Chinook Wastewater Treatment Plant's "good example" goes international

 

April 7, 2021

The Chinook Wastewater Treatment Crew as pictured in the March issue of "Treatment Plant Operator," a trade magazine highlighting effective practices and technology/equipment related to wastewater and industrial discharge treatment operations. Pictured left to right are Cory Fox, Eric Miller and Matthew Finley. The Chinook-based plant's use of low-speed mixers to agitate wastewater was featured in the magazine and reprinted in several international sources.

In 2014 the US Environmental Protection Agency asked the staff at the Chinook Wastewater Treatment Plant (WWTP) if they would help the regulatory agency develop a case study to be shared with other older wastewater treatment plants. What interested the US Agency was how the staff in Chinook was able to remove nitrogen from wastewater using a 1984-era plant built solely to remove solids and maintain a certain oxygen content.

At the time the plant first opened there were few issues about leaving nutrients in discharged water after treatment. The concerns and regulations came several years after the plant began operating. More recent regulations limited the amount of nutrients, like nitrogen, which could be present in treated discharged water. Too much nitrogen in a plant's discharge can generate poisonous algae blooms that result in fish kills and other problems. EPA did the case study and has since shared it widely.

The "good example" spreads around the globe

Eric Miller, manager of Chinook's WWTP, recently shared a copy of the "Treatment Plant Operator," a trade magazine highlighting effective practices and technology/equipment related to wastewater and industrial discharge treatment operations. The article, written by a contract writer from England, has since appeared in "Fluid Handling Pro," another trade magazine distributed in Asia, the Far East, the Netherlands and other parts of Europe. The story was reprinted in at least two foreign languages.

Alert readers may recall a 2014 article in the "Blaine County Journal" in which Miller described the innovation as a classic case of "a change that had good unintended consequences." At that time Miller and WWTP staffers were looking for ways to reduce the cost of electricity used to power a huge 'mixer' that agitated wastewater to, among other things, add oxygen.

"We had a situation," Eric explained, "where we used massive amounts of electricity to power a huge mixer that produced more oxygen than we really needed. In about 2005 or 2006 we installed two much smaller mixers that we could cycle-run less time only when mixing was critical to the treatment process."

Two things happened after the smaller, more versatile mixers were installed: first, the cost of electricity dropped dramatically resulting in about $18,000 per year in savings and, second, the levels of certain undesirable elements (nitrogen, phosphorous and ammonia) dropped below the levels required in the regulations. The EPA saw the drop in nutrients on monthly reports submitted by the Chinook plant. Experts at the EPA knew the Chinook plant was not designed to remove and reduce those kinds of reduced nutrients and decided to learn more about what the operators in Chinook were doing.

A couple of other things helped improve the outcomes. According to Miller, "About the same time we added the two smaller mixers we installed a central control system and then upgraded the control system in 2011. An added probe allowed us to more accurately measure oxygen levels in the wastewater we are treating. With that data we more accurately cycle the mixers when needed." The crew at the WWTP gathers samples of the wastewater, then analyzes the samples in the lab at the plant. "Once we know what and how much we need to remove, we set the control system and it automatically kicks in the mixers to get optimum results."

Low-speed mixers, pictured here, enable Chinook Wastewater Treatment Plant's operators to adjust the angle of the stainless steel propeller blades and fine-tune energy consumption. Two were installed in 2006 to reduce the cost of electricity required to agitate wastewater being treated.

Landia, a Denmark-based company with offices around the world, manufactured the small mixers that lowered the WWTP's power bill and reduced unwanted nutrients in the discharged water. The company hired the writer who did the story for the international publications. "Now," Eric Miller said, "our process and use of the mixing equipment is known all over. The practices we started are being adapted by other plants built in the same era as Chinook's plant."

Asked what's next for the Chinook Wastewater Treatment Plant, Miller said, "Though our plant is old and was built to accomplish a different set of treatment goals, we're getting performance numbers from our process that are equal to those from the newest, most modern plants. Our plan for the foreseeable future is to keep our nearly 40-year old plant maintained and operating. The other option would be to spend several million dollars to build a new plant." Eric Miller and his crew are committed to keeping the WWTP running smoothly and efficiently. The crew is proud to be, as Eric Miller put it, "the poster child" for the company that made the mixers that changed how wastewater is treated in older plants.

 
 

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