Nitrogen in Wastewater and Its Role in Constraining On-site Planning

The requirement to minimise the impact of domestic effluent on public and environmental health is an important component of best management practice for onsite wastewater management. The numerous guidelines prepared by state and local regulators recognise the importance of adequate distribution and assimilation of nitrogen from domestic wastewater. As this element is an essential microbial and plant nutrient there are many pathways for reducing it in the effluent while preventing its loss off-site. Many on-site wastewater management guidelines seem singularly driven by the need to prevent the assimilation of nitrogen on the basis of poor science, rather than its assimilation using best management practices and current research data. This paper reviews the current literature with respect to the nitrogen in domestic wastewater, the sources and possible pathways from product purchase through household use/consumption and the treatment train into the soil application area. Many of the sources of this element are from both the human diet and human metabolism and reduction at source is mostly unachievable. Reduction in other areas will be examined. The outcome of the review is to compare and contrast the disparity of views with regards to its significance in imposing unrealistically large areas for assimilation of nitrogen back into the environment. Is the concern about nitrogen based upon poor science or is the risk to human health justified?