Methodology to Set Regulations for Safe Reuse of Wastewater and Sludge for Agriculture in Developing Countries Based on a Scientific Approach and Following the New WHO Guidelines

Abstract

This chapter describes, using the quantitative microbial risk assessment (QMRA) methodology proposed by WHO, how to set affordable standards for reuse of wastewater or sludge in agriculture using helminth eggs (Ascaris lumbricoides) as an example. The development of a risk-based model for Ascaris lumbricoides infection and its application to assess human risks associated with helminths egg exposure from crops irrigated with untreated wastewater, as well as crops grown in biosolid-enriched soil are explained. From QMRA results it becomes evident that WHO guidelines for wastewater reuse in agriculture seem more stringent than needed in developing countries, while for sludge reuse it will be the opposite. Even though more information is needed to confirm this conclusion from a single research, cautious approach when revalorizing sludge for agricultural purposes is recommended. Additionally, this work shows that intervention methods, other than wastewater and sludge treatment as suggested by WHO, can play an important role in controlling risks.