Mountain dairy wastewater treatment with the use of a 'irregularly shaped' constructed wetland (Aosta Valley, Italy)

In mountain areas, economical activities related to milk processing represent both a key source of income and job opportunities. One of the main characteristics of cheese production is the seasonal variability in the volume of milk processed and wastewater production that tend to limit the capacity of ecosystems to absorb their inputs. In alpine environment, the scarcity of plain surfaces and the climatic conditions results in the need for high CW performances of variable nutrient inputs in different seasons. By evaluating a CW seasonal efficiency for dairy wastewaters in a mountain region (Aosta Valley-NW Italy), this research was aimed to understand how performances of nutrient removal could be affected by seasonal shift in temperature and loadings. Results indicate that the “irregularly shaped” CW, designed to fit the natural landscape, shows best organic removal efficiency in winter (93 and 96% mass removal for BOD5 in summer and winter respectively), in presence of high organic loadings and low temperatures. Even if nitrate removal is more variable during seasons (71 and 33% mass removal in summer and winter respectively) and differently affected by environmental conditions, overall performance meet the need of high removal efficiency.