Natural Deep Eutectic Solvents (NADES) are composed of supramolecular interactions of two or more natural compounds, such as organic acids, sugars, and amino acids, and they are being used as a new media alternative to conventional solvents. In this study, a new application of NADES is presented as a possible technology for biofilm structural breaker in complex systems since the current solvents used for biofilm cleaning and extraction of biofilm components use hazardous solutions. The NADES (betaine:urea:water and lactic acid:glucose:water) were analyzed before and after the biofilm treatment by attenuated total reflection Fourier-transform infrared spectroscopy and fluorescence excitation-emission matrix spectroscopy. Our results indicate that the green solvents could solubilize up to ≈70 percent of the main components of the biofilms extracellular matrix. The solubilization of the biomolecules weakened the biofilm structure, which could enhance the biofilm solubilization and removal. The NADES have the potential to be an environment-friendly, green solvent to extract valuable compounds and break the main structure from the biofilm, leading to a greener method for extracellular polymeric substance (EPS) extraction and biofilm treatment in various water treatment systems.

Reverse osmosis (RO) membranes inevitably foul due to the accumulation of material on the membrane surface. Instead of trying to reduce membrane fouling by chemical modification of the membrane, a different approach was taken here based on adding a sacrificial coating of two polyelectrolytes onto the membrane. After membrane fouling, this coating was removed by flushing with a highly saline brine solution, and a new coating was regenerated in situ to provide a fresh protective layer (PL) on the membrane surface. The utility of this approach was demonstrated by conducting four consecutive dead-end filtration experiments using a model foulant (alginate, 200 ppm) in a synthetic brackish water (2,000 ppm NaCl). Brine removal and regeneration of the PL coating restored the water flux to an average of 97 ± 3% of its initial flux, compared to only 83 ± 3% for the pristine membrane. The average water flux for the PL coated membranes was 15.5 ± 0.6 L m-2 h-1 until the flux was decreased by 10% versus its initial flux, compared to 13.4 ± 0.5 L m-2 h-1 for the non-treated control. The use of a sacrificial PL coating could therefore provide a more sustainable approach for addressing RO membrane fouling.

The growing demand for fresh water has resulted in increasing use of reverse osmosis (RO) membrane systems for seawater desalination. A major operational problem of RO membrane filtration systems is biofouling – biomass growth causing an unacceptable membrane performance decline. Biofouling reduces the produced water quantity and quality and increases costs. The need for fouling remediation is mainly derived from destructive trial-and-error research with practical membrane modules. Therefore, a clear need existed for the development of a small-sized membrane fouling simulator (MFS) for systematic, low-cost studies. Since the introduction of the MFS in 2006, many articles have appeared which are evaluated in this review. The review describes (i) the location of biofouling in full-scale installations, (ii) development of MFS, (iii) characterization, reproducibility and representativeness of fouling development in the MFS, (iv) applications such as assessing the impact of anti-scalant or biocide dosage, phosphate limitation, feed spacer geometry and linear flow velocity and (v) early warning for biofouling. MFS studies have increased the understanding of biofouling and enabled improved practical membrane performance such as selection of dosed chemicals and feed spacer design. Future MFS studies are anticipated to enable the development of advanced biofouling control strategies.