This animation illustrates how a standard Polychem chain and flight scraper system is assembled and installed.
Clare Pierson: Black & Veatch conducted a ceramic membrane research study in early 2009. Why did the company do this, and what were the results?
Jonathan Clement: This research study was a global initiative with the intent of looking at ceramic membranes in the water market, including water reuse and drinking water treatment, in response to a lot of interest from our clients.
Ceramic membranes, up until recently, have only been primarily used in Japan. Black & Veatch noted that ceramic membranes have tremendous advantages, but we didn’t know enough about their performance, so we started this initiative and included Stockholm and Singapore.
The study has now been concluded, and we found that ceramic membranes perform in a range where they can be feasible and effective, and they basically worked how we anticipated them to work. The only thing is that they are relatively expensive; however, they have significant advantages over conventional polymeric membranes.
Pierson: What are the main differences between ceramic membranes and polymeric membranes? What are the advantages and disadvantages to using ceramic membranes?
Clement: Ceramic membranes are based on aluminum oxides and have a rock-hard texture, like a stone. They have pores within their configuration, but there are no fibers that can break. Polymeric membranes typically need replacing every five to seven years, while ceramic membranes can last 15 to 20 years, possibly indefinitely. You can use a wide variety of chemicals to clean ceramic membranes that would be otherwise damaging to use on polymeric membranes. Also, we can use oxidants with ceramic membranes, which we tested in Singapore, and that is very valuable. We have found that ceramic membranes are very close to being indestructible.
A disadvantage, though, is that they are relatively expensive, due to special construction needs. The modules require significant material around them—stainless steel, high-pressure equipment, etc.—but some of that is changing. Polymeric membranes started out expensive, too, but prices have dropped. It is likely there will be new, more efficient designs that will lower the cost of ceramic membranes.
Pierson: What applications are ceramic membranes typically best suited for? When would polymeric membranes be the better choice?
Clement: What we do know is that ceramic membranes can be used with a wide variety of water. We have done tests in California, Stockholm, the Netherlands and Germany with all kinds of water—surface water used for drinking, water reuse testing, etc. It seems to work over a wide range of water qualities, so there isn’t really any limitation where they could be applied.
Certainly right now polymeric membranes are more cost-effective, but it is very site-specific and depends on a project’s particular conditions. The only way to know is to pilot test.
Pierson: What is the potential for growth in the ceramic membrane market in the U.S. and abroad? Is the technology readily available for water plants to install, or is it still primarily being researched and studied?
Clement: We are at a critical point for potential growth of ceramic membranes. The potential for growth is very, very big. A number of American companies have now positioned themselves to offer ceramic membranes in the market.
There are two small applications in the U.S. A large-scale, state-of-the-art ceramic membrane potable water plant is being designed in the Netherlands and will be operational in about one and a half years. They are using a new, more efficient design and have tested it and are ready to go ahead at this point.
When the cost of ceramics becomes comparable to polymeric, and once the first large-scale ceramic membrane plant is built in the U.S., I am certain the market will follow quickly.
Jonathan Clement is global practice and technology leader for Black & Veatch. Clement can be reached by e-mail at [email protected].