Partially-treated wastewater (PTW) is a valuable resource that can be reused or reclaimed to enhance the supply of freshwater. PTW can be used to recharge groundwater for subsequent withdrawal as drinking water, or to prevent seawater intrusion. PTW can also be substituted for freshwater to irrigate crops. Although wastewater reclamation and reuse play an important role in sustainable water-resource management, risks of contaminating groundwater or crops from pathogen-laden wastewater must be avoided. The PIs career goals are: (1) to elucidate the fundamental mechanisms that affect pathogen mobility and inactivation in water reuse applications, (2) to help develop new management protocols and technologies to promote widespread adaptation of wastewater reuse and reclamation, and (3) to disseminate this information through both traditional (e.g., peer-reviewed publications) and innovative educational (e.g., CleanWater wiki) approaches. The specific objectives of the proposed work are: (1) to identify the environmental conditions that control filtration of pathogens during groundwater recharge with partially-treated wastewater, and pathogen inactivation during natural treatment of wastewater in waste stabilization ponds; (2) to increase the number of minority and female students in science and engineering by integrating research and education on environmental issues; and (3) to provide students with international experience in research and education. The PI will study viable Cryptosporidium parvum oocysts, an important waterborne pathogen that causes severe diarrhea in people and animals. The hypotheses guiding the proposed research are: (1) Wastewater organic matter (WOM)including natural organic matter, bacterial extracellular polymeric substances, and algal exudates influences the interactions between oocysts and subsurface materials or wastewater particles; (2) Interactions with WOM control oocyst transport in the subsurface environment; and (3) Photo-oxidation of pathogens under sunlight depends on the interactions between oocysts and WOM. The tasks to be completed are: (1) select model testing systems; (2) characterize oocysts and model surfaces; (3) quantify deposition kinetics of oocysts with the selected surfaces; (4) quantify transport, retention, and release of oocysts at pore scale and Darcy-scale; (5) determine the solution conditions that promote oocyst-particle association and removal of oocysts by sedimentation; and (6) study the role of WOM-oocysts and particle-oocyst association on inactivation of oocysts by reactive oxygen species formed under sunlight.
This research will be the first systematic study to focus on how pathogen mobility and inactivation are influenced by surface interaction between pathogens and wastewater organic matters. The results from well-controlled laboratory studies conducted under conditions relevant to groundwater recharge and wastewater treatment by stabilization ponds will lay an essential groundwork for future fieldwork efforts. The results and the experimental techniques developed in this project will be applicable to other studies on environmental transport and inactivation of pathogenic bacteria, viruses, and protozoan. The laboratory findings will directly benefit the PIs Engineers-Without-Border project on pathogen removal using low cost and low maintenance water-treatment methods in Guatemala.
Natural removal and inactivation of pathogens for wastewater reuse potentially offer energy-saving methods to control pathogens, supplement an often scarce resource (i.e., drinking water), and protect human health. Successful completion of the proposed research will build an important foundation for a comprehensive risk assessment of waterborne pathogens in reclaimed water. The PIs ongoing educational activities include incorporating research results into class-room instruction, and organizing workshops on water quality issues for Proyecto CHE (Project Children for Higher Education). The PIs CleanWater Wiki site and workshop-based TV programs developed for University of Illinois TV station will allow the PIs educational activities to reach a broader audience. The PIs educational activities have been and will be assessed for improvements by her education-specialist collaborators.
