Valorization of Wastewater Effluent and Sludge: Agricultural Reuse in Latin America and the Potential for Developing Countries

摘要

Purpose: This paper analyzes the use of wastewater stabilization ponds in Latin America with a detailed case study from Honduras, and discusses how effluents and sludges can be valorized as a sustainable resource for reuse in agriculture. Methods: Ten stabilization pond systems in Honduras were monitored for flow rates, helminth eggs, Shigella species, Escherichia coli, and fecal coliforms, and conventional parameters including BOD5 and suspended solids (SS). Pond sludges were also monitored for helminth eggs, and percent total solids, volatile solids, and fixed solids, and accumulation rates were estimated. Results: The results show that all of the systems monitored removed 100% of the influent helminth egg concentrations and had a 3.0 log10 removal of Escherichia coli and fecal coliforms, and satisfied the 2006 World Health Organization microbiological guidelines for unrestricted irrigation for leaf crops, or restricted irrigation with labor intensive agriculture. Sludge analyses showed that all primary pond sludges were heavily contaminated with helminth eggs. The removal of BOD5 and SS was typical for stabilization pond systems, and organically overloaded ponds did not exhibit significant performance difference from under-loaded ones. Main Conclusions: Wastewater stabilization pond systems can easily meet the 2006 WHO guidelines for agricultural reuse of wastewater. In order to resolve the problem of agricultural demand for water and fertilizer, and the sustainability of wastewater treatment, treatment of wastewater focusing on pathogen removal should be integrated with the productive reuse of the treated effluent. Specifically, treatment objectives for municipalities in developing countries should focus on helminth removal with the objective of valorizing effluents and sludges by meeting the WHO guidelines.