The Role of Location in Sustainable Nitrogen Removal for Onsite Wastewater Treatment Systems

Onsite Wastewater Treatment Systems (OWTSs) play a significant role in nutrient removal to control the impact of nutrient pollution on human and aquatic health. However, studies assessing the sustainability of OWTSs are limited and the impact of the location of the OWTS on sustainability indicators such as greenhouse gas emissions and eutrophication have yet to be examined. This study evaluates the life-cycle environmental and economic impacts of OWTSs relative to their nutrient management capabilities and highlights the influence of locational variation. The results show that the location influences the OWTS’s nutrient removal, life-cycle environmental impacts and cost. The less permeable soil type and higher soil temperature both positively improved the TN removal efficiency, reduced nutrient-related impacts like eutrophication, and improved cost-effectiveness. Compared to the advanced OWTS, the locational variation of soil conditions had a higher impact on the conventional OWTS due to its strong reliance on the performance of the drainfield. On the other hand, locational variation of energy mix had a strong influence on environmental performance of the advanced OWTS in terms of greenhouse gas emissions and fossil fuel depletion.