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Masthead

UNITING THE VIBRANT WORLD OF WATER - TO PROVIDE A PROACTIVE PLATFORM FOR THE WATER INDUSTRY TO CONVERGE AND WORK TOGETHER IN ACHIEVING SOLUTIONS TO GLOBAL WATER PROBLEMS.

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C O N T E N T S

Ecotechnology – A Complete Solution for RO Reject Water...24

This article explores the possibility for treatment of RO Reject water by eco-friendly technology as an alternate to energy

oriented MEE technology for various uses, achieving the UNEP’s goal and conserving the natural resources as well.

By Dr. Sanat K. Jain

Eco-Logical Conversion of Salts into Resources.............44

This article is a case study of developing a new ecological process for treatment of salts and discusses extra specific

logic of eco-friendly desalination.By Dr. Uday Bhawalkar

Home Made Evaporators for Inland RO Rejects: Predicaments

and Prospects for India.....28The article discusses the challenge of RO rejects

management, predicaments and prospects particularly in remote inland settings.

By Er Dr S Saktheeswaran & Er Dr S Sundaramoorthy

Forward Osmosis: A Latest Technology for Extracting Water

From RO Rejects & Achieving ZLD.........39

The article discusses forward osmosis as the latest technology for extracting water from RO rejects and

achieving ZLD. Read on...By Dr. Harshvardhan Modak

RO Brine Management in Indian Industry..............56This article is an overview of the existing methods on brine treatment, minimization, and disposal practices based on the newest and most updated technologies.By Shailendra Kumar Yadav, Dr. T. Jayasekhar & Dr. A.K.Priya

A Novel Gas Hydrate Based Water Desalination and Eutectic Salt Crystallisation Process.......64This article discuss a new gas hydrate based water desalination technology to address the problem oftechno-economic desalination of high salinity brine.By Amit Katyal

ZLD Project Treats RO Concentrate for Potable Water Use...................68Diminishing potable water supplies and conservation initiatives have prompted utilities to look to unconventional sources and process applications to meet potable water demands, while making the most of their existing resources. Effective treatment of waste streams can be an essential part of meeting these goals. By Phil Locke

RO Reject & Water Management......................66The article gives succinct overview of reverse osmosis technology and alternate use of RO reject. By Rajul Parikh

Masthead ....................................6

Water Wire.................................12

Launch Pad................................16

Event Zone.................................18

Product Zone.............................22

Editorial Calendar......................96

Subscription Form.....................97

Classifieds............................98

Ad.Index...................................101

Editor’s Note............................102

RE

GU

LA

RS

Watershed Management in Urban Perspective - Issues

Design Requirement & Mitigations...........80

By Dinkar Saxena

Thames Water - A Pioneer In Filtration Research.......86

By Tommy Charles Olsen

Reverse Osmosis Reject Water and its Available Uses! ......76

This article discusses Reverse Osmosis reject water and its possible alternative uses.

By Daniel L. Theobald

Saving Dal Lake for Future Generations..............94By Aquamec

C O N T E N T S

A Novel Gas Hydrate Based Water Desalinationand Eutectic Salt Crystallisation Process

This article discuss a new gas hydrate based water desalination technology to address the problem of techno-economic desalination of high salinity brine.

By Amit Katyal

Reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a semi-permeable membrane to a region of low solute

concentration by applying a pressure in excess of the osmotic pressure. The largest and most important application of reverse osmosis is the separation of pure water from seawater and brackish waters; seawater or brackish water is pressurized against one surface of the membrane, causing transport of salt-depleted water across the membrane and emergence of potable drinking water from the low-pressure side.

However limitations exist as reverse osmosis can only desalinate water with salinity close to that of sea water or slightly above it with a recovery rate of around 50%. With sea water salinity being close to 35000 mg/l, the reject brine from sea water reverse osmosis (SWRO) plants has a salinity close to 80,000 mg/l to 100,000 mg/l. The disposal of this reject brine from sea water reverse osmosis plants is a big environmental problem. This high salinity reject brine cannot be disposed in surface water bodies as it will pollute these surface water bodies. Also this reject brine cannot be disposed in sea, as it will damage the sea life because of which, some developed countries have banned disposal of high salinity brine in sea. For example, as per French law, the maximum salinity of water to be disposed in sea cannot be higher than 10% than the sea water salinity at point of disposal.

Fracking or Hydraulic fracturing is a well stimulation technique in which pressurized liquid is used to fracture the rock. The fracking technique is commonly applied to wells for shale gas, tight gas, tight oil and coal seam gas. Fracking requires very high volumes of water (around 7 volumes to every 1 volume of oil produced)

to fracture the rocks. This fracking water contains numerous chemicals when injected and comes back to the surface from the fracking well in further polluted form along with oil and gas. Pollution control laws of developed countries prohibit disposal of this highly polluted and saline frac flowback water in surface water bodies as it may pollute these surface water bodies. Fracking wells are much costly to drill compared to conventional wells and existing costly water treatment technologies make them even less economically viable. The most economical method for disposing this highly saline water is to discharge it into deep wells located far-off from the oil and gas well sites. However this discharge of highly saline water into deep wells is highly controversial as it is known to cause earthquakes and pollute ground water. Because of this, pollution control lobbies are asking for a complete ban on fracking.

At present, there does not exist any economically viable and technically feasible water desalination technology to treat high salinity brine like that coming out of sea water reverse osmosis plants or fracking wells. As mentioned earlier, reverse osmosis based system cannot desalinate high salinity brine. These systems can desalinate water with maximum salinity near sea water salinity.

Efficient forms of distillation based desalination systems like Multi-effect distillation systems (MED), Multi stage flash distillation systems (MSF) and Mechanical and thermal vapour compression desalination systems (MVC and TVC) can also viably desalinate water with maximum salinity near sea water salinity.

Freezing based desalination systems are only available on pilot scale whereas inefficient forms of distillation like thermal evaporation have very high energy consumption.

64 Water Today l December 2015

To address the problem of techno-economic desalination of high salinity brine, a new gas hydrate based water desalination technology has been developed.

Gas hydrates are inclusion compounds of low molecular weight gases like oxygen, nitrogen, hydrogen, carbon dioxide, methane, hydrogen sulfide, argon, kryton or xenon with water. Some higher hydrocarbons like ethane, propane and butane and some chloro-fluoro carbons (CFCs) also form gas hydrates. One unit of gas hydrates consists of single molecule of these gases existing in a cage formed of water molecules.

These gas hydrates are similar in structure to ice but unlike ice they are stable at temperatures higher than 0 C/ 32 F (freezing point of water) and at pressures above atmospheric pressure. When formed out of saline water, gas hydrates expel salt, leaving behind the excess salt in water. It is this property of gas hydrates which is used in the present water desalination technology.

As gas hydrates are formed at temperatures higher than ice forming temperatures, so gas hydrate based water desalination technologies presents an advantage over long existing but techno-economically non-viable freeze thaw desalination. Also as heat of formation of gas hydrates is much lower than heat of vaporization of water so gas hydrate based water desalination technologies are much less expensive in operation compared to distillation based technologies. Unlike reverse osmosis, gas hydrate based water desalination technologies can desalinate water of any salinity upto eutectic composition.

The proposed gas hydrate based water desalination technology is capable of viably desalinating high salinity water like reject brine of sea water reverse osmosis (SWRO) plants and highly saline produced water with a level of salinity up to eutectic saline composition. It is capable of concentrating salt water to its maximum possible eutectic composition of around 230000 mg/l. Further it works as a eutectic salt crystallizer resulting in crystallization of salt if operated on eutectic saline. The invention does not requires the rigorous distillation or freezing conditions for attaining its goals thus resulting in very low infrastructure cost and very low operating cost. Numerous innovations included in the present technology makes it probably the cheapest gas hydrate based water desalination technology possible. The proposed gas hydrate based water desalination technology is capable to viably desalinate high salinity water like reject brine

of sea water reverse osmosis (SWRO) plants and highly saline fracking water/ produced water with a level of salinity up to eutectic saline composition at an electric energy consumption of just around 0.05 kwh/ litre of desalinated water. As electrical form of energy is required by the system so the system can very easily be integrated with non-conventional forms of energy like tidal energy, wind energy and solar energy.

The desalinated water coming out of proposed gas hydrate based water desalination technology may not be of drinking water quality. However this desalinated water can be used for irrigational and industrial use. Also in case the desalination system is used for desalinating frac flowback water then the desalinated water can be reused for fracking operations.

In addition to desalination of reject brine coming out of reverse osmosis plants and desalination of highly saline frac flowback water, the invention has applications in lot of other areas like separation of costly minerals and chemicals from water, waste water treatment, salinity reduction of sea water etc.

A US and Indian patent has been filed for the technology and the desalination system as per the technology has been designed and simulated.

Amit Katyal, an independent researcher/ inventor based in New Delhi, has invented gas hydrate based water desalination technology. A Bachelor in Chemical Engineering from the prestigious Indian Institute of Technology, Delhi, India, he has over 20 years of experience in hydrocarbon sector in diverse segments like research, operations and technical services. Apart from gas hydrate based water desalination technology, he has also developed some very useful softwares for hydrocarbon sector like EQ-COMP, HYD-PREDIC, LIQ-PROP, BUBBLE-SIM and MIX-CP. Additionally, he has also invented another technology which provides a horizontal solution to vertical tray columns used in refineries and other chemical plants. A US, UK and Indian patent has been filed for this horizontal distillation technology. He can be reached at amit@eq-comp. com, amitkatyal.asim@gmail.com or www.eq-comp.com for more information or licensing of technology.

About the Author

Water Today l December 2015 65