SANITARY-LANDFILL LEACHATE TREATMENT METHODS

The leachate generated at the Eastview Sanitary Landfill in Guelph, Ontario, was found to be a highly contaminated wastewater. The City of Guelph wanted to investigate a pretreatment method which would allow treated leachate to meet their sewer use by-law limits. Gore & Storrie Limited was retained to perform treatability studies on the leachate to assess the performance of anaerobic treatment conducted at near ambient temperature (20-23-degrees-C). Bench and pilot scale studies were carried out using hybrid anaerobic reactors which contain both suspended growth and fixed film zones. The treatment process included pH adjustment for metals precipitation prior to anaerobic treatment and aerobic polishing of the anaerobic effluent for additional CBOD5 and TKN removals. Leachate pH adjustment achieved metals removals of 34-99%. At organic loading rates up to 5 kg COD/m3 d, anaerobic treatment achieved CBOD5 removals of 96% at bench scale and 86% at pilot scale. COD removals at the bench and pilot scales were 89 and 78% respectively. Stress tests conducted at organic loading rates up to 20 kg COD/m3 d resulted in poorer performance, but reactor recovery was immediate upon returning to lower loading rates. Aerobic treatment of anaerobic effluent achieved TKN removals of 97-98%. The final effluent from the full treatment process, including pH adjustment and aerobic polishing, met the city's sewer use by-law limits for all parameters.