While less known than polymers, antifoams, or odor masking agents, bioaugmentation proves useful for correcting biomass insufficiency. Unlike pure chemical options, bioaugmentation works by enhancing the microbial community and restoring steady-state or mature biomass conditions.
Science of Bioaugmentation
Bioaugmentation technologies work by introducing specific microorganisms into the environment. In Aster Bio’s case, we introduce microbial consortia into environmental applications such as wastewater or soil bioremediation. The introduced microbes must be screened for the following:
- Desired metabolic and enzymatic capabilities
- Suitability for growth in the target environment
- Fast growth rates unless culture is used to target an ecological niche
Successful applications of bioaugmentation result in restoration of steady-state or mature biomass. Once restored, the system should be able to operate without continued culture addition. As a tool for enhancing biomass, operators would add cultures once monitoring indicates a move backward on the growth curve away from steady-state. Signs of biomass insufficiency include:
- Deflocculation or bulking sludge with increased turbidity and TSS
- Increased ammonia or nitrite in the effluent (loss of nitrification)
- Problems with biomonitoring testing
- Loss of BOD/COD removal efficiency
What to Expect from Bioaugmentation
As with any additive or tool used to improve wastewater treatment efficiency, bioaugmentation programs need to be monitored and adjusted based on goals and system response. The importance of matching the culture and program to the system is key in improving biomass quality and reducing treatment efficiency variation. Bioaugmentation does not replace good operations or severe equipment issues. When comparing bioaugmentation to other operational tools such as polymers or antifoams, it is helpful to see bioaugmentation as a means of directly changing the underlying biomass or biological workers in the treatment system. These changes can be monitored using traditional daily tests but also by using the latest in molecular testing. Aster Bio has used both qPCR and NGS (Microbial Community Analysis) to monitor changes in biomass from changes in influent makeup, operational adjustments, and other activities. We suggest that before and during bioaugmentation programs, users take advantage of molecular testing.
When to Use
As a tool to adjust biological wastewater treatment biomass, bioaugmentation is often the best option in the following:
- System startup
When commissioning a new system, engineers often use sludge from nearby facilities. If sludge is not available in needed quantities or has long transit time, it is good to supplement the added biomass with active bioaugmentation cultures. Given most MLSS is only 5 – 15% active organisms, the use of concentrated living cultures helps get a new biological treatment unit commissioned. - Changing influent composition or loadings
If you are adding new waste streams with significant differences in composition, bioaugmentation helps to reduce adjustment time. Instead of seeing increased TSS or loss of nitrification, bioaugmentation reduces acclimation time and keeps the system at target steady-state. A similar application is systems that receive sudden increases in loadings – examples include seasonal resort areas, fruit/vegetable processing, and industrial facilities following maintenance shutdown. - Shock loadings that cause biomass loss
Shock loadings result in a loss of viable biomass. A common example shock loading is hydraulic shock where high flows create washout conditions and biomass concentration is reduced. Other common shock loadings include sudden toxic shock – examples include quaternary amines, surfactants/solvents, phenol, pH swings, and equipment issues.
What to Look for in Choosing Bioaugmentation Products
While many bioaugmentation products may look similar, there are underlying differences in composition and how they will impact your biomass. When selecting products, I suggesting asking about the following:
- Are the product grown under aseptic fermentation – this ensures higher purity and freedom from potential pathogens
- Concentration – with high shipping costs, you want shelf-stability and concentrated product.
- What about CFU/gram? – plate counting is the way most products are compared. However, cultures that readily grow on agar may not be the best for your application. QA/QC only on plate counts results in a tendency to use fast growing, agar friendly organisms. Ask the vendor about what microorganisms are included and why they were selected for this product.
Bioaugmentation products can come in three forms:
- Liquid – very convenient, but more limited in cultures that you can include, concentration, and shelf-life.
- Dry – more concentrated, can include a very broad range of cultures, and longer shelf-life than liquids.
- Solids – designed for time release, convenient, issues with dissolving time (some dissolve in days others in months – but much depends on placement and application.