A case study of organic micropollutants in a major Swedish water source – Removal efficiency in seven drinking water treatment plants and influence of operational age of granulated active carbon filters

• Published in: The Science of the total environment 2020-03, Vol.706, p.135680-135680, Article 135680
• Main Authors: Tröger, Rikard, Köhler, Stephan J., Franke, Vera, Bergstedt, Olof, Wiberg, Karin
• Format: Article
• Language: English
• Subjects: Carbon; Drinking Water; Granular activated carbon; Mass spectrometry; Micropollutants; PFAS; Sweden; Vattenbehandling; Water Pollutants, Chemical; Water Purification; Water Treatment
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.135680

A wide range of organic micropollutants (n = 163) representing several compound categories (pharmaceuticals, pesticides, per- and polyfluorinated alkyl substances, flame retardants, phthalates, food additives, drugs and benzos) were analysed in water samples from the Göta Älv river (Sweden's second largest source water). The sampling also included raw water and finished drinking water from seven drinking water treatment plants and in addition a more detailed sampling at one of the treatment plants after six granulated active carbon filters of varying operational ages. In total, 27 organic micropollutants were detected, with individual concentrations ranging from sub ng L−1 levels to 54 ng L−1. The impact of human activities along the flow path was reflected by increased concentrations downstream the river, with total concentrations ranging from 65 ng L−1 at the start of the river to 120 ng L−1 at the last sampling point. The removal efficiency was significantly (p = 0.014; one-sided t-test) higher in treatment plants that employed granulated active carbon filters (n = 4; average 60%) or artificial infiltration (n = 1; 65%) compared with those that used a more conventional treatment strategy (n = 2; 38%). The removal was also strongly affected by the operational age of the carbon filters. A filter with an operational age of 12 months with recent addition of ~10% new material showed an average removal efficiency of 92%, while a 25-month old filter had an average of 76%, and an even lower 34% was observed for a 71-month old filter. The breakthrough in the carbon filters occurred in the order of dissolved organic carbon, per- and polyfluorinated alkyl substances and then other organic micropollutants. The addition of fresh granulated active carbon seemed to improve the removal of hydrophobic organic compounds, particularly dissolved organic carbon and per- and polyfluorinated alkyl substances. [Display omitted] •163 organic micropollutants (OMPs) were analysed in river, raw and drinking water from Sweden.•Total concentrations of 27 detected OMPs increased downstream the river.•Removal efficiency of OMPs was affected by treatment strategy and operational age of GAC.•Breakthrough in GAC filters occurred in the order DOC, PFASs and other OMPs.•Topping up with a portion (~10%) of fresh GAC appeared to improve removal of DOC and PFASs.