2-Aminoimidazole reduces fouling and improves membrane performance

Biofouling is difficult to control and hinders the performance of membranes in all applications but is of particular concern when natural waters are purified. Fouling, via multiple mechanisms (organic-only, biofouling-only, cell-deposition-only, and organic + biofouling), of a commercially available membrane (control) and a corresponding membrane coated with an anti-biofouling 2-aminoimidazole (2-AI membrane) was monitored and characterized during the purification of a natural water. Results show that the amount of bacterial cell deposition and organic fouling was not significantly different between control and 2-AI membranes; however, biofilm formation, concurrent or not with other fouling mechanisms, was significantly inhibited (95–98%, p < 0.001) by the 2-AI membrane. The limited biofilm that formed on the 2-AI membrane was weaker (as indicated by the polysaccharide to protein ratio) and thus presumably easier to remove. The conductivity rejection by the 2-AI and control membranes was not significantly different throughout the 75-h experiments, but the rejection of dissolved organic carbon by biofouled (biofouling-only, cell-deposition-only, and organic + biofouling) 2-AI membranes was statistically higher (10–12%, p = 0.003–0.07). When biofouled, the water permeance of the 2-AI membranes decreased significantly less (p < 0.05) over 75 hours than that of the control membranes, whether or not other additional types of fouling occurred concurrently. Despite the initially lower water permeances of 2-AI membranes (11% lower on average than controls), the 2-AI membranes outperformed the controls (10–11% higher average water permeance) after biofilm formation occurred. Overall, 2-AI membranes fouled less than controls without detriment to water productivity and solute rejection.