How To Solve The Problems Of MBBR Media Accumulation And Clogging In MBBR Tank?
How Do We Solve The Problems Of MBBR Media Accumulation And Clogging In MBBR Tanks?
By: Kate Nana
Post Date: March 26th, 2024
Post Tags: MBBR, Secondary Wastewater Treatment
Table Of Contents
1. How to choose MBBR technology
2. Issues of MBBR Media Accumulation and Clogging
With increasingly stringent wastewater discharge standards, there is a demand for effectively removing organic pollutants and nutrients from wastewater. In comparison to traditional activated sludge and fixed biofilm processes, the Moving Bed Biofilm Reactor (MBBR) has gained widespread attention. Currently, MBBR technology has undergone extensive experimental research and has achieved good results in practical applications. Due to its ability to reduce the volume of existing wastewater treatment systems, ease of upgrading existing wastewater treatment plant infrastructure, and its effectiveness, MBBR-type wastewater treatment plants have been constructed in Europe, the United States, Japan, New Zealand, and China.
With increasingly stringent wastewater discharge standards, there is a demand for effectively removing organic pollutants and nutrients from wastewater. In comparison to traditional activated sludge and fixed biofilm processes, the Moving Bed Biofilm Reactor (MBBR) has gained widespread attention. Currently, MBBR technology has undergone extensive experimental research and has achieved good results in practical applications. Due to its ability to reduce the volume of existing wastewater treatment systems, ease of upgrading existing wastewater treatment plant infrastructure, and its effectiveness, MBBR-type wastewater treatment plants have been constructed in Europe, the United States, Japan, New Zealand, and China.
How to choose MBBR technology
1. MBBR Bio Media with Good Biofilm Adhesion Performance:
The surface roughness of the mbbr media should be high to facilitate organic matter retention, microbial reproduction, and biofilm formation. It should also exhibit hydrophilicity to promote the attachment of hydrophilic microorganisms and possess some degree of electrostatic attraction, as microbes generally carry a negative charge and positively charged media facilitate microbial attachment.
2. MBBR Bio Media with Favorable Hydraulic Characteristics:
The mbbr media should have a density close to that of water for easy movement with water flow. It should offer a large surface area to maintain high microbial biomass concentrations. Additionally, the design of the mbbr media's shape and size should promote good flow dynamics.
3. MBBR Bio Media with Sufficient Mechanical Strength and Inertness:
The mbbr media should be wear-resistant and have a long service life. It should not degrade due to biological processes and should be corrosion-resistant in Secondary Wastewater Treatment.
4. MBBR Bio Media with Cost-effectiveness and Ease of Transport:
The cost of mbbr media constitutes a portion of the overall system construction cost, hence selecting economically viable media is crucial. Additionally, the media should be easy to transport to the site of installation.
Issues of MBBR Media Accumulation and Clogging
In general, to prevent the loss of mbbr media and considering the size of the mbbr media, grids with smaller apertures are often installed at various points along the flow and at the effluent end. However, this setup increases the risk of clogging due to the suspension of sludge and mbbr media, impeding the normal flow of water. Once the grids become clogged at the flow points, the water level rises until it overflows, causing mbbr media to flow into subsequent pipelines. Whether it's sludge return pipes, mixed liquor return pipes, sedimentation tank pipes, etc., they can all be clogged by the mbbr media, leading to a complete system shutdown and on the verge of collapse.
1. MBBR Media with Causes of Accumulation
① Excessive Flow Velocity: High water flow velocities can cause excessive movement of mbbr media within the reactor, leading to accumulation. Proper flow velocities ensure the even distribution of mbbr media and prevent localized accumulation.
② Thick Biofilm Formation: Biofilms form on the surface of media in MBBR systems, used to treat organic compounds in the wastewater treatment process. When biofilms become too thick, they can increase adhesion between mbbr media, leading to accumulation. Regular system cleaning and maintenance can help control the thickness of biofilms.
③ Overloading of MBBR Media: If the quantity of mbbr media in the reactor exceeds the design capacity, it can lead to mbbr media accumulation. Proper mbbr media loading ensures sufficient space between mbbr media for effective water flow exchange.
④ Improper Inlet or Outlet Design for Secondary wastewater treatment tanks: Poor design of the inlet or outlet can result in uneven distribution of flow within the reactor, leading to mbbr media accumulation in certain areas.
2. Measures To Address Clogging In MBBR Media
① Installation of Aeration or Backflushing Devices: Installing aeration System at grid locations can effectively prevent grid blockages. This helps dislodge any suspended solids or mbbr media, preventing blockages. Similarly, installing backflushing devices at the mixed liquor return can prevent grid blockages. In practical operation, grids at the mixed liquor return are often prone to blockages. If backflushing devices weren't initially considered in the design, manual backflushing can be performed whenever blockages occur. Although this requires manual intervention and inconvenience in pump disassembly and reassembly, it effectively resolves the issue. Additionally, setting up automatic cleaning devices at regular intervals can prevent grid blockages.
② Installation of Grid Barriers: Placing mesh barriers around the mbbr media prevents mbbr media loss even during blockages. This eliminates the problem of mbbr media entering pipes and causing pipe blockages, facilitating faster system recovery once the blocked grids are cleared.
③ Installation of Level Sensors: Installing high-level sensors in each tank allows the system to halt inflow when a grid blockage causes water levels to rise. This prevents overflow and mbbr media loss, thereby preventing pipe blockages. Once the blocked grids are manually cleared, the system can resume normal operation immediately.
Among these measures, installing grid barriers and level sensors does not fundamentally solve grid blockage issues but prevents mbbr media loss and pipe blockages, reduces workload, and ensures immediate system recovery. Aeration systems and backflushing or automatic cleaning devices significantly reduce the probability of grid blockages. Combining these measures ensures a fail-safe solution.
In practical operation, if the mbbr media doesn't achieve uniform fluidization, accumulation can occur. Therefore, the key to addressing this issue lies in optimizing reactor design, and hydraulic characteristics, and improving the layout of aeration pipelines to achieve uniform fluidization of the mbbr media with minimal energy consumption.
3. Methods to Maintain MBBR Media in a Fluidized State
① Try to evenly distribute the bottom aeration system, and appropriately increase the number of aeration heads and aeration volume in the corners and edges to reduce dead zones.
② Increase the amount of MBBR media appropriately. In addition to the theoretical amount, add the volume quantity of the accumulated portion to ensure that the total number of suspended carriers reaches the theoretical value.
③ It is not recommended to add propellers in the accumulation area.
Furthermore, there has been research on introducing baffle plates in MBBR systems to force the mbbr media to circulate, thereby improving the reactor's structure and operation. This enhances its hydraulic characteristics and aeration performance, allowing it to start with a smaller air volume, thus saving energy and improving reactor efficiency. The structure of the reactor largely determines its hydraulic characteristics. Designing the bottom corners of the reactor as slopes, it prevents mbbr media accumulation in these corners.
