Clean WateR³: evaluation of three treatment technologies to remove contaminants from recycled production runoff

Increased competition for freshwater resources, negative environmental impacts associated with non-treated agricultural and specialty crop production runoff, and potential for more restrictive regulations concerning water use and disposal have provided growers with significant incentives to develop onsite water treatment to enable water reuse. As part of the Clean WateR3 project initiatives, three ecologically based treatment technologies are being evaluated for potential to remove contaminants (e.g., phytopathogens, pesticides, or mineral nutrients) from recycled irrigation runoff. An experimental floating treatment wetland system was assembled to assess the efficacy of nutrient uptake by two types of plants (Juncus effusus L. and Pontederia cordata L.) in two different levels of fertilizer concentration (5 or 12 ppm nitrogen). Initial findings suggest that Pontederia cordata is more efficient at nutrient (phosphorus and nitrogen) uptake than Juncus effusus. In order to determine the potential of vegetated channels to remediate phytopathogens, namely Phytophthora, from irrigation runoff, a series of greenhouse trials were conducted to test the susceptibility of seven wetland plant species to infection by five species of Phytophthora commonly found at plant nurseries in the southeastern United States. Preliminary data suggest that these seven plant species do not appear to be susceptible to the five species of Phytophthora tested. Subsurface bioreactors containing woodchips and haydite have been constructed onsite at an experimental nursery in central Michigan. Experiments investigating the effects of the pesticide chlorpyrifos on denitrifying microbial communities will commence in early Spring 2017.