Nanofiltration for PFAS removal from raw water
Farhan, Mohammad (2025)
2025
Master's Programme in Environmental Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
Hyväksymispäivämäärä
2025-10-14
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202510139875
https://urn.fi/URN:NBN:fi:tuni-202510139875
Tiivistelmä
Per and polyfluoroalkyl substances (PFAS) are environmental contaminants which have been observed in both surface and groundwater in Finland. Since these substances are highly bio accumulative, they endanger human health and the quality of drinking water. Conventional treatment procedures are not always beneficial, especially with short chain PFAS, which have higher solubility, and these might cause difficulty to treat water.
This thesis examines the potential of nanofiltration (NF) technology, specifically focusing on NF90 and NF270 membranes in removing PFAS from Finnish raw water through a review of the literatures. The study is based on published experimental and pilot-scale studies. In addition, it considers the regulatory limits set by the European Union. The study focused on groundwater in Finland as 9 PFAS compounds were identified frequently including several short chain PFAS with higher concentrations compared to surface water. Based on the reviewed literature, NF90 and NF270 membranes were found to be among the most efficient options in removing PFAS from raw water due to low molecular weight cutoff, higher permeability, and suitable operational parameters. Removal efficiencies of the compounds for these two membranes were obtained from literature sources that used feed water with characteristics comparable to Finnish groundwater (e.g., pH, cations). The results showed that both membranes could reduce PFAS concentrations below the guideline value (4.4 ng/L) set by European Food Safety Authority (EFSA). However, NF90 can achieve lower concentrations in permeate particularly for short-chain PFPeA, PFHxA, and PFBS. NF90 can achieve over 98% removal, reducing concentrations from 11.6 ng/L in feed water to 0.23 ng/L in permeate for the combined concentration of 4 PFAS which are PFOS, PFNA, PFOA and PFHxS.
In addition to technical performance, this thesis focuses on the practical concerns of using NF technology in Finnish water treatment plants. One of the key considerations includes pretreatment to control fouling from iron and manganese, where conventional aeration and sand filtration can be a viable option. Hydraulic design parameters such as permeate flux, recovery rate, and maximum feed flow, etc., were presented for optimal design consideration. Cost implications suggested that energy consumption and membrane replacement can be the major contributors in operational expenses. NF concentrate with high PFAS concentration could be another issue where this study found that supercritical water oxidation (SCWO) can be a feasible option for PFAS destruction, as it is already in large-scale operation in other Nordic countries for water phase and it is able to destroy long and short PFAS quickly compared to other technologies such as photocatalysis or electrochemical treatment.
However, as this work was limited to utilization of literature data, further investigation is required to confirm the results under Finnish conditions. Future research should focus on pilot testing and plant-specific monitoring to verify the performance of nanofiltration in removing PFAS in practice. Costs and PFAS waste management should also be evaluated to understand the techno-economic feasibility of NF technology in Finland.
This thesis examines the potential of nanofiltration (NF) technology, specifically focusing on NF90 and NF270 membranes in removing PFAS from Finnish raw water through a review of the literatures. The study is based on published experimental and pilot-scale studies. In addition, it considers the regulatory limits set by the European Union. The study focused on groundwater in Finland as 9 PFAS compounds were identified frequently including several short chain PFAS with higher concentrations compared to surface water. Based on the reviewed literature, NF90 and NF270 membranes were found to be among the most efficient options in removing PFAS from raw water due to low molecular weight cutoff, higher permeability, and suitable operational parameters. Removal efficiencies of the compounds for these two membranes were obtained from literature sources that used feed water with characteristics comparable to Finnish groundwater (e.g., pH, cations). The results showed that both membranes could reduce PFAS concentrations below the guideline value (4.4 ng/L) set by European Food Safety Authority (EFSA). However, NF90 can achieve lower concentrations in permeate particularly for short-chain PFPeA, PFHxA, and PFBS. NF90 can achieve over 98% removal, reducing concentrations from 11.6 ng/L in feed water to 0.23 ng/L in permeate for the combined concentration of 4 PFAS which are PFOS, PFNA, PFOA and PFHxS.
In addition to technical performance, this thesis focuses on the practical concerns of using NF technology in Finnish water treatment plants. One of the key considerations includes pretreatment to control fouling from iron and manganese, where conventional aeration and sand filtration can be a viable option. Hydraulic design parameters such as permeate flux, recovery rate, and maximum feed flow, etc., were presented for optimal design consideration. Cost implications suggested that energy consumption and membrane replacement can be the major contributors in operational expenses. NF concentrate with high PFAS concentration could be another issue where this study found that supercritical water oxidation (SCWO) can be a feasible option for PFAS destruction, as it is already in large-scale operation in other Nordic countries for water phase and it is able to destroy long and short PFAS quickly compared to other technologies such as photocatalysis or electrochemical treatment.
However, as this work was limited to utilization of literature data, further investigation is required to confirm the results under Finnish conditions. Future research should focus on pilot testing and plant-specific monitoring to verify the performance of nanofiltration in removing PFAS in practice. Costs and PFAS waste management should also be evaluated to understand the techno-economic feasibility of NF technology in Finland.