Bringing Wastewater Back to Life

July 13, 2010 7:18 am

Can raw sewage really be processed into pure water? Will industries realize that it is cost-effective and environmentally sound to use it in their processes? The water reuse industry is growing, and technology is growing along with it. Now it’s taken another step forward with Alfa Laval’s latest advance in membrane technology.
 
Alfa Laval has been in the wastewater treatment business for more than 50 years. Products such as decanter centrifuges, drum thickeners and spiral heat exchanges are being used in wastewater and sludge treatment for municipal and industrial applications involving more than 250 million users. Recently another technology has been added to the portfolio.
 
This latest technology, the Hollow Sheet from Alfa Laval, has been developed under the leadership of Nicolas Heinen, who has extensive experience in membrane filtration and wastewater treatment. Alfa Laval is now entering the MBR market with the Hollow Sheet Membrane Filtration Module, challenging existing products on the market. MBR is a growing technology for wastewater treatment driven by improved treatment processes, stronger effluent requirements and water reuse.
 
What makes the Alfa Laval solution unique?
“We have combined the best from two membrane technologies – hollow fibre technology and flat sheet technology, which are both currently used in MBRs installed in wastewater treatment facilities – and turned them into one membrane configuration,” says Ivar Madsen, Manager, MBR Unit, Alfa Laval.
 
Hollow fibre and flat sheet membranes each offer advantages, but until the advent of the Hollow Sheet technology, no membrane has been able to combine the advantages of both products into one. “With the Alfa Laval Hollow Sheet in the MBR, you get complete utilization of the whole membrane area,” explains Madsen. “This results in a much greater filtration capacity and at the same time lower energy consumption – 10 to 25 percent lower air consumption per membrane area than what is achieved by the flat sheet and hollow fibre membranes currently in use. Using the Hollow Sheet instead of the other technologies therefore translates into substantial energy savings.”
A Hollow Sheet MBR is designed with a cross-flow velocity of water and waste materials flowing upwards between the membrane elements while the water (permeate) passes through the membrane sheet. To ensure that this mixed liquid circulates effectively, air bubbles are used to create this cross-flow velocity while providing a scouring effect. The Hollow Sheet membranes are placed in a stainless steel frame within the Alfa Laval Membrane Filtration Module.

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