Technoeconomic Analysis of Hybrid Advanced-Oxidation Processes for the Treatment of Ultrafiltration Filtrate Wastewaters, a Byprocess of Yeast Production

Abstract

Yeast production wastewater is an industrial wastewater with a high organic pollutant content, and it has different adverse effects on the environment as untreated discharge. To treat this kind of wastewater with a high chemical oxygen demand (COD), advanced wastewater treatment technologies have to be used and evaluated with economic parameters for their applicability. The objective of the study was the technoeconomic optimization of ultraviolet Fenton oxidation (UV/FO) and ultraviolet electrochemical Fenton oxidation (UV/EFO) processes as a subsection of hybrid advanced-oxidation processes (AOPs) for the effective degradation of COD from ultrafiltration filtrate wastewaters, a byprocess of yeast production. In optimization studies, the influence of operating parameters such as pH, current density (CD)/Fe2+ concentration, H2O2 concentration, and economic parameters such as sludge disposal, chemical cost, electrode cost, energy cost, and total operating cost was investigated. A double-criteria optimization option has been used to maximize the COD removal efficiency and minimize the total operating cost of the processes by the response surface methodology (RSM), and parametric effects of main factors on the processes were evaluated in a detail. The optimal conditions using the UV/FO process were determined to be an initial pH of 3, Fe2+ concentration of 3.52 g/L, and H2O2 concentration of 79.76 g/L, in which the COD removal was 99.96% and the total organic carbon (TOC) removal was 76%, with a total operating cost of 16.96 $/m3 (1.73 $/kg CODrem). In the UV/EFO process, the optimum conditions were observed to be an initial pH of 3.07, current density of 5.68 mA/cm2, and H2O2 concentration of 180.63 g/L, in which COD removal was 99% and TOC removal was 81%, with a total operating cost of 13.00 $/m3 (1.34 $/kg CODrem). Based on the obtained results, it was found that UV/FO and UV/EFO processes resulted in a considerable amount of COD removal. Almost for the same COD removal efficiency, the UV/EFO process was observed to have a lower cost in terms of sludge disposal and the chemicals used. The UV/EFO process is an effective technology improving the wastewater quality for potential reuse and a cost-effective approach.