Treating wastewater from dairy parlors in a constructed wetland

A constructed wetland consisting in two horizontal sub-surface flow beds to treat dairy parlor wastewater and domestic sewage was built in a mountain agricultural settlement in Northern Italy. The beds were planted with Phragmites australis. Wastewater inflows and outflows were sampled throughout two years of the trial. The efficacy of the wetlands was maintained also during the winter months. The wetland operation brought to significant reduction in BOD5, COD, nitrogen, copper and zinc. SEM/EDX analyses evidenced the precipitation of iron on the outside surface of the root, reported to be acting as a barrier towards uptake of other metals.