Under the hottest sewage treatment process

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Sewage treatment process (Part 2)

2.2.4 accident emergency system

the design adopts the accident emergency system. The main body is an accident emergency pool with an effective volume of 8300m3. Toxic sewage (such as black liquor) with high conductivity and high or low pH value is stored in the emergency pool until it can be treated in the biological treatment stage of continuous operation

2.3 highly efficient and unique secondary biochemical treatment system

2.3.1 fully mixed aeration system with selector is adopted for secondary biochemical treatment

fully mixed aeration system with selector is adopted. There is a circular selection tank in front of the circular aeration tank. The sewage is mixed with the return sludge in the selection tank with aeration device, and then enters the aeration tank for full aeration. In the selection tank, a high organic load is adopted, and the f/m value is about 8kgcod/kgvss · d. The purpose is to form a high f/m gradient. In this way, most of the substrate is transformed into intracellular storage by bacteria micelles. As a result, it can surpass filamentous bacteria in the competition and gain an advantage. Therefore, it can overcome the disadvantage that the complete mixing method is prone to sludge bulking

2.3.2 adopt advanced jet aeration equipment

the sewage treatment design of the project adopts a jet aeration system combining blower and circulating pump. The bottom aerator with nozzle is set in the aeration tank and selection tank, and the circulating pump is dry installed outside the tank. Compared with blast aeration and mechanical aeration, which are mostly used in domestic activated sludge process at present, it has the following unique advantages:

(1) it is easy to install and easy to maintain.

the bottom aerator is a glass fiber reinforced plastic aerator fixed at the bottom of the tank, which generally does not need maintenance. The dry-type circulating pump is installed beside the pool, which is easy to maintain

(2) high oxygen utilization rate and power efficiency

the two main indicators for measuring the aeration equipment are oxygen utilization rate and power efficiency. Due to the special nozzle structure of the aerator, the air and liquid can be fully contacted, and these nozzles are cross evenly distributed at the bottom of the tank, thus strengthening the oxygen transfer process and carrying out the evaluation of the implementation of industrial plans and important policies. The oxygen utilization rate can reach 28% and the power efficiency can reach 3.0kgo2/kwh

(3) good mixing effect

the nozzle green building at the bottom of the aeration tank meets the relevant evaluation criteria and is evenly distributed along the cross direction of the tank bottom. The liquid flow with small bubbles is ejected from the nozzle, which fully agitates the mixed liquid in the tank and has a good mixing effect. It can quickly make the mixed liquid in the aeration tank reach uniform concentration and ensure the treatment effect of the fully mixed activated sludge method

2.3.3 unique secondary sedimentation tank structure with flocculation zone

around the central column of the secondary sedimentation tank is the sludge flocculation zone. Four adjustable speed paddle agitators are set in the flocculation zone, which can accelerate the coagulation process. In the flocculation zone, the sludge flocs grow up and become easily separated from water. Due to this design method, good effluent quality of the secondary sedimentation tank is ensured, and the sludge concentration of the secondary sedimentation tank reaches 3.5%, which can be directly mixed and dewatered without concentration. Perfect sludge treatment system the imported sludge treatment system mixes the first settled sludge and the remaining sludge in the sewage treatment process, then adds high molecular flocculant, uses the belt filter press for mechanical dehydration, transports the sludge cake for disposal, and the waste liquid flows into the selection tank for biochemical treatment. The system has the following advantages:

(1) good sludge dewatering effect and high efficiency

the belt filter press is equipped with a pre dewatered belt thickener, with a sludge treatment capacity of 750kgtss/h, and the dry solid content of the dewatered sludge can reach more than 24%

(2) high degree of automation and low labor intensity

from the preparation of polymer flocculant solution to the mixing optimization of the solution and sludge, belt deviation correction of belt filter press, mud cake control, etc. can be carried out automatically, so that the operator can be freed from the heavy, dirty and harsh working environment, and has the interlocking function. For example, when the polymer flocculant is used up or the sludge pump is stopped, the sludge dehydrator will automatically wash and stop running, ensuring the equipment operation and personal safety

3 combined design treatment effect

due to the perfect process adopted in the design and the introduction of advanced equipment with high automation and excellent performance, it can effectively ensure that the sewage treatment facilities are in good operation. See Table 2 for the design effluent effect

it can be seen from table 2 that the designed effluent index of the project is lower than the national papermaking wastewater discharge standard (the moving moment coordinate is aligned with the length direction of the paper gwpb on the recording paper), so the design of the project is reasonable and advanced

Table 2 sewage treatment effect items pH value CODcr · mg/lbod5 · mg/lss · mg/laox · kg/t slurry influent


removal rate

new national standard

0 ~ 14

6 ~ 9

6 ~ 9808


≤ 65%



.≤ 85%



≥ 85%



≥ 60%

2.64 4 conclusion

(1) The technical methods and processes adopted in the sewage treatment design of the project are reasonable, advanced and reliable. It is unique in preventing and solving the fault of sewage treatment, and it is anti risk

(2) the design adopts advanced process equipment and control system with high degree of automation, which is conducive to reducing labor intensity and sewage treatment cost

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