Journal of Membrane Science 287 (2007) 94–101 Periodic air/water cleaning for control of biofouling in spiral wound membrane elements E.R. Cornelissen a,∗ , J.S. Vrouwenvelder a , S.G.J. Heijman a,b , X.D. Viallefont c , D. Van Der Kooij a , L.P. Wessels a a Kiwa Water Research NV, P.O. Box 1072, 3430 BB Nieuwegein, The Netherlands b Delft University of Technology Faculty, P.O. Box 5048, 2600 GA Delft, The Netherlands c Ecole Nationale Sup´ eri` eure de Chimie de Mulhouse, 3 rue Alfred Werner, 68200 Mulhouse, France Received 11 February 2006; received in revised form 10 October 2006; accepted 10 October 2006 Available online 17 October 2006 Abstract The main problem during the operation of nanofiltration or reverse osmosis membrane plants is fouling of feed spacers in membrane elements due to biofouling and particulate fouling. In order to control biofouling and particulate fouling in membrane elements, both daily air/water cleaning (AWC) and daily copper sulphate dosing (CSD) were investigated and compared to a reference without daily cleaning. A pilot study was carried out for 110 days with three parallel spiral wound membrane elements; AWC, CSD and the reference which were fed by tap water enriched with a biodegradable compound (100 g acetate-C/L). The CSD element, which combined daily copper sulphate dosing and sporadically air/water cleaning, performed best with an increase in pressure drop of 18% and a biomass concentration of 8000 pg ATP/cm 2 within 110 days. This was followed by the AWC element with a pressure increase of 37% and biomass concentration of 20,000pgATP/cm 2 within 110 days. The reference element showed a pressure increase of 120% within 21 days. The presented approach is considered very successful in controlling particulate fouling and biofouling, especially when air/water cleaning is combined with copper sulphate dosing. © 2006 Elsevier B.V. All rights reserved. Keywords: Biofouling; Particulate fouling; Membrane cleaning; Air/water cleaning 1. Introduction Application of membrane filtration in water treatment is in many cases hampered by the occurrence of membrane foul- ing. Four types of fouling are generally distinguished; organic fouling, inorganic fouling (scaling), fouling by particulates and biofouling [1]. Biofouling is the most persistent problem and usually occurs when membranes are applied for the production of drinking water, process water and for desalination of seawa- ter. Biofouling occurs due to accumulation of biomass on the membrane surface by growth and/or deposition leading to oper- ational problems [2]. Biomass formation is usually accompanied by the accumulation of inorganic particles which accelerates the fouling process. The accumulation of biomass is caused by the ∗ Corresponding author. Tel.: +31 306069538; fax: +31 306061165. E-mail addresses: Emile.Cornelissen@kiwa.nl (E.R. Cornelissen), Bas.Heijman@kiwa.nl (S.G.J. Heijman), Xavier.Viallefont@uha.fr (X.D. Viallefont). presence of biodegradable components and biomass in the feed of the membrane installation. A major problem of nanofiltration or reverse osmosis mem- brane plants is the fouling of feed spacers in spiral wound membrane elements due to biofouling and particulate fouling. As a result of this, the pressure drop over the membrane elements increases which disturbs the flow distribution in the feed spacer channels. This results in operational problems in the membrane installation. It is important to reduce and/or prevent this phe- nomenon as efficiently as possible. Many means and methods are available in practice to inactivate biomass during membrane cleaning or during biocide dosing [3]. However, in practice sometimes chemical cleaning alone is not sufficient to con- trol biofouling, because foulants are insufficiently removed by chemical cleaning [4]. Debris from inactivated biomass which is not removed from membrane elements can lead to an accelerated regrowth of biomass during normal production after membrane cleaning [4]. Biomass has to be physically removed. In order to remove (inactivated) biomass from membrane elements, both hydraulical and chemical action can be used which are both 0376-7388/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2006.10.023