Hydrogen Bonding - The Key to Desalination (A Review)
Abstract
Energy crisis today is a major matter of concern. Energy is the most essential ingredient in the process of economic growth and development. The search for alternative sources for various unit operations such as evaporation, drying, distillation, etc. has been in continuum but without much success. Industries being the major consumers of energy, its efficient usage and minimal wastage are of profound importance.
ETPs or Effluent Treatment Plants are one of the components of a majority of the industry where a lot of energy is consumed. In every ETP, separate equipments are present to treat salt water. Desalination techniques such as Flash and Multi Effect Distillation in thermal, Electro dialysis and Reverse Osmosis (RO) in membrane category and many other processes such as freezing and humidification are used. For instance RO today is the most commonly used method for desalination. But the problem that accompanies it is that RO rejects concentrated brine solution every time it is used. This massive tonnage of salt water is then sent through a set of Multi-Effect Evaporators which not only increases the cost but majorly increases the energy requirement. The real problem with all the methods used is the need optimum economic designs and higher efficiency requirements thus making it both eco-friendly and economical for the industry. Modifications and innovations such as Incorporation of vacuum in humidification system increases the evaporation rate of water due to reduction in boiling point. In Electrodialysis, ion exchange resins are incorporated between the electrodes which help separate outions into continuous streams. These provide continuity to the process and also enhance its rate. But still the need for energy turns out to be the major issue. This paper suggests an alternative innovative technique reduction in bonding of water that can virtually eliminate the excessive energy needs in these processes.
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Introduction
Desalination of water is a major concern for both industries as well as for municipal supply across the globe. The demand for freshwater is ever increasing .ie demand for freshwater in the MENA(Middle East and North Africa Region) is estimated to go from 42 today to 200km3 in year 2050[1].Also industries that include Oil & Gas, Refining & Petrochemicals , Power Generation Food and Beverage, Pharmaceutical, Microelectronics, Pulp & Paper, and Mining industries also make use of various desalination technologies to obtain freshwater for different purposes[2].The crisis doesn’t only include the costs of maintenance and running of desalination units but also the environmental impact that these methods are causing. For example Saudi Arabia alone is burning 1.5 million barrels of crude oil per day equivalent to produce freshwater through desalination releasing massive amounts of greenhouse gases into the atmosphere [1].
This paper is an attempt to describe the currently used methods and the problems associated with them both in operation as well as maintenance. Also an alternative innovative technologies that can be adapted instead of or in combination with the current technologies.
Conclusion
Desalination today is a major matter of concern, both for municipal supplies as well as the industry, especially in regions such as MENA where freshwater reserves are scarce. The demand for freshwater is predicted to increase exponentially in the coming decade thus also raising demands for alternative energy resources. Developing countries, currently having abundant water resources, ar e going to face scarcity in the near future due to over exploitation of this valuable natural resource. Also those which do not have access (geographical and economical) to sufficient energy resources are going to suffer if this trend continues [7].
Although current techniques used for desalination are being continuously optimized and economized, the tremendous energy requirements remain a major issue that needs to be catered. Novel technological innovations in ED by various technology providers are slowly giving it better acceptance over RO or other membrane technologies. Use of renewable sources to meet these requirements is a viable option but as of today none of those sources are extracted efficiently enough to meet the ever growing demands of this industry. In experiments conducted by us on a lab scale, the suggested chaotrops and kosmotrops have given us a mere drop of 5-100C.Hence this is currently not a full proof method for scaling up. The alternative suggested in this paper, if implemented on a large scale, can virtually eliminate the concern in relation with energy requirements. Further developments and finally implementation of this novel technique can be done in the near future thus solving the energy crisis that persists, at least in the field of desalination .
