Electrocoagulation (EC) has gained increasing attention as an effective and environmentally friendly technique for purifying water and wastewater. This review provides a comprehensive analysis of the recent literature on EC and identifies new trends and potentials for further research. Initially, the nature of EC and its operating parameters are discussed, while the research trends are analyzed using the Scopus database and VOSviewer software. From 1977 to 2022, 2691 research articles and review papers on EC for water/wastewater treatment were published, with the number of publications increasing from 2 in 1977 to 293 in 2022. In the past five years, most studies focused on treatment performance and the mechanism of EC systems. However, recent emphasis has been placed on combining EC with other treatment processes and addressing emerging pollutants. The innovative applications of EC are highlighted, including the removal of microplastics and per/polyfluoroalkyl substances, the power supply of EC via microbial fuel cells (MFCs) and electro-wetlands (EWs), and the application of power management systems in EC. The review concludes with suggestions for further research to enhance the technology and expand its scope of applications.

Aluminum-based drinking water treatment residuals (DWTR) were encapsulated by alginate to develop a pelletized media (DWTR-CA beads) for phosphorus (P) adsorption. The beads were successfully manufactured to uniform size and shape requirements. The effects of DWTR powder concentration and particle size, and bead mean size on P adsorption, were investigated. The DWTR was found to be an important component in the beads for P adsorption, while the calcium alginate shell contributed little for P adsorption. The maximum P adsorption capacity of the DWTR-CA bead was 19.42 mg P/g wet beads, corresponding to a bead diameter of 3.1 ± 0.2 mm and DWTR concentration of 2% (1% weight/volume (W/V)), mg/mL). The adsorption data fit well with the intra-particle diffusion model and the pseudo-second-order kinetic model, while both the Langmuir and Freundlich adsorption isotherms described the adsorption process well. Furthermore, the study on the effect of pH on P adsorption showed that acidic conditions resulted in a better P adsorption and the DWTR-CA beads have the function of pH neutralization. The findings of this study show that the DWTR-CA beads are a promising adsorbent/substrate for P removal.