LLE: Water, Materials and the Environment: Membranes and Distributed Self-Adaptive Desalination Systems

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Abstract

Inland water desalting and purification based on reverse osmosis (RO) and nanofiltration (NF) membrane technologies generally require high recovery operation for increased water productivity and for reducing the challenge of concentrate (i.e., brine) management. Energy-optimal operation, overcoming operating pressure limitations, and effective mitigation of mineral scaling/fouling are all critical for robust RO/NF processes. The water recovery constraints due to membrane fouling and mineral scaling can be alleviated by effective feed pretreatment.

Also, tailoring membrane surface topography and chemistry have been promoted as approaches to reduce membrane fouling propensity and to increase the efficacy of  membrane cleaning. In exploring the above strategies, examples will be provided regarding: (a) the development of a new class of surface-nano-structured membranes for tuning membrane performance and enhancing the prospects for effective fouling mitigation; and (b) optimization of RO feed pretreatment and self-adaptive operational strategies based on advanced process monitoring, model-based control and machine learning approaches for inland and seawater desalination. Even with successful scale mitigation, the rise in osmotic pressure when water recovery is increased requires higher applied pressure for the target productivity. However, the recovery may be limited due to  RO operating pressure constraints (e.g., imposed by current RO membranes, element construction, and availability and costs of extreme high pressure pumps).

In order to enable the deployment of RO inland water desalting and decontamination, over a wide range of recovery and water feed salinity, a flexible RO (FLERO) configuration was developed that: (a) integrates a pressure intensifier with partial or total (in a semi-batch mode) concentrate recycle modes of operation; and (b) can be used with a relatively low pressure pump even for high salinity feedwater. The utility of the FLERO system was demonstrated in laboratory and field studies demonstrating operational flexibility with a single system using a relatively low pressure feed pump. Finally, the practical deployment a multipronged approach will be presented aimed at improving RO system operation for both seawater desalination and for providing disadvantaged communities with safe drinking water.

Bio

Dr. Yoram Cohen is a Distinguished Professor of Chemical & Biomolecular Engineering (CBE) (since 1981) at the University of California, Los Angeles (UCLA) and a Faculty member of the Institute of the Environment and Sustainability. He is Director of the Water Technology Research (WaTeR) and a co-founder of the Center for Environmental Implications of Nanotechnology (CEIN) that received the 2012 California Governor’s Award in Green Chemistry.

Dr. Cohen is a recognized expert and technology innovator in water treatment and desalination, membrane separation processes and environmental impact assessment. His contributed to environmental protection efforts to promote water reuse, develop clean drinking water supplies for disadvantaged communities, and reduce risks from exposure to chemical contaminants. He received the Lawrence K. Cecil Award (2003) and the Clarence (Larry) G. Gerhold Award (2019) from the AIChE Environmental Division and Separation Division, respectively, and was elected AIChE Fellow in 2009. In 2008, he received the Ann C. Rosenfield Community Partnership Prize for his environmental research, a County of Los Angeles Commendation, a State of California Senate Certificate of Recognition, and a Certificate of Special Congressional Recognition (US) for his contribution to legislation to protect public health and dedicated service to the community.

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