CN101244882A - The Method of Using Ultrasonic to Reduce Sludge in the Process of Sewage Biological Treatment - Google Patents

Abstract

The invention discloses a method for reducing sludge in the sewage biological treatment process by using ultrasonic waves, and relates to a method for reducing sludge in the sewage biological treatment process. It solves the problems of high sludge treatment and disposal cost, high sludge return ratio and high energy consumption. Method of the present invention: one, ultrasonic irradiation device (3) is set in sewage biological treatment system; 20kHz～1MHz, and its irradiation intensity is 1～50W/cm ² ; 4. The sludge treated by the ultrasonic irradiation device (3) is input into the reactor (1) through the feedback loop (2) or the sludge return pipe (6) The repeated circulation is carried out, and the ultrasonic irradiation device (3) operates for 20 to 30 days, so that the sludge is effectively reduced. The invention comprehensively utilizes shock wave to destroy sludge structure and cell lysis, strong oxidant to reduce enzyme activity, and high temperature heat effect to reduce sludge by 50% to 70%. The process of the method is simple.

Description

The Method of Using Ultrasonic to Reduce Sludge in the Process of Sewage Biological Treatment

technical field

The invention relates to a method for reducing sludge in sewage biological treatment.

Background technique

The biological treatment technology that uses the life activities of microorganisms to reduce pollutants is the most important method of sewage treatment. However, in the biological treatment process, the microorganisms themselves continue to grow, and the part that exceeds the sewage treatment requirements forms residual sludge. At present, the annual discharge of dry sludge in China is about 2.0×10 ⁶ t, and it is increasing at a rate of 10% per year. Excess sludge contains a large amount of water, microorganisms including various pathogenic bacteria, difficult-to-reduce organic matter, heavy metals, and other impurities. It has a foul smell and high viscosity, and must be treated and disposed of safely. The treatment and disposal of excess sludge is expensive, accounting for 25% to 65% of the entire sewage treatment cost. Taking the incineration method as an example, it costs more than 2,000 yuan per ton of dry sludge. Moreover, in the process of sludge treatment and disposal, secondary pollution such as leachate, tail gas, and dioxin may also be generated. Based on the above reasons, more than 80% of the sludge in sewage treatment plants in my country has not been effectively treated, which poses a threat to environmental safety and public health. Therefore, according to the principle of cleaner production, it is very important to realize source reduction and reduce the discharge of excess sludge in the process of sewage treatment. It can give full play to the role of sewage treatment plants, eliminate secondary pollution, and achieve the important goal of environmental protection. Relevant literatures at home and abroad record the reduction of excess sludge by ultrasonic waves, that is to say, after the excess sludge is generated, ultrasonic waves are used to reduce its solid matter content or volume. The applicant himself has reported in the literature that the ultrasonic process of the SBR process reduces weight. In this process, the sludge reflux ratio is high, the energy consumption is large, and it cannot be operated continuously.

Contents of the invention

The present invention solves the problem that the sludge in more than 80% of the sewage treatment plants in my country has not been effectively treated, the cost of treatment and disposal is high, the sludge reflux ratio is high, the energy consumption is large, and leachate, tail gas, Secondary pollution such as dioxin poses a threat to environmental safety and public health. A method for reducing sludge in the process of sewage biological treatment using ultrasonic waves is provided. The specific technical solution to solve the above problems is as follows:

The present invention adopts the steps of the method for reducing sludge in the sewage biological treatment process by ultrasonic wave as follows:

Step 1. A feedback loop 2 is set between the water inlet and outlet of the bioreactor 1 of the sewage biological treatment system. One end of the feedback loop 2 is connected to the water inlet of the reactor, and the other end of the feedback loop 2 is connected to the bioreactor. The water outlet is connected, and an ultrasonic irradiation device 3 and a pump 4 are provided on the feedback loop 2;

Step 2: start the sewage biological treatment system, the average residence time of the original sludge in the system is SRT0;

Step 3: The sludge generated during the treatment process of the sewage biological treatment system enters the feedback loop 2, the concentration of the sludge in the feedback loop 2 is 2000-35000 mg/L, and the average residence time of the sludge (SRT1) is the original residence time (SRT0) The ultrasonic frequency of the ultrasonic irradiation device 3 is 20kHz~1MHz, and its irradiation intensity is 1~50W/cm ² . The proportion of the sludge receiving ultrasonic irradiation in the feedback loop 2 is adjusted by the pump 4. The adjustment basis is , the volume ratio of sludge to influent water is: 0.00001～0.001:1, the sludge enters the ultrasonic irradiation device 3 through the feedback loop 2 for ultrasonic irradiation, and the interval between two ultrasonic treatments depends on the hydraulic retention time of sewage and the It needs to be determined by reduction rate;

Step 4: The sludge treated by the ultrasonic irradiation device 3 enters the bioreactor 1 through the feedback loop 2 for further treatment, and the sludge that is not reduced in the system enters the ultrasonic irradiation device 3 again through the feedback loop 2 for further irradiation , repeated cycle, after 20 to 30 days, the system runs stably, and the sludge is effectively reduced.

Another ultrasonic wave of the present invention reduces the steps of the method for sludge in the sewage biological treatment process as follows:

Step 1, the ultrasonic irradiation device 3 is arranged on the sludge return pipeline 6 between the bioreactor 1 and the sedimentation tank 5 in the sewage biological treatment system;

Step 2: start the sewage biological treatment system, the average residence time of the original sludge in the system is SRT0;

Step 3: The sludge generated during the treatment process of the sewage biological treatment system enters the sludge return pipeline 6, the concentration of the sludge in the sludge return pipeline 6 is 2000-35000mg/L, and the average residence time of the sludge (SRT1) is the original residence time The time (SRT0) is more than twice, the ultrasonic frequency of the ultrasonic irradiation device 3 is 20kHz~1MHz, the irradiation intensity is 1~50W/cm ² , the volume ratio of sludge to influent water is: 0.00001~0.001:1, the sludge The mud enters the ultrasonic irradiation device 3 through the sludge return pipeline 6 for intermittent continuous ultrasonic irradiation, and the intermittent time and irradiation time are determined according to the hydraulic retention time of sewage and the required reduction rate;

Step 4: The sludge treated by the ultrasonic irradiation device 3 is input into the bioreactor 1 through the sludge return pipeline 6 for further treatment, so that the sludge that has not been reduced in the system enters the ultrasonic irradiation device again through the sludge return pipeline 6 3 Carry out irradiation again and repeat the cycle. After 20 to 30 days, the system will run stably.

Sludge is effectively reduced.

The present invention uses a low-frequency, high-intensity ultrasonic irradiation device 3 with an irradiation intensity of 1 to 50 W/cm ² . After irradiating the sludge entering the feedback loop 2 or the sludge return pipeline 6, the feedback loop 2 or the irradiated sludge in the sludge return pipeline 6 causes ultrasonic cavitation, which produces a strong shock wave, accompanied by the generation of strong oxidants such as hydroxyl radicals; the shock wave acts on the sludge in the feedback loop 2 or the sludge return pipeline 6 Above all, the spatial structure of the sludge is effectively destroyed, and the microbial cell walls in the sludge in the feedback loop 2 or the sludge return pipeline 6 are damaged or even directly torn; at the same time, various Strong oxidants oxidize the active substances of microorganisms, such as dehydrogenase, so as to modify or reduce their proteins. In addition, ultrasonic cavitation can also produce local hot spots, where the temperature in millions of hot spot areas can reach thousands of degrees Celsius, which has a strong inactivation and dissolution effect on microorganisms, and it is very important for the sludge in the feedback loop 2 or the sludge return pipeline 6 Other substances also have a good pyrolysis effect. The combined effects of these effects destroyed part of the structure of the irradiated sludge; inactivated some microorganisms; decreased the overall dehydrogenase activity; and decreased the net specific growth rate of the sludge. The content of dissolved organic matter, nitrogen, phosphorus, polysaccharide, and protein increases, and the sludge self-decomposition rate increases. After re-entering the sewage biological treatment process through the feedback loop 2 or the sludge return pipeline 6, the sludge activity gradually recovers, and some enter the rapid growth period. Until a hydraulic retention time ends, the above steps are repeated again, and the cycle is repeated, so that the average residence time of sludge (SRT1) is more than twice the original residence time (SRT0), and finally the sludge is reduced by 50% to 70%.

In the present invention, a feedback loop 2 or a sludge return pipeline 6 is set between the water inlet end and the water outlet end of the bioreactor of the sewage biological treatment system, and an ultrasonic irradiation device 3 is used to control the sludge entering the feedback loop 2 or the sludge return pipeline 6 Ultrasonic irradiation is used to comprehensively utilize the shock wave to destroy the sludge structure and cell lysis, the strong oxidant to reduce the enzyme activity, and the thermal effect of high temperature to improve the sludge reduction rate and reduce the sludge by 50% to 70%. The method flow is simple. It is widely used in sewage treatment plants to treat sludge and eliminate secondary pollution.

Description of drawings

Fig. 1 is the schematic diagram of the structure of feedback loop and ultrasonic irradiation in the sewage biological treatment system corresponding to the first treatment method of the present invention, and Fig. 2 is the ultrasonic irradiation device 3 corresponding to the second treatment method in the sewage biological treatment system Schematic diagram of the structure on the sludge return pipeline in .

Detailed ways

Specific implementation manner 1: This implementation manner is described in conjunction with FIG. 1 . The steps of this embodiment are as follows:

Step 1. A feedback loop 2 is set between the water inlet and outlet of the bioreactor 1 of the sewage biological treatment system. One end of the feedback loop 2 is connected to the water inlet of the reactor 1, and the other end of the feedback loop 2 is connected to the biological reaction. The water outlet of the device is connected, and an ultrasonic irradiation device 3 and a pump 4 are provided on the feedback loop 2, and the ultrasonic irradiation device 3 is used to irradiate the sludge entering the feedback loop 2 with ultrasonic waves;

Step 2: start the sewage biological treatment system, the average residence time of the original sludge in the system is SRT0;

Step 3: The sludge generated during the treatment process of the sewage biological treatment system enters the feedback loop 2, the concentration of the sludge in the feedback loop 2 is 2000-35000mg/L, and the ultrasonic frequency of the ultrasonic irradiation device 3 is 20kHz-1MHz. The irradiation intensity is 1-50W/cm ² , and the proportion of the sludge receiving ultrasonic irradiation in the feedback loop 2 is adjusted by the pump 4. Enter the ultrasonic irradiation device 3 through the feedback loop 2 for intermittent continuous ultrasonic irradiation, and the interval between two ultrasonic treatments is determined according to the hydraulic retention time of the sewage and the required reduction rate;

Step 4: The sludge treated by the ultrasonic irradiation device 3 is input into the bioreactor 1 through the feedback loop 2 for further treatment, so that the unreduced sludge in the system is returned to the bioreactor 1 through the feedback loop 2 and then irradiated by ultrasonic waves again. The irradiation device 3 is irradiated again, and the cycle is repeated. After 20 to 30 days, the system runs stably, and the sludge is effectively reduced.

Specific Embodiment 2: This embodiment will be described in conjunction with FIG. 2 . The steps of this embodiment are as follows:

Step 1, the ultrasonic irradiation device 3 is arranged on the sludge return pipeline 6 between the bioreactor 1 and the sedimentation tank 5 in the sewage biological treatment system;

Step 2: start the sewage biological treatment system, the average residence time of the original sludge in the system is SRT0;

Step 3: The sludge generated during the treatment process of the sewage biological treatment system enters the sludge return pipeline 6, the concentration of the sludge in the sludge return pipeline 6 is 2000-35000mg/L, and the average residence time of the sludge (SRT1) is the original residence time The time (SRT0) is more than twice, the ultrasonic frequency of the ultrasonic irradiation device 3 is 20kHz~1MHz, the irradiation intensity is 1~50W/cm ² , the volume ratio of sludge to influent water is: 0.00001~0.001:1, the sludge The mud enters the ultrasonic irradiation device 3 through the sludge return pipeline 6 for intermittent continuous ultrasonic irradiation, and the interval between two ultrasonic treatments is determined according to the hydraulic retention time of sewage and the required reduction rate;

Step 4: The sludge treated by the ultrasonic irradiation device 3 is input into the bioreactor 1 through the sludge return pipeline 6 for further treatment, so that the sludge that has not been reduced in the system enters the ultrasonic irradiation device again through the sludge return pipeline 6 3 Carry out re-irradiation and repeat the cycle. After 20 to 30 days, the system will run stably and the sludge will be effectively reduced.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that the SBR process is used to treat the sewage in a living area. The quality of the sewage is: the chemical oxygen demand is 150-400 mg/L, and the average oxygen demand is 285 mg/L. ;Suspended solids are 100-250mg/L, average solids are 180mg/L; nitrogen content is 26-50mg/L, average nitrogen content is 40mg/L; ammonia nitrogen content is 20-38mg/L, average ammonia nitrogen content is 29mg /L; the phosphorus content is 3～8mg/L, and the average phosphorus content is 4.5mg/L, adopt the sludge produced in the sewage biological treatment system treatment process in the third step of the specific implementation mode, enter the sludge concentration in the feedback loop 2 12000mg/L, the ultrasonic frequency of the ultrasonic irradiation device 3 is 25kHz, the irradiation intensity is 1W/cm ² , the ratio of sludge volume to influent water volume is: 0.0005:1, and the ultrasonic irradiation device 3 conducts ultrasonic waves every 8 hours. Irradiation for 30 minutes; step 4, the sludge treated by the ultrasonic irradiation device 3 is input into the bioreactor 1 through the feedback loop 2 for further treatment, so that the sludge that has not been reduced in the system feedback loop 2 enters the ultrasonic irradiation device 3 again Irradiate again, repeat the cycle, the ultrasonic irradiation device 3 runs for 30 days, the effluent water quality reaches the national level 2 discharge standard, and the sludge is reduced by 58%. Other steps are the same as in the first embodiment.

Embodiment 4: The difference between this embodiment and Embodiment 2 is that the activated sludge method is used to treat the sewage in a living area. The quality of the sewage is: the chemical oxygen demand is 150-400mg/L, and the average oxygen demand is 285mg /L; suspended solid content is 100-250mg/L, with an average content of 180mg/L; nitrogen content is 26-50mg/L, with an average content of 40mg/L; ammonia nitrogen content is 20-38mg/L, with an average content of 29mg/L L; phosphorus content is 3～8mg/L, and average content is 4.5mg/L; Adopt the sludge return pipeline that adopts the ultrasonic irradiation device 3 in step 1 as described in specific embodiment 2 to be located in the sewage biological treatment system Irradiate on 6, the ratio of sludge volume to influent water volume in step 3 is 0.0005:1; the irradiation method is 40kHz ultrasonic, the irradiation intensity is 1W/cm ² , irradiate for 15min every 24 hours, and run in step 4 One month later, the effluent quality reached the national level 2 discharge standard, and the sludge was reduced by 70%. Other steps are the same as in the second embodiment.

Embodiment 5: The difference between this embodiment and Embodiment 1 is that the sludge generated in the sewage biological treatment system in step 3 has a concentration of 5000 mg/L in the feedback loop 2 . Other steps are the same as in the first embodiment.

Embodiment 6: In step 3 of this embodiment, the ultrasonic frequency of the ultrasonic irradiation device 3 is 0.5 MHz, and its irradiation intensity is 10 W/cm ² . Other steps are the same as in the first embodiment.

Embodiment 7: The difference between this embodiment and Embodiment 1 is that the ratio of sludge volume to influent water volume in step 3 is 0.0001:1. Other steps are the same as in the first embodiment.

Embodiment 8: The difference between this embodiment and Embodiment 2 is that in Step 3, the ultrasonic irradiation device 3 irradiates for 20 minutes every 12 hours. Other steps are the same as in the second embodiment.

Ninth specific embodiment: This embodiment and the sludge generated during the treatment of the sewage biological treatment system in step 3, the concentration of the sludge entering the sludge return pipeline 6 is 15000 mg/L. Other steps are the same as in the second embodiment.

Embodiment 10: In step 3 of this embodiment, the ultrasonic frequency of the ultrasonic irradiation device 3 is 0.5 MHz, and its irradiation intensity is 20 W/cm ² . Other steps are the same as those in Embodiment 1 and Embodiment 2.

The present invention sets the ultrasonic irradiation device 3 on the feedback loop 2 or the sludge return pipeline 6 by adding the feedback loop 2 or directly using the existing sludge return pipeline 6 in the wastewater treatment system, so that the ultrasonic treatment can be organically combined In the wastewater treatment system, the system can run continuously without the need to discharge the sludge to an external reactor for treatment.

Claims (10)

1, adopt ultrasonic wave in biological wastewater treatment process, to reduce the method for mud, it is characterized in that the step of this method is as follows:

Step 1, utilize between the feed-water end of the bio-reactor (1) of sewage biological treatment system and water side feedback loop (2) is set, one end of feedback loop (2) is communicated with the feed-water end of bio-reactor (1), the other end of feedback loop (2) is communicated with the water side of bio-reactor (1), on feedback loop (2), be provided with ultrasonic irradiation device (3) and pump (4), adopt ultrasonic irradiation device (3) that the mud that enters in the feedback loop (2) is carried out ultrasonic irradiation;

Step 2, startup sewage biological treatment system, system's primary sludge mean residence time is SRT0;

The mud that produces in step 3, the sewage biological treatment system treating processes enters in the feedback loop (2), the concentration of mud is 2000～35000mg/L in the feedback loop (2), mud mean residence time SRT1 is more than 2 times of original residence time SRT0, the ultrasonic frequency of ultrasonic irradiation device (3) is 20kHz～1MHz, its irradiation intensity 1～50W/cm ²The ratio that the middle mud of feedback loop (2) is accepted ultrasonic irradiation is regulated by pump (4), it is regulated according to being: sludge volume with the water inlet volume ratio is: 0.00001～0.001: 1, mud enters ultrasonic irradiation device (3) through feedback loop (2) and carries out intermittent type continuous ultrasound amplitude photograph, determines according to sewage hydraulic detention time and required reduction rate the pitch time between twice ultrasonication;

Step 4, the mud after ultrasonic irradiation device (3) is handled are handled in feedback loop (2) input bio-reactor (1) once more, make the mud that does not have in the system to reduce carry out irradiation once more through ultrasonic irradiation device (3) once more through feedback loop (2), circulation repeatedly, system stable operation after 20～30 days, mud is effectively reduced.

2, employing ultrasonic wave according to claim 1 reduces the method for mud in biological wastewater treatment process, it is characterized in that adopting the sewage in SBR art breading living quarters, sewage quality is: chemical oxygen demand (COD) is 150～400mg/L, and average oxygen requirement is 285mg/L; Suspended solids is 100～250mg/L, and average solid is 180mg/L; Nitrogen content is 26～50mg/L, and average nitrogen content is 40mg/L; Ammonia-nitrogen content is 20～38mg/L, and the ammonia nitrogen average content is 29mg/L; Phosphorus content is 3～8mg/L, and average phosphorus content is 4.5mg/L; Adopt the mud that produces in the sewage biological treatment system treating processes in embodiment one step 3, the sludge concentration that enters in the feedback loop (2) is 12000mg/L, and the ultrasonic frequency of ultrasonic irradiation device (3) is 25kHz, and irradiation intensity is 1W/cm ², sludge volume with the water inlet volume ratio is: 0.0005: 1, ultrasonic irradiation device (3) carried out ultrasonic irradiation 30min every 8 hours; Step 4, the mud after ultrasonic irradiation device (3) is handled are handled in feedback loop (2) input bio-reactor (1) once more, make the mud that does not have in the system to reduce carry out irradiation once more through ultrasonic irradiation device (3) once more through feedback loop (2), circulation repeatedly, ultrasonic irradiation device (3) operation 30 days, effluent quality reaches 2 grades of emission standards of country, and mud reduces 58%.

3, employing ultrasonic wave according to claim 1 reduces the method for mud in biological wastewater treatment process, it is characterized in that the mud that produces in the sewage biological treatment system treating processes in the step 3, the sludge concentration that enters in the feedback loop (2) is 5000mg/L.

4, employing ultrasonic wave according to claim 1 reduces the method for mud in biological wastewater treatment process, and the ultrasonic frequency that it is characterized in that ultrasonic irradiation device (3) in the step 3 is 0.5MHz, its irradiation intensity 10W/cm ²

5, employing ultrasonic wave according to claim 1 reduces the method for mud in biological wastewater treatment process, it is characterized in that sludge volume is 0.0001: 1 with the water inlet volume ratio in the step 3.

6, employing ultrasonic wave according to claim 1 reduces the method for mud in biological wastewater treatment process, it is characterized in that ultrasonic irradiation device (3) was every 12 hours irradiation 20min in the step 4.

7, adopt ultrasonic wave in biological wastewater treatment process, to reduce the method for mud, it is characterized in that the step of this method is as follows:

Step 1, ultrasonic irradiation device (3) is located on the bio-reactor (1) and the sludge return pipe (6) between the settling tank (5) in the sewage biological treatment system;

Step 2, startup sewage biological treatment system, system's primary sludge mean residence time is SRT0;

The mud that produces in step 3, the sewage biological treatment system treating processes enters in the sludge return pipe (6), the concentration of mud is 2000～35000mg/L in the sludge return pipe (6), mud mean residence time SRT1 is more than 2 times of original residence time SRT0, the ultrasonic frequency of ultrasonic irradiation device (3) is 20kHz～1MHz, its irradiation intensity 1～50W/cm ²Sludge volume with the water inlet volume ratio is: 0.00001～0.001: 1, mud enters ultrasonic irradiation device (3) through sludge return pipe (6) and carries out intermittent type continuous ultrasound amplitude photograph, determines according to sewage hydraulic detention time and required reduction rate the pitch time between twice ultrasonication;

Step 4, the mud after ultrasonic irradiation device (3) is handled are handled in sludge return pipe (6) input bio-reactor (1) once more, make the mud that does not have in the system to reduce carry out irradiation once more through ultrasonic irradiation device (3) once more through sludge return pipe (6), circulation repeatedly, system stable operation after 20～30 days, mud is effectively reduced.

8, employing ultrasonic wave according to claim 7 reduces the method for mud in biological wastewater treatment process, it is characterized in that adopting the sewage in Wastewater Treated by Activated Sludge Process living quarters, sewage quality is: chemical oxygen demand (COD) is 150～400mg/L, and average oxygen requirement is 285mg/L; Suspended solids content is 100～250mg/L, and average content is 180mg/L; Nitrogen content is 26～50mg/L, and average content is 40mg/L; Ammonia-nitrogen content is 20～38mg/L, and average content is 29mg/L; Phosphorus content is 3～8mg/L, and average content is 4.5mg/L; Ultrasonic irradiation device (3) in step 1 is located on the sludge return pipe (6) in the sewage biological treatment system and carries out irradiation, and sludge volume is 0.0005: 1 with the water inlet volume ratio in the step 3; Radiation mode is the 40kHz ultrasonic wave, and irradiation intensity is 1W/cm ², the 24 hours irradiation 15min in every interval, operation is after 1 month in the step 4, and effluent quality reaches 2 grades of emission standards of country, and mud subdues 70%.

9, employing ultrasonic wave according to claim 7 reduces the method for mud in biological wastewater treatment process, it is characterized in that the mud that produces in the sewage biological treatment system treating processes in the step 3, the sludge concentration that enters in the sludge return pipe (6) is 15000mg/L.

10, employing ultrasonic wave according to claim 7 reduces the method for mud in biological wastewater treatment process, and the ultrasonic frequency that it is characterized in that ultrasonic irradiation device (3) in the step 3 is 0.5MHz, its irradiation intensity 20W/cm ²

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