Removal Efficiency Of Microplastics Research Articles

Spatiotemporal characteristics of microplastics in a university wastewater treatment plant: Influence of sudden on-campus population swings

We studied the occurrence and characteristics (sizes, shapes, and polymer compositions) of microplastics (MPs) in a secondary wastewater treatment plant (WWTP) at the University of Mississippi both spatially and temporally. Putative MPs were isolated by sieving, matrix digestion, and density separation, and quantified using stereomicroscopy, with a subset of samples analyzed by Focal Plane Array (FPA) µ-FTIR imaging. In the influent, the highest MP concentration (particles/L ± 1 SD, n = 3) occurred after a football game on campus (62.3 ± 7.6) and the lowest (19.7 ± 2.1) during the summer with little activity on campus. Over 90% of the MPs were removed in the primary treatment. Downstream, MPs were most abundant in the closed loop reactor with concentrations as high as 1962 particles/L. Concentrations in secondary clarifier and final treated effluent were both < 4 particles/L during both normal flow (∼2000 m3/d) and high-flow (>2500 m3/d) periods, and between 16 and 39 particles/L during a low-flow (<1500 m3/d) period. This difference likely stems from changes in plant operations during the low-flow period to support the activated sludge, including longer process times. MPs were mainly composed of polyester, polyethylene, acrylates, polypropylene, polyurethane, polyvinyl chloride, and polystyrene. Fibers were most abundant throughout the system, averaging 61%, followed by fragments (21%), films (13%), and beads and foams (∼5%). Overall, we show that flow rates and treatment times can profoundly influence MPs concentrations in the treated effluent, and that the optimal wastewater treatment conditions also yield the best MP removal efficiency.

The comparison of adsorption kinetics of polystyrene particles with two polyelectrolytes near the isoelectric points

Microplastics are widely regarded as an emerging pollution owing to ubiquitous environmental distributions and toxicological characteristics. The adsorption kinetics of microplastic particles with polyelectrolytes is vital to improve the removal efficiency of microplastics, however, the adsorption kinetics of polyelectrolytes onto the particle surface is far from well understood near the isoelectric point. The adsorption of high and low charge density polyelectrolytes was investigated near the isoelectric point based on the measurement of the electrophoretic mobility. The mobility of particles adsorbing high charge density polyelectrolytes reaches the plateau in several seconds, whereas low charge density polyelectrolyte takes about dozens of seconds to reach the plateau of zero. The adsorption of high charge density polyelectrolyte is enhanced with the decrease of ionic strength, whereas, low charge density polyelectrolyte demonstrates the opposite tendency against ionic strength. All results will facilitate the analysis of the flocculation process of microplastic particles.

Insight into the microplastics release from disposable face mask: Simulated environment and removal strategy

The fight against the COVID-19 epidemic significantly raises the global demand for personal protective equipment, especially disposable face masks (DFMs). The discarded DFMs may become a potential source of microplastics (MPs), which has attracted much attention. In this work, we identified the detailed source of MPs released from DFMs with laser direct infrared spectroscopy. Polypropylene (PP) and polyurethane (PU) accounted for 24.5% and 57.1% of released MPs, respectively. The melt-blown fabric was a dominant MPs source, however, previous studies underestimated the contribution of mask rope. The captured polyethylene terephthalate (PET), polyamide (PA), polyethylene (PE), and polystyrene (PS) in airborne only shared 18.4% of released MPs. To deepen the understanding of MPs release from medical mask into the aquatic environment, we investigated the effects of environmental factors on MPs release. Based on regression analysis, the effects of temperature, incubation time, and wearing time significantly affect the release of MPs. Besides, acidity, alkalinity, sodium chloride, and humic acid also contributed to the MPs release through corroding, swelling, or repulsion of fibers. Based on the exposure of medical mask to simulated environments, the number of released MPs followed the order: seawater > simulated gut-fluid > freshwater > pure water. Considering the risk of MPs released from DFMs to the environment, we innovatively established a novel flotation removal system combined with cocoamidopropyl betaine, achieving 86% removal efficiency of MPs in water. This work shed the light on the MPs release from DFMs and proposed a removal strategy for the control of MPs pollution.

Highly efficient microplastics removal from water using in-situ ferrate coagulation: Performance evaluation by micro-Fourier-transformed infrared spectroscopy and coagulation mechanism

Generation of microplastics (MPs), as a result of the increasing amount of plastic waste from human activities, is an emerging global concern that potentially threatens human health due to its intrinsic toxicity and ability to transfer pollutants. We examined the flocculation/coagulation for efficiently removing MPs (here, polyethylene (PE) and polyethylene terephthalate (PET)) in water by applying in-situ ferrate treatment, which exploits easy preparation and reduces toxic sludge production but has high coagulation efficiency. The PE and PET removal efficiency was evaluated by measuring the amounts of PE and PET in the as-treated supernatant using microscope equipped Fourier-transformed infrared spectroscopy. Overall, in-situ ferrate coagulation removed >80 % of PE and PET in a range of ∼0.9–3.6 mg/L of coagulant dose. In particular, >99 % of PE was removed with 2.7 mg/L coagulants, whereas PET removal efficiency reached 75 % at the highest dose (3.6 mg/L ferrate). However, the presence of organic humic acid (HA) significantly enhanced PET removal efficiency, reaching >99 % at the highest dose (3.6 mg/L ferrate). According to the mechanism study, HA remarkably promoted charge neutralization at low doses, corresponding to the zeta potential reaching zero. In particular, PE and PET exhibited different floc formations owing to ferrate coagulation. Ferrate closely and tightly adhered to the surface of PET, indicating that in-situ ferrate induced the adsorption of MPs. Based on the removal test and mechanism study, in-situ ferrate flocculation/coagulation processes are highly efficient for removing MPs in surface water containing low concentrations of natural organic matter. In the real surface natural water condition, >98 % of MPs removal efficiency was achieved by - twofold decreased ferrate dose (1.8 mg/L) without microfiltration membrane process.

Unraveling microplastics removal in wastewater treatment plant: A comparative study of two wastewater treatment plants in Thailand

Wastewater treatment plants (WWTPs) are considered as a problematic pathway for microplastics (MPs) entering the oceans. This study compares the efficiency of MP removal in two different WWTPs (A1 and A2) with a conventional treatment system located in Bangkok, Thailand. WWTP-A2 is equipped with a pilot-scale ultrafiltration (UF) as a final polishing step. The number of MPs in the influent entering A1 and A2 was 16.55 ± 9.92 and 77.00 ± 7.21 MP/L, respectively. The average of 3.52 ± 1.43 and 10.67 ± 3.51 particles per L was found in the effluent discharged from A1 and A2, respectively, to nearby canals. The removal efficiency of WWTP-A2 built as a closed underground system was shown to be up to 86.14% which is more efficient than the conventional WWTP (A1). MPs were subsequently removed by a UF unit which resulted in a removal efficiency of 96.97%. However, when a large volume of treated wastewater volume is considered, a high concentration of MPs is discharged daily with the final effluent if the efficiency remains the same. The size fraction of 0.5–0.05 mm contributed to the largest proportion of MPs, and fibers were detected as the dominant group at both study sites. Results from a Fourier Transform Infrared Spectroscopy (FT-IR) confirmed that most fibers were polyethylene terephthalate (PET) derived from clothes. MPs retained in the sludge ranged from 2.63 × 104 to 4.74 × 104 particles per kilogram of dry sludge. A significant number of MPs can spread further to the environment by soil application. The results of the study indicate that the design of WWTPs and the addition of advanced tertiary treatment can improve MP removal efficiency of a WWTP. Moreover, the absence of a primary sedimentation tank in both treatment plants may influence the removal efficiency.

Deploying holey rGO-based membranes for MPs removal

The serious environmental issue caused by the rising levels of microplastics (MPs) pollution has aroused much more attention globally, therefore, an effective strategy needs to be established to eliminate MPs from the water. Herein, we first report the preparation of membranes based on holey reduced graphene oxide (h-rGO) nanosheets for efficient removal of MPs in wastewater. Compared with those untreated rGO, the h-rGO nanosheets show a porous structure with an average size of 27.3 nm, which is a benefit for construction membrane for separation of MPs with better water flux (37.19 L m−2 h−1 kPa−1). Employing the fluorescent polystyrene (FP) microspheres and PS beads as model MPs, the as-resulted h-rGO membranes exhibit extremely high MPs removal efficiency of 99.9%. In the case of treatment of the industrial MPs containing wastewater, almost all MPs could be captured by the h-rGO membranes which were confirmed by stereomicroscope. Taking advantage of their physicochemical stability and exceptional MPs removal efficiency, the h-rGO membranes may have great potentials for the removal of MPs in wastewater.

Microplastic- An Imposing Commination to the Aquatic Ecosystem and its Removal Strategies in Wastewater Treatment Plants: A Systematic Review

Plastic is broadly used for various human interests (technological devices, food packaging, medical products, etc.) and there is an increasing concern about the risks for our surrounding environment and health. In particular, microplastics (MPs), both primary and secondary, occur in all environmental pockets and constitute a potential warning, since they easily enter into the food chain. Moreover, microplastics have the ability to absorb diverse pollutants, which thereby get accumulated inside human body via processes of bioaccumulation and biomagnification. A systematic review was conducted to determine the effectiveness of wastewater treatment facilities (WWTPs) in removing microplastics. Published research on the effectiveness of wastewater treatment plants (WWTPs) for microplastic removal were searched using international databases (PubMed, Science Direct, and Scopus). Contamination of MPs in aquatic environment has presently been recorded as a transpiring environmental threat because of their fatalistic impact on the ecosystem. Their sources are numerous, but, undoubtedly, all are from synthetic matters. The sources of MPs are cosmetics and products of personal care, textile and tyre, abrasion processes of some other plastic products, bitumen and paints for road marking. Due to their low density and tiny particle size, MPs get easily extravasated into the wastewater drainage systems. Therefore, the municipal wastewater treatment plants (WWTPs) are designated to be the foremost recipients of MPs prior to getting excreted into the natural water reservoirs. The focus of this article is to put forward an all-inclusive review in order to preferably understand the channels of MPs into the environment, their characteristics in wastewater, and most importantly, the removal efficiency of MPs of the subsisting wastewater treatment technologies, as arrogated by the WWTPs. This review also encompasses the expansion of budding microplastics treatment technologies that have been investigated till date. Then, in the not-too-distant future, effective and standardised techniques for measuring MPs should be developed, as well as a greater understanding of sources and strategies for reducing microplastics contamination of treated effluent.

Distribution and occurrence of microplastics in wastewater treatment plants

Microplastic pollution is an alarming problem into aquatic environment. Wastewater treatment plants (WWTPs) with applied technologies are strictly interested in the technical challenges with budget calculations and sustainable development without contaminants. WWTPs are suspected as potential sources discharging microplastics (MPs) into the environment. This study investigated the distribution and occurrence of MPs in influent and effluent of three typical industrial wastewater treatment plants (WWTPs) named HoaCam WWTP (HC WWTP), DaNang WWTP (DN WWTP), and HoaKhanh WWTP (HK WWTP) in Danang city, Vietnam. The results showed that the abundance of MPs total is 183–443 particles/L and 138–340 particles/L in the influent and the effluent. The average MPs removal efficiency obtained 25.5%, 21.8% and 25.3% at HC, DN and HK of three WWTPs, respectively. Hence, the average loading capacity of MPs discharged to recipient sources is 3.8 × 10 7 , 8.3 × 10 7 and 1.5 × 10 9 particles per day in the HC, DN, HK WWTPs, respectively. The majority of MPs identified in this study included a profile of size, shape type, color and chemical compositions of MPs. The sizes of MPs highly varied from 1.6 to 5000 μ m with the abundant MPs types of fiber and fragment in both the influent and the effluent. In addition, the colors of MPs such as yellow, white, blue and black are presented. Using Fourier Transform Infrared spectroscopy (FTIR), the main polymer compositions of MPs included polyethylene terephthalate (PET), polyethylene (PE), nylon and polyvinyl chloride (PVC) were determined in three WWTPs. • WWTPs were considered as potential sources discharging MPs into the aquatic environment. • The abundance of MPs in the influent is lightly higher than that in the effluent of three WWTPs. • The fibber and fragment shapes in both the influent and the effluent of WWTPs were dominant. • Main polymer compositions of microplastics were polyethylene terephthalate (PET), polyethylene (PE), nylon and polyvinyl chloride (PVC) in WWTPs.

Revealing the influencing mechanisms of polystyrene microplastics (MPs) on the performance and stability of the algal-bacterial granular sludge

Algal-bacterial granular sludge (ABGS) is an energy-saving and environment-friendly wastewater treatment technology; however, the effects of microplastics (MPs) on the performance and stability of the ABGS system remain unknown. Herein, the influencing mechanisms of polystyrene MPs (50 μm) on the ABGS were systematically investigated. The ABGS exhibited a high removal efficiency of MPs (over 96%) at 1 mg/L and 20 mg/L. Although the biomass content, sludge settling and particle size were not obviously affected by MPs, the COD and total phosphorus (TP) removal efficiencies were inhibited by 2.6%-4.1% and 2.9%-5.8%, respectively. Meanwhile, the structural stability of ABGS was damaged by MPs, owing to the excessive oxidative stress, low content of protein-like substance (especially tryptophan and tyrosine), and the large portion of loose protein secondary structure. Microbial community analysis revealed that the relative abundance of some functional bacteria (Candidatus_Competibacter and Rhodobacter) and algal species (Tetradesmus) were decreased under the MPs stress.

Microplastics in 48 wastewater treatment plants reveal regional differences in physical characteristics and shape-dependent removal in the transition zone between North and South China

This study investigated the physical characteristics and removal efficiency of microplastics in wastewater from regions with different climatic conditions and economic development levels. Microplastics with different shapes and sizes were analyzed from the influent and effluent of 48 wastewater treatment plants in three regions of Shaanxi Province (China). Results indicated that the abundance of microplastics in the influent samples was higher in the region with less regional water resources. However, the per capita microplastics emissions was higher in the region with higher economic development level. There were less fibers and more foams and beads in the more developed region. The removal efficiency of microplastics was related to their shape and size. Particularly, the removal efficiency showed a significant negative correlation with the percentage of foams, while it had a significant positive relationship with the proportions of films and fibers. The highest removal efficiency was obtained when the size of microplastics was ranged from 0.5 to 1.0 mm. This study suggests, compared to improving the removal efficiency of microplastics, that reducing the input at source is a more scientific and promising method.

Contamination and Removal Efficiency of Microplastics and Synthetic Fibres in a Conventional Drinking Water Treatment Plant

Microplastics have been detected all around the globe in freshwaters which are frequently used to produce drinking water. Therefore, the contamination of raw water with microplastics that supplies drinking water treatment plants, and their removal efficiency is raising more concern and interest. In the present study, we evaluated the microplastic contamination in a conventional drinking water treatment plant (Geneva, Switzerland) and the contribution of coagulation on the efficiency of the filtration systems (sand and activated carbon filtrations) in the removal efficiency of microplastics (MPs) and synthetic fibres. This work was performed in a pilot station that replicates the main drinking water treatment process. Raw water and effluents of each filtering processes were analysed for the presence of MPs and synthetic fibres with sizes ≥ 63 μm using infrared spectroscopy. The contamination of MPs in raw water and in drinking water ranged from 19.5 to 143.5 MPs/m3 and from 0 to 8 MPs/m3 (in presence and absence of coagulant), respectively. On the other hand, concentration of synthetic fibres ranged from 7.7 to 23.8 synthetic fibres/m3 in raw water and from 0 to 3 synthetic fibres/m3 in drinking water. Results show that on average 89% of microplastics and 81% of synthetic fibres (≥63 μm) are retained in water treatment in absence of coagulant. Better final removal efficiency of microplastics (97%) and synthetic fibres (96%) was observed in drinking water with coagulation treatment. The chemical composition of microplastics and synthetic fibres is found more heterogeneous in raw water than after sand filtration and activated carbon filtration.

Microplastics removal from a primary settler tank in a wastewater treatment plant and estimations of contamination onto European agricultural land via sewage sludge recycling

Wastewater treatment plants (WwTPs) remove microplastics (MPs) from municipal sewage flow, with the resulting bulk of MPs being concentrated within generated sewage sludge which is frequently recycled back onto agricultural land as accepted practice in many European countries as a sustainable fertiliser resource. This circular process means that MPs successfully removed from WwTPs are deposited into the soil and able to return into the natural watercourse by means of run-off or infiltration to groundwater. This study quantifies the removal efficiency of MPs with size ranging between 1000 and 5000 μm in a primary settlement tank (PST) at a WwTP serving a population equivalent of 300,000 and provides MP concentrations in the generated sewage sludge. Our study revealed that the proportion of MPs partitioning in a PST to settled sludge, floating scum and effluent was 96%, 4% and 0% respectively, implying 100% removal of MPs of 1000–5000 μm in size. The generated sewage sludge was estimated to contain concentrations of approximately 0.01 g of MPs or 24.7 MP particles per g of dry sewage sludge solid, equivalent to ∼1% of the sewage sludge weight. Using these figures and data from the European Commission and Eurostat, the potential yearly MP contamination onto soils throughout European nations is estimated to be equivalent to a mass of MPs ranging between 31,000 and 42,000 tonnes (considering MPs 1000–5000 μm in size) or 8.6×1013–7.1×1014 MP particles (considering MPs 25–5000 μm in size). An estimated maximum application rate of 4.8 g of MP/m2/yr or 11,489 MP particles/m2/yr, suggests that the practice of spreading sludge on agricultural land could potentially make them one of the largest global reservoirs of MP pollution. Hence, recycling raw sewage sludge onto agricultural soils should be reviewed to avoid introducing extreme MP pollution into the environment.

Occurrence and distribution of microplastics in wastewater treatment plant in a tropical region of China

Wastewater Treatment Plants (WWTPs) are one of the main contributors to microplastics (MPs) in the environment. However, most of the current studies only reported the occurrence of MPs in WWTPs and rarely focused on the transfer and removal of MPs at each process unit. This work explores the MPs removal efficiency of a tropical urban WWTP during dry and rainy periods. The sewage and sludge samples were collected and analyzed to measure the MPs characteristics using a stereo-microscope and μ-FTIR techniques. Results showed the secondary treatment step eliminated most of the MPs, with an average concentration of 12.98 n/L in the effluent, indicating a 94.09% of total MPs removal rate. Throughout the sewage treatment stage, the most common MPs were black, small in size (25–380 mm), and identified as fibers. Moreover, the concentration of MPs in the effluent was higher in the rainy period compared to the dry period and some control strategies for MPs pollution in WWTPs are offered according to the results of this study.

Holey Ti3C2 nanosheets based membranes for efficient separation and removal of microplastics from water

The accumulation of non-degradable microplastics (MPs) originated from the mass production and huge consumption of plastics of modern industry in the water environment has resulted in severe pollution problems globally. Herein, we report for the first time the preparation of holey Ti3C2Tx (h-Ti3C2Tx) membranes obtained by etching Co3O4 nanoparticles embedded on Ti3C2Tx nanosheets followed by simple vacuum filtration using polymeric membranes as supporting matrix for efficient removal of MPs from wastewater. The h-Ti3C2Tx nanosheets exhibit a planar porous structure which present nano-holes with an average hole-size of 25 nm in diameter, which facilitated the construction of membranes with better water flux for the separation of MPs. Using fluorescent PS (FP) microspheres of different diameters as microplastic models, the obtained h-Ti3C2Tx membranes exhibited extremely high MPs removal performance (up to 99.3% under our conditions). Moreover, a large water flux of 196.7 L h−1 m−2 k Pa−1 can be obtained, which can compete or be larger than that of most of the membranes composed of untreated two-dimension nanomaterials. Due to the physicochemical stability, tremendous large water reflux, and the high MPs removal efficiency of h-Ti3C2Tx membranes, there may be a great potential for practical applications in the separation and removal of various contaminants such as MPs or suspended solids from water.

Coral-inspired environmental durability aerogels for micron-size plastic particles removal in the aquatic environment

Removing microplastics (MPs) from water has been a huge challenge due to their inherent features including small size and high stability. In this research, inspired by the active adsorption and passive adhesion mechanisms of corals to MPs, a new strategy to fabricate polydopamine enhanced magnetic chitosan (PDA-MCS) aerogels was developed with a target to match the surface properties of MPs, achieving high MPs removal efficiency. PDA-MCS aerogels were highly efficient in adsorbing polyethylene terephthalate (PET) microplastics in water at pH values of 6–9, with a removal efficiency of up to 91.6%. Even after three recycles, PDA-MCS aerogels still displayed comparatively high removal efficiency (83.4%). Kinetic and isothermal experiments showed that the adsorption process was the result of electrostatic interactions and physical adhesion between aerogels and microplastics. Moreover, PDA-MCS aerogels maintained high removal efficiency under simulated environmental conditions, and the removal efficiency of PET, polyethylene (PE) and polystyrene (PS) microplastics in waters reached 97.3%, 94.6%, and 92.3%, respectively. Therefore, high-efficiency environmentally durable aerogels adsorbent materials have the potential for the removal of MPs from the aquatic environment.

Tracing microplastics from raw water to drinking water treatment plants in Busan, South Korea

The increasing amount of plastic waste has raised concerns about microplastics (MPs) in aquatic environments. MPs can be fragmented into nanoplastics that can pass through water treatment processes and into tap water; potentially threatening human health because of their high adsorption capacity for hazardous organic materials and their intrinsic toxicity. This case study investigates the identification, fate, and removal efficiency of MPs in Korean drinking water treatment plants. Two sites on the Nakdong River, two lake reservoirs (raw water sources), and four corresponding drinking water treatment plants were targeted to trace the amounts, types, and sizes of MPs throughout the treatment process. Monthly quantitative and qualitative analyses were conducted by chemical image mapping using micro-Fourier-transform infrared spectroscopy. MPs larger than 20 μm were detected, and their sizes and types were quantified using siMPle software. Overall, the number of MPs in the river sites (January to April and October to November) exceeded those in the reservoirs, but only slight differences in the number of MPs between rivers and lake reservoirs were detected from June to October. The annual average number of MPs in River A, B and Lack C and D was not distinctively different (2.65, 2.48, 2.46 and 1.87 particles/L, respectively). The majority of MPs found in raw waters were polyethylene (PE)/polypropylene (PP) (> 60%) and polyethylene terephthalate (PET)/poly(methyl methacrylate) (PMMA) (20%), in addition to polyamide (<10%) in the river and polystyrene (<10%) in the lake reservoirs. Approximately 70–80% of the MPs were removed by pre-ozonation/sedimentation; 81–88% of PE/PP was removed by this process. PET/PMMA was removed by filtration. Correlation of MPs with water quality parameters showed that the Mn concentration was moderately correlated with the MP abundance in rivers and lake reservoirs, excluding the lake with the lowest Mn concentration, while the total organic carbon was negatively correlated with the MP abundance in both rivers (A and B) and lake reservoir C.

Reuse of Water in Laundry Applications with Micro- and Ultrafiltration Ceramic Membrane.

This study compares the performance of a microfiltration membrane, made by silicon carbide (SiC) and an ultrafiltration membrane, made by zirconia (ZrO2), in the treatment of wastewater from a washing machine designed to clean industrial tents. The filtration of deionized water, containing model microplastics (i.e., nylon fiber), was performed. This was followed by the filtration of real wastewater from a single washing cycle of industrial tents, made from polyvinyl chloride (PVC) textile. The filtration parameters of the membranes and physical-chemical parameters of the wastewater, including the concentration of microplastics in the shape of tent fibers (PVC), were calculated before and after filtration. The microfiltration membrane manifested a greater decrease in permeability (95%) compared to the ultrafiltration membrane (37%). The resulting water quality in terms of Total Solids, turbidity, and microplastics concentration was better for the ultrafiltration. This is evident from 99.2% versus 98.55% removal efficiency of microplastics from the laundering wastewater, respectively.

Highly effective removal of microplastics by microalgae Scenedesmus abundans

The highly effective removal of multiple kinds of microplastics (MPs) by microalgae Scenedesmus abundans was accomplished and the main mechanism of the MPs removal was identified as hetero-aggregation. The accurate quantification of removal efficiency was achieved by quantifying free suspended microparticles before and after the microalgae treatment. Scenedesmus abundans was tested against three kinds of plastics, including polystyrene (PS), poly(methyl methacrylate) (PMMA), and polylactide (PLA), and a total removal efficiency (η) higher than 84% was achieved for all MPs. Among these MPs, S. abundans were highly effective for removing PMMA microparticles (η = 98%). For the other two kinds of MPs, pre-exposure was required to achieve a total removal efficiency higher than 70%. As validated by SEM, a long-term exposure to MPs (greater than 2 days) promoted the formation of bound extracellular polymeric substances (EPS) and hetero-aggregation, leading to a much higher fraction of MPs removed by aggregations (ηa greater than 70%). On the contrary, if MPs exposure is short, enhanced adsorption onto solid surfaces can play an important role in the MPs removal, especially in the case of PLA. In this aspect, the abundance of soluble EPS was proportional to the amount of MPs adsorbed onto the container wall. These results suggest that the removal efficiency of microplastics, as well as the underlying mechanism, was affected by both plastic kind and exposure duration. Pre-exposure to MPs greatly increased the removal efficiency and can be a promising strategy for real-life practices.

Coagulation-flocculation performance and floc properties for microplastics removal by magnesium hydroxide and PAM

Microplastics (MPs) have attracted much attention worldwide as one kind of emerging pollutant, with the social demand for plastic products surging and microplastic pollution increasingly serious. In this experiment, magnesium hydroxide formed under alkaline conditions was combined with anionic polyacrylamide (PAM) as a dual-coagulant to deal with the simulated natural water containing polyethylene (PE). And the whole process was monitored by intelligent Photometric Dispersion Analyzer (iPDA), the Flocculation Index (FI) value of flocs and MPs removal efficiency were used as indicators to evaluate coagulation-flocculation performance. The results suggested that the flocs formed were not sufficient to remove PE particles only in the case of dosing magnesium ion. When PAM was added after magnesium hydroxide formation, the maximum FI value reached up to 7.2 and the PE removal efficiency was greatly improved, reaching 84.9% ± 3%. Additionally, flocs settling rate with average size of 57.19 µm reached to 4.8 × 10−3 m/s. At the same time, the types, dosing time and dosage of anionic PAM also had a great influence on the removal of MPs. Based on investigations of zeta potential and floc properties, adsorption bridging and sweeping were the main coagulation mechanisms. The MPs removal behaviors exhibited during coagulation processes have potential application in water treatment.

Identification, Quantification, and Evaluation of Microplastics Removal Efficiency in a Water Treatment Plant (A Case Study in Iran)

Microplastics (MPs) are among the emerging pollutants that recently attracted the researcher’s attention around the world. These particles can absorb other chemicals, and microbial contaminants and enter them into the food chain, and environment. This study was conducted to investigate the occurrence of MPs in raw and treated drinking water and evaluate the MPs removal efficiency in a drinking water treatment plant (DWTP) in Iran. MPs particles were counted at different stages of DWTP, using a scanning electron microscope after the initial preparation steps include filtration, and chemical digestion, and then examined for the nature of the particles using a micro-Raman spectrometer. The concentration of MPs in influent, clarifier’s effluent, and DWTP’s effluent were 1597.7 ± 270.3, 676.2 ± 69.0, and 260.5 ± 48.9 MPs/L, respectively. The total efficiency of the DWTP in MPs removal was 83.7%, which the clarification and filtration stage removed 57.7%, and 26.0% of total MPs, respectively. The most abundant polymers identified were PP, PE, and PET. Despite the effective removal of MPs in the DWTP, on average 2.25 × 1011 ± 4.23 × 1010 MPs are daily discharged into the water distribution system through the effluent of this DWTP.