Differences Between MBR and MBBR technologies
In a previous article, we briefly compared MBR and MBBR technologies, highlighting the pros and cons of each to help beginners understand the differences. In this article, we will explain in more detail the key differences between these two technologies.
Membrane Bioreactor (MBR)
MBR is a new type of water treatment technology that combines membrane separation units with biological treatment units. It replaces the secondary sedimentation tank (or decanter) with a membrane unit and maintains highly activated sludge in the bioreactor. This technology reduces the impact of the wastewater treatment facility and decreases the sludge volume by maintaining low sludge loads. It belongs to the activated sludge method combined with membrane separation.
Moving Bed Biofilm Reactor (MBBR)
The principle of MBBR is to increase the biomass and biological species in the reactor by adding a certain amount of suspended carriers to it, thereby improving the reactor’s treatment efficiency. Since the density of MBBR is close to that of water, it is thoroughly mixed with water during aeration. Additionally, each carrier contains different types of biological species inside and outside, with some anaerobic or facultative bacteria growing inside.
The external surface is suitable for bacterial growth, making each carrier a small reactor where both nitrification and denitrification reactions occur simultaneously, thus enhancing the treatment process.
The core of MBBR is the flotation of uniquely designed biological carriers with the water flow in the reaction tank, allowing the associated and growing biological carriers to fully contact the contaminants and oxygen in the water. Diffusion enters the biofilm and is decomposed by microorganisms. Microorganisms associated with growth can reach high biomass, resulting in a biological concentration in the reaction tank that is several times higher than that of the suspended growth activated sludge process, significantly increasing the degradation efficiency.
Comparison of Treatment Efficiency in Organic Matter Removal:
Both processes have higher removal rates for COD, BOD, and ammonia nitrogen. The MBR process relies on a higher sludge load, while the MBBR process depends on the biofilm on its fillers.
Nitrogen and Phosphorus Removal Efficiency (TN, TP):
The MBBR process is more effective in removing TN, while TP removal requires reliance on chemical phosphorus removal dosing. The MBR process depends on the final biological method for TN removal. TP removal also requires reliance on final chemical phosphorus removal dosing.
Suspended Solids (SS) Removal:
MBBR has no effect on SS removal and requires reliance on a back-end ultrafiltration membrane process for SS removal. The MBR membrane can effectively remove SS.
Cost Comparison:
When comparing costs, it is essential not only to consider the design and installation costs but also to take into account long-term maintenance and spare parts costs. It is also crucial to consider the regular cleaning process necessary for the long-term health of the plant. In the MBBR process, carriers can be added at once, and it is only necessary to enhance biofilm management on the filler in the subsequent process. The investment during the construction period is relatively high, but operation and maintenance are simple.
In the MBR process, the membrane unit generally has a service life of 4-5 years, with a short replacement cycle. During daily operation and management, maintenance tasks such as chemical cleaning and offline cleaning of the membrane unit are required, which are difficult to manage and operate, and the costs are high. The average maintenance and replacement cost of the membrane unit is more than a million annually.
