Qwik Zyme L and Foam Buster Case Study

Independent data collected and submitted by
City of Monticello, IN

Introduction

The City of Monticello, Indiana operates an extended aeration activated sludge treatment system to handle 1.6 MGD of flow. Up until 2019, the city had relied upon chlorination to control foaming caused by FOG filaments, specifically Microthrix parvicella. From 2019 onwards, the facility routinely battled foaming year-round. Several mitigation attempts were made, with limited to no success.

In 2025, the wastewater team in Monticello decided to reach out to Aquafix for assistance. Aquafix’s technical support team identified the challenge and provided a solution utilizing a two-phase biological augmentation approach – Qwik Zyme L and Foam Buster.

Qwik Zyme L is a concentrated blend of enzymes (lipases) specific to the degradation of long chain fatty acids, the main component of fats, oils, and greases. Using these enzymes allows for the biologically safe and effective breakdown of FOG into short-chain fatty acids.

Foam Buster is a specialized blend of key nutrients that readily encourage floc forming bacteria to uptake the newly formed short-chain fatty acids via enzymatic breakdown. Once these fatty acids are consumed by bacteria, the complete reduction of FOG is accomplished, thus eliminating the main food source of FOG filaments.

Métodos

Aquafix’s laboratory team received a sample of the mixed liquor and foam taken from Monticello’s aeration basins. Both samples were observed to have a high volume of Microthrix – a filament commonly found in wastewater systems with high FOG loading and low F/M conditions. The natural buoyancy and complex branching structure of the filament leads to foaming and bulking. Photos were taken of the aeration basin to document the extent of foaming prior to treatment in early June of 2025.

Qwik Zyme L and Foam Buster were recommended to treat the root cause of the foaming filaments – FOG. Both components were dosed based on the average daily flow rate of 1.6 MGD. A higher initial dose rate was utilized for 30-days to ensure the FOG existing in the basins along with the incoming FOG were accounted for during the entirety of the first complete biological sludge age. Qwik Zyme L was metered in at 4 gallons/day. Foam Buster packs were added directly to the aeration basin at a rate of 12 pounds/day.

After the 30-day dosing period, foaming began to subside. The dose rates for Qwik Zyme L and Foam Buster were then halved to manage incoming FOG while the biological processes returned to steady-state.

Photos were taken of the aeration basins following the conclusion of the treatment in August of 2025. A follow-up lab analysis was conducted to confirm filament populations were lowered.

A second follow-up analysis was conducted in October of 2025 to ensure filaments were eliminated from the treatment plant.

Resultados

Figure 1. Photo of Monticello, IN aeration basin foaming taken June 2025 prior to treatment.

Figure 3. 600x (m) Neisser Stain. Low levels of M. Parvicella (red arrow) observed in Monticello MLSS samples. 8/20/25.

Figure 4. Photo of Monticello, IN aeration basin taken August 2025 after treatment.

Discussion

The data collected before and after the treatment program showed full removal of Microthrix filaments in the Monticello, IN wastewater treatment facility. Laboratory

analyses from pre-treatment (6/22/25) showed high to very high abundance of filaments in both foam and MLSS samples. Laboratory analyses immediately following treatment (8/22/25) showed low abundances of filaments in both foam and MLSS samples. The third analysis and second follow-up lab observations (10/2/25) showed no observable filaments.

Photographs taken on-site prior to treatment showed complete coverage of foaming throughout the entire aeration basin, confirming the microscopic observations that were completed in June of 2025. Additional photographs taken following treatment showed no foam was present in the aeration basin, confirming microscopic observations in the first follow-up report completed in both August and October of 2025.

Conclusión

Aquafix’s recommended treatment program utilizing Qwik Zyme L and Foam Buster was successful in eradicating Microthrix filaments and eliminating foaming from the aeration basins at the Monticello, IN wastewater facility.

In addressing and reducing the main-driving force of the Microthrix, FOG, Aquafix’s treatment demonstrated the efficacy in safely removing foaming filaments while maintaining quality biological nutrient removal.

Acknowledgements

Aquafix sincerely thanks the City of Monticello’s wastewater team in their efforts and cooperation throughout the treatment process.