Water Journal : Water Journal April 2011
conference reviews regular features 82 APRIL 2011 water water predominates (as detailed in another conference paper by Robbert van Merkestein of Norit). Wind energy is being used in Australia, and even in oil-rich Arabia solar power is being harnessed for SWRO, since oil for export is too valuable. In Saudi Arabia some seawater is being only 50 per cent desalinated by nanofiltration (NF) rather than RO, since the product can irrigate salt-tolerant crops. Singapore has set a 'Road Map' for the future, aimed at reducing SWRO energy from 3kWh/kL to 1.63kWh/kL, near the theoretical level. With regard to reclamation of wastewater, Professor Amy drew attention to West Basin, San Francisco, where different systems supply five qualities of water (Fit-For-Use). He lamented the fact that in most of the world there are two different agencies for water supply and wastewater treatment, and said integrated planning with distributed treatment will have to be instituted in the future. In many places, the public does not seem to acknowledge that unplanned indirect potable reuse is the norm for the majority of populations where treated sewage is discharged into a river upstream of where water is drawn as a source for drinking water. His "solution" was to direct more resources at MAR in order to attempt to overcome public opposition to re-use: the rationale being that, since groundwater is universally regarded as safe (even though in many instances this is not the case), people will more readily accept water that has been drawn from a groundwater repository. In concluding, Professor Amy expressed regret that the rest of the world seems to base its regulations for quality on those of California, whose regulators are perhaps the most risk-averse in the world. There is a need for much better real data on which to base regulation. Other Papers The conference also provided an excellent opportunity for drawing delegates' attention to other developments in the field of membrane technology -- for example, the movement of the work on ceramic membranes from the research laboratory to pilot plant, and now into the first commercial community treatment plant. Other highlights included pragmatic reports on the operations of two of our big SWRO plants, advances in bio-fouling and brine management, and improvements in understanding and operating membrane bioreactor systems. A few of these papers have been selected for publication in this and future issues. At the Membranes & Desalination Specialty III Conference, PWN Technologies (an offshoot of one of the most progressive water supply companies in the world, in North Holland) announced that they had designed and tested a module containing 200 ceramic membranes, thus decreasing the capex and increasing the online time of the conventional ceramic membrane system used in Japan for direct microfiltration of river water. An agreement has been signed with the Japanese company and a full-scale plant is planned for 2013. The close pore size of the tailored ceramic elements and their ability to stand up to harsh cleaning are obvious benefits. It remains to be seen whether capex and opex will compete with the polymer membrane modules. On another purely engineering topic, a workshop led by Doug Eisberg of Avista Technologies opened the eyes of many to the potential hazards of the pressure vessels containing the membrane modules, which operate at high pressures. The manufacture of the fibreglass vessels is complex and exacting -- it is critical that the machines undertaking the process wind the vessel fibre with 100 per cent accuracy. Doug pointed out the dangers of purchasing vessels that do not carry the special US certification of inspection throughout the manufacturing process. The development of a certification system with minimum standards for pressure vessels was undertaken by the industry in the US after an early incident at Water Factory 21. A vessel end cap blew off and rocketed across the plant a few minutes after a site tour group of Cub Scouts had left the building. With the rapidly expanding market, some new manufacturers are covering up potential defects with a coat of paint, and he outlined a list of potential weak points. Doug also pointed out the danger of tolerating leaks which, if pooled, could lead to corrosion of the metal fittings. It was a sobering session, with many attendees later commenting on what they would be looking for on their pressure vessels when they returned home after the conference. Two papers, by Tobie Welgemoed of MWH and Lindsay Delzoppo of the Queensland DERM, on coal seam gas water, merit publication in our August issue. The scale of the problem/ opportunity can best be exemplified by an estimate of the amount of salts which is likely to be drawn from deep underground as the aquifers are pumped out to release the gas. In the Walloon Basin, where TDS ranges from 20 to 10,000 mg/L, some 300,000 tonnes of solids will have to be dealt with each year until the field tails off, in perhaps 20 years or so. Finally, in closing the conference, Dr Stephen Gray, co- convenor with Neil Palmer of the Membranes & Desalination Specialty Network, thanked the sponsors, Veolia Water Australia and KSB Pumps, the speakers and the trade exhibitors. He finished by encouraging all participants to return in two years' time for the Membranes & Desalination Specialty V Conference. Tobie Welgemoed from MWH. PHOTO: NEIL PALMER PHOTO: NEIL PALMER Doug Eisberg of Avista Technologies.
Water Journal March 2011
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