Another Road Warrior Observation
F:M Issues
In my travels this year, as limited as they have been (yes, I am suffering from severe hotel withdrawal), I have observed a recurring issue hampering the optimum efficiency of wastewater operations. This issue is the lack of food needed to maintain healthy bacteria populations required for effective operation of the wastewater treatment plant (WWTP).
Your WWTP could be any configuration from mechanical to lagoon systems, aerated or anaerobic, basic secondary wastewater treatment to a sophisticated water recovery system, they all rely on healthy happy bacteria (bugs) to perform.
There are many operational process requirements for running your facility to maintain your discharge limits. Keeping your bugs healthy, happy, and doing their jobs requires the correct balance of proper food.
When the correct amount and type of food is not available, the food to microorganism ratio (F:M) is out of order. We are seeing a variety of challenges occur in wastewater facilities experiencing these symptoms.
These issues include improper settling, foaming, and in some cases, facilities unable to meet NPDES (National Pollution Discharge Elimination System) permit removal requirements for BOD, TSS, ammonia, or nitrate. Facilities with F:M problems may also experience odor complaints and rapid deterioration of infrastructure.
In my travels this past year, specifically in the southern part of the United States, there is a recurring complaint;
These municipalities do not have the number of visitors they usually see during the winter months and the wastewater facilities are experiencing a significant reduction in flow.
A reduction in volume of influent flows usually results in a reduction of BOD (Biological Oxygen Demand), COD (Chemical Oxygen Demand), and TSS (Total Suspended Solids) loading to the plant. All the above are measurements of the food available to the bugs in your system. The lack of food causes the bacteria to become less active leading to biomass decreasing as populations die off.
I recently met with a municipality in Arizona. This wastewater system’s average flow is normally 1.2 million gallons per day (MGD) in the winter months, but this year they are only receiving an estimated 850,000 gallons per day.
The assumption is that COVID is causing a reduction in the winter population resulting in reduced flows…
This in turn is causing the wastewater plant to experience excessive foaming, inadequate settling, issues with nitrification and denitrification, along with permit violations.
In addition, I have noticed an issue with the biocidal products that are inundating some systems. The overabundance of sanitary wipes and antibacterial solutions being used by residents and travelers in your community is likely reducing your bacteria populations, especially nitrifying and denitrifying bacteria.
There are many ways for municipal and industrial plants to improve their F:M ratio. One emerging trend in the wastewater industry is bio stimulation.
Bio stimulation is the practice of adding more food, typically an organic carbon source, to the wastewater stream. This carbon can come in many forms, some of which are: Candy Carbon®, methanol, acidic acid, Micro C™, brewery waste, dog food, and pig food. Please, do not use animal feed because the oils and the proteins are harder for your bacteria to digest.
When the F:M imbalance suggests increasing the Microorganism populations, the best solution is bioaugmentation.
Bioaugmentation is the addition of biology. This process can be completed in many ways. One of the quickest and easiest is to add commercially available bacteria from a reputable distributor (this may be one of the least expensive). If you decide to use this method, I recommend that you use only liquid live products that are High in Colony Forming Units (CFU) and High in Species Richness Diversity (SRD).
Other forms of bioaugmentation include hauling activated sludge from neighboring systems. Although this method will work, you need to be aware of possible challenges.
Some communities are not in favor of hauling activated sludge through town. In fact, some in the west will not allow it.
Another challenge is the hauled sludge may not have all the bugs you need. Or more importantly might have bacteria you do not want in your plant. Such as filamentous bacteria which can cause foaming when the preferred food sources, Fats, Oils, and Grease, (FOG) are available.
If you are have any questions or want to learn more about F:M, contact Rick Allen at 970-586-3391 or [email protected].
Copyright, Rick Allen, January 2021, BioLynceus, LLC