Assessing the efficacy of electrocoagulation process for polypropylene microplastics removal from wastewater: Optimization through TOPSIS approach

Abstract

Emerging contaminants, microplastics in particular, pose a substantial risk to human health and the environment. Conventional treatments fail to incorporate focused approaches to eliminate them. This research comprehensively evaluated the effectiveness of electrocoagulation as a techno-economic method for removal of microplastics from water. The research meticulously investigated the effects of various electrode combinations composed of SS (stainless steel) and Al (aluminium) with possible combination as Al-Al, Al-SS, SS-Al and SS. Out of the various combinations considered, it was discovered that the Al–Al coupling demonstrated exceptional efficacy of 95.54% in the elimination of microplastics, with a concurrent reduction in energy consumption. The initial pH value was found to be a crucial parameter, as evidenced by the highest removal efficacy of 92.80% observed at a near neutral alkaline pH of 8. However, in order to determine economic efficacy, it is necessary to consider additional variables including energy consumption, electrode utilisation, and post-treatment conductivity. In order to address the intricacy presented by a multitude of parameters and criteria, it is critical to employ multi-criteria decision-making tools such as Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), which has demonstrated efficacy in real-world scenarios. The optimal electrolyte concentration, as determined by TOPSIS analysis, is 0.5 g/L. Furthermore, the TOPSIS analysis underscored the superior performance of punched hollow cylindrical electrode. The investigation conducted a thorough assessment of the impact of time period and concluded that a 100-min interval offers the highest efficacy in removing microplastics. At an input concentration of 2 g/L, this enhanced optimized system demonstrated outstanding competence in removing microplastics of three different sizes 45–90 μm, 90–180 μm, and 180–355 μm, with the removal efficiencies of 89.80%, 93.12%, and 94.08%, respectively. The current study introduces a pragmatic and exceptionally efficient approach to tackle the urgent problem of microplastic pollution in aquatic ecosystems.