How Nanobubble Pretreatment Helped a Massachusetts Wastewater Facility Restore Nitrification and Achieve Nitrogen Compliance
Wastewater treatment facilities serving food-service districts are increasingly challenged by quaternary ammonium compounds (QACs), disinfectants that can inhibit nitrification even at 2–5 mg/L. For plants with heavy restaurant flow, inhibition from QAC loading is a common cause of ammonia spikes, biological upsets, and recurring nitrogen exceedances.
This was the case at the Derby St. Shops onsite wastewater treatment facility in Hingham, Massachusetts, a retail center with more than 60 food-service businesses. The facility struggled with chronic nitrogen permit exceedances driven by severe QAC inhibition and needed a sustainable, chemical-free solution.
Download the full case study: https://www.moleaer.com/case-study-derby-st
The Challenge: QAC Toxicity, FOG Loading and Limited Options
Woodard & Curran, the site’s operations and compliance team, traced the problem to
- Influent QAC concentrations regularly exceeding 30 mg/L
- High FOG (fats, oils and grease) loading from restaurants
- Limited process flexibility and no ability to expand infrastructure
- Inconsistent performance of chemical quat blockers, which were also not approved for long-term use
These conditions made it difficult for the facility to maintain stable nitrification, leading to ongoing ammonia and total nitrogen exceedances.
The Solution: Nanobubble Pretreatment Ahead of the RBC
To restore biological performance without major upgrades or chemicals, the facility integrated Moleaer’s nanobubble pretreatment solution at the influent to the first Rotating Biological Contactor (RBC).
This low-footprint wastewater pretreatment step strengthened nitrifying bacteria under high toxic loading, enabling the existing RBC process to function as intended.
Nanobubble pretreatment also operates chemical-free, requires minimal maintenance, and fits within constrained plant footprints, making it well-suited for decentralized wastewater facilities.
The Results: Stable Biology and Consistent Nitrogen Compliance
Following installation of the nanobubble pretreatment system, the facility achieved:
- Clear improvements in ammonia removal
- Significant reduction in total nitrogen
- Complete and reliable nitrification, even under toxicity stress
- Elimination of quat-blocking chemicals
- Consistent return to permit compliance
To see the full performance data, download the complete case study.
See the Full Performance Data
The detailed case study includes:
- Influent and effluent data
- Year-over-year ammonia and total nitrogen results
- Nanobubble pretreatment configuration
- Operational improvements and long-term compliance outcomes
Download the Full Case Study
See the full data, year-over-year graphs, and operational details from Derby St. Shops: https://www.moleaer.com/case-study-derby-st
