Comparative life cycle assessment (LCA) study of heterogeneous and homogenous Fenton processes for the treatment of pharmaceutical wastewater

The applicability of any wastewater technology should be related not only to its degradation, mineralization or detoxification efficiency, but also to its environmental impacts. This could be particularly relevant in case of advanced oxidation processes (AOPs), which are usually highly demanding on chemicals, energy, and generating residual fluxes with specific problems and potential environmental impacts (metal ion-containing sludge, exhausted solid catalysts, etc). In this work, the life cycle assessment (LCA) has been applied for the evaluation of both homogeneous and heterogeneous Fenton processes for the treatment of a wastewater coming from a pharmaceutical industry in Toledo, Spain. The application of LCA as tool for the evaluation of AOPs is scarce found in literature, although it provides a systematic estimation of the environmental changes related to the AOP treatment, quantification of consumptions and emissions, and their effects on human health. In this work, the potential environmental impacts were calculated with Gabi 6.0 software by using ReCiPe version 1.06 and ICCP 2007 methods. Additionally, the water footprint (WF) was used in this study for the first time as tool for comparison between both AOP systems. Experimental data, directly obtained from the company and the laboratory were used to carry out the life cycle inventory (LCI) analysis, ensuring high accuracy and sensitivity of the obtained results. The obtained results showed that the recovery of the metallic sludge generated in the homogeneous Fenton process is the most contributing step to environmental impacts followed by the use of chemicals and the heat requirements. The comparison between homogeneous and heterogeneous Fenton processes revealed that the latter is a more environmental friendly alternative for the treatment of the pharmaceutical wastewater. In addition, the use of the heterogeneous process allows the reduction of the water footprint in more than 77% as compared to the homogeneous one. Besides the results regarding to both Fenton processes, this work shows the efficiency of the water footprint as a complementary parameter to the LCA for comparison between advanced wastewater treatments processes which can be intensive use of fresh water as a resource.