Fats, oils, and grease—collectively known as FOG—are among the most persistent and problematic pollutants in municipal wastewater systems. While often overlooked, FOG buildup in wet wells can lead to severe operational challenges, including pump failures, odor issues, and costly maintenance. Understanding the dynamics of FOG in wet wells highlights the need for innovative solutions like IXOM Watercare’s AP500, which is engineered to mitigate these persistent problems

What is FOG and Why Does It Matter?

FOG refers to the lipid-based waste that enters the sewer system primarily from food preparation and industrial processes. Common sources include cooking oils and fats, dairy products, meat drippings, sauces and dressings

When these substances enter the sewer system, they cool and solidify, adhering to pipe walls and wet well surfaces. Over time, this leads to the formation of FOG caps—thick, buoyant layers that float atop wastewater in wet wells.

The Science of FOG Accumulation in Wet Wells

Wet wells are the collection basins in lift stations where wastewater is temporarily stored before being pumped to treatment facilities. These environments are particularly susceptible to FOG buildup due to several factors:

• Temperature Gradients: FOG tends to solidify as it cools. Wet wells often experience temperature drops, especially in colder climates or during nighttime hours, accelerating the solidification process.
• Hydrophobic Properties: FOG compounds are non-polar, meaning they repel water and tend to float. This causes them to accumulate at the surface, forming thick layers that resist mixing and degradation.
• Anaerobic Conditions: Stagnant wet wells can become anaerobic, promoting the production of hydrogen sulfide (H₂S) gas. This not only contributes to foul odors but also accelerates corrosion of infrastructure.
• Microbial Interactions: Certain bacteria can metabolize FOG, but only under aerobic conditions. Without sufficient oxygenation, microbial degradation is minimal, allowing FOG to persist and accumulate.

Consequences of FOG Buildup

FOG accumulation in wet wells leads to a cascade of operational and environmental issues:

• Pump Fouling: FOG can accumulate on float switches and pump impellers, leading to mechanical failures.
• Odor Complaints: Anaerobic decomposition of organic matter produces H₂S, causing strong, unpleasant odors.
• Corrosion: H₂S reacts with moisture to form sulfuric acid, which corrodes concrete and metal components.
• Sanitary Sewer Overflows (SSOs): Blockages caused by FOG can result in untreated sewage spilling into the environment.

According to the EPA, 47% of reported sewer blockages are caused by grease from restaurants, homes, and industrial sources. Historically, municipalities have employed several methods to combat FOG:

• Grease traps and interceptors: Installed at the source to capture FOG before it enters the sewer system.
• Chemical dosing: Uses surfactants or enzymes to break down FOG.
• Vacuum truck cleanouts: Manual removal of FOG caps from wet wells.
• Aeration systems: Introduce oxygen to promote microbial degradation.

While these methods offer partial relief, they often fall short in cost-effectiveness, scalability, and long-term sustainability.

FOG Prevention Reimagined: IXOM Watercare’s AP500 Solution

IXOM Watercare’s AP500 system is designed specifically to address the challenges of FOG buildup in wet wells. It combines high-efficiency aeration with strategic mixing to create an environment where FOG cannot accumulate.

Key Features of the AP500:

• Fine Bubble Aeration: Delivers high oxygen transfer efficiency and promotes aerobic microbial activity to biologically degrade FOG.
• Active Mixing: Prevents stratification and ensures uniform distribution of oxygen. Keeps floatable solids suspended, reducing surface cap formation.
• Low Maintenance Design: Submersible and corrosion-resistant components. No moving parts within the wet well reduces maintenance frequency and costs.
• Energy Efficiency: Operates at low horsepower, making it ideal for continuous use.

The AP500 system is easily installed directly in the wet well. Once operational, it begins to break up existing FOG caps through agitation, introduce dissolved oxygen to support aerobic bacteria and prevent future accumulation by maintaining turbulent flow and oxygen-rich conditions. Field trials have shown that AP500 can eliminate FOG caps within 24–48 hours, significantly reducing odor and corrosion issues.

Implementing AP500 offers both environmental and financial advantages:

• Reduced SSOs: Prevents blockages and overflows.
• Lower Maintenance Costs: Minimizes manual cleanouts and pump repairs.
• Improved Worker Safety: Reduces exposure to hazardous gases.
• Enhanced Community Relations: Fewer odor complaints and environmental violations.
• Extended Equipment Life: Reduces corrosion and wear on pumps and infrastructure.
• Regulatory Compliance: Helps municipalities meet environmental quality standards.

FOG buildup in wet wells is a complex challenge rooted in chemistry, microbiology, and fluid dynamics. Traditional mitigation strategies often fall short, leaving municipalities to grapple with recurring maintenance and environmental risks. IXOM     Watercare’s AP500 system offers a scientifically grounded, field-proven solution that transforms wet wells into self-cleaning, odor-free environments. By leveraging aeration, mixing, and microbial support, AP500 not only eliminates existing FOG but prevents future accumulation—making it a smart investment for any wastewater utility.

If your municipality is facing persistent FOG challenges, it’s time to consider a smarter, more sustainable solution. Contact IXOM Watercare today to learn how the AP500 system can be tailored to your specific needs. Don’t let FOG compromise your infrastructure—invest in the AP500 and take control of your wet wells.