BOD Addition

Effective biological treatment requires a healthy population of microbes.  Occasionally, an additional food source such as MicroC® needs to be added to treatment systems to build up or maintain that healthy population.  This process is called biochemical oxygen demand (BOD) supplementation, and is distinct from adding an external carbon source to facilitate removal of specific contaminants.

The problem

Activated sludge (AS) wastewater treatment systems can lose as much as 10-15 percent of their biomass daily due to endogenous decay.  If the BOD of the wastewater is too low to support enough microbial growth to overcome that endogenous decay, the system will start experiencing operational problems and/or be unable to achieve treatment goals.  When the food to microorganism ratio (F/M) is too low, filamentous bacteria tend to thrive at the expense of floc-forming bacteria.  The proliferation of filamentous bacteria can lead to problems such as foaming, sludge bulking, poor sludge settling, and scum formation.  BOD supplementation can be an effective way to avoid or address these operational problems.

Industrial facilities occasionally shut down for annual or periodic turnaround maintenance.  During these times, their biological wastewater treatment systems need BOD supplementation to keep their microbial populations alive.  These populations are often highly specialized, so the BOD source needs to be capable of sustaining the biomass that has acclimated to that particular wastewater feed.  This enables a seamless transition back to normal operating conditions when the maintenance period is completed.

Occasionally, a biological treatment system will need to establish a microbial population, either because the system is new or because it has experienced a process upset that harmed the biomass.  In these cases, BOD supplementation can support and promote microbial growth until a stable biomass is achieved.

How EOSi can help

EOSi’s MicroC® 2000 is a consistent BOD source with well-defined kinetic and yield characteristics.  Our technical team works with treatment plant operators to conduct respirometry and other tests to evaluate how the biomass will acclimate to MicroC® 2000.  The EOSi team also helps calculate proper MicroC® 2000 feed rates, recommends operational adjustments, and provides guidance on process monitoring to ensure a viable biomass is established. When time is critical, as with process upsets, EOSi’s robust supply chain means we can quickly mobilize and provide the BOD source you need to get your treatment system functioning again.