Browsing by Author "Hillis, Peter"

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    Combined coagulation and membrane microfiltration for removal of natural organic material (nom)
    (1999-03) Hillis, Peter; Judd, Simon J.
    The removal of natural organic matter (NOM) is a key requirement of many processes in potable water treatment. Conventionally, removal of NOM and colloidal material has been achieved by coagulation with inorganic coagulants followed by either direct rapid gravity filtration alone or clarification (sedimentation or flotation) followed by at least one stage of rapid gravity filtration. An alternative to conventional processes is to combine membrane microfiltration (MF) with coagulation for NOM removal. The advantages of MF technology over traditional sand filters is the maintenance of an absolute barrier throughout the filtration process, thereby enhancing the physical separation process by presenting an absolute barrier to suspended materials. This thesis presents the results from such a system. A 9.6m2 hollow fibre hydrophilic polysulphone MF membrane system was used in combination with ferric sulphate under controlled pH conditions. The system was operated under constant flow condition and the coagulant concentration varied to assess performance. Coagulation conditions which promoted rapid aggregation of particles was found to give best performance with respect to pressure development, this coincided with a zeta potential at or near zero. Also, a pre-flocculation time of 20 seconds was found to be sufficient to allow complete removal of material associated with the coagulation process. Comparison with other workers showed similar results for the specific cake resistance despite considerable differences in both the scale and type of system used.
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    A model for predicting dissolved organic carbon distribution in a reservoir water using fluorescence spectroscopy
    (Elsevier Science B.V., Amsterdam., 2004-02-01T00:00:00Z) Goslan, Emma Harriet; Voros, Sandrine; Banks, Jenny; Wilson, Derek; Hillis, Peter; Campbell, Andrew T.; Parsons, Simon A.
    A number of water treatment works (WTW) in the north of England (UK) have experienced problems in reducing the dissolved organic carbon (DOC) present in the water to a sufficiently low level. The problems are experienced in autumn/ winter when the colour increases and the coagulant dose at the WTW needs to be increased in order to achieve sufficient colour removal. However, the DOC content of the water varies little throughout the year. To investigate this further, the water was fractionated using resin adsorption techniques into its hydrophobic (fulvic and humic acid fractions) and hydrophilic (acid and non-acid fractions) components. The fractionation process yields useful information on the changing concentration of each fraction but is time consuming and labour intensive. Here, a method of rapidly determining fraction concentration was developed using fluorescence spectroscopy. The model created used synchronous spectra of fractionated material compared against bulk water spectra and predicted the fraction concentrations to within 10% for a specific water. The model was unable to predict fraction concentrations for waters from a different watershed.