Impact of organic matter from leachate discharged to wastewater treatment plants on effluent quality and UV disinfection

There are growing concerns over the negative effects of leachate organic matter (LOM) on ultraviolet (UV) disinfection and effluent quality when leachate is co-treated with domestic wastewater. In this study, the effects of LOM on wastewater effluent quality were evaluated through field studies at wastewater treatment plants (WWTPs) that receive and do not receive leachate. Impacts of leachate on effluent quality were determined through UV measurements at 254 nm (UV254), fluorescence measurements, and the quantification of conventional parameters which included nutrient and organic constituent concentrations. Results showed that some leachate impacts can be observed using UV254 spectroscopy in wastewater influent and effluent when present at volumetric contributions as low as 0.01%. In addition, leachate impacted wastewater samples showed a higher dissolved organic nitrogen and dissolved organic carbon concentrations in the effluent relative to effluents from WWTPs without leachate. At leachate volumetric contributions greater than or equal to 0.1% (0.10-14.8%), UV254 transmittance in wastewater effluents was below 65%. A typical guideline for effective UV disinfection at WWTPs is above 65% transmittance. Furthermore, fluorescence characterization of leachate-impacted wastewater showed a higher intensity of humic-like peaks relative to wastewater without leachate. This research provided a better understanding of the potential implications of accepting leachate at WWTPs. These effects, however, can be managed by ensuring that leachate discharge is maintained at acceptable volumetric contributions and evenly spread out over the discharge period. (C) 2019 Elsevier Ltd. All rights reserved.