Summary
The structure includes tank body, filler, water distribution device and aeration device. The working principle is as follows: a filler is arranged in the aeration tank as the carrier of the biofilm. The wastewater to be treated flows through the filler at a certain flow rate after being oxygenated, and contacts with the biofilm. The biofilm and the suspended activated sludge work together to purify the wastewater.
1. Requirements for filter material
(1) Large specific surface area (2) high porosity (3) high strength of material (4) stable (5) reasonable price
2. Function of pool wall
The main body of the structure plays a supporting role.
3. Bottom ventilation system, sludge discharge system and supporting seepage structure
4. Water distribution system rotating water distributor
Performance features:
1) The biological filter has a very good treatment effect and can meet the most stringent environmental protection requirements in any season.
2) No secondary pollution.
3) Microorganisms can grow on the organic matter in the fillers without additional nutrients. Therefore, the speed of reuse and start-up after shutdown is fast. It can achieve a good treatment effect immediately after shutdown or shutdown for 1 to 2 weeks, and the best treatment effect can be achieved in a few hours. After 3 to 4 weeks of stopping operation, the system can be started immediately, and the best treatment effect can be recovered in a few days.
4) The biofilter has a large buffer capacity, can automatically adjust the concentration peak to make the microorganism work normally all the time, and has a strong ability to withstand the impact load.
5) The operation adopts full-automatic control, which is very stable without manual operation. There are few vulnerable parts, the maintenance management is very simple, basically can realize the unmanned management, workers only need to inspect whether there is a machine failure.
6) The body of the biofilter adopts the assembled type, which is convenient for transportation and installation; when the treatment capacity is increased, only components need to be added, which is easy to implement; it is also convenient for separate treatment under the condition of gas source dispersion.
7) The energy consumption of this kind of filter is very low, and the pressure loss of the filter is only about 500pa after half a year of operation.
technological process:
1. The single-stage biological aerated filter with carbon oxidation should be used to remove the carbon organic matters in the sewage;
2. When it is required to remove the organic matter containing carbon and complete the nitrification of ammonia nitrogen, the single-stage biological aerated filter with carbon oxidation can be used, and the load can be reduced appropriately; the two-stage series process of carbon oxidation filter and nitrification aerated filter can also be used;
3. When the carbon source of influent water is sufficient and the quality of effluent water has high requirement on total nitrogen, the combination process of pre denitrification filter and nitrification filter should be adopted;
4. When the total nitrogen concentration of the influent is high and the carbon source is insufficient, and the effluent has strict requirements on the total nitrogen, the post nitrification process can be used and the carbon source can be supplemented; or the pre denitrification filter can be used with additional carbon source, and the return rate of the nitrification liquid of the pre denitrification filter can be determined according to the designed NO3-N removal rate and the carbon nitrogen ratio of the influent, and the input amount of the additional carbon source needs to be determined after calculation.
type | Volume loading | Hydraulic load (filtration rate) | Hydraulic retention time of empty bed |
Carbon oxidation filter | 3.0~6.0kgBOD5/(m·d) | 2.0~10.0 m/(m·h) | 40~60min |
Nitrifying filter | 3.0~6.0NH3-N/(m·d) | 3.0~12.0 m/(m·h) | 30~45min |
Denitrification biofilter | 3.0~6.0kgNO3-N/(m·d) | 6.0~12.0 m/(m·h) | 20~30min |
Carbon oxidation / nitrification filter | 1.0~3.0kgBOD5/(m·d) 0.4~0.6kgNH3-N/(m·d) |
1.5~3.5 m/(m·h) | 80~100min |
Pre denitrification biofilter | 0.8~1.2kgNO3-N/(m·d) | 8.0~10.0 m/(m·h) | 20~30min |
Post denitrification biofilte | 1.5~3.0kgNO3-N/(m·d) | 8.0~12.0 m/(m·h) | 20~30min |
matters needing attention:
1. The dissolved oxygen in the effluent of carbon oxidation filter and nitrification filter should be controlled at 3.0 ~ 4.0mg/l.
2. The increase of filtration rate is disadvantageous to carbon oxidation, and some non dissolved organic matters are discharged for degradation, 6m / h is recommended.
3. However, in a certain volume load range, the increase of filtration rate will not reduce the removal rate of BAF, but also increase the nitrification and denitrification efficiency. The main reasons are as follows: 1. High filtration rate enhances the mass transfer efficiency in the filter, which makes more opportunities for contact between air, sewage and organisms; 2. Under high filtration rate, the biofilm renews rapidly and enhances the biological activity. 3、 At low speed, the filter material is easy to block, which shortens the backwashing cycle, while frequent backwashing is unfavorable to the nitrifying bacteria with slow propagation speed.
4. When the filter is mainly used for carbon oxidation, when the required BOD5 is 10-20mg / L, the recommended volume load is 3.5-5.0kg BOD5 / (m · d), when the required BOD5 is 5-10mg / L, the recommended volume load is 2.5-3.2kg BOD5 / (m · d).
5. When the filter is mainly used for carbon oxidation and nitrification, the volume load of BOD5 is recommended to be ≤ 3.0kgbod5 / (m · d). The study shows that when the volume load of BOD5 is greater than this value, the removal of ammonia nitrogen is inhibited, and when the volume load of BOD5 is ≥ 4.0kgbod5 / (m · d), the removal of ammonia nitrogen is obviously inhibited.
6. The effluent CODcr is 60 mg / L, and the influent load should be 4.0-5.0 kgcodcr / (m · d). When CODcr ≤ 50 mg / L, the influent load should be controlled below 3.0 kgcodcr / (m · d).
7. When there are nitrification and denitrification requirements in the filter, the volume load of nitrification and denitrification needs to be calculated. It is recommended that the volume load be less than 2.0kg NH3-N / (m · d) and 5.0kg NO3-N / (m · d) respectively, and 0.3-0.8kg NH3-N / (m · d) and 0.8-4.0kg NO3-N / (m · d) are recommended.
8. When denitrification is needed and the carbon source is insufficient, the denitrification tank can be placed in front of the nitrification tank, and part of the effluent from the nitrification tank can be returned to the denitrification tank to form pre denitrification. It has the following advantages: A. use the organic matter in the sewage as the carbon source to reduce the external carbon source. b. Organic matter is removed in the denitrification tank to ensure the nitrification capacity in the carbon oxidation / nitrification tank. c. The aeration capacity of the system is relatively small. d. Less sludge. For the domestic sewage with sufficient BOD5 and nitrogen removal, the advantages of pre denitrification process are obvious considering the operation cost.
9. The post denitrification process is more suitable for the following places: A. wastewater with significantly lower BOD5 content (high proportion of industrial wastewater). b. When it is used in the renovation and upgrading of the sewage plant, the nitrification index is not considered before. The BOD5 of the effluent is low, but the ammonia nitrogen is high.
10. In order to avoid the influence of carbon removal on nitrification, the post denitrification should be carried out in the pre-treatment stage to remove a part of BOD5. The design filtration rate of C / N tank is 6-10m / h, and the nitrification load should meet the following requirements: inlet BOD5 ≥ 60mg / L, about 0.3KG NH3-N / (m · d), when BOD5 = 20-50mg / L, about 0.6kg NH3-N / (m · d), when BOD5 ≤ 20mg / L, about 1.0kg NH3-N / (m · d), if methanol is used as the external carbon source, then DN is added The amount is 3.3kgch4o/kgno3-n.
11. The recommended denitrification load is 0.4-0.5 kgno3-n / (m · d), filtration rate ≥ 10 m / h, and the best influent BOD5 / NO3-N ≥ 6. Generally, the removal rate of BOD5 in DN tank is ≤ 60%, and the removal rate of CODCr is ≤ 70%. The remaining CODcr will enter the nitrification reactor. In order to ensure the nitrification capacity of N tank (greater than 0.5kgnh3-n / (m · d)), the load of CODCr is ≤ 2.0kgcodcr / (m · d).
Filler type | Plate thickness mm |
Theoretical plate number m3 |
Specific surface area m²/m³ |
Voidage m²/m³ |
Pressure dropMPa/m³ | Accumulation weightkg/m³ | Liquid loading m³/m².hm |
Maximum f factor-1 m/s(kg/m3) |
SB-125Y | 1.5-2.0 | 55 | 125 | 0.985 | 2X10m-1 | 37.5 | 0.20-100 | 3 |
SB-250Y | 0.8-1.0 | 65 | 250 | 0.97 | 3X10m-1 | 39.5 | 0.20-100 | 2.6 |
SB-350Y | 0.4-0.5 | 85 | 350 | 0.94 | 2X10m-1 | 41.5 | 0.20-100 | 2 |
SB-500Y | 0.23-0.3 | 125 | 500 | 0.93 | 3X10m-1 | 65 | 0.20-100 | 1.8 |
SB-125X | 1.5-2.0 | 45 | 125 | 0.985 | 1.4X10m-1 | 37.5 | 0.20-100 | 3.5 |
SB-250X | 0.8-1.0 | 55 | 250 | 0.97 | 1.8X10m-1 | 39.5 | 0.20-100 | 2.8 |
SB-350X | 0.4-0.5 | 75 | 350 | 0.94 | 1.3X10m-1 | 41.5 | 0.20-100 | 2.2 |
SB-500X | 0.23-0.3 | 115 | 500 | 0.93 | 1.8X10m-1 | 65 | 0.20-100 | 2 |