Semiquantitative microbiological risk assessment for water reuse in agriculture: a case study in Brazil

Abstract

Water reuse is a feasible alternative for non-potable and potable needs, e.g., irrigation. Nonetheless, this option is associated with environmental and public health risks. Therefore, a microbiological health risk assessment was carried out regarding the application of agricultural reuse of water in the neighborhood of Wastewater Treatment Plants (WWTP). This study was carried out in cities in the central region of Brazil, using a semiquantitative methodology. Escherichia coli density in treated wastewater was used as an input, which was obtained from the city wastewater utility. The same exposure scenario was defined for two crops – sugarcane and pasture – at the surroundings of four WWTP under study. As receptors, the following were adopted: farmers; water reuse transport workers; the local community; and sugarcane industry workers. The estimated risks for all groups were considered acceptable. Furthermore, such risks should be reduced to despicable (despicable risk should be understood as low risk) if improvements in the wastewater treatment system and more efficient configurations of barriers are adopted. It can be concluded that risk assessment clarifies the options for system-management, allowing for better informed decision-making and encouraging public confidence in the safe application of water reuse. HIGHLIGHTS The reclaimed water showed E. coli above the limits recommended by the WHO and the Brazilian guidelines.; Acceptable risk was obtained for agricultural reuse of sugarcane and pasture.; Farmers had the greatest health risk.; The risk becomes despicable by increasing the treatment of recycled water and adopting more barriers.; The most suitable for Brazil is to adopt standards based on a fit-for-purpose approach supported by risk assessment.;

Keywords

• agricultural reuse
• damage
• domestic wastewater
• hazard
• non-potable use
• vulnerability