Approaches to Mitigation of Landfill Leachate-Induced UV Transmittance Impacts

Landfill leachate management has become an increasingly important component in integrated and sustainable solid waste management as a result of gradually tightened regulations and significant associated expenses. Discharge of leachate to publicly owned treatment works (POTWs) is a common and preferred leachate management practice in the United States, due to the lowest treatment cost and the least management complexity as compared to other strategies. However, leachate can significantly interfere with UV disinfection performance at POTWs due to introduction of strongly UV-quenching substances in the leachate. Since a regulatory trend is pushing POTWs from traditional chlorination to alternative UV disinfection, there is an immediate and urgent need to mitigate the UV transmittance impacts of leachate at POTWs. Unfortunately, the knowledge on the origin and nature of UV-quenching DOMs in landfill leachate is extremely limited, and the technologies for mitigation of UV absorbance are not well tested, optimized, and developed.

The long-range goal of this research is to develop successful leachate management strategies for mitigation of UV transmittance impacts. The primary objective of this proposal is to identify the origin and nature of UV-quenching substances in landfill leachate, and develop technically and economically viable on-site treatment technologies to address the UV transmittance issue at POTWs. Preliminary laboratory studies, in conjunction with literature data, show that leachate UV absorbance can be significantly reduced after an effective removal of dissolved organic matters (DOMs), thereby suggesting that the UV transmittance problem is principally caused by UV-quenching DOMs. Therefore, the central hypothesis is that the leachate UV transmittance issue can be well addressed by development and application of appropriate on-site leachate treatment technologies targeting at UV-quenching DOMs. This primary objective can be achieved by pursuing the four specific objectives:

1. To identify the origin and nature of UV-quenching DOMs in landfill leachate;
2. To preliminarily screen physical/chemical on-site treatment technologies for UV-quenching DOMs;
3. To further evaluate the performance of selected on-site treatment technologies combined with subsequent secondary treatment and advanced technologies at POTWs;
4. To comprehensively review and compare the tested technologies, and make recommendations to the solid waste industry for improved sustainability