'Green' water treatment for the green industries: Opportunities for biofiltration of greenhouse and nursery irrigation water and runoff with constructed wetlands

Data obtained to date suggest that biological filtration using constructed wetlands is an alternative for treating greenhouse and nursery waste and irrigation water. Both planted and unplanted wetlands can effectively remove organic contaminants, reducing the potential for environmental contamination, chemical carryover from one crop to the next, or development of resistant pathogens from continuous exposure to low-level pesticide residuals. Although systems with plants appear to be more robust, in many cases removing contaminants more quickly, those without plants have the advantage of not using productive space. Provided that differences in effectiveness between planted and unplanted systems can be accommodated in either increased residence time or increased system size, unplanted biofilters may be a better choice. More research is needed on constructed wetland biological filters to verify their effectiveness with additional greenhouse chemicals. Removal rates target chemicals in planted and unplanted treatments wetlands are needed to determine design criteria to achieve desired treatments results. This allow potential users to better compare costs and benefits associated with using planted or unplanted constructed wetlands biofilters to clean irrigation and wastewater. Long-term studies are needed to examine the 'life expectancy' of the treatments tanks, including potential disposal requirements for any chemical residuals left in tank at the end of its useful life.