Modeling of biofilm kinetics in TILT® Moving Bed Biological Reactor (TILT® MBBR)

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Biofilms are complex layers of microorganisms that coat surfaces exposed to substrates. Biofilms consist of many different types of microbial colonies including bacteria, fungi, algae, protozoa, and non-cellular materials. Biofilm accumulation is a dynamic process that is the net result of growth and detachment and is affected by several external factors, including wastewater composition and concentration, liquid velocity, concentration of particles, particle-particle collisions, and particle-wall collisions. The microbial colonies excrete a matrix of extracellular polymeric substances (EPS), which encloses the biofilm and protects the colonies from degradation, predation, antimicrobials, aggregation, and toxins. In attached growth wastewater treatment processes, biofilm formation involves a series of distinct stages consisting of reversible attachment, irreversible attachment, maturation, and detachment. Biofilm attachment begins at the solid-liquid interface of the surface and wastewater surroundings. The TILT® Moving Bed Biological Reactor (TILT®-MBBR) is an alternative approach for biofilm process that contains medium packed biofilm carriers (typically 40 to 60% bulk volumetric fill). The hydrodynamic strength in this reactor significantly affects the microbial adhesion to the solid-liquid interface by acting as a repulsive or attractive force and thereby influencing the rate of the biofilm kinetics. A hydrodynamic boundary exists in the area of the interface where there is an insignificant flow velocity, therefore the thickness of the boundary layer is dependent upon the linear velocity and the shear forces of the surrounding wastewater medium. The objective of this proposal is to develop a mathematical modeling for TILT®-MBBR in collaboration with H2Flow Equipment Inc. The proposed model will be used to determine the biofilm kinetics of aerobic heterotrophic and autotrophic bacteria and to develop an economical, robust, and efficient model for different municipal and industrial wastewater during the biological organic treatment. The focus of the model