Microplastic contamination in a conventional wastewater treatment plant in Thailand

Abstract

Plastic waste has become a global environmental concern. One type of plastic waste is microplastics (MPs), which can spread easily in the environment. Wastewater effluent is one of the land-based sources of MPs. This study investigates the amount of microplastic (MP) pollution in an urban wastewater treatment plant (WWTP) in Thailand. Water samples were collected and examined to find the types, morphology and sources of MPs. Wastewater was filtered through a set of sieves ranging from 5 mm to 0.05 mm. Sludge samples were also collected to find the potential risk from the application of dried sewage sludge. Fourier-transform infrared spectroscopy (FTIR) was used to confirm the types of MPs. The amount of MPs in the influent was 26.6 ± 11.8 MPs/L. More than one-third of MP particles were removed after a grit trap, followed by 14.24% removal in the secondary treatment. If the peak flow rate of the WWTP is reached, 2.32 × 109 MP particles can be released daily. The amount of MPs in a sludge sample was 8.12 ± 0.28 × 103 particles/kg dry weight. Dry sludge is one of the potential sources of MP contamination in agricultural soil. Most MPs in the liquid fraction and sludge sample were fibres. Results from FTIR analysis showed that the major types of MPs in the WWTP were polyester fibres, followed by polypropylene, polyethylene, silicone polymer and polystyrene. This finding indicates that a conventional WWTP may act as a path by which MPs enter the environment.

Microplastics in Sewage Sludge: A Known but Underrated Pathway in Wastewater Treatment Plants

“…This aspect is of great importance because it is very useful for understanding the origin of particles [81]. From the analysis of the examined literature, among the MPs identified in the SeS, fibers and fragments substantially predominate [35,41,55,[57][58][59]61,[63][64][65][66][67][68][69][70][71][72][73]75,76] (Table 1). Both are already present in the influent WW, the former derive mainly from the washing of synthetic clothing at home or industrial level [82], while the latter are contained for instance in many cosmetics as scrubber, given their irregular shape [3,81,83] or derive from the fragmentation of larger particles [81].…”

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

“…The size of most microplastics found in WWTP was different. For example, reference [19] found that the main size was 0.05-0.5 mm whilst reference [7] reported that the major size was 100-355 µm. in WWTP.…”

“…Consequently, several plastic particles release into the main river and the Gulf of Thailand. There are only a few studies on the presence of microplastics in the influent and effluent from WWTPs [9], [19], especially from industrial WWTPs which might be a huge source of microplastics contamination in the environment. This work is one of the first studies about the fate of microplastics in central industrial WWTPs in Thailand.…”

Biodegradation of Microplastics by Microorganisms Isolated from Two Mature Landfill Leachates

“…Microplastics are environmental contaminants that have received necessary attention due to their increased quantity and persistence. It is restricted to small plastic pieces ranging from about 5 mm to a few micrometers in diameter (Andrady, 2017;Costa et al, 2018;Accinelli et al, 2019;Yuan et al, 2020;Tadsuwan and Babel, 2021). They are spread within the environment through atmospheric dust, rain, laundry waste, landfill sites, and wastewater treatment plant (Dris et al, 2018;Tadsuwan and Babel, 2021).…”

“…It is restricted to small plastic pieces ranging from about 5 mm to a few micrometers in diameter (Andrady, 2017;Costa et al, 2018;Accinelli et al, 2019;Yuan et al, 2020;Tadsuwan and Babel, 2021). They are spread within the environment through atmospheric dust, rain, laundry waste, landfill sites, and wastewater treatment plant (Dris et al, 2018;Tadsuwan and Babel, 2021). A study showed that 275 million metric tons of plastic waste were generated by 192 countries in 2010.…”