For the trade press
Dallas - Tuesday, October 24, 2006
WEFTEC 06
Siemens Water Technologies Sees Growing Demand for Low-Pressure Membranes in Water Reuse Applications
Water reuse is on the rise as global demand for the world's fresh water supplies increases. By recycling and reusing treated wastewater, communities and industries can save on the costs of clean water, ensure adequate supplies, and help to preserve a diminishing natural resource. The increase in water reuse has been driven largely by innovative treatment technologies that are both cost effective and reliable in removing harmful bacteria and pathogens. Siemens Water Technologies has seen a steady increase in the demand for its water reuse technologies, especially its Memcor membrane products. These hollow-fiber, low-pressure membranes have been used extensively in municipal and industrial applications worldwide, treating both secondary and tertiary wastewater to a high quality standard.
"Since we installed our first tertiary reuse system in the early 1990's, we've seen a significant increase in the global demand for membrane systems," says Chuck Gordon, Executive Vice President of the Water Technologies Systems Unit. "Although membranes are thought of as a drinking water filtration solution, our membranes are increasingly being used for water reuse in areas where potable water is scarce or in industries that need a reliable, high quality water source."
Membranes offer several advantages over conventional treatment systems, including lower life-cycle cost and a smaller footprint. Life-cycle cost savings result from reduced process steps and chemicals required to achieve high quality water. The membranes' compact design means a smaller system footprint, which becomes increasingly important to plants with limited space for expansion. For example, Siemens Water Technologies was recently awarded the membrane bioreactor (MBR) project for the Beijing Olympics, which required high-capacity treatment in a small area.
Another key advantage of these membranes is the high quality water they produce. With a pore-size of less than 0.04 micron, they provide greater than 4-log removal of Cryptosporidium, Giardia and bacteria, over 1.5-log virus rejection and a SDI of less than 2, regardless of changing feed water conditions. The high-log removal values also reduce disinfection dosages required for most urban applications.
The State of California's Title 22 regulation defines water recycling criteria for surface uses, including irrigation, golf courses and some types of agriculture. Because Memcor membranes act as a verifiable physical barrier against micro-organisms, and consistently achieve turbidity levels of less than 0.1 NTU (Nephelometric Turbidity Unit), the California requirements are easily met. In fact, Memcor membranes are now used in some of the largest reuse plants in California, such as Water Factory 21 and the West Basin Municipal Water District. Combined, these two plants produce over 120 million gallons of recycled water every day.
"Another reason for membranes' growing popularity is the fact that configurations and materials have been expanded and refined," says Gordon. "For example, we offer both pressurized and submerged membrane systems, membrane bioreactors and packaged systems for industrial and satellite treatment. Material improvements from our initial polypropylene membrane, such as chlorine-resistant membranes, higher membrane permeability and lower particle size cut-offs, offer customers high water quality at a lower cost."
Memcor submerged membrane systems are used worldwide in some of the largest reuse plants. In Singapore, the Kranji Newater Reclamation Plant was contracted to ensure a sustainable drinking water supply. The 14.7-MGD facility uses dual membrane treatment followed by ultraviolet disinfection to process secondary treated wastewater effluent. The membrane system includes six cells with 480 membranes in each, to pre-treat five, two-stage reverse osmosis (RO) membrane skids for removing dissolved minerals. Competed in late 2002, the facility makes more water available for potable use while ensuring a steady supply of non-potable water for industrial users.
Located in the Arizona desert, Scottsdale, Ariz., had been planning for the possibility of drought for many years. When a drought occurred, along with the increasing cost of wastewater disposal, the city decided to implement a water reuse program. To treat its reclaimed water, the Scottsdale Water Campus facility uses membrane technology as pre-treatment to RO. This produces high-quality processed water suitable for landscape irrigation and groundwater recharge. Since its implementation, Scottsdale's reuse program has saved 25 billion gallons of potable water, and the Scottsdale Water Campus is one of the largest municipal facilities in the world that treats raw wastewater to potable quality for aquifer recharge.
Converting conventional filtration plants to a Memcor submerged membrane system offers significant cost savings, as no new buildings are required. Membranes provide the greatest flexibility for meeting future regulations, are easily automated, and have the shortest construction time. They are ideal for retrofitting conventional plants that want to upgrade or expand but have limited space. A water filtration plant in the City of Kennewick, Wash., was expanded from 7.5 mgd to 15 mgd by installing submerged membranes in the existing granular media basins. Reuse plants are also starting to use this same approach.
Siemens Water Technologies delivers cost-effective, reliable water and wastewater treatment systems and services to municipal, industrial, commercial and institutional customers worldwide. The division "Water Technologies" is part of Siemens' Industrial Solutions and Services Group (I&S) which is a system and solution provider for industrial and infrastructure facilities and global service provider for the plant and projects business covering planning, installation, operation and the entire life cycle. In fiscal 2005 (to September 30), I&S employed a total of 31,700 people worldwide and achieved total sales of EUR 5.390 billion.
Visit company websites at http://www.usfilter.com and http://www.siemens.com/water .