Water
Tapped: a cascade of benefits to Melbourne Water treatment
But Yarra Valley tap water is cleaner still, due to management by Melbourne Water. Now three water-treatment plants in the Yarra Valley are being upgraded, using game-changing new filtration technology—no major capital works required.
“The key drivers on this project were size—the new plant has to fit inside the existing plant rooms—ease of maintenance, and of course price,” says Barney Simmons, lead mechanical engineer at Black & Veatch.
The engineering, procurement and construction (EPC) company and its consortium partner CPB Constructions are charged with upgrading and increasing capacity of the picturesquely named Cresswell, Frogley and Yarra Glen plants to meet future needs.
Although many of Australia’s water-treatment plants are built in rural or industrial areas and typically have the land to expand, buildings that house the plants serving suburbs, towns and cities are not so elastic.
Construction of plant buildings is expensive, so when GE last year released the latest version of its ZeeWeed ultrafiltration membrane technology, the water-treatment industry came up for air, because the ZeeWeed 1500 Rackless Module System (RMS) offers increased capacity for water treatment within a much smaller footprint than previously.
ZW1500 RMS is a great leap forward in decades of incremental development of GE’s ZeeWeed hollow-fibre membrane technology. It offers 50% greater processing capacity per square metre of floorspace due to its slim, cylindrical construction which replaces the earlier, already space-efficient, cassette-based system.
“When you have existing buildings and not really the budget to do a lot of construction work, that is a significant selling point,” says Sean Cohen, Australia and New Zealand after-market services leader with GE Water & Process Technologies.
“Our teams walk in with this design and customers go, ‘Oh, that’s pretty slick!’ You can see that tightening up the mechanics like this is the next big trend in the industry.” Sean Cohen, GE Water
The modularity of the system also means that Melbourne Water can expand its plant to the capacity required now, and add modules as needed.
“In the past,” says Cohen, “you had to project future growth to the biggest system you would need at some point in the future, and build steel frameworks to support that, even though you might not use that full capacity until two, four, six years down the track.”
The rackless-ness of the new system means a utility need only ever spend for the present, freeing available funds for other urgent projects; and eliminating the risk of funding a white elephant should projected need not eventuate.
Simmons praises the flexibility of GE’s approach to the tender process and in working through changes in scope of the projects.
Now, he says, “The design capacity at each site has an allowance for future growth based on population projections over the next 20 years. It was a design objective to allow sufficient space that additional membrane modules could be added to each processing train in future, if more capacity was required.”
Adds Cohen: “Melbourne Water had a design goal for the first round, which will carry them through probably the first two or three years of less than 10% projected growth, then they can come back in three or five years’ time when they’re expecting the population to grow again and say, ‘Right! Now we need to add another 20 or 30% capacity.’” says Cohen.
“It’s just a very clever design,” he says of a system which also costs less to ship than comparable systems, because it’s so much smaller. ZW1500 RMS also has fewer parts than earlier systems; parts that might break or need replacing, and that would have been kept on hand just in case. Fewer components, also means the processing trains are faster and easier to assemble.
“All these flow-on effects really make a huge difference in cost when you add them up,” says Cohen.
The works at Cresswell water plant are scheduled for completion in February 2017, with Yarra Glen and Frogley to follow at roughly three-monthly intervals.
Although these Melbourne Water systems receive water from protected catchments with limited public access, and therefore yield very high-quality water in the first instance, levels of dissolved and suspended solids can be variable. The water still requires filtration to ensure consistent compliance with Australia’s strict drinking-water standards.
The key requirement is for “4-log reduction of protozoa such as cryptosporidium”, says Simmons. “There are also requirements for reduction in turbidity, colour and levels of dissolved iron, aluminium and manganese.”
ZeeWeed membranes, which have been deployed in more than 70 locations around Australia—including the Great Barrier Reef coast, the Queensland town of Maleny and Sydney International Airport—are legendary for removing dissolved and suspended solids, as well as potentially dangerous viruses, and rendering water that meets or exceeds drinking requirements.
It’s this combination of proven technology in the much-improved ZW1500 RMS system that Cohen says is so appealing for utilities such as Melbourne Water and its consortium of contractors, which must hit high bars of water standards while seeking savings that allow them to stick to budget.