Seasonal Considerations for Year-Round Operation of On-Farm Wetlands in Temperate Climates: A Review

On-farm constructed wetlands (CW) have been increasing in application over the past several decades to treat a variety of agricultural wastewaters. These systems have been found to be relatively low cost, require minimal maintenance, and provide a very efficient and sustainable means of treating harmful contaminants during the warm seasons before reaching nearby waterways. With farm size increasing in many regions and more waste being generated, it becomes increasingly important to have a viable means of treating wastewaters on a year-round basis. However, temperate climates can present challenges in the treatment of these wastewaters. This paper aims to bring together and review previous research on the use of CWs for treating agricultural wastewater in temperate climates where below freezing temperatures can exist. Focus is placed on the use of various wetland designs, wastewater types, management practices, maintenance, operational challenges and overall treatment capacities. This study highlights the need to carefully consider several factors (i.e. waste type, design, climate, vegetation, management) before using these systems for year-round treatment. Continued research in wetland management will be key in getting wide scale adoption from the agricultural community in temperate climates.