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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. [ABSTRACT FROM AUTHOR]

Meso-scale constructed wetlands have not been commonly used for the examination of interactions and operations within differently designed wetland systems. Sixteen meso-scale constructed wetland systems (4 operations with 4 replicates each) were therefore evaluated between November 2008 and June 2010. These systems were used to examine key operations identified in the literature including hydraulic loading rates, nutrient loading rates and nutrient recycling modes. The wetlands were managed in the following modes: normal, recycling, high nutrient loading and high flow rate. The designs were such that the influents could be varied at set loading rates and concentrations. The ammonia removal rates for the meso-scale integrated constructed wetland (ICW) systems were similar to other full-scale ICW systems that have been in operation in the south-east of Ireland for the past decade. These comparable results highlight the potential cost-effectiveness of these meso-scale experimental designs for the examination of novel operations for future ICW developments. [ABSTRACT FROM AUTHOR]

Abstract: Non-point source pollution such as land-spreading of nitrogen-rich piggery wastewater poses a significant threat to surface waters. The aim was to examine the treatment of anaerobically digested piggery wastewater using four different meso-scale integrated constructed wetland (ICW) systems planted with Glyceria maxima. Four replicates were used for each system to assess differences due to nutrient loading, hydraulic loading and effluent recycling. All systems were effective in removing total organic nitrogen, ammonia-nitrogen, nitrate-nitrogen and molybdate reactive phosphorus. However, ammonia-nitrogen removal was the greatest challenge for high flow rates (>100m3/ha/d). Nitrification was higher in summer than winter. Findings show for the first time that effluent recycling within ICW was beneficial to lower ammonia-nitrogen but was associated with higher operational costs. The cost–benefit ratio based on ammonia-nitrogen removal for standard, recycling, high nutrients and high flow rate treatments was 1.08:1.04:1.06:1.00. It follows that a high flow rate was only marginally more cost-effective. [Copyright &y& Elsevier]

Abstract: An economic analysis was performed on treatment options for pig manure in Ireland. Costs were based on a 500sow integrated pig farm producing 10,500m3 of manure per year at 4.8% dry matter. The anaerobic digestion of pig manure and grass silage (1:1; volatile solids basis) was unviable under the proposed tariffs, with costs at € 5.2m−3 manure. Subsequent solid–liquid separation of the digestate would cost an additional € 12.8m−3 manure. The treatment of the separated solid fraction by composting and of the liquid fraction by integrated constructed wetlands, would add € 2.8 and € 4.6m−3 manure, respectively to the treatment costs. The cost analysis presented showed that the technologies investigated are currently not cost effective in Ireland. Transport and spreading of raw manure, at € 4.9m−3 manure (15km maximum distance from farm) is the most cost effective option. [Copyright &y& Elsevier]