Biofilter technology as an efficient solution for disposing pesticide-contaminated wastewater in viticulture and fruit growing

Agricultural activities, particularly the cleaning of pesticide sprayers, are a major source of point-source water pollution. The lack of application of effective and simple treatment methods for pesticide-contaminated wash water and wastewater in South Tyrol, Italy, necessitates innovative solutions. This study evaluates the performance of biofilters in degrading pesticides from agricultural wastewater, which accumulates during the cleaning of application equipment or the disposal of left spray liquid. Over a five-year period, three biofilters, consisting of two similar systems were tested at a wine and fruit farm in Italy. These biofilters, capable of evaporating 6000 to 8000 L of water annually, achieved a 98-99 % reduction in pesticide residues. However, phosphonic acid and tetrahydrophthalimide (THPI) were detected in the water going to the plant boxes, exceeding regulatory limits, along with residues of captan, acetamiprid, phosmet, and flonicamid. Analysis revealed that pesticide degradation primarily occurred in the uppermost boxes of the biofilter. Copper accumulation was notable in the first box, with minimal accumulation in lower boxes. These findings demonstrate that biofilters effectively degrade most pesticide residues, even in highly contaminated wastewater, and offer an efficient and sustainable solution for managing agricultural wastewater in fruit production and viticulture. The results contribute to a deeper understanding of biofilter performance under northern Italian climate conditions.