Evaluating the impacts of leachate co-treatment on a full-scale municipal wastewater treatment plant in Canada.

Abstract

The objective of this study was to evaluate the impacts of leachate co-treatment on a full-scale municipal WWTPby comparing plant performance at varying levels of leachate contributions and hydraulic loadings.Leachate BOD:COD ratio was 0.08±0.07 and indicated a stabilized, old matrix and concentrations of zinc, iron, aluminum, chloride and sulfate were 0.174, 38, 1.47, 1803 and 119.1mg/L, respectively. The average volumetric leachate ratio (VLR%) was approximately 0.01% corresponding to a daily volume of 30m3 but reaching a maximum of 270m3(VLR% = 0.1%) and fluctuating on a daily-basis. A cluster analysis revealed 5 VLR% groupings that were used for subsequent analyses:no leachate, 0<Low≤0.001, 0.001<Medium≤0.02, 0.02<High≤0.05, 0.05<Very high≤0.2. Treated effluent concentrations of TKN, ammonia, fecal coliforms (FC),E. coli(EC), TSS and TP experienced atrend where effluent quality was improved at low and medium VLR%compared to no leachate addition, but deteriorated in high and very high VLR%.Treated effluent UVT% and EC were not statistically significantly different at varying VLR%, but FC was.Plant hydraulic had a significant impact on removal rates.Ammonia removals and nitrite concentrations improved inhigh flow conditions, whileTP, BOD and cBODremovals deteriorated. Finally,VLR%, leachate COD, TKN ammonia, chloride and arsenic had significant relationships with plant performance. Thus,for leachate with comparable age and strength, VLR% should not exceedlow to medium contributions(0 and 0.02%)during co-treatment at this WWTP.