A comparative study of synchronous treatment of sewage and sludge by two vermifiltrations using an epigeic earthworm Eisenia fetida

Reduction and stabilization of sewage sludge during the clarification of municipal wastewater was synchronously shown to be improved significantly in a pilot-scale vermifiltration using an epigeic earthworm Eisenia fetida. The present study aimed to select a better filter media suited to vermifiltration performance by the comparisons of sludge yields, the characteristics of the by-products of vermifiltration-vermicast and the abrasions of earthworms between ceramsite and quartz sand. It was observed that the sludge yield of the CVB (Ceramsite Vermibed) ranged from 0.07 to 0.09 kg SS/kg COD(removed) at ambient temperature of 4-29 °C, representing 81% and 50% lower than that of the SVB (Quartz Sand Vermibed) and other reduction systems mentioned in this study. In addition, the sludge morphology variations described that the vermicast sludge from the CVB was more completely digested by earthworm than that of the SVB. The abrasions of the body wall of the earthworms in the CVB depicted less injured than that of in the SVB. So the ceramsite as filter media was better suited for the vermifiltration than the quartz sand.