title: Application of pulsed UV-irradiation and pre-coagulation to control ultrafiltration membrane fouling in the treatment of micro-polluted surface water.
abstract: A major cause of ultrafiltration (UF) membrane fouling is the accumulation of microorganisms and their associated soluble products. To mitigate fouling the application of pulsed short-wavelength ultraviolet (UVC) light (around 254 nm) within the membrane tank together with pre-coagulation was investigated. In mini-pilot-scale tests carried out in parallel with conventional pre-treatment (CUF), the impact of pulsed UV (CUF-UV) at different UV irradiances and fluxes on the increase of trans-membrane pressure (TMP) was evaluated and explained in terms of the quantity and nature of membrane deposits in the membrane cake layer and pores. The results indicated that at a flux of 20 L m-2h-1, the pulsed UV (1 min within 31 min cycle) at 3.17 × 10-2W/cm2prevented any measureable increase in TMP over a period of 32 days, while there was a fourfold increase in TMP for the conventional pre-treatment. For the CUF-UV system the concentration of bacteria and soluble microbial products was much less than the conventional CUF system, and the cake layer was thinner and contained less biopolymers (proteins and polysaccharides). In addition, the pores of the CUF-UV membrane appeared to have less organic deposits, and particularly fractions with a high molecular weight (>10 kDa). At a lower UV irradiance (1.08 × 10-2W/cm2), or higher flux (40 L m-2h-1) with the same UV irradiance, there was a measurable increase in TMP, indicating some fouling of the CUF-UV membrane, but the rate of TMP development was significantly lower (∼50%) than the conventional CUF membrane system. Overall, the results show the potential advantages of applying intermittent (pulsed) UVC irradiation with coagulation to control UF membrane fouling.
authors.affiliation: Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. Electronic address: w.yu@imperial.ac.uk.
authors.forename: Wenzheng
authors.initials: W
authors.lastname: Yu
authors.affiliation: Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London WC1E 6BT, UK. Electronic address: l.campos@ucl.ac.uk.
authors.forename: Luiza C
authors.initials: LC
authors.lastname: Campos
authors.affiliation: Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. Electronic address: n.graham@imperial.ac.uk.
authors.forename: Nigel
authors.initials: N
authors.lastname: Graham
mesh_terms: D008567:Membranes, Artificial; D014462:Ultrafiltration; D014466:Ultraviolet Rays; D014876:Water Pollution; D018508:Water Purification
chemical_list: D008567:Membranes, Artificial
keywords: Coagulation; Membrane fouling; UVC light; Ultrafiltration; Water treatment