Struvite Reactor Cleaning Maintenance for Metro Wastewater Reclamation District
The Metro District treats 130 million gallons of wastewater per day requiring treatment and controlled reuse. During the process of treating wastewater, struvite can crystallize and build up inside lines and valves which requires frequent, laborious maintenance to clean.
The solution to this problem is to remove struvite from wastewater before it can build up in lines using a struvite reactor. An added benefit of this process is that struvite can be reused as a fertilizer. It contains nutrients such as phosphorus necessary for plant growth and can be stored in a compact form that is easy to handle, transport, and apply.
SCOPE OF WORK
The 74’ tall struvite reactor built for the Metro Wastewater Reclamation District by our client PCL Construction is the largest in the world. It holds 377,000 gallons of digested sludge material.
During the annual inspection of the tank's interior lining, areas were discovered that needed maintenance and repair. In order to do this work, the tank needed to be drained first. Once the tank is drained the hardened struvite has to be cleaned off the interior of the tank and components before repairs can be done.
Challenges
When an elevated tank is drained there is a significant amount of pressure, static pressure head, that is released from the bottom. The static pressure head corresponds to the height of the tank and the density of the fluid it contains. Based on the 74’ height of the fully loaded storage tank, our calculations determined there would be too much pressure generated to safely drain the tank from the bottom.
Another issue is the most common problem with struvite, which is build-up. The linings inside the tank are crucial to minimize the build-up of struvite. When draining and cleaning the tank, it is critical not to damage the lining.
World's largest struvite reactor built by PCL Construction for Metro Wastewater Reclamation District. It holds 377,000 gallons of digested sludge material.
OUTCOME
The first contractor Metro hired was not able to drain and clean the tank safely and effectively. This is where Kinetic came in. Working with the contractor and owner, the team collaborated on an alternative solution.
Utilizing the remote capabilities of our hydrovac trucks, hydrovac hose entered the tank nearly 80' over the top and reached all the way back down to the bottom of the 74' tall tank. Then the tank was drained by vacuuming out the sludge.
Kinetic’s hydrovac crews have mastered the required skills to clean with pressurized water safely and effectively in sensitive areas. Their experience ensured the tank lining remained unharmed during the draining and cleaning process.
With the tank drained and cleaned, Metro Wastewater was able to have necessary repairs performed so their tank would pass inspection. Kinetic also helped them determine a proactive maintenance schedule to help keep their struvite reactor working at peak performance.