The Abundance and Characteristics of Microplastics in Central Industrial Wastewater Treatment Plants

Abstract

Central industrial wastewater treatment plants (WWTPs) are an important source of microplastics in the environment. This study investigated the microplastics present in WWTP from two industrial estates in Thailand. Both WWTPs (WWTP A and WWTP B) operate with an activated sludge process. The result showed that the abundance of influent, post sediment tank, and RO process of WWTP A was 101.87 ± 0.47, 11.04 ± 0.08, and 0.44 ± 0.04 particles/L, respectively. On the other hand, the abundance of influent and effluent of WWTP B was 148.44 ± 0.91 and 33.53 ± 0.55 particles/L. The removal rate of microplastics showed 89.22% for WWTP A, 77.54% for WWTP B, and the highest in the tertiary process (99.54% for reverse osmosis system (RO) process from WWTP A). In addition, shape, size, colors, and polymer were detected. Most of the microplastics from both WWTPs were pellet (46.14 and 56.82%), ranging (20-212 µm), and white/clear. Based on the FTIR result, polypropylene (PP) and polyethylene (PE) were the most common polymer types.