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7.
1.
3 Biological contact oxidation process
The biological contact oxidation method has the advantages of low energy consumption, less residual sludge, and good effluent quality
.
It is a biological membrane treatment process between activated sludge method and biological filter, also known as submerged biological filter, used for domestic sewage, urban sewage, food processing and other organic industrial wastewater, and used for The micro-pollution of surface water source water has achieved good results
The reasons why the biological contact oxidation method is favored are:
①High biological activity and long sludge age;
②The mass transfer conditions are good, and the metabolism of microorganisms is mostly affected by the renewal speed of the medium on the surface of the bacteria, and the mass transfer plays a decisive role;
③High oxygenation efficiency, 3kgO 2 /(kw·h), 30% higher than no filler;
④ There are filamentous bacteria;
⑤ There is a higher concentration of biofilm, 10-20g/L, and the concentration of activated sludge is 2-3g/L
.
7.
1.
3.
1 The structure of biological contact oxidation tank
It is composed of tank body, filler, water distribution system and aeration system; the height of the filler is generally about 3.
0m, the height of the water layer above the filler layer is about 0.
5m, and the height of the water distribution area under the filler layer is generally 0.
5 to 1.
5m.
The pool type is square and round, and the top is a stable water layer
.
The characteristics of the filler have a great influence on the biomass in the contact oxidation tank, the utilization rate of oxygen, the water flow conditions and the contact reaction of wastewater and biofilm; it is divided into hard filler, soft filler, semi-soft filler and spherical suspension type fillers and the like
7.
1.
3.
2 Classification of biological contact oxidation tanks
According to the relative position of aeration and filler, it is divided into split flow type (multiple use in foreign countries) and direct flow type (multiple use in domestic), as shown in Figure 7-5 and Figure 7-6
.
Figure 7-5 Split-flow biological contact chlorination tank structure
Figure 7-6 The structure of the direct current biological contact oxidation tank
The water flow in the split filler area is relatively stable, which is beneficial to the growth of biofilms, but the scouring force is not enough, and the biofilms are not easy to fall off.
Blow aeration or surface aeration devices can be used, which are more suitable for advanced treatment; direct aeration devices are mostly The blast aeration system can make full use of the tank capacity, the turbulence between the fillers is intense, the biofilm is renewed quickly, the activity is high, it is not easy to be blocked, and the maintenance is difficult
7.
1.
The advantages of the biological contact oxidation method are as follows
(1) Process
①Using various forms of packing to form the coexistence of gas, liquid and solid phases, which is conducive to the transfer of oxygen;
②The three-dimensional structure of biofilm is formed on the surface of the filler;
③It is beneficial to maintain membrane activity and inhibit the proliferation of anaerobic membrane;
④The load is high and the processing time is short
(2) Operational aspects
① Shock load resistance, with a certain intermittent operation function;
②Simple operation, no need for sludge backflow, no sludge expansion and filter flies;
③The amount of sludge generated is small and it is easy to settle;
④ Low power consumption
The disadvantages of the biological contact oxidation method are as follows
①The removal efficiency is lower than the activated sludge method; the project cost is high
②Improper operation may block the filler; water distribution and aeration are not easy to be uniform, and local dead corners appear
③ A large number of metazoans will easily cause a large amount of biofilm to fall off instantaneously, which will affect the quality of the effluent
.