ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Identification and removal of microplastics from contaminated semi-urban agricultural soil using electrochemical treatment technology

Mahesh Shivaswamy, Nisarga K. Gowda, and Sahana Mahesh

Department of Environmental Engineering, Sri Jayachamarajendra College of Engineering, Constituent College of JSS Science and Technology University (Formerly SJCE), JSSTI Campus, Mysuru, India

E-mail: maheshs@sjce.ac.in

Received: 16 August 2022  Accepted: 1 December 2022

Abstract:

The persistence of microplastics (MPs) in agricultural lands using plastic mulch will be an issue of major environmental concern in meeting the sustainable development goals (SGDs) of the near future. This research work aims at identifying and removal of MPs from rainfall runoff water (RRW) from MP-contaminated agricultural lands using the novel electrochemical coagulation (ECC) treatment technology. The MPs were extracted from the soil samples before identification. The pH, moisture content, MP abundance in soil, and particle size were determined. The RRW from the agricultural land loaded with MPs was treated using stainless steel (SS) electrodes in an electrochemical reactor. The removal efficiency of MPs, COD, chloride, and TDS at 45 min electrolyzing time was 98%, 46%, and 48%, respectively. Higher percentages of MP removal were achieved for increased MP concentrations in RRW. The difference in dry sludge generated during ECC for raw RRW and MP-loaded RRW was 2.42–4.09 kg/m³ of RRW treated. SEM, EDS, and ATR-FTIR spectroscopy analysis revealed the disintegration pattern of MPs into nano-sized particles. EDS of agricultural soil showed 8.2% carbon and 48.1% oxygen, whereas MP particles showed 62–64% carbon and 20–22% oxygen, respectively. The ATR-FTIR spectra for both spiked and extracted MP particle from the contaminated soil showed C–H stretch, CH₂ bends, etc.; the MP particle was identified as LDPE-type plastic mulch. The EDS of ECC sludge showed loads of MPs with 47% C, 35% O, 1.6–2.3% Al, 2–2.6% Si and 10.3–12.9% Fe. The ECC process showed its effectiveness in 98% MP removal from the RRW in a short hydraulic retention time (HRT) of < 45 min.

Graphical Abstract

Keywords: Microplastics; Rainfall runoff water (RRW); Electrochemical treatment; COD; Chloride; Analytics; Soil; Agricultural land; Plastic mulch

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02615-0

Chemical Papers 77 (4) 2125–2139 (2023)