What is the principle of the MBBR process that has now received more attention due to “the outbreak”? The MBBR process is used for the removal of organic substances, nitrification and denitrification. This system consists of an activated sludge aeration system where the sludge is collected on recycled plastic carriers. These carriers have an internal large surface for optimal contact water, air and bacteria.
The rapid construction of Huoshenshan and Leishenshan hospitals that is a result of the Novel Coronavirus outbreak has proven the Chinese people’s ability and perseverance! Due to the peak of the epidemic, the popular MBBR process has become the focus of industry attention, and it was applied to the sewage treatment facilities for the Leishenshan hospital in Wuhan.
1.Introduction to MBBR
The MBBR process principle is based on the basic principle of the biofilm method. By adding a certain amount of suspended carrier to the reactor, the biomass and biological species in the reactor are increased, thereby improving the processing efficiency of the reactor. Because the density of the filler is close to water, when it is aerated, it is completely mixed with water, and the environment in which microorganisms grow is three phases: gas, liquid, and solid.
The collision and shearing effect of the carrier in the water makes the air bubbles smaller and increases the utilization rate of the oxygen. In addition, each carrier has different biological species inside and outside. Some anaerobic or facultative bacteria are grown inside, and aerobic bacteria are grown on the outside. In this way, each carrier is a miniature reactor, so that the nitrification reaction and denitrification reaction coexist, thereby improving the processing effect.
2.The principle and characteristics of MBBR
1) Principle of MBBR process
The MBBR process principle is to increase the biomass and biological species in the reactor by adding a certain amount of suspended carriers to the reactor, thereby improving the processing efficiency of the reactor. Because the density of the filler is close to water, when it is aerated, it is completely mixed with water, and the environment in which microorganisms grow is three phases: gas, liquid, and solid. The collision and shearing effect of the carrier in the water makes the air bubbles smaller and increases the utilization rate of oxygen. In addition, each carrier has different biological species inside and outside. Some anaerobic or facultative bacteria are grown inside, and good bacteria are maintained on the outside. In this way, each carrier is a miniature reactor, so that the nitrification reaction and denitrification reaction coexist, thereby improving the processing effect. The MBBR process has the advantages of both traditional fluidized bed and biological contact oxidation. It is a new and efficient sewage treatment method. The carrier is in a fluidized state by relying on the aeration in the aeration tank and the lifting of the water flow. The activated sludge and the attached biofilm, which makes the moving bed biofilm use the entire reactor space, give full play to the advantages of both the attached phase and suspended phase organisms, make them strong and avoid disadvantages, and complement each other. Unlike previous fillers, suspended fillers can frequently and repeatedly come into contact with sewage and are therefore called “moving biofilms.”
2) Advantages of MBBR
Compared with the activated sludge method and the fixed-filler biofilm method, MBBR not only has the efficiency and operational flexibility of the activated sludge method, but also has the characteristics of impact resistance, long sludge age, and low residual sludge of the traditional biofilm method.
(1) Packing characteristics
Fillers are mostly made of polyethylene, polypropylene and its modified materials, polyurethane foam, etc. The specific gravity is close to water, mainly cylindrical and spherical, with no clumping, no clogging, and with simple film removal.
(2) Good denitrification ability
A good nutrient, anoxic and anaerobic environment is formed on the filler. Nitrification and denitrification reactions can take place in a reactor, which has a good effect on the removal of ammonia nitrogen.
(3) Organic matter removal properties
The sludge concentration in the reactor is relatively high, and the general sludge concentration is 5-10 times that of the ordinary activated sludge method, and can be as high as 30-40 g / L. It offers improved organic matter treatment efficiency, and strong resistance to impact load.
(4) Easy maintenance
There is no need to set a packing bracket in the aeration tank, and it is convenient to maintain the filling and the aeration device at the bottom of the tank, and at the same time, it can save investment and floor space.
3) MMBR disadvantages
(1) The packing in the reactor is in a fluidized state by aeration and the lifting effect of water flow. In actual engineering, the phenomenon of local packing accumulation is easy to occur. In order to avoid packing accumulation, the layout of the aeration line and the structure of the reactor need to be improved. The structure of the reactor largely determines its hydraulic characteristics. In actual engineering, when the length-depth ratio of a single reactor is about 0.5 and the length is not greater than 3m, it is beneficial for the filler to move completely. In the actual engineering design, a large number of experiments should be used to optimize the structure and hydraulic characteristics of the reactor, reduce energy consumption, and further improve the economic benefits of MBBR.
(2) The effluent of the reactor is often provided with grid plates or grids to avoid the loss of filler, but it is easy to cause blockage. In actual projects, a movable grid plate can be set up to perform manual cleaning regularly, and an air blowback device can also be set up to prevent clogging.