Can Bioaugmentation be a new design parameter for Wastewater treatment plants?

Hello dear water and wastewater fellows!

Bioaugmentation is a technique that increases the treatmentcapability of biological wastewater treatment plantsthrough the addition of exogenous microorganisms in the system. This is currently used technique to give new life to old systems or to recover systems from eventual shocks (very high organic matter loads in a short period of time), for example.

So, recently some new idea has shown up: Is it possible to design systems considering the application of those microorganisms?

A common parameter used in the (activated sludge) WW systems design is the F/M relation and a common number used is 0,15.

In this case, if we establish the desirable amount of solids in the tank ("M") and the concentration of intake BOD ("F"), it's possible to determine the aeration basin volume, ok? (yes!).

Using bioaugmentation techniques, is possible to change radically this "balance", because is possible to increase the total amount of microorganisms in the sludge, seeing that the system will be capable to degrades more organic matter than only the original 0,15 F/M relation established.

This "new" design parameter is not 0,15 F/M anymore. this number will increases as much as microorganisms are loaded in the system in its operation. But this new "reason" between this microorganism's amount and the intake organic matter will depend on the product (biological blend) manufacturer data (among other parameters).

So, this is my question: In this scenario, what is your opinion about use bioaugmentation techniques as a parameter to increase the biodegradation capability in new systems design?In other words, can we design "smaller" systems, considering the use (or even the "dependence") of exogenous microorganisms in the system operation?

Regards!

1 Answer

1. I think bioligical reactors – like wastewater teatment basins – mostly are designed trough empirical arguments. The mentoined F/M relation, or the age of sludge are parameters for characterising the biological processes. It can be true, but I learned from the bankfiltering radically different views:

   1. The biological cleaning happens in biofilms. The biofilm is the living space of bacterias and is adhered on solid biofilmhoder surface (sand by bankfiltration, flocks by wastewatertreatment).
   2. The cleaning process can be divide in two subpocesses.
      1. First we have to transport the substrate to and into the biofilm. This is a „logistic” function described by physical (hidrodinamics and diffusion) parameters.

   The nondimensional Pe-number and the also nondimensional L/d geometric relation are the main parameters for this subprocess, and trough these parameters can be designed (determined the geometry) biological reaktors.

   The substattransport is a requisite, but it’s not enough. We need also great surface for our bacterias inside the reactor. Small Peclet-number (Pe~10) would be satisfied this two needs.

   The biodegration depends from Pe-number by inversely way (1/Pe).

   1. After that the biodedration happens in the biofilm, wich has a bio-chemical character. The Michaelis-Menten enzyme- and the Monod qrowth-kinetics describes this process. pH, Ne (Nernst-factor, the nondimensional redox potential) are the main „climatic” parameters here.

   I think to influence the bio-chemical process – for increasing the efficiency of cleaning – it can be only setting trough the climatic parameters, because the pattern of the substrate and bacteria(enzyme) must be the same.