WATER E X PLOR ATION
GRIME DOES PAY WHEN IT COMES TO WASTEWATER FILTERS A grimy layer on wastewater filters could slow the spread of antibiotic resistance. B E S E Super-adsorbent crystals of Cr-soc-MOF-1.
Dalal Alezi
than 100 adsorption-desorption cycles. Eddaoudi also emphasizes that wateradsorbing MOFs are ready to provide effective solutions to challenges other than regulating humidity, such as tackling water scarcity and environmental sustainability, in energy-efficient ways. Possibilities include harvesting drinkable water from air for use in water desalination and purification.
“O u t p e r f o r m s all exisiting MOFs in terms o f c a p a c i t y, reversibility and cyclic p e r f o r m a n c e .” The researchers are now working to scale up their water-adsorbing materials in order to demonstrate commercial potential and move into real-world applications. Abtab, S.M.T., Alezi, D., Bhatt, P.M., Shkurenko, A., Belmabkhout, Y., Aggarwal, H., Weseliński,L.J., Alsadun, N., Samin, U., Hedhili, M.N. & Eddaoudi., M. Reticular chemistry in action: A hydrolytically stable MOF capturing twice its weight in adsorbed water. Chem 4, 94-105 (2018).
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Accumulating grime on sewage treatment membranes has long been considered a problem, yet it may help remove antibiotic-resistant bacteria and antibiotic resistance genes from wastewater that is treated in anaerobic membrane bioreactors. Because wastewater is laced with antibiotics used in hospitals, homes and agriculture, treatment plants are potential hotspots for bacteria to develop resistance and transfer resistance genes between species. Peiying Hong of KAUST’s Water Desalination and Reuse Center, together with her Ph.D. student Hong Cheng, wanted to know how the biofouling, or buildup of grime, of membranes that filter pollutants from sewage affects their ability to filter antibiotic-resistant bacteria and bacterial antibiotic resistance genes. “The conventional wisdom is that biofouling is a problem and, as engineers, we would like to eradicate the biofoulant layer because it hinders the flow of water,” explains Cheng.
“But, our study showed that biofouling can help remove contaminants from wastewater by functioning as a layer that adsorbs them.” Hong and Cheng used a labsized bioreactor fed with synthetic wastewater containing three types of antibiotic-resistant bacteria and three types of antibiotic resistance genes. The experimental reactor treats wastewater using nonoxygen-consuming, or anaerobic, microorganisms that consume and degrade its solid materials and pollutants. Anaerobic membrane bioreactors have potential as sustainable alternatives to the aerobic membrane bioreactors. The aerobic ones use oxygen-consuming microorganisms to degrade pollutants, requiring lots of energy to aerate the system. The treated wastewater was filtered through three increasingly Peiying Hong (left) and Ph.D. student Hong Cheng study the biofouling of membranes that filter pollutants from sewage and antibiotic-resistant bacteria and bacterial antibiotic resistance genes.