Polyacrylamide-Modified Basalt Fibers for Passive Reclamation of Oil Sands Process Water

This study investigates the potential of cationic polyacrylamide (CPAM)-modified basalt fibers (BF) as biocarriers for biofilm-based organic transformation in oil sands process-affected water (OSPW) in a lab-scale investigation. The fibers underwent Soxhlet extraction and epoxy treatment for CPAM coating, enhancing their hydrophilicity and surface charge, which improved microbial attachment and facilitated biodegradation of naphthenic acids (NAs), reducing their concentrations from 70.4 to 25.5 mg/L over 108 weeks. Results illustrated rapid removal of organics in the initial phase, likely due to NAs sorption onto the BF surface, followed by slower removal in subsequent stages supported by biodegradation. The desorption study confirmed that biodegradation was the dominant mechanism. Fourier-Transform Infrared Spectroscopy and synchronous fluorescence spectroscopy indicated chemical transformations on BF along with a significant decrease in fluorescent organic compounds. Molecular weight analysis confirmed the transformation of complex organics into smaller molecules. Microtox showed a significant reduction in toxicity from over 50% to approximately 15–20%. eDNA sequencing revealed aerobic bacteria in outer zones and anaerobic microbes in the middle and core, while Cercomonas sp. was a dominant eukaryotic player facilitating organics attenuation. These findings suggest the use of BF in treatment wetlands or end pit lakes for OSPW treatment, offering a sustainable solution.