In treatment of groundwater with reverse osmosis, the applied antiscalant can significantly contribute to the formation of biofouling, especially when legislation enforces the use of biodegradable, phosphorous-free products. As an alternative to extensive piloting, the use of the membrane fouling simulator (MFS) is proposed here to assess the biomass growth potential of different antiscalants. The biomass growth potential of two newly developed, phosphorous-free antiscalants was compared to a blank (no antiscalant) and a phosphorous-based antiscalant. The difference in biomass growth potential in the four experiments was significant, with the phosphorous-based antiscalant showing little biomass accumulation and strong and moderate biomass accumulation for the two newly developed phosphorous-free antiscalants. The results of visual observation and pressure measurements of the MFS were compared to the results of autopsy of the membrane sheets. Visual and pressure measurements were found to be a more reliable method to judge the biomass accumulation than membrane autopsy. In a comparison study of MFSs and test rigs with 4″ spiral-wound membrane modules, similar results were found, validating MFS use for simulating membrane modules.
Keywords: antiscalant, biofouling, groundwater, membrane fouling simulator, nanofiltration, reverse osmosis