Abstract
Photoelectrocatalysis (PEC), photolysis (PL), and photocatalysis (PC) were applied to increase the biodegradability of wastewaters effluents sampled from a plant collecting both municipal wastewaters and aqueous waste. In PEC, the catalyst was a porous TiO2 photoanode obtained by plasma electrolytic oxidation and electrically polarized during operation. In PC a dispersion of TiO2 powders was used. The same irradiation shielding, and similar catalyst surface areas were set for PC and PEC, allowing a straightforward evaluation of the catalytic effect of the electrical polarization of TiO2 during operation. Results showed that the chemical oxygen demand (COD) and color removal rates follow the order: PEC > PL and PEC > PC. The specific biodegradability rate (SBR) increased following the same order, the PEC process allowing SBR values more than twice higher than PL and PC. The operating costs were calculated based on the electrical energy per order of COD, color, and SBR values, demonstrating that at the laboratory scale the energy demand of PEC is significantly lower than the other two tested processes.
Highlights
This study aims to verify the feasibility of the application of PEC on this type of water with a view to its practical application in wastewater treatment plants (WWTPs) authorized to treat aqueous waste (AW)
PEC was validated for improving the biodegradability of real wastewater treatment plant effluents (WWTPEs) collected downstream a WWTP treating both municipal WWs and AW
Values (567.56 ± 224.20 mg O2 gVSS −1 gCOD −1 h−1 ) more than twice of those measured by PL (262.07 ± 89.27 mgO2 gVSS −1 gCOD −1 h−1 ) and three times of those measured by PC
Summary
Given the extremely different composition of the industrial and municipal WWs both in terms of nature and concentration of pollutants, a universal strategy for water remediation is not feasible. Several techniques including physical approaches, biological treatments, conventional chemical, and advanced oxidation processes have been proposed for the finishing of WWs [5,6,7,8,9]. Among them, advanced oxidation processes (AOPs) demonstrated a great potential in removing persistent organic pollutants and in increasing the biodegradability of WWs, and for this reason, they are often suggested in combination with conventional biological treatments [10,11,12,13]. Among the several advanced oxidation techniques reported in literature or already implemented at the industrial scale, photoelectocatalysis (PEC) for water treatment is relatively unexplored [14]
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