Better water technology is on tap

Figure 1. Using tagged polymer and taking measurements every six seconds afford better control in highly variable systems. Source: Nalco.

All three use a fluorescent “tagged” polymer that, when added to the water, reacts with dehydrogenase, an enzyme pro-duced by living organisms, explains Daniel M. Cicero, senior product manager with Nalco’s cooling-water programs and tech-nology group. When tag-containing water passes through an in-line fluorometer, measured fluorescence directly correlates to concen-tration of treatment chemical, i.e., scale or corrosion inhibitor, or dispersant, he says. The Trasar controller gives analyses every six seconds. The measurements provide an ongoing indication of the scale-forming stress on the system and are said to allow much bet-ter control in highly variable systems.

To eliminate guesstimating, Nalco’s technology suite incor-porates a chemical modeling tool. “Users input the local water conditions, variability, special operational realities and other data,” Cicero says. “The program analyzes the data and offers treatment and control guidance.” This may involve suggestions both as to dosage and changes in operation.

“We have documented many cases where performance im-proved or the causes of problems were uncovered as a result of 3D Trasar technology,” Cicero notes. Before using the technology, it was often unclear that any improvement was even possible, he adds. For instance, with many U.S. refineries trying to maximize output, scaling or fouling of heat exchangers can be a real worry. “3D Trasar has identified ways to avoid the expense of mechanical changes [on exchangers] and eliminate the operational problems,” he says.

The suite also contains 3D Trasar Web, to which controllers upload data hourly. It can produce graphs, retrieve data and, when normal operating limits are exceeded, generate alarms that can be sent via e-mail, digital paging or text messaging. “Many users op-erate several cooling systems in different locations. 3D Trasar Web gives them consistent visibility on every one,” Cicero explains. Systems can be benchmarked against each other, improving trou-bleshooting, maintenance and performance evaluation.

Continuous corrections

Ciba Specialty Chemicals, Basel, Switz., is currently testing online cationic demand control (OCDC) at a German municipal water treatment plant. Ciba hopes to launch this technology, which will be called Ciba Aquawatch, later this year.

“You measure and adjust the dosage continuously,” explains Doug Chamberlin, head of Ciba’s global industry market center for water solutions, Bradford, U.K. In the German municipal applica-tion, the focus is organic colloids, which tend to have a negative electric charge. “We add a combination of coagulants, which dis-rupt the charge, and then flocculants to make a bigger particle,” he says. That eases and speeds sludge dewatering and creates a drier sludge cake.

Chamberlin believes the OCDC technology can be deployed to reduce chemical oxygen demand and biological oxygen demand in industrial wastewaters.

Meanwhile, Ciba in late 2006 in Europe launched Irgatreat MF443, a corrosion inhibitor that finds use in heat exchangers, pasteurizers and chillers. “Irgatreat MF443 contains organics, which have much less impact on environment because they’re bio-degradable,” Chamberlin notes. Ciba hopes to launch the technol-ogy in the U.S. in early 2008, he adds.

Fractal-based flowpath

Figure 2. New treatment system halved deionization chemical us-age and reduced water loss to 2% of total water treated. Source: Rohm and Haas.

The Advanced Amberpack system, introduced in 2004 by Rohm and Haas Co., Philadelphia, Pa., already has proven itself in min-ing and power generation. A six-month demonstration of this skid-mounted, fully automated technology ended in May at an Ana-darko Petroleum Corp. coal-bed methane (CBM) production site in Wyoming’s Powder River Basin. “The water produced with the methane has to be treated before release to the environment,” ex-plains Jay Miers, market development manager with Rohm and Haas’ ion-exchange resins group.

Another successful application is halfway around the globe in Siberia. In January of this year, OJSC Novosibirskenergo installed the technology at its Novosibirsk Power Plant No. 4 (Figure 2). This allowed the power company to cut deionization chemical us-age by 50% and water loss from 10% of total water treated to 2%. “No major issues [have been] encountered during operation,” notes power plant manager Sergei Miroshnokov, who predicts that “we can do maintenance once a year.”

What’s unique about this technology is its fractal-geometry-based liquid flowpath. The entire liquid distributor is approxi-mately 2 in. thick, compared to the 4 ft. typically required for stan-dard ion-resin exchange beds, Miers says. Patented by Amalga-mated Research Inc. of Twin Falls, Idaho, the technology delivers near-perfect plug flow, he claims. It also offers an essentially infi-nite turndown ratio, he adds, meaning “you’ll get the same even distribution [of liquid] regardless of flowrate.”

Advanced Amberpack boasts excellent rinse characteristics, says Miers. “Typically, an ion-exchange system will require four to seven bed volumes of water to rinse the bed. We’re down to one.” That also reduces regeneration time. “Ion exchange operates between eight-24 hours in service, with the regeneration cycle typically two hours,” he explains. With Amberpack, though, “we’re at two-to-eight-hour service cycles, with regeneration at about 40 to 45 minutes.”

Another plus is its small footprint. A conventional 250-gal./min. system typically requires a six-foot ID vessel. “With dished [vessel] heads, you’d be at about a nine-foot height,” Miers says. In contrast, Amberpack generally cuts that to a four-foot ID vessel and less than seven feet in height, he claims. However, the CBM demonstration project’s vessel is taller because the inlet stream has a concentration of total dissolved solids that exceeds 1,000 ppm, he notes.

A new wrinkle on the technology is the development of par-allel vessel systems for potable and wastewater applications that use the same basic ion-exchange process and vessel designs but remove only a single component from a stream, notes Miers.

Membrane momentum

Meanwhile, Siemens has engineered a system to treat wastewater from Petro-Canada’s Wild Turkey CBM wells near Gillette, Wyo., in the Powder River Basin. It’s modular with six parallel treatment trains, “which allows the system to start up with one train at a time, with more being placed in operation as new wells are brought online,” Gupta notes. The system features specially mixed media for removing or reducing iron and manganese from the raw pro-duced water, and a RO membrane system to take out dissolved sol-ids and minimize the waste steam, he explains. “This is the first commercial application of RO technology to treat CBM-produced wastewater,” Gupta claims.

The new system comprises filtration, chemical feed(s), pri-mary RO and brine-recovery RO. Primary RO removes about 95% of the dissolved salts and produces 80% to 85% of the treated wa-ter, he says. “The brine or reject stream from the primary RO sys-tem is further treated in a brine-recovery RO system to recover ad-ditional treated water.” Total combined water recovery is 90% to 95%.

Stripping selenium

GE Water & Process Technologies, Trevose, Pa., sees a broader role for its ABMet (Advanced Biological Metals Removal) ap-proach. The system uses granular-activated-carbon beds inoculated with specific strains of selenium-reducing bacteria to remove the mineral, explains Tim Pickett, ABMet technology manager.

Proven in the mining industry since 2001, the technology will see its first use in coal-fired power plants soon, with two units ex-pected to be commissioned in December. No installations at chemical plants are in the works as yet.

Each compact modular unit can treat up to 2 million gal./d. The system can handle streams with influent selenium concentra-tion as high as 2-to-5 mg./L., cutting the concentration in the efflu-ent by as much as 99%. Operating costs can be as low as $0.50 per 1,000 gal., says Pickett.

ABMet can be coupled with conventional water-treatment methods, he adds. This offers a less-complex alternative to conven-tional physical/chemical treatment processes, Pickett believes. That means minimal sludge generation — “up to a thousand times less” — as well as “virtually no chemical addition.”

Diagnostics’ developments

Whatever the process water or wastewater, end-users need diag-nostics to guide treatment decisions — and biology is playing a growing role.

“Water and biology go together very well. On the water side, you want to remove organisms; on the wastewater side, you want to use organisms,” explains Daniel Oerther, associate professor in the University of Cincinnati’s Department of Civil and Environ-mental Engineering, Cincinnati, Ohio.

For cooling systems, Ciba has developed a far faster tech-nique for spotting Legionella pneumophila, the pathogen behind Legionnaire’s Disease. In contrast to existing Petri-dish tests that take seven days to get yes/no results, “it will give results in two hours,” says Chamberlin. He foresees strongest demand for the technique in Europe, where stringent standards exist for biological treatment of cooling water. He expects Ciba to launch this technol-ogy, currently undergoing trials, at the end of 2007. “We’ll be demonstrating it in our plants, as well.”

“We use epifluorescent microscopy, a method which has been used in microbiological area for some years,” Chamberlin notes. The technique gives the amount of L. pneumophila present, alive or dead, as well as the CFU (colony forming unit) metric. But samples taken from the process equipment’s water circuits still must be analyzed in a laboratory, not in the field. “You need labo-ratories managed to the correct level of microbiological hygiene,” he explains.

Oerther’s also developing diagnostic tools to improve treat-ment units’ performance. “What we do with a variety of tools is fingerprint — identify and quantify — the DNA of the organisms,” he says. For instance, if he were examining wastewater, he would look for harmful species like salmonella, E. coli or cryptosporid-ium.

“You need to be able to detect low quantities of organisms with very few false positives or false negatives,” Oerther explains. “And you want high specificity. The target is one organism in 100 milliliters of sample — truly a needle in a haystack.” Plus, on the wastewater-treatment side, different processes require different types of assays — what’s appropriate for an anaerobic digester won’t suit an activated sludge unit.

The techniques he employs already find use in medical re-search on infectious diseases. “They do the same things we do. People have been working with these techniques for about last 15 years,” Oerther notes. However, since the 2001 scare from anthrax in the U.S. mail, there’s been an investment in developing tech-niques to rapidly identify organisms in the environment, he says.

CH2M Hill utilized these organism-fingerprinting techniques in post-Hurricane-Katrina Louisiana to help restart chemical plants and refineries. “They wanted to know which organism to use to seed the industrial-wastewater-treatment systems,” recalls Oerther, who consulted on the projects. “So we used our tools to identify which seed sludge was optimum for their processes… We allowed them to have much faster restarts.”

Lack of regulatory drivers has slowed their commercializa-tion, Oerther says. “[However] people could use them, if they chose to.”

Besides regulations, changing economics and priorities, of course, influence decisions about installing technology. For exam-ple, Sandy observes: “Bar none, the hottest technology now is membrane technology. Systems we would’ve ruled out five years ago because of price, we’d look at today.” Maybe that’s not ex-actly recycling or even reuse, but it is good engineering economics.