By Peter Chawaga, Associate Editor, Water Online
For decades, industrial operations have relied on phosphorus in compounds used to treat cooling water. With rising concerns around algal bloom, caused by excessive nutrients including phosphorus in waterways, regulatory bodies are beginning to crack down on this practice and alternatives are becoming necessary.
Phosphorus is found throughout water treatment processes at many industrial facilities. Orthophosphate is used for steel corrosion control, polyphosphate for deposit control. Organic phosphonates are used for calcium scale inhibition and phosphorus is incorporated into several dispersant polymers.
“Phosphorus compounds are very common in water treatment and have been used successfully for decades,” said Mike Mowbray, the director of product management for U.S. Water, who has written on the topic. “In many commercial cooling and boiler treatment chemistries, combinations of the different phosphorus compounds are used together.”
However steeped in the chemical’s use an operation might be, regulators aren’t likely to back down from their concerns any time soon.
“Excess phosphorus which is discharged with cooling water will generally end up in a stream or river,” said Mowbray. “Even if the company discharging the cooling water sends it to a municipal treatment facility, some of the phosphorus will pass through the treatment and into the environment.”
As water systems around the country know, phosphorus feeds algae growth, which, if unchecked, will deprive aquatic life of oxygen and in extreme cases, poison drinking water. But it won’t be easy for operations to wean themselves off of the chemical.
“Because phosphorus-based chemistry is so effective, it can be challenging to find replacements which provide the same level of corrosion protection or deposit control,” Mowbray said. “The costs to industry and the country … could be very large. So, there is a reluctance to abandon technology with such a long and proven track record.”
But technology providers can equip operations with alternatives to phosphorus, offering effective corrosion protection and scale control chemistry that does not utilize the nutrient. For U.S. Water, it was a matter of developing an alternative based on the efficacy of phosphorus and, now, convincing operations that it will be a good fit.
“Once we had proven the concept in laboratory settings, we ran a series of field trials with customers from several of the markets we serve in order to gain experience in the operational differences between our new technology and the better understood phosphorus chemistries,” Mowbray said. “Having gained this experience, we are now able to have detailed conversations with other plant operational personnel to help them understand whether converting from phosphorus-based technology makes sense at their facility.”
However, the transition won’t be easy. Any new technology will require new control parameters, introducing a new approach to treatment that can be burdensome to adjust to.
“This doesn’t necessarily imply that the new technology is difficult to work with,” Mowbray said. “But it is important to understand that it must be managed differently. Operations managers that ingrain this concept quickly will be able to successfully operate with the newer chemistries… Every new technology has a learning curve which some climb faster than others.”
As regulations continue to fight against phosphorus discharge and operations are increasingly forced to explore alternatives, it is important to keep some first steps in mind.
“Work with a professional water treatment engineer and begin with a system-wide survey to gain an understanding of the critical requirements, as well as system variables,” said Mowbray. “The better understood the entire system is, and how it impacts operations, the more successful the transition will be to non-phosphorus technology.”
Image credit: "Cooling towers at Buildwas Power Station. 7 June 2017.," ricsrailpics Follow © 2017, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/