Fate Of Microplastics In Wastewater Treatment Plants Research Articles

Long-Term Occurrence and Fate of Microplastics in WWTPs: A Case Study in Southwest Europe

Microplastic (MP) water pollution is a major problem that the world is currently facing, and wastewater treatment plants (WWTPs) represent one of the main alternatives to reduce the MP release to the environment. Several studies have analysed punctual samples taken throughout the wastewater treatment line. However, there are few long-term studies on the evolution of MPs over time in WWTPs. This work analyses the performance of a WWTP sited in Southwest Europe in relation with annual occurrence and fate of MPs. Samples were monthly taken at different points of the facility (influent, secondary effluent, final effluent, and sludge) and MPs were quantified and characterised by means of stereomicroscopy and FTIR spectrophotometry. The majority of MPs found in wastewater and sludge samples were fragments and fibres. Regarding to the chemical composition, in the water samples, polyethylene (PE), polyethylene terephthalate (PET) and polypropylene (PP) stood out, whereas, in the sludge samples, the main polymers were PET, polyamide (PA) and polystyrene (PS). The MPs more easily removed during the wastewater treatment processes were those with sizes greater than 500 µm. Results showed that the MPs removal was very high during all the period analysed with removal efficiencies between 89% and 95%, so no great variations were found between months. MP concentrations in dry sludge samples ranged between 12 and 39 MPs/g, which represented around 79% of the total MPs removed during the wastewater treatment processes. It is noticeable that a trend between temperature and MPs entrapped in sewage sludge was observed, i.e., higher temperatures entailed higher percentage of retention.

Influence of wastewater treatment process on pollution characteristics and fate of microplastics

The increasing abundance of microplastics (MPs) in rivers and oceans continues to face major challenges. In particular, MPs with smaller particle sizes are difficult to identify and quantify when they reach the environment. This study investigated four typical wastewater treatment plants (WWTPs), including urban WWTPs and industrial WWTP with different treatment technologies. The results showed that the average abundance of MPs in the influent and effluent was 538.67 ± 22.05 n/L to 1290 ± 65.26 n/L and 20.44 ± 1.19 n/L to 40.67 ± 11.12 n/L. The primary and secondary treatment processes can effectively remove MPs between 51.04% and 72.82% from wastewater. After tertiary treatments, the removal efficiency was further increased to more than 90%. The study aims to explore the removal mechanism of MPs in each stage of the wastewater treatment process and to reveal the fate of MPs in WWTPs, and help to understand their future monitoring to optimize the wastewater treatment process.

Characteristics and removal efficiency of microplastics in sewage treatment plant of Xi'an City, northwest China

Wastewater treatment plants (WWTP) are the important source of microplastics (MPs) in the environment, but the distribution and property of MPs in WWTPs are not fully understood. The study systematically investigated the transportation, characteristics and fate of MPs in both sewage and sludge of WWTP in Xi'an, a western region of China to complement the research on the fate of MPs in WWTP in inland China. The consequence was abundance, size, shape, color and type of MPs in sewage and sludge of different treatment processes were analyzed and compared by the metallurgical microscope and Fourier Transform Infrared (FTIR) spectrometer. Results showed that the MP abundance decreased from 288.5 n/L of the influent to 22.9 n/L of the effluent, corresponding to the removal rate of 92.1%. Among them, the secondary treatment has the best removal effect, with a removal rate of 72.1%. With the treatment process, the distribution of MPs with different characteristics is constantly changing, which leads to differences in the distribution of MPs in sludge and sewage. It is speculated from the characteristics of MPs that domestic sewage is still the main source of microplastics in Beishiqiao WWTP. Restricting the use of plastic products in daily life or finding alternatives is of great significance to the construction of MPs pollution.

Wastewater treatment plant effluent as a source of microplastics: review of the fate, chemical interactions and potential risks to aquatic organisms.

Wastewater treatment plant (WWTP) effluent has been identified as a potential source of microplastics in the aquatic environment. Microplastics have recently been detected in wastewater effluent in Western Europe, Russia and the USA. As there are only a handful of studies on microplastics in wastewater, it is difficult to accurately determine the contribution of wastewater effluent as a source of microplastics. However, even the small amounts of microplastics detected in wastewater effluent may be a remarkable source given the large volumes of wastewater treatment effluent discharged to the aquatic environment annually. Further, there is strong evidence that microplastics can interact with wastewater-associated contaminants, which has the potential to transport chemicals to aquatic organisms after exposure to contaminated microplastics. In this review we apply lessons learned from the literature on microplastics in the aquatic environment and knowledge on current wastewater treatment technologies, with the aim of identifying the research gaps in terms of (i) the fate of microplastics in WWTPs, (ii) the potential interaction of wastewater-based microplastics with trace organic contaminants and metals, and (iii) the risk for aquatic organisms.