Desalination, Vol.131, No.1-3, 257-269, 2000
Comparison of NF/RO membrane performance in integrated membrane systems
Within the framework of the project 'Integrated multi-objective membrane systems for control of microbials and DBP precursors, funded by AWWARF and USEPA, four integrated membrane systems (IMSs) for surface water treatment were investigated. The identified IMSs are based on pretreatments including slow sand filtration, bank filtration, coagulation-sedimentation-rap id filtration (CSF) and ultrafiltration respectively. The IMSs were tested on three locations in the US and three locations in The Netherlands. One of the primary objectives of the project was to compare membrane performance, a conventional NF system applied to ground water was used as a reference. Membrane performance was studied by normalising process data towards the mass transfer coefficient (MTC) and normalised feed channel pressure drop (NPD). Results show that a soil passage is to be preferred, especially when the water can be extracted under anaerobic conditions; such an IMS leads to a low cleaning frequency at low costs. When soil passage is not possible due to local circumstances, ground water conditions can be approximated by slow sand filtration after a CSF pretreatment, Since slow sand filtration is a space consuming technique, an IMS was investigated based on ultrafiltration after CSF pretreatment. After optimization of both CSF pretreatment and ultrafiltration no significant fouling of the RO membranes was observed.
Keywords:nanofiltration;reverse osmosis;fouling;scaling;productivity;integrated membrane system;costs