Another industrial installation by Columbian TecTank in New Zealand.
Click here to enlarge image"We wanted to use a bolted steel tank because it involved substantial cost savings and because the interior coating could be factory applied for greater quality control," Clarke notes. "We knew an off-the-shelf coating for that tank wasn't going to work."
What has worked is a coating developed specifically for the Boeing application by Columbian TecTank, of Kansas City, Mo.
"Normally, tank coatings can handle pH variations of 3 to 11," explains Columbian TecTank sales manager Erik Carson, "but this application was well outside those parameters."
"We looked at all our coating possibilities and determined we really needed to invent a new one. It had to be a thicker coating, but one that would retain its flexibility, that wouldn't crack when the bolts go through it, and that would hold up to the two-coat, heat-curing process at our plant," Carson explains.
It took three months and four experimental coatings to perfect the one used for Boeing. And it wasn't just the coating that was new. By the time the process was completed, Columbian TecTank had changed the coating application equipment and nozzles, and even some of the procedures on their line. They used different gasketing on the Boeing tank, as well, according to Carson.
From the holding tank at Boeing, the influent is pumped as needed to a bank of reverse osmosis chambers. These units were already in place to further purify city water, but considerable excess capacity has allowed it to be used for the entire recycling program. After passing through reverse osmosis, air strippers remove any remaining volatile organics.
"The water is held in another one-million-gallon bolted steel tank and draws off to process through reverse osmosis as needed by the MPF and by four of our larger cooling towers at the plant," says Clarke. "If the system senses a drop in pressure, city water kicks in to make up the difference, but that water has a different chemistry and must be treated before it's used."
Conclusion
The savings to Boeing is already $300,000 a year in city water purchases. Boeing has achieved a 90% reduction in wastewater leaving the site, and the program is still in the shake-down phase. In the near future, a new control room for the IWTP will enhance the performance and monitoring of the recycling program, and additional capacity and distribution will take recycled water to all 43 of the plant's cooling towers and buildings. IWW
For more information, contact Columbian TecTank at 913-621-3700 or [email protected]