Effects of advanced oxidation process on biological treatment of spent fermentation broth

The present study aimed to establish the feasibility of the wastewater treatment process generated from an oleaginous fermentation plant. Treatment of spent fermentation broth (SFB) poses significant environmental challenges due to its high organic load, recalcitrant compounds, and potential toxicity. The synergistic effects of combining ozone-based advanced oxidation process (O₃-AOP) with biological treatment for the efficient degradation of pollutants in spent fermentation broth. O₃-AOP aimed to decolorize SFB and improve the biodegradability index (BI). After O₃-AOP pretreatment, color, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) were reduced by 92, 22.3, and 4.7%, respectively, with the improvement of BI from 0.59 to 0.72. Furthermore, the anaerobic-aerobic sequential system (AASS), where anaerobic digestion (AD) was followed by an aerobic treatment process (ATP), ~ 93.08 and 91.53% COD and BOD reduction were achieved. In turn, 197 mL of maximum cumulative bio-methane was produced during AD. The inoculum for AASS resulted in color enhancement during the digestion process. O₃-AOP post-treatment, after AASS, lowered the color to 80 NTU, with a final 93.6% color removal efficiency. Before and after treatment, the water quality index (WQI) decreased from 12,642.83 to 719.65 (weighted arithmetic WQI), suggesting the unacceptability of the water for portable usage. However, the phytotoxicity analysis of 70% seed germination suggested its nontoxic nature in agricultural field activity. Through the WQI assessment, it was evident that the pollution potential of the SFB was reduced significantly during the treatment process, but the treated stream was not suitable for potable use, and further treatment processes, such as membrane filtration and evaporators, were recommended to re-use the water within the system to reduce the freshwater demand. The findings influence the augmentation of sustainable and environmentally friendly wastewater treatment approaches for the biotechnological industry.