ABATEMENT OF ANTIBIOTICS, RESISTANT BACTERIA, AND UNPLEASANT ODOR IN SWINE MANURE OF PRESERVED PLANT NUTRITIONAL PROPERTIES | PROJECT REFLUA

Advanced oxidation processes are known for their ability to reduce organic pollutants and bacteria in wastewater. However, the evaluation of their performance is often limited to a narrow range of environmental parameters. This study evaluated the effectiveness of a simple acidic oxidation treatment (H₂O₂ at pH 3 for 24 hours) in addressing various environmental concerns related to the management and soil spreading of swine effluent collected from three Italian farms. The reduction of (i) nine commonly used antibiotics by LC-MS/MS, (ii) bacterial load and amoxicillin-resistant bacteria by total viable count on selective media, and (iii) foul odor emissions by an electronic nose was assessed in manures collected from weaning barns, as this is a phase of the pig life cycle where extensive antibiotic treatments are mostly administered. Additionally, the impact of the treated effluent on plant nutrition was examined using a maize pot experiment. The single treatment demonstrated an ability to reduce the antibiotic load by 53%, slightly outperforming spontaneous dissipation, which resulted in a 48% reduction. The treatment also eliminated the bacterial load in the amoxicillin-resistant fraction, reduced unpleasant odors by approximately 50%, and preserved the fertilizing capability of the treated manure. The effectiveness of the treatment in reducing untargeted molecules such as antibiotics, microorganisms such as bacteria, and unpleasant odors was found to be inversely proportional to the total organic content of the aqueous matrix. Higher carbon content in the effluent corresponded to lower performance of the reactive oxygen species (ROS) produced by the treatment. However, it is reasonable to assume that would be possible to adjust the number and intensity of treatment to achieve the desired level of abatement. There is a direct relationship between the abatement of bacterial load and unpleasant odors in manures, attributed to the biological source of noxious volatile molecules. The preserved fertility of the treated effluent, along with its beneficial effects on S, Cu, and Fe uptake by maize, highlights its potential value as a fertilizer or soil amendment. These findings suggest the treatment holds promise for potential applications and pave the way for a more general assessment of the several environmental concerns connected to animal manure exploitation.