MIXING, WEIGHING & CONVEYING


GASMIX MEETS TIGHT & TRICKY CHALLENGE


A wastewater treatment plant (WWTP) in Wisconsin has increased the biogas yield at its AD plant by 25%, thanks to the installation of a new digester mixing system from Landia


nstead of capacity decreasing because of rags, grit and debris steadily accumulating at the bottom of two digesters (334,000 gallons (1,264m3


I T ) and 183,000 gallons (693m3 )


respectively), the tanks’ contents at the city of Sparta (situated between Milwaukee and Minneapolis) are now comprehensively mixed by Landia’s GasMix system.


Easy maintenance


A simple, yet highly effective design, comprising the proven Landia Chopper Pump and strategically-angled venturi nozzles, all


mechanical equipment can be accessed on the outside of the digesters for easy maintenance.


Sparta’s Wastewater Treatment Plant Manager, Ed Hanson, commented: “Our old, basic mixing system just blew air upwards in the digesters, which wasn’t very efficient. Also,


MOUNTING KIT COPES WITH TOUGH CONDITIONS


he PR 6003 mounting kit, from Minebea Intec, offers fast commissioning and combines maximum accuracy with maximum safety in a compact system. The kit has been specially developed for demanding applications in industrial silo weighing, and is available to order now.


The mounting kit guarantees reliable measurements, even under the toughest conditions, including wind loads, earthquakes or vibrations. With a nominal load range of 500kg to 75 tonnes, the system offers exceptional bandwidth and flexibility. Depending on the environmental conditions, there is a choice between mild steel or stainless steel for additional protection against corrosion. "Our goal was to create a product that is not only technically impressive, but also makes everyday life easier for our customers," explained Yannick Salzmann, Product Manager at Minebea Intec.


With permissible horizontal forces of up to 82 kN and an anti-lift device that can withstand forces of up to 120 kN, the mounting kit offers a "wind and earthquake calculation tool" to optimise the design of silo structures.


Installing the PR 6003 is particularly easy. The dummy function allows installation without a load cell to prevent damage to the load cell. With the optional jack-up tool, the silo can be lifted without an external lifting tool to remove the safety plates. The compact design with a weight of less than 20kg enables installation by just one person. Once installed, the system is durable and maintenance-free.


www.minebea-intec.com 22 MAY 2025 | PROCESS & CONTROL


we couldn’t get to it to carry out maintenance or make repairs without draining the tanks down. This can take you offline for a long time, which nobody wants when trying to produce biogas.


Variable intake


“Eventually, the old mixing system was failing; just providing some minor recirculation, with very little actual mixing taking place. When it became time to drain down the first digester and install the Landia GasMix, we found a huge amount of debris inside.”


Sparta’s wastewater treatment plant serves 10,000 people in what is known as the ‘Bicycling Capital of America’. In addition to domestic wastewater, the WWTP also receives effluent from a large food processing plant, a major dairy, plus leachate from the county’s landfill, and septage brought in from hauliers. Although the WWTP has some screening, there is very little pre-treatment in place before it reaches the inlet.


“The Landia GasMix installation went very well,” said Hanson. “Landia were here to help every step of the way, especially as this was a tight and tricky challenge with very limited space for the new mixing set-up. We had to move some of our recirculation pumps.


Plenty of turbulence


“At the start-up of the new system, we could see immediately that the Landia GasMix created plenty of turbulence and did a great job grabbing the gas from the top of the digester. Everything went smoothly, so six months later, we went ahead with installing another Landia GasMix for our second


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