AS THE PROBLEMS associated with water scarcity and declining water quality become more apparent in some parts of the county, water reuse is becoming an increasingly common option for communities to augment their water supplies. Water reuse is also becoming a more widespread option for managing wastewater rather than simply discharging into a surface water body. As water reuse becomes more common, the use of membranes has become more mainstream, acting as a physical barrier for pathogens and other chemical compounds of interest. However, a major issue regarding membranes is their long-term integrity and the cost of cleaning and continually monitoring membrane performance to ensure proper operations. Ideally, membranes would be resilient to challenges to integrity and be able to recover from damages.
Recently, there has been advancement in self-healing materials in structural, coating, and biomedical research applications. An upcoming research project being led by Dr. Jaehong Kim of Yale University and funded by the Water Research Foundation, Self-Healing Hydrogel-Composite Membranes: From Proof of Concept to Water Reuse Application, aims to build on these advances to develop self-healing membranes for use in water reuse applications. If successful, this would allow the use of membranes with less need for ongoing maintenance and integrity monitoring. This may also allow for water reuse to be practiced in locations where long-term maintenance of membranes may be a hindrance to application due to financial or technical capacity constraints.
The current generation of membranes that are being used are only operational as long as the integrity of the membrane is preserved over time. This is generally done through continuous monitoring and developing new methods of detecting membrane damage. However, current monitoring techniques can be costly and cannot currently locate the exact location of a breach, not to mention repairing a breach. Such monitoring can be especially difficult for decentralized treatment systems or small systems that may not have the capacity for traditional monitoring and maintenance protocols. By developing membranes that are more resilient to damage, there may be less need for monitoring and ongoing maintenance. This may allow small and decentralized systems to still utilize membrane-based treatment and maintain a level of assurance in the quality of treatment that is being provided.
The concept of “self-healing” commonly refers to the property of a material to restore its original properties after being damaged. Self-healing materials have been developed before, but many of these materials require outside stimulus such as heat, light, or pH changes for the self-healing properties to take effect. In addition, many self-healing materials are sensitive to moisture. For obvious reasons, these are all properties that would preclude self-healing materials from being used in a water treatment application, so further innovation is needed.
For this upcoming research, hydrogels are being investigated which do not have the same limitations. Hydrogels are materials that can absorb large amounts of water and swell to a high degree while maintaining their structure. In the context of membranes, they can create a barrier to foulant disruption that may plague other types of membranes and may have the potential to reduce fouling of membranes. The hydrogel network size within a membrane can be used as a sieve to reject solutes while allowing water to pass through. In addition to their own self-healing property, hydrogels have been used to impart self-healing to composite materials. In such cases, the swelling ability of hydrogels is usually the mechanism of healing.Costs are rising, supplies are dwindling and the clock is ticking. Explore solutions and new ways to collaborate by joining your colleagues in San Diego next February at the Western Water Summit. Click here for details