Abstract

The presumed risk to public health has led to a growing interest in the production of exceptional quality biosolids intended to contain undetectable levels of three classes of pathogens: bacteria, enteric viruses, and helminth eggs (parasitic intestinal worms). This study assessed the performance of an enhanced electrokinetic technology which permits the simultaneous dewatering, heavy metal removal and inactivation of the swine helminth, Ascaris suum, from wastewater sludge in one operational unit for the production of exceptional quality biosolids. The process is based on the electrokinetic (EK) phenomena, initiated by the introduction of direct electric current through the biosolids, preceded by a brief period of ohmic heating. A series of bench-scale tests were performed on combined primary and secondary sewage sludges obtained from the wastewater treatment plant in Auteuil, QC. Two additional tests were repeated at a pilot scale with success. The results demonstrated that the enhanced EK treatment is capable of delivering a product virtually free of viable Ascaris suum ova introduced to the conditioned sludge with a brief exposure at a temperature of 55°C. In addition, dewatering levels up to 23 % total solids (TS) and mean removal levels of over 54 %, 30 %, and 24 % for heavy metals such as Zn, Cd, and Pb, respectively, within a period of 3 days were reported. Consequently, the sanitized biosolids generated during the enhanced EK treatment process can be transformed into a high quality soil amendment that could be safely applied to agricultural lands.