Occurrence Characterization and Contamination Risk Evaluation of Microplastics in Hefei’s Urban Wastewater Treatment Plant

Abstract

As one of the primary nodes in the flow of micro-plastics (MPs) in the environment, it is critical to examine and assess the Sewage Treatment, occurrence, and removal of MPs in waste treatment plant (WWTP). This research explored the shape, size, and composition of MPs at various stages of the WWTP process in the south of the city of Hefei, China, in dry and rainy weather conditions, as well as the removal effectiveness of MPs in a three-stage process. The collected MPs were quantitatively and qualitatively examined using an Osmosis electron microscope and micro-FTIR. The pollution risk of MPs in WWTP was assessed using the EU classification, labelling and packaging (CLP) standard and the pollution load index (PLI). The findings revealed that the average abundance of fibrous MPs was greatest in WWTP sewage and sludge, 49.3% and 39.7% in dry weather, and 50.1% and 43.2% in rainy weather, respectively. The average distribution of MPs in the 0–500 μm range was highest in WWTP wastewater and sludge, 64.9% and 60.4% in dry weather and 67.9% and 69.0% in rainy weather, respectively. Finally, the overall removal rate was 87.7% and 83.5%. At the same time, it has been demonstrated that MPs with varied compositions are strongly tied to human activities, and environmental conditions (such as rainy weather) also influence their source. In both dry and wet weather, the amount of polymers and the risk score were linked to the pollution risk of MPs in WWTP. In wet weather, the MPS pollution index was more variable. The pollution indices of MPs in row water and tail water were 2.40 and 2.46, respectively, which were heavily contaminated, and 1.0 and 1.2, which were moderately polluted. MPs in dewatered sludge had severely polluted indexes of 3.5 and 3.4, respectively. As a result, there is still MPs efflux or buildup in sludge during and after the WWTP process, which presents an ecological contamination concern.

Research Progress on Occurrence, Removal and Fate of Microplastics in WWTPs

“…According to Table 1, the average value of MPs abundance in domestic effluent is 46.94 n/L, and according to the daily effluent treatment volume of 144 million m 3 in China's WWTPs in 2019, it can be estimated that China's WWTPs will discharge 6.76×10 12 MPs into the natural environment every day. Most of the MPs removed in sewage plants are retained in the sludge, and the average value of MPs abundance in sewage treatment plant sludge shown in the statistics of Table 2 is 3.80×10 4 n/Kg, which, combined with the national production of sludge, roughly estimates that MPs entering the environment through the sludge in our country every year will be as high as 1.89×10 14 MPs.…”

Characteristics of Microplastics in a Hospital Wastewater Treatment Plant Effluent and Hazard Risk Assessment

“…To identify the level of error and contamination during sample preparation and testing, 4 distilled water samples were kept in the testing environment for 7 days. In addition, nitrate cellulose (NC) lters (4 lters on the Petri dish) were placed near the microscope, hood, and the testing environment for 7 days (Jiang et al, 2020;Meng et al, 2023;Shari et al, 2023).…”

“…Fionn Murphy et al conducted a study on microplastics in the e uent of a wastewater treatment plant in 2016, which revealed the following microplastic counts: 51.7 N/l at the in uent and 0.25 N/l at the e uent of the treatment plant. In this treatment plant, the e ciency of microplastic removal has been 98 41…”

Risk factors and characteristics of microplastics in the hospital wastewater treatment plant

“…To identify the level of error and contamination during sample preparation and testing, 4 distilled water samples were kept in the testing environment for 7 days. In addition, nitrate cellulose (NC) lters (4 lters on the Petri dish) were placed near the microscope, hood, and the testing environment for 7 days (Jiang et al, 2020;Meng et al, 2023;Shari et al, 2023).…”