Microfiltration membrane plant start up: A case study with autopsy and permeability recovery analysis

Authors: Porcelli, N.¹; Hillis, P.²; Judd, S.¹

Source: Environmental Technology, Volume 30, Number 6, May 2009 , pp. 629-639(11)

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Abstract:

A potable water treatment plant, supplied from a low NOM (natural organic matter), low turbidity source with precoagulation and two-stage pressure sand filtration, had a MF (microfiltration) membrane process added to meet UK Water Regulations. An autopsy of the membrane modules showed that despite upstream coagulation/filtration with chlorination, a biofilm of EPS (extracellular polymeric substances) and inorganic particulates had developed. Backwashing under laboratory conditions yielded an almost full recovery. Laboratory-scale modules of fouled fibres from pre-commissioning and post-commissioning were assembled and cleaned. The recovery was modelled and optimized with a response surface experiment using variables of concentration, soak period and temperature. The pre-commissioning fibres were more recovered by longer chemical soak times at higher cleanant concentrations than the post-commissioning fibres. Comparative tests on post-commissioning fibres indicated that full recovery was possible with organic acids. It was concluded that start-up of new membrane plants may involve fouling conditions not necessarily representative of those under routine operating conditions, such that modification to prescribed cleaning operations may be required.

Keywords: microfiltration; fouling; autopsy; case study; chemical cleaning

Document Type: Research article

DOI: http://dx.doi.org/10.1080/09593330902849467

Affiliations: 1: Cranfield University, Cranfield, Bedfordshire, UK 2: United Utilities, Great Sankey, Warrington, UK

Publication date: 2009-05-01