Electrochemical-enzymatic hybrid process achieves effective removal of micro- and nanoplastic in plastic recycling facilities

초록

Significant amounts of micro- and nanoplastics (MNPs) are released during the plastic recycling process, highlighting the need for effective prevention technologies beyond the capabilities of existing wastewater treatment technologies. In this study, a hybrid system that integrated electrochemical capture and enzymatic depolymerization was developed to address challenge and prevent the release of MNPs into the environment. Effluent containing MNPs from wastewater treatment plant associated with a plastic recycling facility (PRF) was evaluated using a specially designed electrocoagulation reactor. The removal efficiency of microplastic and nanoplastic were determined to be over 99 % and 84 % respectively. The captured MNPs were effectively depolymerized into low-molecular-weight organics using the commercial lipase Novozym (R) 51032. This study is the first to report on the simultaneous removal of MNPs from the final effluent of a commercial PRF, highlighting the capability of the system to effectively manage MNPs. It successfully conducted quantitative analysis of nanoplastic, a challenging task, using nanolens based advanced Raman spectroscopy. Based on high energy efficiency and the combined MNP removal mechanisms of electrocoagulation and enzymatic treatment, this hybrid system was capable of removing MNPs from wastewater generated by PRFs. Furthermore, this system demonstrated resource recovery of terephthalic acid (TPA) through enzymatic depolymerization. With further optimization and multi-stage validation, it is intended to achieve near-zero discharge of MNPs.

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