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Water quality


Water quality – Constructed wetlands

Constructed wetlands

Given the positive claims made for Constructed Wetlands, in terms of their effluent characteristics and low direct operational costs, plus the widespread interest in them by the agricultural sector, a decision was taken in 2004 to establish an integrated Constructed Wetland at the Greenmount Campus of the College of Agriculture, Food and Rural Enterprise (CAFRE) in Co. Antrim, to provide a site to test the efficiency of the Constructed Wetlands system under controlled conditions.

What is a constructed wetland?

A constructed wetland is a series of shallow ponds connected in a series to allow dirty water to be retained and naturally remediated treated through natural physical, chemical and biological processes. Ponds within a constructed wetland system are designed to blend into the natural topography of the site to allow water to flow slowly under gravity between ponds. The subsoil base of constructed wetland ponds must be impermeable clay material to ensure that the dirty water is retained. Vascular reed plant species planted in the shallow water in the ponds slow the flow of dirty water through the pond system while their roots and vegetation provide an environment for a wide range of naturally occurring microbes to process the nutrients from the farmyard dirty water.

CAFRE constructed wetland

The Greenmount ICW design followed specifications for constructed wetlands developed in the Republic of Ireland with respect to vegetation planting and size appropriate to treat the dirty water from the dairy unit at Greenmount campus.

The constructed wetland consists of five ponds which were constructed in the summer of 2004 and planted in autumn of 2004. To allow the wetland plants to become established the wetland was not used to treat dirty water until November 2005. A report produced by Agri-Food and Biosciences Institute (AFBI) in October 2009 summarises the surface and ground water quality monitoring data from the CAFRE wetland from November 2005 until February 2008. The report presents a preliminary assessment of the appropriateness of constructed wetlands for treating farmyard dirty water.

Knowledge transfer open day focusing on constructed wetlands

A knowledge and technology transfer open day focusing on constructed wetlands was held on 15 September 2010 at Greenmount campus, CAFRE. The event was attended by farmers and growers and focused on how the technology could be adopted to treat dirty water on their farms. A report on the open day can be found through clicking on the following document.

Treating farmyard dirty water using constructed wetlands

A technical note has been jointly produced by CAFRE and AFBI on ‘Treating farmyard dirty water using constructed wetlands’.

Additional documentation