Constructed wetlands are suitable to treat wastewater from Italian cheese productions

Abstract

Two horizontal sub-surface flow constructed wetlands (h-SSF CW) were set-up and controlled to determine their efficiency in reducing the polluting load of wastewater from Parmigiano-Reggiano and Grana Padano cheese production. Besides, comparisons were made of biomass production and nutrient uptake of cattail (Typha latifolia) reaped at different stages. The average concentrations of the influent waters were about 250-320 mg/l TSS, 940-1060 mgO2/l COD, 600-700 mgO2/l BOD5, 35 mg/l TKN, 8-13 mg/l total P, 60-170 mg/l animal and vegetable fats and oils. The removal of COD, BOD5 and animal/vegetable fats and oils were above 95%, while resulted 60-65% for nitrogen and very different for phosphorus, varying from 75% in one CW to 20% in the other. Results demonstrated that h-SSF CW could help to solve the problem of the cost-effective disposal of cheese dairy wastewater, being a suitable treatment for reducing pollutants to values in conformance with Italian standards for discharge to a watercourse. Typha latifolia showed considerable biomass yield, though the N and P uptake was quite low if compared with nutrients inputs in CW (about 10%). There is the possibility to maximise biomass yield and nutrient uptake reaping cattail twice a year instead of only one time.