Enhancing Microplastics Removal from Wastewater Using Electro-Coagulation and Granule-Activated Carbon with Thermal Regeneration

Abstract

Discharge from sewage treatment plants (STPs) is a significant pathway of entry for microplastics (MPs) to the environment. Therefore, STPs should be considered as an important barrier to the distribution and circulation of MPs in the aquatic environment. In this study, the fate and material-specific properties of MPs were investigated in an STP-equipped and granule-activated carbon (GAC) tower with a thermal regeneration system. This system functioned with a tertiary treatment unit. The GAC with thermal regeneration removed 92.8% of MPs and was useful for removing MPs with a specific gravity less than that of water and with a size of 20–50 µm, which had negligible removal in the conventional STP process. In addition, a lab-scale electric-coagulation experiment was conducted to examine its potential utility as a pretreatment process for further enhancing the removal efficiency of MPs by GAC. After 30 min of electro-coagulation using aluminum electrodes, 90% of MPs were converted into separable flocs by centrifugation. These flocs may be effectively removed by GAC or other tertiary treatment steps. This study demonstrates that GAC with thermal regeneration is a tertiary process that can efficiently prohibit the release of MPs from STPs and circulation of MPs in the natural environment.

Plastic waste management for sustainable environment: techniques and approaches

“…These compounds are lighter than water, which is rarely removed in primary and biological treatments. About MP removal efficiency, similar results were obtained for the DWTP (drinking water treatment plant) equipped with the GAC filtration system (88% cumulative removal) [ 101 ]. Moreover, adsorbents prepared from plastic waste without the addition of any environmental-related problematic raw materials or products have gained much attention.…”

“…Kim et al [ 101 ] investigated worms that can consume polystyrene to a strain of bacteria that lives in the larvae’s gut. They placed polystyrene as the only carbon source with 50 superworms in a chamber and observed that the worms had consumed around 70% of the plastic in the first 21 days.…”

Examining Current and Future Applications of Electrocoagulation in Wastewater Treatment

“…While EC has been a well-studied area of research, there are relatively few studies specifically focused on MPs removal. These studies indicate that EC could effectively remove MPs, i.e., more than 90% removal in optimum reaction conditions from real wastewater [92][93][94][95] and artificial wastewater [77,96].…”

Notes on Common Misconceptions in Microplastics Removal from Water

“…They focused on the removal of various types of PTFE plastics using an aluminum electrode. The authors achieved more than 90% removal efficacy by electrocoagulation of particles that could not be removed with other methods [47].…”