Fate of dissolved organics and generated sulfate ions during biofiltration of oil sands process water pretreated with sulfate radical advanced oxidation process

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-02, Vol.458, p.141390, Article 141390
• Main Authors: Arslan, Muhammad, Ganiyu, Soliu O., Lillico, Dustin M.E., Stafford, James L., Gamal El-Din, Mohamed
• Format: Article
• Language: English
• Subjects: Biofiltration; Oil sands process water; Peroxymonosulfate; Removal; Solar activated SR-AOP; Sulfate
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.141390

[Display omitted] •SR-AOP pre-treatment results in high SO42− ions and partial DOC/COD removal.•Post-biofiltration with petroleum coke and sand successfully attenuated DOC/COD.•Anaerobic degradation of organics in peat was followed by methylotrophy in sand.•Slow sulfate removal was potentially linked to C(1)-sulfur compounds metabolism. Fate of dissolved organics and sulfate ions was studied in fixed bed biofilters (FBBs) treating pre-treated oil sands process water (OSPW) in the presence of industrially relevant substrates namely petroleum coke (PC) and sand. For pre-treatment, the solar-activated sulfate radical advanced oxidation process (SR-AOP) was performed using 2.5 and 5 mM peroxymonosulfate (PMS) as a precursor with solar irradiation of 119.5 W h m−2. Excellent degradation of naphthenic acids (NAs) was attained by SR-AOP, attaining 88 % and 97 % total NAs after 9 h of treatment at 2.5 and 5 mM of PMS, respectively. However, the treatment increased the toxicity due to byproducts and metabolites following the poor removal of dissolved organics, i.e., 13 % and 21.5 %, respectively. Electron paramagnetic resonance spectrometry (EPR) analysis exhibited that hydroxyl radical (⋅OH) and singlet oxygen (1O2) were the predominant active species produced during SR-AOP. The post-treatment biofiltration improved the mineralization of dissolved organics (45 %) and NAs (99 %) as well as removed the residual toxicity (>80 %). Taxonomy-based transcriptomics analyses (RNA) confirmed the enrichment of microbes involved in the degradation of hydrocarbons and carboxylic acids, methylotrophy, and potentially C(1)-sulfur compounds metabolism. Scanning electron microscopy with energy-dispersive X-ray spectroscopy indicated the potential of PC to support sulfur deposition, but at slower rates. This study indicates that the produced water can be efficiently reclaimed by using advanced oxidation and biofiltration approaches.