Treatment of hospital wastewater through the CWPO-Photoassisted process catalyzed by ilmenite

Abstract

In this work, the feasibility of the CWPO-Photoassisted process for the on-site treatment of real hospital wastewaters has been evaluated using the low-cost mineral ilmenite. The ability of the process for the degradation of pharmaceuticals was firstly demonstrated in both deionized water and hospital wastewater matrices. Although the latter led to slow constant rates due to scavenging effects (0.42 and 0.02min−1, respectively), the complete elimination of the pharmaceuticals was reached in both cases operating at 30°C and using 1gL−1 ilmenite. The complete removal of coliforms in the hospital wastewater was also achieved. The treatment of the hospital wastewater was fairly efficient (TOC conversion above 80% in 5h reaction time) operating at 50°C with a catalyst load of 1gL−1 and the stoichiometric amount of H2O2, which was attributed to the combination of both CWPO and photocatalytic reactions. A lumped kinetic model allowed to describe fairly well the evolution of the global parameters viz. TOC and H2O2 along the process where both CWPO and photocatalytic reactions were considered. The unique properties of ilmenite allowed the fast degradation of the organic pollutants by CWPO into hydroxylated species, while further photocatalysis led to the formation of short-chain organic acids and their subsequent mineralization. Finally, the stability of ilmenite was confirmed upon three sequential runs.