Summary: Purified water is being demanded by virtually every sector of the population—from households to major corporations. Finding a practical and affordable way to treat water has become paramount. The following discusses how certain segments are handling the situation and what benefits may result from proposed solutions.
No matter the season or how strong the economy, there’s always demand for cleaner, purified water. More people are demanding better tasting water. This is water that’s free of chlorine odor and low in sodium and other dissolved solids. These elements are the unappetizing features of municipal water supplies across the United States. Nationwide sales of non-sparkling pure water in vending machines, retail outlets, and office and home deliveries grew at double-digit rates during the last half of the 1990s.
Water is among the fastest growing beverage sectors, outpacing most liquor, beer and soft drinks. Because of ever increasing consumer awareness of potential health concerns and the poor aesthetic quality of tap water, the industry for water purification systems is growing. But, as we’ll see, the demand for pure water isn’t only limited to drinking water. To meet the increasing demand, the water purification industry is looking for and introducing flexible technology in a variety of markets.
Ensuring quality performance
Carbon filters are available and well known for their filtration abilities. But according to published reports when activated carbon filters are used alone, they are less likely to do a very good job of reducing dissolved minerals. Carbon filters can make “cloudy” water look and taste better but they’re not capable of thoroughly purifying water. Similarly, distillation units will turn water into steam and condense it into a purer state. But even this can carry over harmful chemicals due to low boiling points.
Reverse osmosis (RO) membrane technology has proven to be reliable and effective for everything from households to municipalities. RO is a pressure driven process where water passes through a semi-permeable barrier that removes dissolved minerals and other solutes. The main advantage of using RO technology is that it typically removes 98 percent of all dissolved minerals, depending on the system and feed water. RO membranes manufactured today operate at lower pressures than those from even a few years ago. Some of today’s membranes are designed to operate at pressures as low as 100 pounds per square inch (psi) in commercial and industrial systems. While the home drinking water market is the highest volume for RO systems, there’s a large and growing demand for commercial drinking water systems and pure water systems for business and industry. Here are a few examples.
Inside a vending machine
Water vending has been a tremendous success since its beginning. Vending machines use municipal water hooked up to the back of the machine. As it enters, it travels first through a five-micron (µm) filter and a carbon filter. These remove particles, chlorine and some organics. From there, the water moves to the RO membrane, which removes many undesirable elements including sodium, iron, lead, mercury and nitrates. The water goes through a metering device and then through an ultraviolet (UV) light that further disinfects the water. When the water exits the machine, it’s approximately 99.9 percent bacteria-free and, because of the RO membrane, virus-free. Others may incorporate ion exchange and even ozone as alternative or additional treatment methods.
Water vending machines can appear as stand-alone units outside a supermarket, convenience store and other retail locations—even a water treatment dealer’s office. They can appear as smaller end-of-aisle units inside similar retail locations. They can appear as compact units inset in a wall facing either inside or outside, depending upon conditions such as climate—i.e., in northern areas where it’s colder in winter, inside; in the Sunbelt, outside. They can be permanent kiosks located in parking lots anywhere a car, van or truck may be driven up to so customers can conveniently fill up bottles.
As such, water vending machines are everywhere today and increasing in popularity in countries where clean water isn’t readily available. For those people, taste is less an issue than safety. Domestically, safety is an issue but taste is more so, which leads to restaurants using small RO systems in their daily operations.
For the discriminating patron
Restaurants are switching to purified water because so many of their customers have purification equipment at home or the office and don’t like the taste of municipal tap water. Municipal water goes into restaurants and runs through a water softener. This process uses ion exchange to remove most particles and minerals including lead and reduces dissolved ions. The next step in the purification process is an activated carbon filter that removes chlorine, volatile organic compounds (VOCs) and trihalo-methanes (THMs). THMs are disinfection by-products (DBPs) of chlorination, which the U.S. Environmental Protection Agency (USEPA) says have been linked to some forms of cancer and other medical problems.
As described earlier, the RO process removes almost all chemical contaminants including dissolved minerals and small organics such as THM precursors and pesticides. The result is a glass of water that looks and tastes like bottled water. Ice is frozen clear because it’s virtually impurity free and coffee and tea taste better, but the benefits of softening and RO accrue to the owner as well. In areas where water is really hard, residue build-up on dishwashers, pipes and other equipment in this water intensive industry is reduced. In addition to restaurants, some industries are using water treatment for spot-free rinsing. The leading users for this application are car washes.
At the car wash
RO membranes are helping spot-free car washes deliver on the “spot free” promise. RO membranes and ion exchange softeners remove calcium and magnesium mineral salts that stay behind as white residue on newly washed cars. It’s the hardness from these dissolved minerals that, when dry, leaves white spots and streaks. In extreme cases, mineral deposits can clog valves, pipes and other equipment. More than half of self-service car wash operators in the United States use some type of water treatment system.
The primary motivator for investing in water treatment equipment is to provide a spot-free rinse. Even a full service, hand dried wash benefits from water treatment as well because of lower labor costs. Most water treatment systems are installed to reduce the amount of labor involved for towel drying cars as they emerge from the wash and rinse cycle. The speed and quality of the service can be improved while drying expenses are held down. The car wash operator and the customer both receive a better value. To address these and other applications from purified water, RO manufacturers are developing better products.
To meet the increasing demand for applications like these, extra low energy water purification membrane products for commercial and light industrial applications are now becoming available. These new products are targeted for systems purifying as much as 10 gallons per minute (gpm) of water (about 2 cubic meters per hour, m3/hr) where low pressure operation is desired. The new technology operates at a nominal pressure of 100 pounds per square inch gauge (psig), or 6.9 bar, and has 99 percent stabilized salt rejection. The performance of dry elements stabilizes in about 30 minutes.
In addition, the new elements deliver more water at a higher purity than before. For example, at the same feed conditions the newest products can purify 2,400 gallons per day (gpd) of water with 99 percent salt rejection; older low energy products purified only 1,900 gpd with 98 percent salt rejection. The result of this new technology is more water that’s purer. Businesses like car washes and restaurants plus vending machine operators and other light industry end-users that require a source of purified water will immediately benefit from this new technology.
To address the increasing demand for purified water, RO manufacturers are developing better products. There’s a drive toward lower pressure operation, as commercial systems will ultimately operate off line pressure similar to point-of-use units for home drinking water. Lower operating pressure will reduce pump costs resulting in lower system costs. RO membranes capable of delivering a high flow of excellent water at pressures under 100 psi are currently being developed toward this end. While commercial applications offer water treatment professionals many sales opportunities, this is also a huge opportunity for service. Small business and building owners don’t have time or knowledge to service their RO systems. There’s a need for timely, professional, knowledgeable service at a reasonable price. Not only will this result in happy customers, it will also result in repeat sales and referrals.
About the author
Jon Goodman is a global marketing manager of FILMTEC® membranes for The Dow Chemical Co. He can be reached at [email protected]