Grant: College - University Idea to Innovation Grants

The greenhouse industry in Ontario is being encouraged to recirculate its process water to both conserve water and reduce pollution from discharges to the environment. 100% recirculation is prevented because of the accumulation of salts and other contaminants. The greenhouse industry is actively seeking economical technologies that could be adopted industry wide. Conventional technologies have waste concentrates that require disposal. This collaborative research will investigate the use of salt accumulating plants in constructed wetland systems to remove salt limiters. It is anticipated that this approach will remove 25-50% of the salts in process water. Complete removal of salts may not be possible with salt accumulating plants if space for a treatment wetland is limited or volumes requiring treatment are large. The simplicity of this approach and its economical viability makes even partial removal a highly attractive treatment solution for the greenhouse industry. The constructed wetland system proposed will also contain anaerobic bioreactor cells containing woodchips which will remove excess nitrate, sulfate and other contaminants allowing recirculation of process water or safe disposal to the environment (if still required). While salts are the problem for recirculation, nutrients (NO3 and PO4) are largely the problem when disposing to the environment. By combining salt accumulating plants in a highly efficient vertical flow treatment wetland cell with an anaerobic woodchip cell, a treatment solution for both recirculation and disposal is accomplished. Low cost treatment technologies with minimal O&M requirements are desired by the greenhouse industry for full or partial recirculation of process water and will be actively adopted if proven effective. Aqua Treatment Technologies (ATT) is an established and reputable company that has specialized in optimizing constructed wetlands for new industries. The results of this research will be used by ATT and immediately commercialized for application in the greenhouse sector.