Activated Carbon Filtration Research Articles

Impact of biological activated carbon filtration and backwashing on the behaviour of PFASs in drinking water treatment plants

PFASs are present in surface water, tap water and even commercial drinking water and pose a risk to human health. In this study, the treatment efficiency of 14 PFASs was studied in a large drinking water treatment plant (DWTP) using Taihu Lake as the source, and it was found that the ozone/biological activated carbon (O3-BAC) process was the most effective process for the removal of PFASs in DWTPs. For the O3-BAC process, there were differences in the removal of PFASs by BACs (1,4,7,13 years) of different ages. The sterilization experiments revealed that for GAC, its physical adsorption capacity reached saturation after one year, while for BAC with mature biofilms, biosorption was the main mechanism for the removal of PFASs. The abundance of Alphaproteobacteria and Gammaproteobacteria in biofilms was positively correlated with the age of the BAC. The microbial community with higher abundance is beneficial to the biodegradation of organic matter and thus provides more active sites for the adsorption of PFASs. PFASs can leak in the early stage of filtration after backwashing, so it is necessary to pay close attention to the influent and effluent concentrations of PFASs during biofilm maturation after backwashing.

Effects of a Volatile Organic Compound Filter on Breath Profiles Measured by Secondary Electrospray High-Resolution Mass Spectrometry.

Environmental volatile organic compounds (VOCs) from the ambient air potentially influence on-line breath analysis measurements by secondary electrospray ionization high-resolution mass spectrometry (SESI-HRMS). The aim of this study was to investigate how inhaling through a VOC filter affects the detected breath profiles and whether it is feasible to integrate such filters into routine measurements. A total of 24 adult participants performed paired breath analysis measurements with and without the use of an activated carbon filter for inspiration. Concordance correlation coefficients (CCCs) and the Bland−Altman analysis were used to assess the agreement between the two methods. Additionally, the effect on a selection of known metabolites and contaminants was analyzed. Out of all the detected features, 78.3% showed at least a moderate agreement before and after filter usage (CCC > 0.9). The decrease in agreement of the remaining m/z features was mostly associated with reduced signal intensities after filter usage. Although a moderate-to-substantial concordance was found for almost 80% of the m/z features, the filter still had an effect by decreasing signal intensities, not only for contaminants, but also for some of the studied metabolites. Operationally, the use of the filter complicated and slowed down the conductance of measurements, limiting its applicability in clinical studies.

Can activated carbon filtration of groundwater cause radiation safety problems?

Abstract Activated carbon filtration is commonly used to remove groundwater contaminants in water utilities. During its use, also groundwater radon is adsorbed on activated carbon where it radioactively decays to Pb-210 within a few days. The intermediate stages of radioactive decay produce gamma radiation outside the filter, which can be harmful to health. In addition, EU legislation sets a clearance level of 1 kBq/kg for the Pb-210 concentration of waste, above which disposal of carbon waste can be complicated, depending on national legislation. This study focused on activated carbon filters from two groundwater plants. Measurements were made over the service lifetime of the activated carbon and included measurements of adsorption of radon from water to carbon, radiation dose rates outside the filters and Pb-210 concentrations in the carbon. The study observed a rapid decrease in the radon adsorption rate of activated carbon during the first year of use. This phenomenon has a significant effect on the concentration of Pb-210 in the activated carbon waste at the end of service life. The calculated forecast model clearly showed that the risk of exceeding the clearance level of Pb-210 increases if the radon concentration in the raw water exceeds 100 Bq/L.

A Peripherally Located Air Recirculation Device Containing an Activated Carbon Filter Reduces VOC Levels in a Simulated Operating Room.

Electrosurgery procedures produce airborne contaminants including volatile organic compounds (VOCs). The effectiveness of commercial grade activated carbon at removing toluene, a typical VOC, from the air in an enclosed simulated operating room (OR) when interfaced with an air recirculation device was tested. The concentration of toluene in the air was measured using gas sensitive semiconductor VOC sensors. When the air recirculation device containing activated carbon was turned on, the concentration of toluene in the air decayed exponentially. When the device was off, the toluene concentration reduced much more slowly. After 130 min, a VOC sensor placed near the air recirculation device showed VOC reductions of approximately 30% when the device is on and less than 1% when the device is off. Changing the activated carbon filter after 22 h of constant use showed an abrupt increase in the rate of toluene removal.

Reversible fouling by particulate matter from natural seawater reduces RED performance while limiting biofouling

Reverse Electrodialysis (RED) has shown to be a promising technology for electricity production but membrane fouling can influence the energy yield, thus, it is crucial to gain knowledge on the impact and prevention of fouling. We used a sequence of pre-treatments (dual-media filter, microfilter and activated carbon filter) to fractionate foulants in seawater based on size and investigated its effect on RED. Fouling reversibility was studied by applying a cleaning procedure with reversal and increased flow and air sparging at the end of the experiment. After 63 days of operation, when using only the dual-media filter as pre-treatment, the pressure drop increased by 520 mbar in the seawater compartments without affecting the electrochemical measurements. The application of the cleaning procedure allowed to recover 90 % of the pumping power losses. A membrane autopsy showed the development of a biofilm layer on the membrane of the stacks receiving the most treated water while it was not detected when only the dual-media filter was used, which showed that the presence of particulate matter could help limit biofouling development. Together with the performance recovery, we concluded that the application of the dual media filtration system is a suitable and cost effective pre-treatment for RED.

Effectiveness of Coconut Charcoal Shell Activated Carbon Filtration to Lower Fe in Cisterns Water: A Case Study in Arsopura, Keerom Regency, Papua

Clean water consumed daily should not contain excessive Fe (iron) because it can cause health problems. The Fe can be reduced by filtering using activated carbon such as those found in coconut shells. For this reason, this study will analyze the effectiveness of iron filtration in excavated well water in Arso Pura, Keerom Regency, Papua Indonesia. The method used is an experiment with Randomized Complete Block Design (RCBD). Purposive sampling was carried out on community dug well water in Arso Pura, Keerom Regency, Papua by measuring Fe levels before and after using coconut shell activated carbon and the use of miner areas of 2 Inches, 3 Inches and 4 Inches. The results of the Anova test, namely a p-value of 0.00<0.05, indicate that filtration with coconut shell charcoal and the addition of a cross-sectional area of the cross-sectional area have a significant effect or significantly different treatment on Fe (Mg / l). The result was with a cross-sectional area of 2 inches H with a decrease of 47.62%; 3 Inch to 59.05%, and 4 Inch to 63.81%. The results of the screening have not been able to meet the requirements for Fe levels in potable water. For this reason, a larger miner expansion mechanism and/or a different filtration approach is needed that must be carried out on the dug well water in Arsopuro to make it drinkable.

Effectiveness of Coconut Charcoal Shell Activated Carbon Filtration to Lower Fe in Cisterns Water: A Case Study in Arsopura, Keerom Regency, Papua

Effectiveness of Coconut Charcoal Shell Activated Carbon Filtration to Lower Fe in Cisterns Water: A Case Study in Arsopura, Keerom Regency, Papua

Research on advanced treatment of phenolic chemical wastewater and carbon replacement by the multi-layer biological activated carbon filter

After a series of biochemical processes, the wastewater engendered by the production of phenolic resin is ultimately left with a majority of difficult degradation organic matter. Most of these organic compounds are harmful to the water environment and require further advanced treatment before discharge. In this study, the original simple biological activated carbon (BAC) filter column device was improved. The new multi-layer BAC filter does not require backwash after improvement. The treatment efficiency of the multi-layer BAC filter was studied through long-term operation, and the variation of pollutants in the wastewater was analyzed. The results indicated that the multi-layer BAC filter could effectively remove hardly biodegradable organic matter, ammonium‑nitrogen (NH4+-N), and total nitrogen (TN), and its mechanism was mainly that hardly biodegradable organic matter and TN were removed by adsorption and biodegradation, while NH4+-N was only removed by microbial degradation. The pore-size distribution characteristics on the BAC surface were analyzed, and it was found that the adsorption and biodegradation reactions mainly occurred in the microporous region. The experiment on carbon replacement indicated that the service time of the BAC system could be prolonged by choosing the correct time of carbon replacement and adding the appropriate amount of microorganisms. Based on high-throughput sequencing, it was found that the microbial communities on BAC at the same height were significantly different before and after carbon replacement. The results of this paper are of some relevance for the upgrading of advanced treatment processes for chemical wastewater in practical engineering.

NO2 levels inside vehicle cabins with pollen and activated carbon filters: A real world targeted intervention to estimate NO2 exposure reduction potential

Traffic related nitrogen dioxide (NO2) poses a serious environmental and health risk factor in the urban environment. Drivers and vehicle occupants in general may have acute exposure to NO2 levels. In order to identify key controllable measures to reduce vehicle occupant's exposure, this study measures NO2 exposure inside ten different vehicles under real world driving conditions and applies a targeted intervention by replacing previously used filters with new standard pollen and new activated carbon cabin filters. The study also evaluates the efficiency of the latter as a function of duration of use. The mean in-vehicle NO2 exposure across the tested vehicles, driving the same route under comparable traffic and ambient air quality conditions, was 50.8 ± 32.7 μg/m3 for the new standard pollen filter tests and 9.2 ± 8.6 μg/m3 for the new activated carbon filter tests. When implementing the new activated carbon filters, overall we observed significant (p < 0.05) reductions by 87 % on average (range 80 - 94.2 %) in the in-vehicle NO2 levels compared to the on-road concentrations. We further found that the activated carbon filter NO2 removal efficiency drops by 6.8 ± 0.6 % per month; showing a faster decay in removal efficiency after the first 6 months of use. These results offer novel insights into how the general population can control and reduce their exposure to traffic related NO2. The use and regular replacement of activated carbon cabin air filters represents a relatively inexpensive method to significantly reduce in-vehicle NO2 exposure.

Produção e uso de filtros de água com carvão ativado derivado de matérias sustentáveis

Objective: to evaluate the efficiency of water treatment filters using activated carbon from different sources of biomass residue. Methods: this is a descriptive experimental study of a quantitative nature carried out at the Centro Universitário Católica de Quixadá, Ceará-Brazil, during the period from January to June 2018. Activated carbon filters were prepared, and subsequently, their efficiency in water treatment was evaluated. Wood waste, green coconut husk, cashew nut shell, and bamboo stem were used as a source of raw material. The water treatment filter was assembled using the column chromatography method by adding sand and cotton as other filter media. Physicochemical parameters were used to evaluate the efficiency of the built filters. Results: principal component analysis selected two water quality components, explaining 80.081% of the total variance. The cophenetic correlation coefficient of r=0.9572 indicates that the estimated dendrogram was good, considering the water quality parameters. Among the filters, bamboo showed the best response among the filters tested, being responsible for the reduction of several factors such as color, turbidity, total hardness, and sodium. Conclusion: activated carbon filters derived from discarded wood and cashew nut shells had little influence on improving water quality compared to the control sample

Transport behavior of nanoplastics in activated carbon column.

Nanoplastics can be produced directly from some artificial products, such as cosmetics, or indirectly from the breakup of large pieces of plastic waste. They have a small particle size, large specific surface area, and stable structure and can concentrate toxic compounds in water. The discharge of nanoplastics into the water environment through urban piping systems or surface runoff may lead to the contamination of surface water resources, which poses a great threat to the safety of drinking water. As a common adsorbent, granular activated carbon (GAC) is widely used in the advanced treatment of drinking water. However, most of the studies focused on the transport ability of nanoplastics in quartz sand, and there is a lack of research on the migration behavior of nanoplastics in activated carbon media. In this study, the stability and pore characteristics of GAC were studied, and its regeneration efficiency was investigated. The transport curves of PSNPs, which have a particle size of 98 ± 9nm and specific surface area of about 67 m2/g, were compared under different ionic strengths, ionic species, flow rates, pH, and humic acid (HA) concentrations. And DLVO theory was used to analyze the transport behavior of nanoplastics in activated carbon column. All experiments were performed at room temperature to make the results generalizable. The results showed that GAC had stable pore structure and excellent adsorption capacity. The surface area and pore volume of GAC are 759 m2/g and 0.357 cm3/g, respectively. And the regeneration rate of GAC can reach 90% and 83.3% after the first two regeneration cycles. On the other hand, at high ionic strength and low pH, the repulsive barrier between PSNPs and activated carbon gradually disappeared; then, more PSNPs were deposited in the activated carbon media, and the concentration of PSNPs in the effluent water was lower. Both the flow rate and HA promoted the transport of PSNPs, but the breakthrough curves of PSNPs did not change significantly when the HA concentration was further increased. At the same ion concentration, PSNPs tend to deposit on the surface of activated carbon in the background solution of Ca2+ compared with Na+. This study reveals the migration mechanism of PSNPs in the activated carbon filter column, which is of great importance to ensure the safety of drinking water and human health.

Effectiveness of Activated Carbon Filter Corn Cob and Durian Skin Dnature Lowers Lead Levels (Pb) in Rain Water

Lead levels (Pb) cause adverse effects on health, toxic effects on the gastrointestinal tract, nerves and kidneys. This study aims to determine the effectiveness of using activated carbon filters for corn cobs and durian husks in reducing lead (Pb) levels in rainwater that passes over zinc. This type of study is an experiment by comparing the decrease in lead (Pb) levels before and after the filtration of activated carbon of corn cobs and durian husks with adsorption times of 30 minutes and 35 minutes. The results of the study before processing obtained lead (Pb) levels in 3 different locations, namely 0.079 mg / l, 0.053 mg / l, and 0.059 mg / l. After processing the activated carbon of corn cobs and activated carbon of durian skin, it is effective in reducing lead (Pb) levels &lt; 0.05 mg / l in accordance with water quality standards according to Permenkes No. 23 of 2017. This can be seen after filtration of activated carbon of corn cobs with an adsorption time of 30 minutes, which is 91% of 0.007 mg / l in PM houses, and an adsorption time of 35 minutes, which is 100% of 0.0 mg / l in HD houses. Then after filtration of activated carbon durian skin with an adsorption time of 30 minutes, which is 64.4% of 0.021 mg / l in HD houses, and an adsorption time of 35 minutes, which is 60.4% of 0.021 mg / l in SU houses. This research suggests that health agencies provide empowerment to the community about the management of clean water and the use of activated carbon in reducing levels of harmful metals, especially lead (Pb).

H2S gas adsorption study using copper impregnated on KOH activated carbon from coffee residue for indoor air purification

Hydrogen sulfide (H2S) can negatively affect human health in confined spaces at even very low concentration due to its strong toxicity. In this work, coffee residue was used to prepare the activated carbon, then was further developed into a copper-impregnated activated carbon filter (Cu/AC) for H2S adsorption. The carbonization temperature has a great influence on the texture characteristics of activated carbon. The optimal activated carbon (BET: 1422 m2/g, Vtotal: 0.655 cm3/g) was achieved at 450 ℃ carbonization and at 750 ℃ KOH-activation. Copper catalyst greatly altered the surface properties of activated carbon by producing a lot of functional groups. The Cu/AC filter showed good H2S adsorption performance (max adsorption capacity: 132.22 mg/g) as it can completely remove H2S with an initial concentration of 400 ppm in a 0.1 m3 chamber within 10 min. The adsorption capacity depended not only on BET surface area, but also on the metal catalyst (copper). In addition, functional groups produced by copper-impregnation also enhanced the adsorption performance and the rate of adsorption, especially oxygen-containing functional groups (eg. O-H and C-O). The isotherm studies showed that the adsorption of H2S on the Cu/AC filter obeyed the Langmuir model, while the adsorption kinetics followed the pseudo-first-order and pseudo-second-order models. The adsorption mechanism is governed by initial film diffusion and subsequent intraparticle diffusion. Furthermore, the Cu/AC filter had excellent regeneration and reusability (still maintained >95% remove efficiency after 5 cycles). Finally, the current study suggested that coffee residue is good activated carbon precursor and can be used as an excellent adsorbent for H2S in confined spaces.

Microbial Water Quality through a Full-Scale Advanced Wastewater Treatment Demonstration Facility.

The fates of viruses, bacteria, and antibiotic resistance genes during advanced wastewater treatment are important to assess for implementation of potable reuse systems. Here, a full-scale advanced wastewater treatment demonstration facility (ozone, biological activated carbon filtration, micro/ultrafiltration, reverse osmosis, and advanced oxidation) was sampled over three months. Atypically, no disinfectant residual was applied before the microfiltration step. Microbial cell concentrations and viability were assessed via flow cytometry and adenosine triphosphate (ATP). Concentrations of bacteria (16S rRNA gene), viruses (human adenovirus and JC polyomavirus), and antibiotic resistance genes (sul1 and bla TEM ) were assessed via quantitative PCR following the concentration of large sample volumes by dead-end ultrafiltration. In all membrane filtration permeates, microbial concentrations were higher than previously reported for chloraminated membranes, and log10 reduction values were lower than expected. Concentrations of 16S rRNA and sul1 genes were reduced by treatment but remained quantifiable in reverse osmosis permeate. It is unclear whether sul1 in the RO permeate was from the passage of resistance genes or new growth of microorganisms, but the concentrations were on the low end of those reported for conventional drinking water distribution systems. Adenovirus, JC polyomavirus, and bla TEM genes were reduced below the limit of detection (∼10-2 gene copies per mL) by microfiltration. The results provide insights into how treatment train design and operation choices affect microbial water quality as well as the use of flow cytometry and ATP for online monitoring and process control.

Evaluation of ozone removal devices applied in ventilation systems

Applying ozone removal devices in ventilation systems is an effective way to reduce building occupant exposure to ozone. However, little is known about the performance of commercially-available ozone removal devices under realistic usage conditions, especially for technologies that have recently emerged for general ventilation such as ultraviolet photocatalytic oxidation (UV–PCO) and catalysis (without UV). A total of 14 ozone removal devices that are representative of products on the market were selected: 11 activated carbon filters, 2 UV-PCO devices, and 1 catalyst filter without UV. We tested these devices with an “ozone stress test” by exposing them to 70 ppb, 107 ppb, and 500 ppb of ozone at 25 °C, 50% RH, and 2.5 m/s face velocity. The device performance was evaluated by the average efficiency at each ozone level, degradation rate at 500 ppb, pressure drop, and a quality factor that combines efficiency and pressure drop. Results show a wide range of single-pass removal efficiency from 3% to 93% at 70 ppb. All devices degraded at a slow rate; at 500 ppb, most devices degraded at 1.5%/h relative to their efficiency at the beginning of this period. The catalyst (no UV) and three 12″ activated carbon devices achieved high efficiency at the least cost of pressure drop. The loading and source of carbon had a significant impact on the efficiency of activated carbon filters. A two-fold increase in carbon loading led to nearly a two-fold higher single-pass removal efficiency. Coal-based carbon degraded 20 times faster than coconut shell-based carbon.

Semi-crystalline microplastics in wastewater plant effluents and removal efficiencies of post-treatment filtration systems

Microplastics (MPs) are ubiquitous in the environment and have been found in every environmental compartment. Wastewater and wastewater treatment plants (WWTPs) have been identified as possible point sources contributing to the emission of microplastic particles (MPP) into the aquatic environment. So far, MPP in wastewater effluents have mainly been analyzed by spectroscopic methods resulting in concentrations as number per volume. In this study, we present mass concentrations in the secondary effluents of four German municipal WWTPs, removal efficiencies of seven post-treatment systems and the resulting load emissions. Differential Scanning Calorimetry (DSC) was used for the analysis of semi-crystalline MPs. The concentrations of secondary effluents ranged from 0.1 to 19.6 µg L-1. Removal efficiencies > 94% were found for a microfiltration membrane (MF), two cloth types of a pile cloth media filter (PCMF), a micro strainer, a discontinuous downflow granulated activated carbon filter (GAC) and a powdered activated carbon (PAC) stage with clarifier and rapid sand filtration. A rapid sand filter (RSF) at WWTP B showed a removal efficiency of 82.38%. Only a continuous upflow GAC filter at WWTP C proved to be unsuitable for MP removal with an average removal efficiency of 1.9%.

Effects of biological activated carbon filter running time on disinfection by-product precursor removal.

Biological activated carbon (BAC) filtration is usually considered to be able to decrease formation potentials (FPs) of disinfection by-products (DBPs) in drinking water treatment plant (DWTP). However, BAC filters with long running time may release microbial metabolites to effluents and therefore increase FPs of nitrogenous DBPs with high toxicity. To verify this hypothesis, this study continuously tracked BAC filters in a DWTP for one year, and assessed effects of old (running time 8-9 years) and new (running time 0-13 months) BAC filters on FPs of 15 regulated and unregulated DBPs. Results revealed that dissolved organic carbon (DOC) removal was slightly higher in the new BAC than the old one. All fluorescent components of dissolved organic matter evidently declined after new BAC filtration, but fulvic acid-like and soluble microbial product-like substances increased after old BAC filtration, which could be caused by microbial leakage. Correspondingly, new BAC filter generally removed more DBP FPs than the old one. 46.5% HAA7 FPs from chlorination and 44.3% THM4 FPs from chloramination were removed by new BAC filter. However, some DBP FPs, especially HAN FPs, were poorly removed or even increased by the old BAC filter. Proteobacteria could be a main contributor for DBP precursor removal in BAC filters. Herminiimonas, most abundant genera in new BAC filter, may explain its better DOC and UV254 removal performance and lower DBP FPs, while Bradyrhizobium, most abundant genera in old BAC filter, might produce more extracellular polymeric substances and therefore increased N-DBP FPs in old BAC effluent. This study provided insight into variations of DBP FPs and microbial communities in the new and old BAC filters, and will be helpful for the optimization of DWTP design and operation for public health.

Does Biological Activated Carbon Filtration Make Chlor(am)inated Drinking Water Safer

Biological activated carbon (BAC) filtration is an effective technology for the removal of natural organic matter. However, one potential drawback of BAC, especially old BAC, is that effluents can contain soluble microbial products released from the biofilm, which are recognized as more toxic nitrogenous DBPs (N-DBPs) precursors. So far, limited studies reported the risk of DBP formation potentials (FPs) increase caused by the microbial leakage of BAC. This study compared removal differences of DBP FPs between two BAC filters operated for 1 year and 8 years in a drinking water plant. The results showed that the total summed haloacetic acid FPs and trihalomethane FPs decreased by 34.31% from chlorination, and 55.01% of the total summed halogen acetonitrile FPs from chloramination were removed by the new BAC. However, Chlorinated haloacetonitriles FPs increased by 2.33% after old BAC filtration. To sum up, BAC filtration decreased most DBP FPs, but a potential risk regarding more toxic N-DBP FPs from old BAC should receive more attention.

Development of respirator design for children using bamboo-based activated carbon filter and bipolar ionization

This paper proposes a respirator for children integrated with bamboo-based activated carbon filters and bipolar ionization as the sterilizer to increase protection from Covid-19 and other pathogens. The respirator, named as Bion-Kids, was designed based on the children's head-and-face anthropometry from direct measurement. The duration of sterilization process is controlled based on the activities, which are classified using the Recurrent Neural Network (RNN) model with dataset acquired from the accelerometer. Manufacturing process of the main body prototype comprises heat bending and 3D printing. The bamboo-based activated carbon filter was synthesized by applying heat and pressure at the strewed activated carbon particles on the N95 filter. Observation using scanning electron microscope showed the ability of the bamboo-based activated carbon filter to adsorb and trap the particles. Result of the qualitative fit test and questionnaire survey indicated that Bion-Kids is suitable and comfortable for the children's face. The result of filtration and bipolar ionization sterilization system analysis have also met the ISO14698 standard by not showing any infiltration of microorganisms on the blood agar media. This device may become an early-stage personal protective equipment against the transmission of Covid-19 and other pathogens.

Microplastic occurrence after conventional and nanofiltration processes at drinking water treatment plants: Preliminary results

Microplastics (MP) have been detected in almost all matrices, including drinking water, and assessing the contamination of drinking water with this type of pollution is of the utmost sanitary importance. This study aims to evaluate MP contamination of inlet river water and drinking water at three drinking water treatment plants (DWTPs) in the Paris region in France. Each plant performs water treatment processes that are efficient for particulate matter removal such as coagulation-flocculation, sand filtration, and granular activated carbon filtration. One of the plants also has a parallel water treatment file that uses microfiltration and nanofiltration processes. This file was investigated to assess its efficiency compared to the others. To our knowledge, this study is the first to investigate MP contamination in a DWTP using nanofiltration processes. The drinking water distribution network was also investigated, with samples taken at three network points. Microplastics contamination of sizes 25–5,000 μm was characterized using micro-Fourier transform infrared spectroscopy (μ-FTIR) in large volume samples (500 L) with complete mapping of each sample. Concentrations ranging from 7.4 to 45.0 MP/L were found in inlet water while concentrations ranging from blank level (0.003 MP/L) to 0.260 MP/L were found in outlet drinking water (overall removal rate above 99%). Polyethylene, polypropylene, and polyethylene terephthalate were the main polymers found both at the inlet and outlet, but ratios varied significantly at the outlet. No MP were detected in four out of the six samples from the nanofiltration file, and were not found to have significantly different concentrations compared to blank level. Concentrations in the distribution network were higher overall than at the corresponding DWTP outlet, although a high degree of variation between samples was observed. Our results suggest that membrane processes of microfiltration and nanofiltration are more efficient than typical treatment processes, and also that a MP re-contamination within the distribution network itself might occur.