Water. desalination + reuse

RESEARCH The high fouling resistance in the Filmtec Seamaxx membrane was largely born out in the Canary Isles plant in that no chemical cleaning was necessary after a year of operation and the Filmtec Seamaxx addition gave 20-25% greater flux. TDS data including boron levels were determined by Dow's Tarragona laboratories and third party certified laboratories. Particular attention to boron levels is called for under recent World Health Organization (WHO) requirements. The 2003 WHO requirement for boron concentrations in drinking water at below 0.5 mg/l, and a 2.4mg/l limit in 2011 guidelines, present challenges for seawater RO systems. While the Canary Islands trial showed Filmtec Seamaxx elements to be slightly less resistant to boron than the Filmtec product, the permeate levels – at less than 1mg/l – were significantly less than the WHO's more recent guideline. In the commercial-scale operation, ROSA again was shown to perform well. Comparison of permeate quality through ROSA and TDS/boron measurements taken by Dow and external certified laboratories showed deviations of 3-12% while ROSA flow factor and observed operating pressures showed equivalent values of 0.96 and 1.12 respectively. Long-tERm tHinking The eight-month pilot trial and the accelerated fouling trial at the Global Water Technology Centre were both part of the testing regime prior to Filmtec Seamaxx's launch in October 2013. And Salgado says the value of commercial-scale operating data was further demonstrated in the Canary Isles revamp. In the two Tarragona studies the final cost of water was 10-15% lower than the cost with previously available state-of-the- art RO elements according to Salgado. This, she says, provides scope for operators to strike a balance between capital and operating costs when determining the membrane capacity they need under their given financing structure. Ultimately Dow claims the Tarragona facility has hugely reduced the time take to bring a product market saying it has "cut the time from idea to launch by half." The company emphasizes too how the trust that Salgado highlighted as so important emerges from being able to replicate commercial operating conditions: "Because we can validate it like our customers run it, we also have more confidence in the reliability and sustainability," Dow says. l Figure 6. As with the long-term trial, feed pressure difference during the fouling study remained steady. Figure 7. The greater fall off in flow in the Filmtec elements demonstrates Seamaxx's superior resistance to fouling. Figure 8. Permeate conductivity simulation with ROSA is close to the actual findings for both elements. November-December 2014 | Desalination & Water Reuse | 35 |

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