Postbiotics are one of those under‑used but high‑leverage tools in biological wastewater treatment. They don’t add new microbes the way bioaugmentation does—instead, they add the biochemical signals, enzymes, metabolites, and structural components that high‑performing microbial communities naturally produce. Think of them as microbial performance boosters rather than microbes themselves.
Here’s how they elevate system performance in a way operators can actually feel in the basin.
🌱 What Postbiotics ArePostbiotics include:

• Enzymes (proteases, lipases, amylases, cellulases)
• Organic acids (lactic, acetic)
• Peptides and biosurfactants
• Cell wall fragments and signaling molecules
• Metabolites that modulate microbial behavior

They’re essentially the “working molecules” of a healthy microbial community—delivered directly, without needing the microbes that made them.
🚀 How Postbiotics Improve Biological Treatment Performance1. Faster Hydrolysis of Complex WastesHydrolysis is the rate‑limiting step in many biological treatment. Postbiotic (free) enzymes:

• Break down fats, oils, and grease into usable fatty acids
• Split proteins into amino acids
• Convert starches and cellulose into simple sugars

This gives the existing biomass more accessible food, reducing lag time and improving COD removal.

2. Stabilized Microbial CommunitiesPostbiotics contain quorum-sensing molecules and cell wall fragments that:

• Encourage beneficial guilds (e.g., floc formers, nitrifiers)
• Reduce stress responses
• Improve floc structure and settling

You get denser, more resilient biomass.

3. Improved Nitrification and Nutrient RemovalOrganic acids and cofactors in postbiotics:

• Support nitrifier metabolism during shock loads
• Reduce pH micro‑gradients inside flocs
• Enhance electron transfer efficiency

This leads to more stable ammonia oxidation and better total nitrogen removal, especially in cold or variable conditions.

4. Reduced Filamentous PressureSome postbiotic compounds:

• Disrupt filamentous quorum signals
• Strengthen EPS production by floc-formers
• Improve shear resistance of flocs

The result is less bulking, better SVI, and tighter sludge.

5. Enhanced Sludge ReductionPostbiotic enzymes accelerate endogenous respiration by:

• Breaking down dead cell material
• Increasing solubilization of bound organics
• Supporting fermentative pathways

This can translate into lower sludge yield and reduced hauling costs.

6. Better Resilience to Toxic or Variable LoadsPostbiotics often include:

• Antioxidants
• Stress‑response metabolites
• Chelators that bind inhibitory metals

These help the biomass recover faster from toxicity, pH swings, or hydraulic shocks.

🧪 Why Operators Like Postbiotics

• They work immediately—no lag for microbial growth
• They’re stable and easy to dose
• They don’t compete with existing biomass
• They enhance what’s already there

They’re especially powerful in systems with:

• High FOG
• Industrial variability
• Cold weather nitrification issues
• Filamentous instability
• High sludge production

In composting—as in activated sludge, biosolids stabilization, and other biological treatment systems—the real work is performed by a dynamic microbial consortium. What looks like “rotting” is actually a structured succession of microbial guilds responding to substrate availability, temperature, moisture, and oxygen transfer.

Two functional groups dominate this process: bacteria and fungi. Their interaction is not static; it shifts through phases of competition, inhibition, and cooperation as the organic matrix changes. Understanding this succession is key to optimizing any aerobic stabilization process, whether in a backyard pile or a biosolids windrow.
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1. Functional Guilds: Rapid Responders vs. Structural Degraders

​This division mirrors what wastewater professionals see in RBCs, trickling filters, and aerobic digesters: bacteria handle the fast, soluble load; fungi and actinomycetes step in when the substrate becomes more complex.
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2. Temperature-Driven Succession: Three Distinct Phases
Microbial dominance in composting is governed largely by temperature, which itself is a byproduct of metabolic heat release.

Act I: Mesophilic Phase — Bacterial Bloom
Typical Range: ~20–40°C
Fresh nitrogen-rich inputs trigger a surge of mesophilic heterotrophic bacteria. Their rapid oxidation of soluble organics increases temperature and oxygen demand.

• Dynamics: Bacteria outcompete fungi due to faster growth rates and access to soluble substrates.
• Outcome: Heat accumulation pushes the system into thermophilic conditions, suppressing most fungal activity.
  
  

Act II: Thermophilic Phase — High-Rate Oxidation
Typical Range: ~45–70°C
As temperatures rise, mesophiles decline and thermophilic bacteria take over. This phase is analogous to high-rate aerobic digestion.

• Fungal Status: Most fungi are inhibited or sporulate; activity is concentrated in cooler outer zones.
• Notable Group: Actinobacteria, filamentous bacteria often mistaken for fungi, thrive here and contribute to lignocellulose breakdown and geosmin production (the “earthy” odor).
  
  

Act III: Curing Phase — Fungal Recolonization
Typical Range: Cooling to ambient
Once readily biodegradable organics are depleted, metabolic heat drops and the system cools.

• Dynamics: Fungi re-establish dominance, targeting lignin, the most recalcitrant fraction of plant biomass.
• Importance: Lignin degradation exposes cellulose and hemicellulose, enabling secondary bacterial activity and driving humus formation—the stable end product.
  
  

This curing phase is analogous to the endogenous respiration period in biosolids stabilization, where slow-growing organisms finish the job.

3. Carbon–Nitrogen Balance Through a Microbial Lens
The classic “Browns vs. Greens” rule maps directly to microbial ecology:

• Excess Nitrogen (Greens):
  High soluble organics → bacterial overgrowth → oxygen depletion → anaerobic pockets → odor generation (VFAs, reduced sulfur compounds).
• Excess Carbon (Browns):
  High lignocellulose → limited bacterial activity → insufficient heat generation → fungal-dominant, low-temperature composting.
  

Just as in wastewater treatment, substrate balance dictates microbial selection.

4. Operational Practices That Influence Microbial Performance

1. Limit late-stage turning:
   Excessive agitation disrupts fungal hyphae during the curing phase. Similar to biofilm systems, structural integrity matters for lignin degradation.
2. Particle size reduction:
   Shredding carbon-rich materials increases surface area, improving fungal colonization and oxygen penetration.
3. Moisture control:
   Bacteria require thin-film water for substrate transport; fungi tolerate lower moisture.
   Over-drying shifts the system toward fungal dominance and uneven decomposition.
   
   

Summary

• Bacteria drive the high-rate oxidation of soluble organics and thermophilic heat generation.
• Fungi are essential for degrading lignin and completing humification.
• Succession—not a single microbial group—is what stabilizes organic matter effectively.
• Operational controls (moisture, aeration, particle size, C:N ratio) determine which guild dominates and when.

 

As city managers and engineers responsible for maintaining efficient and reliable wastewater infrastructure, you're aware that the collection system is the backbone of urban sanitation. However, one persistent threat often lurks unseen until it causes major disruptions: fats, oils, and grease (FOG). Commonly entering the system from food service establishments, households, and industrial sources, FOG can solidify and accumulate, leading to a cascade of operational headaches. In this article, we'll dive into why grease poses such significant problems in collection systems, with a particular emphasis on lift stations—critical components that pump wastewater uphill or across long distances. We'll explore the formation of hydrogen sulfide (H2S) in anaerobic zones, the damage to pumps and floats, and the heightened risk of sanitary sewer overflows (SSOs). Understanding these issues is key to proactive management and cost savings.

How Grease Infiltrates and Accumulates in Collection Systems
Grease doesn't just disappear down the drain. When hot FOG from cooking or cleaning cools in pipes, it congeals into solid deposits, often combining with other debris like wipes or solids to form blockages. In the U.S., FOG deposits are responsible for over 45% of sewer pipe occlusions, leading to increased maintenance costs and environmental risks. These accumulations reduce pipe capacity, slow flow, and create ideal conditions for further problems downstream. While main sewer lines bear the brunt initially, the effects are amplified in lift stations, where wastewater pools and gravity can't always do the work.

The Unique Vulnerabilities of Lift Stations
Lift stations are engineered to handle variable flows, but they're particularly susceptible to grease buildup due to their design. Wastewater collects in a wet well, where pumps activate based on level sensors or floats. Over time, FOG forms a "grease cap" or scum layer on the surface, which can harden and adhere to sidewalls, floats, and other components. This accumulation accounts for roughly 30% of sewage backups in lift stations, turning routine operations into emergencies. The confined space and stagnant conditions exacerbate issues, making lift stations a hotspot for grease-related failures.

H2S Formation: The Corrosive Byproduct of Anaerobic Zones
One of the most insidious effects of grease in lift stations is the creation of anaerobic environments. Beneath a thick grease cap, oxygen levels plummet, allowing sulfate-reducing bacteria to thrive. These microbes convert sulfates in the wastewater into hydrogen sulfide (H2S) gas—a toxic, corrosive compound with a rotten-egg odor. H2S not only poses health risks to maintenance crews entering confined spaces but also reacts with moisture to form sulfuric acid. This acid attacks concrete walls, metal pipes, and equipment, accelerating structural degradation. In force mains and downstream structures, H2S can drive down pH levels, leading to crown corrosion in manholes and influent lines. For city managers, this means higher repair bills and shorter asset lifespans; engineers might see this as a call for enhanced ventilation or chemical dosing strategies to mitigate anaerobic conditions.

Damage to Pumps and Floats: Operational Nightmares
Grease doesn't just corrode—it clogs and encrusts. Pumps in lift stations can become fouled as FOG adheres to impellers and seals, reducing efficiency and causing overheating or outright failure. Floats and sensors, which detect water levels to trigger pumps, often get coated in a greasy layer, preventing proper actuation. When floats stick, pumps may run dry or fail to start, leading to overflows or backups. In severe cases, this requires frequent pump-outs—sometimes more than twice a year—to clear solids and grease, adding to operational costs. The combination of mechanical wear and corrosion from H2S can shorten pump life dramatically, turning a reliable system into a maintenance sinkhole.

The Escalating Risk of Sanitary Sewer Overflows
Perhaps the most alarming consequence of grease buildup is the increased likelihood of SSOs—events where untreated sewage spills into streets, properties, or waterways. Blockages from FOG reduce flow capacity, and in lift stations, encrusted sensors can allow levels to rise unchecked until overflow occurs. These spills not only carry pathogens like typhoid but also violate environmental regulations, potentially incurring fines and public backlash. Globally, FOG is linked to a significant portion of SSOs; in the U.S., it's a factor in 40-50% of annual blockage-related incidents. For engineers, modeling tools like CMOM (Capacity, Management, Operations, and Maintenance) plans can help predict and prevent these risks, but prevention starts upstream with grease interceptors and public education.

Strategies for Mitigation and Why It Matters
To combat these issues, consider implementing robust FOG management programs. Regular wet well cleanings, biological treatments to break down grease, and upstream controls like properly maintained grease interceptors can make a difference. Monitoring H2S levels and investing in corrosion-resistant materials for lift stations can extend infrastructure life. As city leaders, prioritizing these measures not only safeguards public health and the environment but also optimizes budgets—preventing a single SSO can save thousands in cleanup and repairs.
In summary, grease in collection systems isn't just a nuisance; it's a multifaceted threat that undermines the reliability of lift stations through anaerobic H2S production, equipment damage, and overflow risks. By staying informed and proactive, city managers and engineers can keep their systems flowing smoothly, ensuring sustainable urban wastewater management for years to come.
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Technologies for Addressing FOG in Collection Systems

• Grease trap maintenance programs
  Routine inspection and maintenance can be improved with the use of biological treatment. Microbes have proven effective in reducing FOG and BOD5 entering the municipal collection systems. Unlike solvents and surfactants treatments, the microbial treated grease does not solidify downstream.
  
  
• Mixing/aeration in lift stations
  Adding mixing/aeration in a lift station wet well reduced anaerobic conditions preventing H2S formation and keeps grease from forming a solids cap.
  
  
• Biological treatment in gravity lines and lift stations
  The same biological treatment process used in grease traps can also be adapted for collection system maintenance. Benefits include reduced SSO, H2S, and lower BOD5/FOG entering the treatment plant.