Microbubble-enhanced cold plasma activation for efficient treatment of oil sands process-affected water: Exploring agricultural reuse potential

The effective treatment of oil sands process-affected water (OSPW) remains a critical environmental challenge due to the presence of persistent and toxic naphthenic acids (NAs). This study shows the potential of microbubble-enhanced cold plasma activation (MB-CPA) for the effective degradation of NAs in OSPW. In the MB-CPA system, two corona plasma discharge needle electrodes were placed in parallel above a water flow through a Venturi tube where microbubbles form spontaneously to rapidly transfer reactive oxygen and nitrogen species (RONS) generated from the discharge into water. Degradation efficiencies of isonipecotic acid (IA) and 5-phenylvaleric acid (PVA) in solution and in real OSPW were monitored by using surface-enhanced Raman spectroscopy (SERS) for sensitive quantification. Our results show that MB-CPA achieved near-complete degradation of model NAs within 90 min. When applied to real OSPW, plasma treatment reduced toxicity, enhanced nitrogen species availability. Our tests showed that the treated OSPW demonstrated a 30% higher germination rate and increased seedling growth compared to untreated water, attributed to the reduction of harmful NAs and the introduction of plant-usable nitrogen species. These findings demonstrate the potential of MB-CPA as a promising technology for sustainable wastewater treatment.