Emerging challenges for pathogen control and resource recovery in natural wastewater treatment systems

Natural wastewater treatment systems have been used for centuries to recover resources through agriculture and aquaculture water reuse. Because the management of wastewater using natural methods relies on the integration of environmental, engineered, economic, and social systems, pathogens cannot be effectively monitored and controlled in these systems using a single approach or a single indicator organism (e.g., monitoring for coliform indicator bacteria). Different types of pathogens are removed at different rates in natural wastewa-ter treatment systems and certain diseases are more important in some regions than they are in others. For natural systems in tropical regions that incorpo-rate water reuse for agriculture or aquaculture, parasites such as soil-transmitted helminths, Schistosoma, Taenia, or food-transmitted trematodes may be of greater public health concern than some bacterial pathogens. Professionals and practitioners must consider how social and environmental systems might be shaped by the use of natural wastewater management systems, and how, in turn, natural wastew-ater management may impact existing socio-environmental relationships. Because of this, effective pathogen monitoring and control in natural wastewater treatment systems requires coordinated participation from stakeholders in multiple sectors.