IN-SITU REMOVAL OF ANTIBIOTICS IN SOIL BY COLD PLASMA

Antibiotics are extensively used in clinical settings to treat or prevent human diseases, in veterinary science for farm and domestic animal health and in agriculture for crop protection. Due to their incomplete biological degradation, human and animal antibiotics are released through discharges from wastewater treatment plants into the environment and return in the food chain via leachates from landfills, wastewater reuse for irrigation purposes. Consequently, once antibiotics are found in the environment, they pose a serious threat for soil and water quality since they inhibit active microorganisms of the ecosystem that could be vital in many subsurface processes such as soil and groundwater remediation and nitrogen, sulphur and carbon cycles. More importantly, the continuous presence of antibiotics in the soil and water will gradually allow harmful microbes and bacteria to develop resistance to these medicines that our defense depends on. It is therefore necessary to develop efficient, cost-effective and environmentally friendly methods for the decontamination of antibiotics-polluted soils. In this study, cold atmospheric plasma was examined for the in-situ remediation of antibiotic-polluted soil. The experiments were conducted in a cylinder-to-grid dielectric barrier discharge (DBD) reactor driven by a high voltage nanosecond pulse generator. The effect of CAP operating conditions such as treatment time, applied voltage, discharge frequency and initial pollutant concentration was investigated and optimised. The main ciprofloxacin degradation intermediates were identified using liquid chromatography-mass spectrometry (LC-MS) and a possible CAP-mediated degradation pathway was proposed.