Water wisdom

[More Images]



KMS’ automated manufacturing line has been designed to create membranes that have a wide range of properties, from high rejection and high pressure to low rejection and low pressure. “We can then dial in the properties of the membrane that our mathematical model predicts will give us the lowest operating cost,” observes Koch. “Generally speaking, reverse osmosis (RO) systems will operate more economically of the purity of the raw water going into the system is improved, so we’re also in the final stages of developing an ultrafiltration (UF) system that can more economically purify that water.”

While some observers have in the past claimed that RO technology may have reached its peak, Koch begs to differ. “I still think it’s possible to make up flat-sheet membranes that give you higher rejection with lower trans-membrane pressure – that would be wonderful,” he says. “Another area that I’m interested in is making seawater RO membranes out of hollow fibre, not flat sheet rolled into spirals.”

With recent advances in the textile industry enabling fibres to be spun at immense speed, with hundreds of fibres simultaneously, Koch thinks the scope for development is significant. A major factor here is that the cost of hollow textile fibres per foot is much lower than it is for UF membrane applications. “It’s just an engineering problem to make composite RO membrane in a hollow-fibre geometry; I think it ought to be possible to spin these RO hollow fibres at high speed and with great numbers simultaneously to gain a higher consistency and therefore a higher rejection,” the KMS president states. “That, I think, is the next great challenge in the membrane business.”

But KMS doesn’t see the drive for new technologies ending with just changes to the membrane. A holistic approach to system design, fouling and pre-treatment, and all the other variables that play a role in the membrane process, is likely to provide the best options, in terms of capital cost, to the end-user.

Advertisement

FEATURED COMMENT Please click here to comment on this article

“There are still tremendous opportunities in the membrane bioreactor (MBR) area and all sorts of engineering modifications that can reduce the capital cost of MBR cartridges,” Koch explains. “We also have lots of ideas about reducing the amount of air used to scour the fouling off the membrane. We’re a long way from having optimisation of all the variables that go into the MBR field, which is probably the most under-developed area in RO desalination.” Koch also says that the biggest improvement on the UF side is the potential use of a fibre reinforced with a braid enabling it to be super-strong, thus solving breakage problems.

As the industry has grown, it has come in from some strong criticism from environmentalists about its effects on marine life and the harmful effects caused by brine discharge into the oceans. But Koch, like other company executives at IDA, is unequivocal in his assertion that the sector is doing its best to counter these accusations. “Modelling studies have shown that concentrated salt is very rapidly dissipated – if you go out a hundred metres away from the discharge pipe, salt concentration is reduced to the levels seen in the general body of the sea,” he argues. “I think it’s an inaccurate criticism and we need to use facts and data to disprove that as a serious concern. Long term, the general public will come to realise that that’s a criticism without any merit.”

Another major issue that is affecting the Middle East is that of privatisation, and Koch remains a strong advocate of the process as providing the greatest competitive benefits to the end-user. “The way it ought to work is that investment groups and companies like ours should build the plants, operate them and then sell the water over the fence to the municipality or industry,” he continues. “The more plants you build, the better you can operate them, and the cheaper the cost you can deliver to the municipality or client.”

Much of what Koch says highlights his appreciation of the value of cost to the client, and his confidence in the technologies that his company can provide. “I think the membranes have been proved to be theoretically the lowest-cost way to purify water,” he concludes.

“And as the industry gets bigger and bigger and more people invest in development projects, the cost of the systems will continue to decrease.”

KMS’s large-diameter MegaMagnum element
• Pressure vessel that houses 18-inch diameter, 60-inch length element
• The active membrane area has been increased by 12% to 3,500 square feet
• The housing is made from a glass-reinforced epoxy, which is stronger than previous vessels
• The new MegaMagnums will be available in Q1 2010

---