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CONSTRUCTED WETLANDS FOR MINEWATER TREATMENT: ENVIRONMENTAL BENEFITS AND ECOLOGICAL RECOVERY

The ecology of the River Pelenna (in South Wales) was impoverished by polluted discharges from abandoned coal mines. A series of passive constructed wetlands was created in order to treat these discharges and to improve the ecology of the river. A three‐year Environment Agency R&D project investigated the performance, environmental benefits and sustainability of the constructed wetlands. It showed that the treatment systems were removing most of the iron contamination. In the reaches downstream from the minewaters, the dissolved‐iron concentration quickly dropped below the target level. Invertebrate abundance, trout and riverine bird populations increased in following years. However, occasional overflows from the systems have significantly affected the ecology of one stretch of river. The research work has provided an insight into the potential for ecological recovery associated with future minewater treatment.