HJ 578-2010Technical specifications for oxidation ditch activated sludge process (English PDF)

5.1 Design Flow

5.1.1 Urban sewage design flow

5.1.1.1 The design flow rate of urban dry flow sewage shall be calculated according to formula (1).

Dr d mQ QQ= (1)

Where. - Design flow of dry sewage, L/s; drQ dQ -- integrated domestic sewage design flow, L/s;

mQ -- industrial wastewater design flow rate, L/s.

5.1.1.2 The design flow rate of urban combined sewage should be calculated according to formula (2).

Dr sQ QQ= (2)

Where. Q--Sewage design flow, L/s;

drQ - design flow of dry sewage, L/s;

sQ - rainwater design flow, L/s.

5.1.1.3 The integrated domestic sewage design flow is the product of the service population and the corresponding comprehensive domestic sewage quota, and the integrated domestic sewage quota shall be According to the local water quota, combined with the level of the internal drainage and drainage facilities in the building and the popularity of the drainage system, it can be used according to local conditions.

80% to 90% of the water quota is designed.

5.1.1.4 The total coefficient of change of the integrated domestic sewage volume shall be determined based on the measured data of the actual change of the local integrated domestic sewage, and no determination is made.

When the data is available, it can be valued according to the relevant provisions of GB 50014, as shown in Table 1.

Table 1 Total coefficient of variation of integrated domestic sewage

Average daily flow/(L/s) 5 15 40 70 100.200 500 >= 1 000 Total coefficient of variation 2.3 2.0 1.8 1.7 1.6 1.5 1.4 1.3

5.1.1.5 The design flow rate of industrial wastewater discharged into the municipal pipe network shall be based on the discharge of industrial pollution source wastewater within the coverage of urban municipal drainage system.

Statistical survey data is determined.

5.1.1.6 The design flow of rainwater is determined by reference to the relevant sections of GB 50014.

5.1.1.7 In areas with high groundwater levels, the amount of infiltration groundwater should be considered. The amount of infiltration groundwater should be determined based on actual measured data.

5.1.2 Industrial wastewater design flow

5.1.2.1 Industrial wastewater design flow rate shall be designed according to the actual wastewater discharge flow measured at the total discharge port of the plant or industrial park. Test method should be consistent HJ/T 91 regulations.

5.1.2.2 The change of industrial wastewater flow rate should be measured according to the characteristics of the process.

5.1.2.3 When the actual measurement data cannot be obtained, it can be determined by reference to the relevant provisions of the current national industrial water consumption, or according to the same industry.

The scale is determined analogously to the existing plant drainage data for the process.

5.1.2.4 When industrial wastewater and domestic sewage are combined, the amount of domestic sewage and bathing water in the factory or industrial park is determined.

Should comply with the relevant provisions of GB 50015.

5.1.2.5 The design flow of the centralized sewage treatment plant in the industrial park can be determined by reference to the method for determining the design flow of urban sewage.

5.1.3 Design flow of different structures

5.1.3.1 Lifting pump house, grid well and grit chamber should be calculated according to the design flow of combined sewage.

5.1.3.2 The primary sedimentation tank should be designed according to the dry sewage flow rate, and the combined flow design flow check should be carried out. The check time of the check should not be less than 30 min.

5.1.3.3 The reaction tank and the secondary sedimentation tank shall be calculated according to the amount of dry sewage, and a certain amount of combined water shall be considered if necessary.

5.1.3.4 Water conveyance facilities such as pipelines after the reaction tank shall be designed according to the maximum daily sewage flow rate.

5.2 Design water quality

5.2.1 The design water quality of urban sewage should be determined according to the actual survey data. The measurement method and data processing method should conform to HJ/T 91.

Provisions. When there is no survey data, the design can be converted according to the following criteria.

1) The five-day biochemical oxygen demand (BOD5) of domestic sewage is calculated as 25-50 g per person per day;

2) The amount of suspended solids in domestic sewage is calculated as 40-65 g per person per day;

3) The total nitrogen content of domestic sewage is calculated from 5 to 11 g per person per day;

4) The total phosphorus content of domestic sewage is calculated from 0.7 to 1.4 g per person per day.

5.2.2 The design water quality of industrial wastewater shall be determined according to the actual measured data of industrial wastewater entering the sewage treatment plant, and its determination method and the data processing method shall comply with the provisions of HJ/T 91. When there is no actual measurement data, it can be determined by reference to the emission data analogy of similar factories.

5.2.3 The influent of the bioreactor should meet the following conditions.

1) the water temperature should be 12 ~ 35 ° C, the pH should be 6.0 ~ 9.0, the BOD5/CODCr value should be greater than 0.3;

2) When there is a requirement to remove ammonia nitrogen, the ratio of total alkalinity (calculated as CaCO3)/ammonia nitrogen (NH3-N) of influent should be greater than or equal to 7.14, dissatisfaction the alkalinity should be added at the foot;

3) When there is a demand for total nitrogen removal, the BOD5/total nitrogen (TN) value of the influent should be greater than or equal to 4.0, the total alkalinity (calculated as CaCO3)/ammonia nitrogen value it should be greater than or equal to 3.6. When it is not satisfied, it should be supplemented with carbon source or alkalinity;

4) When there is phosphorus removal requirement, the ratio of BOD5 to total phosphorus (TP) in the sewage should be greater than or equal to 17;

5) When it is required to simultaneously remove phosphorus and denitrification, it is desirable to meet the requirements of 3) and 4) at the same time.

5.3 Contaminant removal rate

The pollutant removal rate of the oxidation ditch can be calculated according to Table 2.

Table 2 Oxidation ditch pollutant removal rate

Sewage category main process Contaminant removal rate /% Suspended matter (SS) Five-day biochemical oxygen demand (BOD5) Chemical oxygen demand (CODCr) TN NH3-N TP Urban sewage pre-treatment (pre-treatment) oxidation ditch, secondary sedimentation tank 70-90 80-95 80-90 55-85 85-95 50-75 Industrial wastewater pre-treatment (pre-treatment) oxidation ditch, secondary sedimentation tank 70 ~ 90 70 ~ 90 70 ~ 90 45 ~ 85 70 ~ 95 40 ~ 75 Note. According to the water quality, process flow, etc., the primary sedimentation tank may not be provided, and the secondary sedimentation tank may be set according to the groove type.

6.1 General requirements

6.1.1 When discharging water directly, it should meet the requirements of national or local emission standards; when it is discharged into the next-level processing unit, it should meet the next level.

The water intake requirements of the unit.

6.1.2 The flow state in the ditch shall be an overall mixed, partial push flow, and the influent amount is much lower than the circulating liquid mixture in the pool to form a dissolved oxygen (DO) ladder.

degree.

6.1.3 When the water quality and water volume change greatly, it is advisable to set up facilities to adjust water quality and water volume.

6.1.4 The sludge concentration in the ditch should be maintained at 2 000 ~ 4 500 mg/L.

6.1.5 The minimum flow velocity at the bottom of the ditch shall not be less than 0.3 m/s.

6.1.6 According to the requirements of nitrogen and phosphorus removal, separate anaerobic zone (pool) and anoxic zone (pool) can be set.

6.1.7 Process design should consider a flexible mode of operation.

6.1.8 Process design should take into account the effects of water temperature.

6.1.9 The oxidation ditch can be arranged in two or more groups, and the influent water distribution well should be set when multiple groups are arranged.

6.1.10 The design of the inlet pump house, grille, grit chamber, primary settling tank and secondary settling tank shall comply with the relevant provisions of GB 50014.

6.2 Pretreatment and pretreatment

6.2.1 A grid should be installed before the water inlet system, and a grit chamber should be set up for the urban sewage treatment project.

6.2.2 When the suspended solids (SS) is 1.5 times higher than the design value of BOD5, the primary sedimentation tank should be set before the biological reaction tank.

6.2.3 When the influent water quality does not meet the conditions specified in 5.2.3 or contains substances affecting biochemical treatment, appropriate water quality should be taken according to the influent water quality.

Pretreatment process.

6.3 Process

6.3.1 The following process should be adopted for the oxidation ditch.

Pre-water treatment or pretreatment of oxidation ditch secondary sedimentation tank Sludge treatment system, excess sludge return sludge

Figure 1 Oxidation ditch process

6.3.2 Different trench types can be used according to factors such as site, water quality and water volume. The main process types are detailed in Appendix A.

Record B.

6.3.3 Single-slot oxidation ditch, double-slot oxidation ditch, vertical axis aerator oxidation ditch, concentric radial flow oxidation ditch, microporous aeration oxidation ditch should be separate Set the second settling tank; the three-slot oxidation ditch should not be provided with a separate secondary settling tank. The design of the secondary settling tank shall comply with the provisions of GB 50014.

6.4 Pool capacity calculation and main design parameters

6.4.1 Removal of carbon source contaminants

6.4.1.1 When removing carbon source contaminants, the volume of the bioreactor can be calculated as follows.

1) Calculated according to sludge load.

twenty four ( )

QS SV

2) Calculated according to sludge age.

Co e24 ( )

1 000 (1 )

QY S SV

X Kv d cT

Xv=yX (5)

d d20 T( )

TK K theta -= · (6)

Where. V - the volume of the biological reaction tank, m3;

So--bioreactor inlet BOD5 mass concentration, mg/L;

Se--bioreactor effluent BOD5 mass concentration, mg/L, when the removal rate is greater than 90%, can be excluded;

Q--Design flow rate of biological reaction tank, m3/h;

X--the average mass concentration of mixed liquid suspended solids (MLSS) in the biological reaction tank, g/L;

Xv--the average mass concentration of mixed volatile solids (MLVSS) in the biological reaction tank, g/L;

Ls--BOD5 sludge load of bioreactor, kg/(kg·d);

Y--the ratio of MLVSS to MLSS in unit volume mixture, g/g;

Y--sludge yield coefficient (VSS/BOD5), kg/kg;

Thetac--design sludge age, d;

Attenuation coefficient at KdT--T°C, d-1;

The attenuation coefficient at Kd20--20 °C, d-1, should be 0.04~0.075;

T--design temperature, °C;

thetaT--temperature coefficient, should be taken from 1.02 to 1.06.

6.4.1.2 Oxidation ditch treatment of urban sewage or water quality similar to urban sewage industrial wastewater to remove carbon source pollutants, the main design parameters can be the values specified in Table 3 are taken. When the difference between the quality of industrial wastewater and the quality of urban sewage is large, the design parameters should be tested or referenced to similar projects.

set.

Table 3 Main design parameters for removing carbon source pollutants

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