Comparative life cycle assessment of five chemical methods for removal of phenol and its transformation products

Abstract

Many technologies have been evaluated for the treatment of phenolic wastewater, however, the removal efficiency was the major performance indicator. In this work, a detailed comprehensive outlook is presented to evaluate and compare the environmental performance of five different technologies for the removal of phenol and its transformation products based on the life cycle assessment (LCA) perspective. The considered five methods are adsorption by activated carbon (AC), electro-Fenton, solar photo-Fenton, solar photocatalysis by TiO2, and photocatalysis by a composite of TiO2 and AC (TiO2/AC). A virtual case study of an influent of 100 m3/d contaminated with 100 mg/L of phenol is considered in this study. The impact categories associated with the CML 2000 baseline method were considered such as abiotic depletion, eutrophication, global warming (GWP100), and aquatic ecotoxicity, besides the single-score calculated by the Eco-indicator 99 (E) method. It was observed that the solar photo-Fenton process is the most environmentally friendly technology (Eco-indicator score = 0.044 pt) because it depends on renewable energy and relatively benign chemicals. On the other hand, the electro-Fenton process revealed the highest impacts (Eco-indicator score = 1.48 pt) due to the high impacts of global warming, depletion of the abiotic resource, and human toxicity resulted from the electricity consumption. The impacts of photocatalysis and adsorption processes were highly influenced by the production of TiO2 and activated carbon. An economic analysis was performed and evidenced that the adsorption process is the most affordable, while electro-Fenton was the costliest process.