Control and Supervision Strategies on Desalination Processes: Focused on Key Process Variables

Dear Colleagues,

The accelerated population growth and industrialization present around the world during the last decades have significantly increased the demand for resources; therefore, it is becoming more difficult to meet the basic needs of human beings, limiting the availability of drinking water, food, and electrical energy. Although water covers most of the Earth, only about 2.5% of it is available as fresh water. However, the percentage of fresh water available for consumption is much lower because nearly three-quarters of this resource is frozen in glaciers and ice caps, making its use in the short term practically impossible. It is estimated that by 2030 there will be a 40% water deficit worldwide.

Desalination technologies appear to be an attractive solution to satisfying part of the global water shortage. Desalination consists of taking water with a high concentration of total dissolved solids (TDSs) and passing it through a treatment process until it reaches the appropriate concentration ranges for its respective use. In order to obtain fresh water through desalination, two types of systems can be used, which are categorized as thermal and membrane systems. The latter system separates the feed water into two streams, one of water with low concentration— called permeate—and another with the concentrate of the rejected salts—called rejection. Within this category of membrane desalination systems, the most used technology is reverse osmosis (RO).

In this Special Issue, we want to delve deeper into certain factors that require special attention during the RO process. One of these factors is the so-called concentration polarization factor, which causes a series of phenomena that affect RO membranes directly and, consequently, the quality of the product water and the energy consumption of the process. The concentration polarization occurs when, as feed water flows through the RO system, salts are retained by the semipermeable membrane and form a concentrated layer on its surface. The concentration at this point gradually increases because as the water flow continues to pass through the membranes, salts continue to accumulate, causing an even higher concentration than the inlet concentration: scaling. This phenomenon limits mass transfer in the process, causing an increase in operating pressure, energy consumption, and scaling formation. It also decreases the quality and flux of the permeate. The challenges are broad, including energy demand and supply, use of renewable energies in desalination, intermittent operation, capacity development of personnel, operation and maintenance, water quality, intakes and outfalls, environmental impact and mitigation actions, case studies, pre-treatment, reverse osmosis, funding and costs, etc.

Prof. Dr. German Eduardo Devora
Dr. Jesús Álvarez-Sánchez
Guest Editors

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• reverse osmosis
• concentration polarization factor
• biofouling
• permeate flux
• mass transfer coefficient
• process design
• perfomance
• seawater reverse osmosis (SWRO)
• brackish water reverse osmosis (BWRO)
• operating pressure
• energy consumption