Adapting to socioeconomic, operational and environmental challenges of dairy farm effluent purification in Uruguay through the use of surface flow constructed wetlands

Abstract

The 3600 dairy farms in south-western Uruguay, with about 750,000 cows in 2008, play an important economic role. Only about 200 of the farms have a sewage treatment system, since no legal regulations for the disposal of effluents exist, the cost of construction is high and neither direct benefits nor incentives are given. The current systems are mainly lagoons that often lack maintenance, resulting in the eutrophication of rivers. One of our goals was to implement a low cost, robust surface flow constructed wetland using native plants, in order to test the acceptance and willingness to pay of the farmers and to see if the effluent water quality met the national standards even if operating under the lack of maintenance. Within a small catchment, 6 farmers attended a seminar series on water(shed) quality, importance of wetlands and sewage treatment options, explaining the functioning of constructed wetlands and the costs of construction. One of the farmers decided to construct a double lagoon system followed by a surface flow CW using Scirpus americanus. However, construction of the ponds occurred by the farmer himself resulting in inadequate dimensioning. The exceptionally dry summer 2008/2009 also delayed planting but by now plants have established themselves and other emergent macrophytes have followed. So far visual water quality as well as biodiversity has improved. Furthermore, farmers and technicians have become interested in the use of CW and other implementations are envisioned. Also, the legislation on dairy farm effluent is about to change which will boost the necessity for all kinds of sewage systems.