Page 255 - ro membanes

238 10. COMPARISON OF GRANULAR MEDIA AND MEMBRANE PRETREATMENT
outside-in filtration direction, and airewater backwash. These products are projected to be commercially available by the year 2025.
Meanwhile, a number of companies, such as Suez, Veolia, H2O Innovation, and Wigen Water are already offering Universal (Open Platform) UF/MF rack systems, which can accommodate the latest models of pressure-driven UF membrane products made of PVDF material from most of the key membrane manufacturers of products and services for the desalination industry (Guibert, 2014; Sweizbin, 2017).
Another challenge that faces the wider use of membrane pretreatment is the limited dura- bility, loss of integrity, and relatively short useful life of the membranes. The limited pretreat- ment membrane lifespan has also adverse effect on the costs for their replacement. Currently, the annual MF/UF seawater membrane replacement costs are typically comparable to the annual replacement costs of the SWRO membranes they are installed to protect. These chal- lenges are expected to be addressed with the development of alternative ceramic membrane materials or other plastic materials, which are less sensitive to integrity failures from sharp objects and biofouling (Kang et al., 2016).
To date, the main emphasis of the research and development in the field of membrane pre- treatment technology has been on the effective removal of particulate and colloidal fouling. However, worldwide experience with seawater desalination over the last two decades indi- cates that abating microbial fouling is often the most challenging aspect of saline water pretreatment. Therefore, it is very likely that the paradigm of membrane pretreatment tech- nology in the future will change from focus on removal of particulate and colloidal foulants from saline water to emphasis on removal of soluble easily biodegradable organics in mem- brane biological reactors, similar to these used in wastewater treatment. As a result, a new generation of bioreactor-based membrane pretreatment technologies is likely to emerge, develop, and excel before this type of pretreatment receives widespread acceptance in desa- lination plants.
References
AWWA, 2007. Manual of Water Supply Practices M46, Reverse Osmosis and Nanofiltration, second ed. American Water Works Association, Denver, Colorado.
Guibert, D., 2014. MF/UF developments: universal rack design and process convergence. In: Proceedings of AMTA Technology Transfer Workshop, Ann Arbor, Michigan, May 13, 2014.
Kang, J.S., Sung, S.C., Lee, J.J., Kim, H.S., 2016. Application of ceramic membrane for seawater desalination pretreat- ment. Desalination and Water Treatment 5 (55), 26700e26705. Taylor & Francis.
Molina, G.V., Marzal, M.A., Hoehn, K.U., 2009. Designing membrane systems for coming future: Perth II desalination plant. In: Proceedings of IDA World Congress, Dubai, November 7e12, 2009.
Pearce, C., 2011. UF/MF Membrane Water Treatment Principles and Design. Water Treatment Academy, TechnoBiz Communications.
Prihasto, N., Qi-Feng, L., Seung-Hyun, K., 2009. Pre-treatment strategies for seawater desalination by reverse osmosis system. Desalination 249, 308e316. Elsevier.
Ransome, T.R., Ferguson, M., de Miguel, A., Sibma, S., 2015. Operation of a large scale RO plant with ultrafiltration pretreatment: challenges in early operation. In: Proceedings of IDA World Congress on Desalination and Reuse, 2015, San Diego, CA, USA. Ref: IDAWC15_Ransome_51524.
Sweizbin, J., 2017. A concept for open platform membrane system. In: Proceedings of 2017 Membrane Technology Conference & Exposition, February 13e17, Long Beach, California.