The use of integrated constructed wetlands (ICW) for the treatment of separated swine wastewaters

The use of constructed wetlands for the treatment of wastewater is an approach that has received increasing attention over the last 30 years due to their innate ability to deal with a wide range of highly variable influent types. The treatment of swine wastewater is an on-going issue due to its generally higher nutrient concentrations and the limited land available to owners. The implementation of the European Union Nitrates Directive and Water Framework Directive is currently placing considerable pressure on agriculture in EU member states with its focus on the improvement and sustained quality of surface waters. The limit of 170 kg of organic nitrogen/ha/annum imposed by the Nitrates Directive can cause severe difficulties for wastewater management in the piggery industry in Ireland, where spreadlands are already receiving high application rates of organic N. A replicated mesocosm integrated constructed wetland (ICW) approach was examined for the effective treatment of anaerobically digested separated swine wastewater with emphasis on nutrient removal. These mesocosm systems are based on operations identified in the available literature as well as on the ICW Concept pioneered in Ireland. The removal efficiency yielded substantial results over an 18 month period and highlighted high mass removal of ammonia–nitrogen (98.1–99.9%) from the influent. The removal recorded in all operational replicates throughout the study period showed that wetlands based on the ICW concept may very well prove to be a viable and sustainable approach for the treatment of swine wastewaters in Ireland whilst successfully addressing both the Nitrates and Water Framework Directives.