Sustainable Chromium Removal Using Electrocoagulation: Life Cycle Assessment of Different Electrode Materials

Chromium is a significant and hazardous pollutant found in wastewater generated from industries such as electroplating, dye production, and leather manufacturing. Due to its high toxicity, carcinogenicity, and negative impact on human health and ecosystems, chromium removal from water sources is essential. Electrocoagulation has emerged as a highly effective technology for treating water and wastewater pollutants. This study assesses the effectiveness and sustainability of this procedure in removing chromium using three conventional electrode materials: iron, aluminum, and stainless steel. An analysis was conducted on the effects of two qualitative parameters: electrode material and surface quality. In this study, a novel parameter (surface quality) that includes both solid and rough textures was introduced. The results indicated that iron and stainless steel have superior chromium removal efficiencies in comparison to aluminum. Aluminum was found to be inefficient for chromium removal because of its low removal efficiency (14.4%) and high energy consumption (3.739 kwh/m3). Surface roughness demonstrated diverse impacts on different materials, enhancing aluminum removal efficiency by 57.2% and decreasing energy consumption for stainless steel by 10.74%, indicating rough surfaces can be a functional energy-saving approach. However, roughness also has disadvantages on steel and iron, increasing electrode consumption by 15.3% and 29.5%, respectively, and increasing the bulk of the passivation layer by 182% and 131%, respectively. To assess the environmental impacts of this process, three electrode materials were defined as distinct scenarios. These were evaluated through life cycle assessment in accordance with ISO 14040 guidelines. The impacts were evaluated by the CML baseline method, taking into account the electrode and energy consumption. Results revealed that stainless steel had considerable environmental burdens on impact categories including ODP, POCP, EP, HTP, GWP and ADP (F), accounting for 35–43% across these categories. In comparison to the other materials, iron had minimal effects on environmental performance, contributing only 9% to FAETP, whereas Al and SS contribute 58 and 33%, respectively. Consequently, solid iron is recommended as the most environmentally sustainable electrode, whereas rough stainless steel continues to be the most efficient electrode material.