Estimation of reduced and increasing health risks by installation of urban wastewater systems

This paper aims to propose a methodological framework for quantifying the reduction and increase of health risks associated with urban wastewater systems. A risk assessment model was used to quantify reduction in disease burden while a life cycle assessment approach was used to quantify increasing risks by environmental loading. Disability adjusted life years (DALYs) was used to quantify health risks. This framework was applied to a hypothetical watershed to evaluate health risks by installation of wastewater treatment systems. In this hypothetical case, 55 DALYs per year of health risk would be reduced for 200,000 people in the downstream community by constructing wastewater systems for 200,000 people, while a range from 1.9 to 22 DALYs per year of health risks would be generated by materials and energy consumption for construction and operation of wastewater systems. However, this result would significantly change, depending on the parameters used in this analysis. The proposed methodology should be improved to obtain more precise results, but it will suggest useful information to discuss the overall effects due to the installation of various types of urban wastewater systems.