title: The impact of climate change on the treatability of dissolved organic matter (DOM) in upland water supplies: a UK perspective.
abstract: Climate change in the UK is expected to cause increases in temperatures, altered precipitation patterns and more frequent and extreme weather events. In this review we discuss climate effects on dissolved organic matter (DOM), how altered DOM and water physico-chemical properties will affect treatment processes and assess the utility of techniques used to remove DOM and monitor water quality. A critical analysis of the literature has been undertaken with a focus on catchment drivers of DOM character, removal of DOM via coagulation and the formation of disinfectant by-products (DBPs). We suggest that: (1) upland catchments recovering from acidification will continue to produce more DOM with a greater hydrophobic fraction as solubility controls decrease; (2) greater seasonality in DOM export is likely in future due to altered precipitation patterns; (3) changes in species diversity and water properties could encourage algal blooms; and (4) that land management and vegetative changes may have significant effects on DOM export and treatability but require further research. Increases in DBPs may occur where catchments have high influence from peatlands or where algal blooms become an issue. To increase resilience to variable DOM quantity and character we suggest that one or more of the following steps are undertaken at the treatment works: a) 'enhanced coagulation' optimised for DOM removal; b) switching from aluminium to ferric coagulants and/or incorporating coagulant aids; c) use of magnetic ion-exchange (MIEX) pre-coagulation; and d) activated carbon filtration post-coagulation. Fluorescence and UV absorbance techniques are highlighted as potential methods for low-cost, rapid on-line process optimisation to improve DOM removal and minimise DBPs.
authors.affiliation: Grantham Institute for Climate Change, Imperial College London, South Kensington, London SW7 2AZ, UK; Department of Civil and Environmental Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK. Electronic address: j.ritson12@imperial.ac.uk.
authors.forename: J P
authors.initials: JP
authors.lastname: Ritson
authors.affiliation: Department of Civil and Environmental Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK.
authors.forename: N J D
authors.initials: NJ
authors.lastname: Graham
authors.affiliation: Department of Civil and Environmental Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK.
authors.forename: M R
authors.initials: MR
authors.lastname: Templeton
authors.affiliation: Walker Institute for Climate Systems Research and Soil Research Centre, Geography and Environmental Science, School of Human and Environmental Sciences, University of Reading, Whiteknights, Reading, RG6 6DW, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Clark
authors.affiliation: Wolfson Carbon Capture Laboratory, School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
authors.forename: R
authors.initials: R
authors.lastname: Gough
authors.affiliation: Wolfson Carbon Capture Laboratory, School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
authors.forename: C
authors.initials: C
authors.lastname: Freeman
mesh_terms: D002244:Carbon / Q000032:analysis; D057231:Climate Change; D006113:United Kingdom; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000706:statistics & numerical data*
chemical_list: D014874:Water Pollutants, Chemical; D002244:Carbon
keywords: Catchment water quality; Climate change; Coagulation; Disinfection by-products; Dissolved organic carbon; Drinking water treatment