Efficient removal of succinic acid by continuous hydrodynamic cavitation combined with ozone and side influent injection.

Micropollutants (MPs) encompass a range of human-made pollutants present in trace amounts in environmental systems. MPs include pharmaceuticals, personal care products, pesticides, persistent organic pollutants, micro- and nano-plastics, and artificial sweeteners, all posing ecological risks. Conventional municipal wastewater treatment methods often face challenges in completely removing MPs due to their chemical characteristics, stability, and resistance to biodegradation. In this research, an Advanced Oxidation Process, combining hydrodynamic cavitation (HC) with dissolved ozone (O) and side injection, was employed to efficiently degrade succinic acid (SA), an ozone-resistant compound and common byproduct. The HC/O process was run to treat different synthetic effluents, focusing on evaluating the influence of O-to-total organic carbon (TOC) ratio, cavitation number (C) and O dosage. Notably, the results from a series of 14 experiments highlighted the critical significance of a low O-to-TOC ratio value of 0.08 mg/mg and C value of 0.056 in HC for achieving efficient SA removal of 41.2% from an initial SA solution (106.3 mg/L). Regarding a series of four proof-of-concept experiments and their replications, the average TOC removal reached 62% when treating wastewater treatment plant effluent spiked with SA. This significant removal rate was achieved under initial conditions: C of 0.02, O-to-TOC ratio set at 0.77 mg/mg, TOC concentration of 47.7 mg/L, 106 mg/L of SA, and a temperature of 25 °C. Notably, the electrical energy per order required for the 62% reduction in TOC was a modest 12.5 kWh/m/order, indicating the potential of the continuous HC/O process as a promising approach for degrading a wide range of MPs.