Views: 0 Author: Site Editor Publish Time: 2025-06-16 Origin: Site
The Role of MBBR Biological Fillers in Wastewater Treatment Engineering
Material: Commonly used polymer materials such as polyethylene (PE) and polypropylene (PP), which are corrosion-resistant, aging-resistant, and have a density close to water (facilitating suspension).
Shape: Mostly hollow columns, spheres, honeycombs, etc., with rough or porous surfaces to increase the specific surface area (typically 500-800 m²/m³) for microbial attachment.
Density: Slightly lower than water (about 0.96-0.98 g/cm³), which can be uniformly suspended under aeration or stirring to avoid sedimentation.
Foundation for Biofilm Formation: The filler surface provides an attachment site for microorganisms such as bacteria, fungi, algae, and protozoa, forming a stable biofilm structure.
Niche Differentiation: The biofilm can form aerobic, anoxic, and anaerobic zones from the outer layer to the inner layer, corresponding to different functions such as organic matter degradation, nitrification, and denitrification, achieving simultaneous removal of COD, ammonia nitrogen, total nitrogen, and other pollutants.
Example: In the treatment of nitrogen-containing wastewater, nitrifying bacteria in the aerobic zone of the filler surface convert ammonia nitrogen into nitrate, while denitrifying bacteria in the anoxic zone reduce nitrate to nitrogen, completing the nitrogen removal process.
High Biomass Load: The biological concentration in the traditional activated sludge method is usually 2-4 g/L, while the microbial concentration attached to the biofilm in MBBR can reach 10-20 g/L, increasing the treatment efficiency per unit volume by 3-5 times.
Shock Load Resistance: The biofilm adheres to the fillers and is not easily lost with the water flow. When the influent water quality fluctuates (such as sudden increases in COD or ammonia nitrogen concentration), the high biomass can quickly respond to maintain stable treatment effects.
Data Support: In a chemical wastewater treatment project, after adopting the MBBR process, the COD removal rate increased from 60% of the traditional activated sludge method to over 85%, and the ammonia nitrogen removal rate increased from 50% to 95%.
Dynamic Suspension Promotes Mixing: The continuous movement of fillers in the water flow fully contacts the wastewater, accelerating the diffusion of pollutants to the biofilm. Meanwhile, the collision and friction between fillers update the biofilm surface, promoting the shedding of aged biofilm and maintaining microbial activity.
Mass Transfer Model: The movement of fillers makes the wastewater form a turbulent state in the reactor, reducing the liquid film resistance on the biofilm surface and improving the mass transfer efficiency of substances such as oxygen and organic matter. For example, the oxygen utilization rate can be 10%-20% higher than that of the traditional process.
Industrial Wastewater Treatment: For high-concentration organic wastewater (such as pharmaceutical and food processing wastewater), fillers can carry toxic-resistant microorganisms to resist organic matter 冲击；for wastewater containing refractory pollutants (such as benzene series in petrochemical wastewater), specific flora in the biofilm can be gradually domesticated to achieve pollutant degradation.
Municipal Wastewater Treatment: In the upgrading and reconstruction of municipal wastewater, MBBR can be used as a tertiary treatment unit, and the ammonia nitrogen removal is strengthened by nitrifying bacteria on the fillers to meet the first-class A discharge standard (such as ammonia nitrogen ≤5 mg/L).
Miniaturization and Modularization: The presence of fillers reduces the volume of the MBBR reactor, making it suitable for scenarios with tight land use (such as community wastewater treatment stations), and the treatment scale can be flexibly controlled by adjusting the filler dosage.
| Influencing Factor | Specific Requirements | Impact on Treatment Effect |
|---|---|---|
| Specific surface area | The larger, the better (≥500 m²/m³), increasing microbial attachment sites | For every 100 m²/m³ increase in specific surface area, the COD removal rate can increase by 5%-8%. |
| Porosity | High porosity (≥80%) to avoid internal clogging of fillers and promote material transport | Low porosity easily leads to anaerobic metabolism in the inner layer of the biofilm, producing odor. |
| Mechanical strength | Resistance to water flow impact and friction between fillers, with a service life of ≥5 years | Damaged fillers will cause biofilm shedding, affecting treatment stability. |
| Surface hydrophilicity/hydrophobicity | Hydrophilic surfaces are more prone to biofilm formation, which can be improved by modification (such as adding hydrophilic agents). | The biofilm formation time of hydrophobic fillers is prolonged by 1-2 weeks. |
| Filler filling rate | Usually 30%-50% of the reactor volume; too high will increase water flow resistance, and too low will result in insufficient biomass. | The optimal filling rate needs to be determined through pilot tests. Generally, every 10% increase in filling rate can increase the treatment load by 15%. |
High Efficiency and Energy Saving: The high activity of the biofilm reduces the aeration demand (aeration volume can be 20%-30% lower than the traditional process), and no backwashing is required, resulting in lower energy consumption.
Simple Management: No frequent sludge discharge is needed, and the sludge production is 40%-50% less than that of the activated sludge method, reducing the sludge treatment cost.
Strong Adaptability: Special fillers (such as fillers loaded with anaerobic ammonium oxidation bacteria) can be added to treat high ammonia nitrogen wastewater, or the surface of fillers can be modified to enhance the adsorption capacity for heavy metals.
A Papermaking Wastewater Treatment Project: The MBBR process was adopted, and the filler dosage was 40% of the reactor volume. After treatment, COD decreased from 1200 mg/L to below 80 mg/L, and SS <10 mg/L, meeting the reuse standard.
Upgrading and Reconstruction of a Urban Sewage Plant: An MBBR tank was added after the secondary sedimentation tank, and the fillers were loaded with nitrifying bacteria. The ammonia nitrogen removal rate increased from 60% before reconstruction to 98%, and the effluent quality met the first-class A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants.
