| Summary: | The present study investigates the viability of using four processes namely; Fenton, Sono-Fenton (SF), Electro-Fenton (EF), and sono-electro-Fenton (SEF) to reduce COD from hospital wastewater. Response surface methodology (RSM) was used to analyze the impact of several operational factors on COD reduction. The optimum circumstances for the Fenton technique were Fe2+ of 1.998 mM, H2O2 of 21.572 mM, pH = 3.2, and 97.029 min, in which COD REF% was 95.13, 90.96% turbidity removal, and 91.67% phenol removal. The concentrations of ferrous ions and hydrogen peroxide were found to be the main factors controlling the Fenton technique's efficacy, with a 75.83% contribution and 10.35%, respectively. The optimum circumstances for the EF technique were FeSO4 of 0.7 mM, a current density of 20 mA/cm2, and 56.36 min, in which COD REEF% was 97.055, 91.35% turbidity removal, 95.56% phenol removal, and specific energy consumption was 12.926 kWh/kg. In Electro-Fenton technique concentration of FeSO4 and the current density are the two most important factors in COD-reducing efficacy, with a 52.48% contribution and 24.97%, respectively. The SF's best results were achieved with 10 mM H2O2, 0.8 mM Fe2+, 97.029 min at pH = 4, and 100 W of US power giving a COD reduction rate of 92.19%, 83.65% turbidity reduction, and 86.11% phenol reduction. For SEF, a COD removal rate of 91.04%, 84.62% turbidity removal, and 91.67% phenol removal were achieved at an SEC of 4.3 kWh/kg COD using FeSO4 concentration of 0.2 mM, current density of 10 mA/cm2, time of 56.36 min, and US power of 100 Watts. Compared to using only the Fenton and EF techniques, the COD reduction is significantly enhanced when the US, combined with the above techniques, is applied at two distinct levels of power (50 and 100 Watts). SEF was found to be the best performance among other in terms of lower SEC required, lower Fe2+ consumption and lower time for operation. The findings contribute to advancing wastewater treatment technologies and provide valuable insights for the implementation of SEF process in the treatment of hospital wastewater, leading to improved environmental and health outcomes and overcoming the drawbacks of traditional methods specifically sludge generation.
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