AWWA WQTC64017

Although the majority of the membrane WTWs comply with the design specifications, Suez- Environnement (SE) experience indicates that the fouling propensity of the feed water is not systemically well determined, which can limit the plant output and provides inadequate final water quality. Thus, the need for further investigation of pretreatment processes or operational procedure to prevent membrane fouling was identified as an area of interest for SE, which has to face this issue at a number of membrane plants. In that context, the objective of the project was to assess methods to improve the reliability for the operation of existing ultrafiltration (UF) membrane water treatment facilities for various feed waters. This project included the assessment of conventional pretreatment consisting of a clarification step and in-line coagulation to reduce foulant contaminant and guarantee suitable final water quality. The integrated process including coagulation, settling and UF confirmed a significant improvement of the overall performances of the membrane process albeit some difficulties encountered with membrane clogging and ageing. The use of small doses of coagulant directly injected upstream the membrane, a process patented by Degremont and called "Micro-coagulation", appeared also as an effective way to control fouling from dissolved organic compounds and low water temperature. However, low removal of natural organic matter throughout the process may limit the use of the micro-coagulation on water where disinfection byproducts are an issue. Includes 9 references, tables, figures.