This investigation aimed to compare the disinfection by-product formation potentials (DBPFPs) of three UK surface waters (1 upland reservoir and 2 lowland rivers) with differing characteristics treated by (a) a full scale conventional process and (b) pilot scale processes using a novel suspended ion exchange (SIX) process and inline coagulation (ILCA) followed by ceramic membrane filtration (CMF). Liquid chromatography-organic carbon detection analysis highlighted clear differences between the organic fractions removed by coagulation and suspended ion exchange. Pretreatments which combined SIX and coagulation resulted in significant reductions in dissolved organic carbon (DOC), UV absorbance (UVA), trihalomethane and haloacetic acid formation potential (THMFP, HAAFP), in comparison with the SIX or coagulation process alone. Further experiments showed that in addition to greater overall DOC removal, the processes also reduced the concentration of brominated DBPs and selectively removed organic compounds with high DBPFP. The SIX/ILCA/CMF process resulted in additional removals of DOC, UVA, THMFP, HAAFP and brominated DBPs of 50, 62, 62, 62% and 47% respectively compared with conventional treatment.

The influence of pre-treatment on the suppression of irreversible (IR) fouling of ceramic membranes challenged with three UK surface waters has been studied at pilot scale. An initial scoping study compared the efficacy of suspended ion exchange (SIX) and clarification (coagulation followed by sludge blanket clarification) individually and in combination. Direct membrane filtration following in-line coagulation (ILCA) was also investigated with and without SIX. The impact on the various organic fractions, specifically high molecular weight (HMW) biopolymers (BPs) and humic substances (HSs), and lower molecular weight (LMW) building blocks (BBs) and neutrals, was studied using liquid chromatographyorganic carbon detection (LC-OCD). Results revealed SIX and coagulation to preferentially remove the LMW and HMW organic fractions respectively. Residual HMW organic matter (primarily BPs) following SIX pretreatment were retained by the membrane which led to rapid irreversible fouling. Coagulation pre-treatment provided stable membrane operation and the residual LMW organics were not significantly retained by the membrane. Combining clarification and SIX resulted in

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In-line coagulation adsorption (ILCA) followed by ceramic microfiltration (CMF) was tested at pilot scale and compared to a full scale traditional process consisting of coagulation and dissolved air flotation (DAF) followed by rapid gravity sand filtration (RGF), for treating a reservoir water source which is prone to high concentrations of algae. The ILCA CMF process was shown to remove 10–16% more dissolved organic carbon (DOC) and reduced disinfection by-product formation potential (DBPFP) by 9–13% in comparison to conventional treatment (optimised coagulation). ILCA effectively controlled membrane fouling allowing the ceramic membranes to be operated at high flux (200 l/m2h) with low membrane fouling (0.9–1.9 kPa/day). A process comprising ILCA and direct ceramic microfiltration was shown to provide very stable treated water quality under a range of challenging conditions. Additionally, the process is more compact showing significant reductions (circa 60%) in footprint relative to a conventional DAF/RGF process.