Fact # 1:
Industries need water.
Industries need water, a lot of water. In fact, worldwide, high-income countries use about 60% of their water for industrial use, according to the U.S. Centers for Disease Control and Prevention. Water is required for nearly every step of production across multiple industries; fabricating, processing, washing, diluting, cooling, and transporting a product are just a few manufacturing activities that require water. Water is also used by smelting facilities, petroleum refineries, semiconductor fabs, and indus­tries producing chemical products, food, and paper products. Water is literally embedded in the footprint of virtually every item created on the planet.

Fact # 2:
Water resources are under attack.
The water that used to be available to the industry was relatively inexpensive and unregulated to an extent. Fifty years ago, any industrial plant could simply take water from the nearby water source and, when done using it in its operation, dispose of the produced wastewater into the environment.

Not anymore. Human activity and economic development have put growing pressure on water availability. Accelerated urbanization and the expansion of municipal water supply and sanitation systems have also contributed to the rising demand. Meanwhile, over the past 100 years, many plants and facilities have disposed of their industrial wastewater into bodies of freshwater. The 2018 United Nations’ World Water Development Report noted that 70% of industrial waste is dumped untreated into streams and rivers, where it pollutes drinking water.

As a result, in 2022, disposing wastewater into the environment is no longer that easy. In most cases, it is under extreme regulation and the disposal options are very expensive. Different countries have different regulations regarding what can be discharged into local water bodies, and these regulations are becoming stricter every year.

And let’s not forget the intensifying climate crisis; extended droughts, extreme weather events, and increasing number of record-high temperatures are just a few of the warning signals our planet has experienced over recent years. Water availability is one of the top global risks according to a World Economic Forum Global Risk Report estimating a 40% shortfall in water supply globally by 2030 if no changes are made in how water is managed.

It goes without saying that scarcity and cost of water pose a huge threat to most industrial facilities.

Fact # 3:
Industries and water can be a vicious circle.
As water becomes unavailable, expensive, and highly regulated, industrial facilities have to rethink their overall water manage­ment to sustain plant efficiency and economic viability.

Using alternative water resources (municipal wastewater for example) means that raw water intake in an industrial plant may be cheap but low quality, and in most cases will require treat­ment to meet the tight industry quality specifications. Many industries are now also looking at the internal water cycle, where effluent water from one process can often be used in another process in the same facility if properly treated. This is a win-win situation, with lower charges for water consumption and reduced costs of effluent disposal as the volume for disposal and intake is reduced. Let’s not forget that wastewater generated in industrial processes also requires treatment to comply with disposal regulation or reuse purposes.

Fact # 4:
Industrial water treatment is easier said than done.
Industrial water treatment systems treat water to render it more appropriate for a designated use, whether process related or disposal.

However, treating industrial water is not a simple task. There are dozens of pollutants in water that can affect and influence industrial processes, and each of them require their own unique treatment. However, the majority of issues related to water treatment can be categorized into three main challenges: scaling, fouling, and biofouling.

Scaling happens when the chemistry and temperature conditions of the water cause precipitation of the dissolved mineral salts present in the water inside pipes and equipment. These salts, when precipitated in the plant’s water systems, may build up in layers, for example on the metal surfaces of heat exchangers, which results in less efficient heat exchange as the scale becomes thicker. Scale also reduces the interior diameter of pipes, thus in­creasing the energy required to pump the water through the pipes. When precipitated in the water treatment system, due to concentration in membranes, it significantly affects the system efficiency and availability. Some salts are more challenging than others—but any sparingly soluble salt needs to be addressed when designing a water treatment system.

Fouling occurs when inorganic contaminants (e.g., silt or clay) collect on the surface or in the pores of a membrane. Foulants restrict water flow through the membrane, resulting in opera­tion challenges such as higher hydraulic resistance, greater energy consumption, and even damage to equipment, pro­ducts, and other system components.

Biofouling refers to the process in which microorganisms, plants, algae, or other biological contaminants grow on or in surfaces and pores of equipment, particularly membranes. These foulants are particularly partial to warm environments with low flow rates, where they are able to attach to the surface and multiply. They release a protective substance known as extracellular polymeric substance, and together they form a slimy gel layer known as biofilm. Membranes with biofouling can be challenging to clean and in some cases may need replacement. Over time, flow will be restricted in membranes with biofouling, resulting in greater differential pressure, decreased membrane flux, greater pressure requirements, and higher energy costs.

As mentioned, water treatment is complex. Different streams, such as raw water, boiler feed, and cooling tower makeup and blowdown, have different contaminants and require different water treatment systems. Choice of system is also dictated by the water purity level required for different applications from cooling tower makeup to ultrapure water for microelectronics.

As a result, there is no one-treatment-system-fits-all solution. The technologies implemented in these systems and the order in which they are interlaced require a unique expertise and often a creative approach to manage water in the facility in the most optimal and cost-effective way.

Fact # 5:
Water treatment requires a holistic approach.
Treatment of different streams in an effective way means more than simply throwing a bunch of treatment technologies into the plant. It requires a holistic approach that can look at the various streams and needs of the plant and orchestrate an overall water management system that can maximize the plant’s efficiency.

As an example, in most industrial facilities, there are two important water-demanding processes: cooling and heating.

For cooling, a cooling tower is normally used, which requires make-up water to operate and disposes of low-quality blow­down water. Similarly, for heating, boilers are used, which, due to their high-temperature operation, require extremely high-quality water as makeup and also produce blowdown for dis­posal. In most cases, each of these processes require a multi-stage treatment scheme to bring the makeup water to the required quality.

Cooling tower water makeup will normally require an ultrafiltra­tion or media filter stage to remove suspended solids, colloidal and particulate. Following the filtration stage, a membrane-based system such as reverse osmosis or nanofiltration may be required to remove soluble salts and other pollutants to prevent scaling and corrosion in the cooling tower. Boiler makeup will also usually require the above systems, but due to the even higher quality requirements will require an additional polishing stage, such as an ion exchange system, to remove soluble salts and other pollutants to a higher extent. A holistic approach would be to think how to reuse the blowdown of both systems to reduce disposal and save on fresh water intake.

The blowdown of both cooling towers and boilers can be combined (90% comes from the cooling towers) and treated to reach the needed makeup quality. In addition, the brine/wastewater coming out of the blowdown treatment system can be further treated by high recovery systems, and even evaporators and crystallizers, which can bring the facility to a zero-liquid discharge state, where no liquid is coming out of the plant but only solid waste, which is easier and cheaper to dispose of.

Reusing blowdown as makeup can reduce blowdown disposal costs by 95% and reduce makeup costs by 20% (with the use of high-recovery technologies).

Fact # 6:
The holy grail of water management is high recovery.
For all the reasons mentioned above, it is critical not only to treat water but to recover and recycle as much of it as possible. High recovery of water from wastewater is the most sustainable solution to practically enable plants to minimize discharge costs and have additional clean water recovery for reuse.

However, achieving high recovery from industrial water is extremely complex due to the complex nature of the water chemistry, which is mostly characterized by high scaling and biofouling potential. Raising recovery in most conventional treatment systems will, in most cases, cause a drastic deterioration in membrane performance and therefore increase the operating expenses of the treatment.

If we use the above example, conventional systems manage to recover 30%-50% of their blowdown to be used as makeup, while high-recovery technologies can increase it to over 90%, and even re­duce the capital and operating costs of downstream expensive systems such as evaporators and crystallizers. Luckily, with today’s new technologies in many cases, plants can maximize the recovery of water to 95% and above.

In 2022, water management is crucial for the sustainability of plant operation. The holistic approach enables us to view as an asset water streams that a few years ago would have been considered a liability.

About the author
Iris Jancik is the CEO of IDE Amer­icas, a subsidiary company of IDE Water Technol­ogies. She holds a BS in civil engineering from the Technion, Israel Institute of Technology, and has recently completed her studies towards her MBA in international business from Texas A&M University.

About the company
IDE Water Technologies is a world leader provider of desalination and water treatment solutions and specializes in the development, engineering, construction and operation of some of the world’s largest and most advanced thermal and membrane desalination facilities and industrial water treatment plants. IDE partners with a range of customers—municipalities, energy, mining, semicon­ductors, power plants, and more—on all aspects of water projects and delivers approximately 3 million m3/day of high-quality water worldwide. Visit www.ide-tech.com.

Source: Water Conditioning & Purification International Magazine