Big Sky WWTP Scales Up with INVENT’s Hyperboloid Technology
Big Sky, Montana, has upgraded its wastewater treatment plant to accommodate the growing volume of wastewater resulting from population growth and expanded sewer system connections. A Membrane Bioreactor (MBR) system was chosen as the optimal solution, supported by INVENT’s innovative mixing and aeration technologies. These technologies ensure efficient biological treatment and enable the reuse of treated water for golf course irrigation and snowmaking even under extreme climatic conditions.
Over recent years, the City of Big Sky has experienced significant population growth. In addition, a strategic initiative to connect more households to the municipal sewer system and reduce reliance on septic tanks has doubled the volume of wastewater treated over the past three decades.
To meet this increased demand, engineers from AE2S in Bozeman, Montana, were tasked with designing a major upgrade and expansion of the existing Big Sky Wastewater Treatment Plant (WWTP). After a thorough evaluation, a Membrane Bioreactor (MBR) system was selected for its ability to produce high-quality effluent. This treated water will be stored in local reservoirs for beneficial reuse, including irrigating golf courses in the summer and supporting snowmaking in the winter.
A key advantage of MBR systems is their ability to operate with high sludge concentrations for effective biological treatment. In such systems, reliable and energy-efficient mixing in anaerobic and anoxic zones is essential. To meet these requirements, INVENT Environmental Technologies was selected to provide advanced mixing solutions for the new biological reactors and fermenters. Working closely with AE2S engineers, INVENT proposed the HYPERCLASSIC®-Mixer Evolution7 as the ideal solution.
The hyperboloid mixer design delivers highly efficient solids suspension and homogeneous mixing – critical for processes such as enhanced biological phosphorus removal and denitrification. The HYPERCLASSIC® system’s unique shape, low rotational speed, and radial flow pattern ensure thorough bottom cleaning and prevent sedimentation. To ensure reliable operation in Montana’s harsh winter conditions, special cold-weather adaptations were made to the gearbox.
Beyond the biological reactors, the equalization tank presented a unique dual-function challenge: it required both mixing and intermittent aeration. Conventional aeration systems were unsuitable due to the tank’s irregular operating pattern. INVENT addressed this by installing the HYPERCLASSIC®-Mixing and Aeration System, which integrates mechanical mixing with intermittent air dispersion.
As this marks the first installation of the HYPERCLASSIC®-Mixing and Aeration System in Montana, a Standard Oxygen Transfer Rate (SOTR) test was conducted at INVENT’s headquarters in Erlangen, Germany. The full-scale clean water test, performed at design water depths, validated the system’s oxygen transfer efficiency. A comprehensive test report was submitted to AE2S and the City of Big Sky and received full approval.
The successful implementation of INVENT’s mixing and aeration technologies at Big Sky WWTP highlights the importance of tailored, high-performance solutions in modern wastewater treatment – particularly in regions with extreme climates and sustainability-focused goals.
