variations of enzymatic activities of earthworms and of microbes. The results demonstrate that the VSS reduction by three earthworm biofilters can meet the requirement of execess sludge treatment (upwards of 40%). Notably, earthworm biofilters filled with wooden bead can offer the best habitat for earthworms and microbes. The SOD and ACP of earthworms have the lowest and highest values of the fiter media, respectively, indicating that earthworms suffer less adverse effect from wooded bead filter material. Furthermore, the highest DHA value of microbes also suggest that the wooden bead is the optimum filter material for biochemical degradtaion concideration. The earthworm enzymatic activities of superoxyde dismutase are the lowest and the acid phosphatase and the microbe dehydrogenase enzymatic activities are the highest. This indicates that and microbes perform best their degradation function. Therefore, wooden bead is good for performance of earthworm biofilters.