CN101774728A - Sewage treatment method with low residual sludge discharge - Google Patents

Abstract

The invention discloses a sewage treatment method with low residual sludge discharge and relates to a sewage treatment method. The invention solves the problem of secondary pollution which is easily caused by a large amount of residual sludge generated in the traditional sewage treatment method. In one method, the sewage is discharged after being processed by a biological reactor and a precipitating pool; the sludge discharged by the precipitating pool is partially refluxed to the biological reactor; part of the sludge is returned to the biological reactor again after being processed by a cavitating processor; and the residual sludge is discharged. In the other method, the sewage is discharged after passing through the biological reactor and the precipitating pool; the sludge discharged by the precipitating pool is partially refluxed to the biological reactor, and part of the sludge is returned to the biological reactor again after being processed by an anaerobic selector and the cavitating processor; and the residual sludge is discharged. The sewage treatment method with low residual sludge discharge can be applied to a biological sewage treatment system.

Description

Sewage Treatment Method with Low Excess Sludge Discharge

technical field

The invention relates to a method for sewage treatment.

Background technique

The activated sludge method, which utilizes the life activities of microorganisms to degrade pollutants in water bodies, is one of the biological treatment methods widely used in urban sewage treatment plants. The method is to discharge the sewage after being treated by biological processors and sedimentation tanks. Part of the sludge is returned to the biological processor to ensure a stable concentration of activated sludge, and the rest of the sludge is discharged from the system to become excess sludge. The continuous reproduction and growth of microorganisms in the activated sludge has caused a large amount of excess sludge. The remaining sludge contains a large amount of water, microorganisms, refractory organic matter, heavy metals and other impurities. The cost of mud treatment and disposal is high, accounting for 25-65% of the entire sewage treatment cost.

Contents of the invention

The invention aims to solve the problem that the excess sludge produced in the existing sewage treatment method is large and easily causes secondary pollution, and provides a sewage treatment method with low excess sludge discharge.

The sewage treatment method of the low excess sludge discharge of the present invention is carried out according to the following steps: the sewage is discharged after being treated by the biological processor and the settling tank; the sludge in the settling tank is refluxed to the In the biological processor, 5% to 28% (volume) of the sludge in the sedimentation tank is returned to the biological processor after being treated by the cavitation processor, and the remaining sludge is discharged.

The cavitation processor is a mechanical cavitation device or a hydraulic cavitation device.

When using a mechanical cavitation device to treat sludge, the frequency of the mechanical cavitation device is 20-100 kHz, the action energy density is 0.1-1.8 W/mL, and the action time is 1-15 min.

When using a hydraulic cavitation device to treat sludge, the vacuum degree of hydraulic cavitation is 0.1-0.7atm, and the action time is 0.5-5min.

The sewage treatment method with low residual sludge discharge of the present invention can destroy the sludge floc structure by using cavitation, reduce the sludge particle size, release the organic matter contained in the sludge, and efficiently dissolve cells, so that the microbial organic cell matter Dissolved in water to form a self-produced substrate matrix that can be reused by microorganisms. When microorganisms in the bioreactor use these self-substrates as growth substrates to repeat the metabolic process, the amount of biosolids discharged from sewage treatment facilities is reduced, and the remaining Sludge output is reduced by 60-100%, achieving the purpose of reducing excess sludge discharge in the water treatment process.

The method for reducing excess sludge discharge in the sewage treatment process of the present invention can also be carried out according to the following steps: the sewage is discharged after being treated by a biological processor and a sedimentation tank; The reflux ratio is back to the biological processor, and 5% to 28% (volume) of the sludge in the sedimentation tank is returned to the biological processor after being treated by anaerobic selector and cavitation processor, and the remaining sludge is discharged .

The action time of the anaerobic selector is 3 to 24 hours;

The cavitation processor is a mechanical cavitation device or a hydraulic cavitation device.

When using a mechanical cavitation device to treat sludge, the frequency of the mechanical cavitation device is 20kHz-100kHz, the action intensity is 0.1-1.8W/mL, and the action time is 1-15min.

When using a hydraulic cavitation device to treat sludge, the vacuum degree of hydraulic cavitation is 0.1-0.7atm, and the action time is 0.5-5min.

The sewage treatment method with low residual sludge discharge of the present invention can destroy the sludge floc structure by using cavitation, reduce the sludge particle size, release the organic matter contained in the sludge, and utilize anaerobic selector and cavitation device The combined effect of the combined effect can improve the lysis effect, so that the microbial organic cell material can be dissolved in water to form a self-produced substrate matrix that can be reused by microorganisms. When the microorganisms in the bioreactor use these self-substrates as growth substrates to repeat the metabolic process , The amount of biological solids discharged from sewage treatment facilities is reduced, and the output of excess sludge is reduced by 70-100%, so as to achieve the purpose of reducing the discharge of excess sludge in the process of water treatment.

Detailed ways

Specific implementation mode one: The sewage treatment method with low residual sludge discharge of this embodiment is carried out according to the following steps: the sewage is discharged after being treated by a biological processor and a sedimentation tank; The reflux ratio of % (volume) is returned to the biological processor, and 5% to 28% (volume) of the sludge in the sedimentation tank is returned to the biological processor after being treated by the cavitation processor, and the remaining sludge is discharged.

The sewage treatment method of the biological processor and the sedimentation tank in this embodiment is a conventional method; the reflux ratio is the ratio of the volume flow rate of the refluxed sludge to the volume flow rate of the influent.

Cavitation treatment produces a strong shock wave to the sludge, effectively destroys the spatial structure of the sludge, and causes damage or even direct tearing to the cell wall of the microorganisms in the sludge, and has a strong inactivation and dissolution effect. At the same time, cavitation oxidizes the active substances of microorganisms such as dehydrogenase, thereby modifying or reducing their proteins. 1. The protein content increases, the sludge self-decomposition rate increases, and the surplus sludge output is reduced by 60% to 100% compared with the existing sewage treatment method.

Embodiment 2: This embodiment differs from Embodiment 1 in that: the cavitation processor is a mechanical cavitation device or a hydraulic cavitation device. Others are the same as in the first embodiment.

Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that: the cavitation processor is a mechanical cavitation device, the frequency of the mechanical cavitation device is 20-100 kHz, and the action energy density is 0.1-1.8 W/mL, the action time is 1-15min; the other is the same as the specific embodiment 1 or 2.

Embodiment 4: This embodiment differs from Embodiments 1 to 3 in that: the cavitation processor is a mechanical cavitation device, the frequency of the mechanical cavitation device is 30-90 kHz, and the action energy density is 0.2-1.7 W /mL, and the action time is 2 to 14 minutes; the others are the same as those in Embodiments 1 to 3.

Embodiment 5: This embodiment is different from Embodiments 1 to 4 in that: the cavitation processor is a mechanical cavitation device, the frequency of the mechanical cavitation device is 60kHz, the action energy density is 1.0W/mL, and the effect The time is 8 minutes; others are the same as those in Embodiments 1 to 4.

Embodiment 6: This embodiment differs from Embodiments 1 to 5 in that: the cavitation processor is a hydraulic cavitation device, the vacuum degree of hydraulic cavitation is 0.1-0.7 atm, and the action time is 0.5-5 minutes. Others are the same as those in Embodiments 1 to 5.

Embodiment 7: This embodiment differs from Embodiments 1 to 6 in that: the cavitation processor is a hydraulic cavitation device, the vacuum degree of hydraulic cavitation is 0.2 to 0.6 atm, and the action time is 1 to 4.5 minutes . Others are the same as those in Embodiments 1 to 6.

Embodiment 8: This embodiment differs from Embodiments 1 to 7 in that: the cavitation processor is a hydraulic cavitation device, the vacuum degree of hydraulic cavitation is 0.4 atm, and the action time is 3 minutes. Others are the same as those in Embodiments 1 to 7.

Embodiment 9: This embodiment differs from Embodiments 1 to 8 in that: the reflux volume ratio is 40-80%. Others are the same as those in Embodiments 1 to 8.

Embodiment 10: This embodiment is different from Embodiments 1 to 9 in that: the reflux volume ratio is 60%. Others are the same as the specific embodiments 1 to 9.

Embodiment 11: This embodiment differs from Embodiments 1 to 10 in that: the reflux ratio is 50%; the cavitation processor is a mechanical cavitation device with a frequency of 80 kHz and an active energy density of 1.2W/mL, the action time is 15min. Others are the same as those in Embodiments 1 to 10.

In this embodiment, domestic sewage from the second campus of Harbin Institute of Technology is selected as the treatment object. The chemical oxygen demand (COD) of the incoming water is 106-362 mg/L, the total nitrogen (TN) is 39-72 mg/L, and the total phosphorus (TP) is 1.2～10.3mg/L, ammonia nitrogen (NH ₃ -N) is 36～70mg/L; the moisture content of the inoculated sludge is 99%, the pH is 6.9, the suspended solids (SS) is 9034mg/L, and the effluent quality after treatment Stable, in which COD is 50-84mg/L, TN is 10-15mg/L, NH ₃ -N is 18-20mg/L, and the pH of the sludge decreases by 2-7% during the ultrasonic process, the range of change is not large, and the effluent The water quality is the same as the effluent water quality of the traditional activated sludge process, basically in line with the provisions of the secondary standard GB18918-2002 for the discharge of pollutants from urban sewage treatment plants, and the amount of residual sludge is compared with the amount of sludge produced by the traditional activated sludge process , can be reduced by 62%, the reduction effect is obvious, and it is beneficial to reduce the impact of excess sludge on the environment.

Specific embodiment twelve: the sewage treatment method of the low excess sludge discharge of this embodiment is carried out according to the following steps: the sewage is discharged after the treatment of the biological processor and the sedimentation tank; ) back to the biological processor, 5% to 28% (volume) of the sludge in the sedimentation tank is returned to the biological processor after being treated by anaerobic selector and cavitation processor, and the remaining sludge emission.

The sewage treatment method of the biological processor and the sedimentation tank in this embodiment is a conventional method; the reflux ratio is the ratio of the volume flow of the refluxed sludge to the volume flow of the influent.

The sewage treatment method with low residual sludge discharge of this embodiment can destroy the sludge floc structure by using cavitation, reduce the sludge particle size, release the organic matter contained in the sludge, and use the anaerobic selector and cavitation The combined effect of the device improves the lysis effect, dissolves the organic cell material of microorganisms in water, and forms a self-produced substrate matrix that can be reused by microorganisms. When the microorganisms in the bioreactor use these self-substrates as growth substrates to repeat the metabolic process At the same time, the amount of biological solids discharged from sewage treatment facilities is reduced, and the output of residual sludge is reduced by 70-100%.

Embodiment 13: This embodiment is different from Embodiment 12 in that: the action time of the anaerobic selector is 3-24 hours. Others are the same as in Embodiment 12.

Embodiment 14: This embodiment is different from Embodiment 12 or Embodiment 13 in that: the action time of the anaerobic selector is 5-22 hours. Others are the same as those in Embodiment 12 or 13.

Embodiment 15: This embodiment is different from Embodiments 12 to 14 in that: the action time of the anaerobic selector is 15 hours. Others are the same as the specific embodiments 12 to 14.

Specific Embodiment 16: This embodiment differs from specific embodiments 12 to 15 in that: the cavitation processor is a mechanical cavitation device or a hydraulic cavitation device. Others are the same as those in Embodiments 12 to 15.

Specific Embodiment 17: This embodiment differs from specific embodiments 12 to 16 in that: the cavitation processor is a mechanical cavitation device, the frequency of the mechanical cavitation device is 20 kHz to 100 kHz, and the action energy density is 0.1~1.8W/mL, the action time is 1~15min. Others are the same as those in Embodiments 12 to 16.

Embodiment 18: This embodiment differs from Embodiments 12 to 17 in that: the cavitation processor is a mechanical cavitation device, the frequency of the mechanical cavitation device is 30 kHz to 90 kHz, and the action energy density is 0.2～1.6W/mL, the action time is 2～14min. Others are the same as those in Embodiments 12 to 17.

Specific Embodiment 19: The difference between this embodiment and specific embodiments 12 to 18 is that: the cavitation processor is a mechanical cavitation device, the frequency of the mechanical cavitation device is 50 kHz, and the action energy density is 0.2- 1.2W/mL, the action time is 8min. Others are the same as those in Embodiments 12 to 18.

Specific embodiment 20: This embodiment differs from specific embodiments 12 to 19 in that: the cavitation processor is a hydraulic cavitation device, the vacuum degree of hydraulic cavitation is 0.1-0.7 atm, and the action time is 0.5～5min. Others are the same as those in Embodiments 12 to 19.

Specific embodiment 21: This embodiment differs from specific embodiments 12 to 20 in that: the cavitation processor is a hydraulic cavitation device, and the vacuum degree of hydraulic cavitation is 0.2-0.6 atm, and the action time is 1 to 4.5 minutes. Others are the same as those in Embodiments 12 to 20.

Specific embodiment 22: This embodiment differs from specific embodiments 12 to 21 in that: the cavitation processor is a hydraulic cavitation device, the vacuum degree of hydraulic cavitation is 0.4atm, and the action time is 2.5min. Others are the same as those in Embodiments 12 to 21.

Specific Embodiment 23: This embodiment differs from specific embodiments 12 to 22 in that: the reflux volume ratio is 40-80%. Others are the same as those in Embodiments 12 to 22.

Embodiment 24: This embodiment is different from Embodiments 12 to 23 in that: the reflux volume ratio is 60%. Others are the same as those in Embodiments 12 to 23.

Specific embodiment 25: This embodiment differs from specific embodiments 12 to 24 in that: the reflux volume ratio is 50%, the ultrasonic action time of the anaerobic selector is 8 hours, and the mechanical cavitation device The frequency is 80kHz, the action energy density is 1.2W/mL, and the action time is 15min. Others are the same as those in Embodiments 12 to 24.

In this embodiment, the domestic sewage of the second campus of Harbin Institute of Technology is selected as the treatment object, and the COD of the influent is 106-362mg/L, the TN is 39-72mg/L, the TP is 1.2-10.3mg/L, and the NH3-N is 36-70mg /L; the moisture content of the inoculated sludge is 99%, the pH is 6.9, and the SS is 9034mg/L. The effluent quality after treatment is stable, in which the COD is 50-84mg/L, the TN is 10-15mg/L, and the NH ₃ - N is 18-20mg/L, the pH of the sludge is reduced by 3-6.5% during the ultrasonic process, the change is not large, the effluent water quality is the same as that of the traditional activated sludge process, and meets the second-level pollutant discharge of urban sewage treatment plants According to the provisions of the standard GB18918-2002, the amount of excess sludge can be reduced by 83% compared with the amount of sludge produced by the traditional activated sludge method, and the reduction effect is obvious, which is beneficial to reduce the impact of excess sludge on the environment.

Claims (10)

1. the sewage water treatment method of low residual sludge discharge is characterized in that the sewage water treatment method of low residual sludge discharge carries out according to the following steps: sewage discharging after biological processor, settling tank are handled; The reflux ratio of mud in the settling tank by 30～100% (volumes) is back in the biological processor, the mud of 5%～28% in the settling tank (volume) is back in the biological processor remaining mud discharging after the cavitation process device is handled.

2. the sewage water treatment method of low residual sludge discharge according to claim 1 is characterized in that reflux ratio is 40～80%.

3. the sewage water treatment method of low residual sludge discharge according to claim 1 and 2 is characterized in that described cavitation process device is mechanical cavitation apparatus or Hydrodynamic cavitation device.

4. the sewage water treatment method of low residual sludge discharge according to claim 3, when it is characterized in that utilizing mechanical cavitation apparatus to handle mud, the frequency of mechanical cavitation apparatus is that 20～100kHz, interaction energy metric density are that 0.1～1.8W/mL, action time are 1～15min.

5. the sewage water treatment method of low residual sludge discharge according to claim 3, when it is characterized in that utilizing the Hydrodynamic cavitation device to handle mud, the vacuum tightness of Hydrodynamic cavitation is that 0.1～0.7atm, action time are 0.5～5min.

6. the sewage water treatment method of low residual sludge discharge is characterized in that the sewage water treatment method of low residual sludge discharge carries out according to the following steps: sewage discharging after biological processor, settling tank are handled; The reflux ratio of mud in the settling tank by 30～100% (volumes) is back in the biological processor, the mud of 5%～28% in the settling tank (volume) is back in the biological processor remaining mud discharging through anaerobic selection device, cavitation process device after handling.

7. the sewage water treatment method of low residual sludge discharge according to claim 6, be 3～24h the action time that it is characterized in that the anaerobic selection device.

8. according to the sewage water treatment method of claim 6 or 7 described low residual sludge discharges, it is characterized in that described cavitation process device is mechanical cavitation apparatus or Hydrodynamic cavitation device.

9. the sewage water treatment method of low residual sludge discharge according to claim 8, when it is characterized in that utilizing mechanical cavitation apparatus to handle mud, the frequency of mechanical cavitation apparatus is that 20～100kHz, interaction energy metric density are that 0.1～1.8W/mL, action time are 1～15min.

10. the sewage water treatment method of low residual sludge discharge according to claim 8, when it is characterized in that utilizing the Hydrodynamic cavitation device to handle mud, the vacuum tightness of Hydrodynamic cavitation is that 0.1～0.7atm, action time are 0.5～5min.