Construction and validation of a long-channel membrane test cell for representative monitoring of performance and characterization of fouling over the length of spiral-wound membrane modules

Abstract

a b s t r ac tA long-channel membrane test cell (LCMTC) with the same length as full-scale elements was developed to simulate performance and fouling in nanofiltration and reverse osmosis spiral-wound membrane modules (SWMs). The transparent LCMTC enabled simultaneous monitoring of SWM performance indicators: feed channel pressure drop, permeate flux and salt passage. Both permeate flux and salt passage were monitored over five sections of the test cell and were related to the amount and composition of the accumulated foulant in these five sections, illustrating the unique features of the test cell. Validation experiments at various feed pressures showed the same flow profile and the same hydraulic behaviour as SWMs used in practice, confirming the representativeness and suitability of the test cell to study SWM operation and fouling. The importance to apply feed spacers matching the flow channel height in test cell systems was demonstrated. Biofouling studies showed that the dosage of a biodegradable substrate to the feed of the LCMTC accelerated the gradual decrease of membrane performance and the accumulation of biomass on the spacer and membrane sheets. The strongest permeate flux decline and the largest amount of accumulated biomass was found in the first 18 cm of the test cell. The LCMTC showed to be suitable to study the impact of biofilm development and biofouling control strategies under representative conditions for full-scale membrane elements.

The membrane fouling simulator: development, application, and early-warning of biofouling in RO treatment

“…Such device should be representative for conventionally used membrane modules, thus involving the used materials (properties and structure) such as membrane and spacer, the height of the flow channels and hydraulics. The membrane fouling simulator (MFS) was introduced in 2006 [4] and since then many articles have appeared on various research aspects of biofilm characterization [2,3,[27][28][29][30][31][32][33][34][35][36], biofouling control [5,[37][38][39][40][41][42][43][44][45][46][47][48][49], and strategies for early warning of biofouling [50][51][52][53][54][55] applying the developed MFS.…”

“…This means that the concentrate of a pressure vessel can be fed into a second pressure vessel, increasing the total water production of the installation. An industrial size membrane element has a length of 1 m (40 inches) and contains membrane sheets with a length of 0.93 m [31].…”

“…Fouling development can be studied by sensitive monitoring of the FCP and visual observations through the simulator sight window. A variety of MFSs have been developed [3] for varying purposes such as for studying (i) feed spacers geometry causing variation of flow channel height in MFSs [37], (ii) the hydraulic biofilm resistance with permeate production [107,108], (iii) biofilm processes and its impact on hydraulics [109], and (iv) the impact and sequence of biofouling development on membrane performance parameters including FCP, permeate flux and salt passage in a recently developed 1 m long MFS (long-channel membrane test cell) with five sections over the length, enabling the measurement of permeate flux and salt passage over the test cell length [31]. This 1 meter long MFS is characterized by a more rigid structure (4 cm wide membrane sheets, 24 bolts with metal support) compared with the earlier developed prototype cell, and proved to be representative for membrane modules for both flow profile and flow pressure drop relationship.…”

“…This 1 meter long MFS is characterized by a more rigid structure (4 cm wide membrane sheets, 24 bolts with metal support) compared with the earlier developed prototype cell, and proved to be representative for membrane modules for both flow profile and flow pressure drop relationship. This 1 m long MFS with the sight window has been tested up to 15 bar [31], therefore, there is a need for the development of a high pressure simulator suitable for operation at pressure up to 80 bar representing membrane modules used in practice for seawater desalination. The next-generation of high pressure MFSs would enable the study of the effect of hydraulic pressure and concentration polarization (CP) and advanced biofouling control strategies.…”

Technical Concepts for the Investigation of Spatial Effects in Spiral-Wound Microfiltration Membranes

“…Another approach is to derive the filtration performance of SWMs from observations in flat sheet test cells [34,35,36,37]. Mo and Ng [35] created a test channel (1.00 m × 0.03 m) to measure protein permeation, flux, and pressure drop along the feed channel in a reverse osmosis application.…”