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Technology Buoys Water Treatment

April 22, 2016
Developments spur improvements as plants place higher priority on water.

Water treatment has changed from being almost an afterthought into a critical issue for many chemical makers. For instance, companies such as Dow and Air Products have set ambitious water-conservation goals. In addition, Dow and BASF, both of which not only operate large plants but also produce water treatment membranes, are making technological advances. Progress also is occuring at other vendors such as GE Water and Process Technologies and Suez Advanced Solutions U.K., and in academia such as at Lulea University of Technology in Sweden.

The scale of the water treatment challenge reflects the broader issues of water availability and quality, notes Tracy Young, core R&D program director for the consumer and infrastructure solutions division of Dow Chemical, Midland, Mich. “According to the United Nations, by 2030, it is estimated that our world will need 30% more water, 45% more energy and 50% more food to keep up with rising populations, affluence and demand,” she notes.

The water treatment issues facing the chemical industry are changing and becoming increasingly challenging, believes Peter Macios, executive product manager, water and process technologies for GE Water and Process Technologies, Trevose, Pa.: “With increased regulation, environmental shifts, concerns with water scarcity, and ongoing cost pressures, we are seeing our customers look more closely at the use of impaired waters for open evaporation cooling systems. For example, there is increased interest in having technical evaluations done on the use of municipal reclaim water.”

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Corporate Initiative

Dow’s response to this challenge is its 2025 Sustainability Goals, which focus on redefining the role of business in sustainability through leadership and action — working together at the intersection of business, government and society to help drive the transition to a more sustainable planet and society. (See: “Sustainability Metric Spurs Efforts.”)

Deposit Removal

Figure 1. One year’s treatment with polymer formulation substantially reduced hardness deposition in boiler steam drum. Source: GE Water.

To this end, the company is promoting projects that advance a circular economy in water reuse by tackling the problem in three main areas: leading collaborations, providing water treatment technologies that minimize fresh water intake, and enabling the use of recycled water and alternative models for beneficial water reuse.

One area of particular focus for the company is the Middle East, where the imbalance between water supply and demand is particularly acute. In November, Dow announced the expansion of its facilities at the King Abdullah University of Science and Technology (KAUST) Research & Technology Park, Thuwal, Saudi Arabia, with the construction of a new Middle East R&D center.

“We already have a large reverse osmosis (RO) pilot system with advanced analytics in Saudi Arabia and are also carrying out research into how to deal with the fouling issues in this region, for example, by developing new anti-fouling coatings,” notes Young.

One problem specific to the Arabian Gulf is the red tide events caused by algal blooms. This mandates pretreating the seawater using filtration technology to ensure reverse osmosis (RO) works at peak efficiency.

“In fact, we look at the whole operating protocol here, including biocides, filtration pretreatments and RO. We are supplying the whole solution and central to this is the resin and compounds used in the process. So we are working very closely with KAUST to develop membranes and fibers with improved permeabilities that can handle this harsh environment — that’s the importance of applied research,” she adds.

Dow has seven R&D facilities worldwide, allowing both its researchers and customers to simulate, test and optimize water treatment and reuse more broadly and effectively. For example, the center in Spain has enabled the company’s Tarragona plant to use Filmtec ECO RO membranes to treat and re-use municipal wastewater. The plan here is to use up to 90% reclaimed water at the site in coming years.

“Filmtec ECO RO membranes are the first product in a next-generation portfolio of more sustainable, higher-efficiency membranes that facilitates lower energy usage and reduced regeneration costs,” says Young, who adds that over the next ten years they will help produce over 10 billion m3 of clean water around the world.

Meanwhile, in mid-April, Dow announced an investment in OxyMem Ltd., Athlone, Ireland, to spur the commercialization of the University College Dublin spinoff’s wastewater treatment technology — the Membrane Aerated Biofilm Reactor. The technology potentially could bring wastewater treatment closer to energy neutrality by reducing energy consumption for aeration by up to 75%, believe the companies.

In terms of broader collaborations, Dow is a founding member and sponsor of the University of Arizona’s Water and Sustainable Technology Center. This is a working partnership among Pima County, Tucson Water, various other industrial partners and University of Arizona researchers. Together, they hope to pair research strength with the experience of Dow and others to collectively tackle issues of water scarcity and re-use.

Multibore Membrane

Figure 2. Ultrafiltration membrane made of fibers with seven capillaries can remove microorganisms such as viruses and bacteria. Source: BASF.

“We want to partner more with municipals and also with our customers,” Young explains. “This is all tied into how we look at innovation. Following the recent drought in California and the earlier one in Texas, public/private partnership discussions are much more prevalent now. We must make engineers from all industries aware of the issues around using impaired water — both in terms of the treatments that are available now and those that are coming down the line.”

Membrane chemistry, she believes, will continue to be the area for breakthroughs in new technology: “Of course, there is a thermodynamic limit, so we are always looking at lower energy use, ease of operation, minimizing waste and improving design. All of these build on the circular-type approach.”

Global Goals

Air Products, Allentown, Pa., set a goal in 2010 of reducing controllable water consumption by 10% by 2015, and achieved that reduction four years ahead of schedule. This involved improving process efficiency as well as relying more heavily on recycled and alternative sources of water. (See: “Water Conservation Efforts Pay Off.”)

Air Products conducted plant-level water use reviews in conjunction with GE Water and Process Technologies, a long-time partner, to identify opportunities to save water and reduce costs.

For the chemical industry as a whole, water treatment issues are changing and becoming increasingly challenging, says GE’s Macios. He believes the answer lies in next generation chemistries, sophisticated computer modeling and customized pilot studies — all of which are central to the products offered by the company today.

One particular challenge for the chemical industry is the question of phosphorous discharges associated with cooling water treatment, he notes.

“GE has chemistries such as GenGard for cooling water treatment that can be deployed to offset these challenges, but we are also looking to future innovations and advanced chemistries to help customers better support non-phosphorous water programs in all regions of the world,” he adds.

This and other water-treatment processes will become ever more important if the projected long-term growth and development in ethylene production in North America driven by low feedstock costs emerges, Macios contends. However, in the near-term, producers are focused on optimization of assets and improved operations. “This is leading customers to leverage GE technologies and solutions developed for improving charge gas compressor operations, new solutions to improve quench water quality, and advancements in ethylene fractionation performance,” he says.

Another change is the growing relationship between the water treatment challenges faced by the chemical industry and the food and beverage industry. For one, the FDA Food Safety Modernization Act, which was enacted into law in 2011, has placed a new proactive focus around the whole supply chain for producers. “This directly affects customers that need the latest chemistries for internal boiler treatment to improve operations and ensure steam quality is compliant with FDA secondary direct food contact regulations,” notes Macios.

For GE, a key product here is the Solus AP internal treatment platform which controls deposit formation on boiler heat-transfer surfaces (Figure 1).

Unique Fibers

BASF, Lugwigshafen, Germany, used the International Desalination Association World Congress in San Diego, Calif., last September to highlight the latest developments in its water treatment technologies.

At the heart of these is the small-pore Multibore ultrafiltration membrane range. Designed for ease and speed of installation, these membranes contain seven individual capillaries within a fiber (Figure 2) — an arrangement that substantially boosts the membrane’s stability and avoids the risk of fiber breakage, says the company. The membrane can intercept particles, including microorganisms such as bacteria and viruses.

BASF also chose the Congress to highlight some of its R&D work, including a novel polymeric high-performance anti-scalant that provides excellent iron-fouling prevention, according to the company.

Among soluble metal ions, iron presents the most serious fouling problem to an RO membrane, especially when in contact with air or other oxidative compounds. So, BASF scientists mimicked the composition of iron-containing brackish water in Western Australia and used this in its in-house flat-sheet RO pilot unit in Ludwigshafen for tests with a widely used commercial anti-scalant as well as with its new product.

The new anti-scalant outperformed its rival, notes BASF water solutions laboratory manager Sujandi Sujandi. “With this new and innovative solution, BASF offers RO plant operators a secure, flexible and reliable operation with feed water having multiple scaling potentials without the need to dose additional anti-scalant.” The company will not reveal the make-up of the new anti-scalant.

Electrochemical Technology

In February, Suez Advanced Solutions U.K., Bristol, U.K. launched what it terms an entirely different way of handling wastewater generated during chemical manufacturing — electrochemical technology (ECT). It can remove heavy metals such as nickel, chrome, arsenic, cadmium and copper, pharmaceutical compounds, oils and hydrocarbons, bacteria and parasites.

ECT applies a current between an anode and a cathode that generates reactions to destabilize pollutants and convert them into more-biodegradable compounds. Three different reactions can occur: electrocoagulation, electroperoxi-coagulation (EPC) and electro-oxidation (EO). Depending on the types of pollutants present, treatment can involve an individual reaction in isolation or a combined package (Figure 3).

Electrochemical Treatment

Figure 3. The types of pollutants determine if an individual electrochemical process or a combination of them are used. Source: Suez Advanced Solutions U.K.

“The technology can work at temperatures up to 80°C and operating pressure is between 0.5 and 0.7 bars. The reaction time is just a tenth of a second since it is a continuous system,” notes Yolanda Aguilera, process engineer at Suez.

Currently, four companies within the chemical sector are using the technology while another has carried out a pilot trial to establish the maximum capability of the ECT reactors before designing its full plant. “This proved the efficiency of the system in terms of COD [chemical oxygen demand] removal, which was one of the key issues this company had,” says Aguilera.

Three different reactors exist for electrocoagulation: ECI to treat 1–15 m3/h, ECII to treat 15–60 m3/h and ECIII to treat 50–500 m3/h. EPC uses the same type of reactors as electrocoagulation while EO also has three different reactor sizes. Many reactors can be linked in series to increase treatment capacity, she notes.

Suez now is working on a new reactor design for treating up to 1,000 m3/h of wastewater, and also is trialling new photo-anodes that can oxidize non-biodegradable organic matter.

Nano-Cellulose Technology

Also in February, researchers at Lulea University of Technology’s Division of Materials Science, Lulea, Sweden, conducted the final tests of the European Union-funded Nano Select project that began in February 2012. The project involves the development of water filtration membranes based on nano-cellulose technology.

“The membranes are manufactured in sheet form and their functionality depends on the amount and type of nano-cellulose used,” explains Aji Mathew, associate professor.

Essentially the membranes are rolled into modules; the adsorption efficiency of the nano-cellulose filters was found in laboratory tests to compare very favorably with conventional industrial filters.

Field trials carried out by two companies in Spain, one a water treatment company and the other a manufacturer of leather goods, have confirmed the results.

The filters used were 90–120 mm in length and handled typical flow rates of 5 L/min, says Mathew, who adds higher flow rates are possible at higher pressures.

The companies tested three different nano-filters, each of which could handle the dyes, metal ions and nitrates present in the streams.

The technology had been optimized for these specific pollutants, she notes, but can be used for any type of pollutants that carry a surface charge. So, it would be suitable for treating both the process water and effluent associated with chemical manufacturing.

“From now on, industry must take the initiative to scale up and lead the development from where our research stopped,” she declares.

A commercialization process to bring the filters to market could take 3–5 years but the industrial interest to make this happen already is in place, Mathew believes.

Seán Ottewell is Chemical Processing's Editor at Large. You can email him at [email protected].

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