Device and process for denitrification of sludge anaerobic digestion biogas slurry based on micron-sized diatomite powder

Abstract

The invention relates to the technical field of wastewater denitrification, and discloses a device and a process for denitrification of sludge anaerobic digestion biogas slurry based on micron-sized diatomite powder. By constructing a two-stage nitrosation-anaerobic ammonia oxidation high-efficiency low-consumption denitrification system based on micron-sized diatomite powder, rapid enrichment of functional microorganisms and shortening of a process starting period are realized. The diatomite powder improves the abundance of ammonia oxidizing bacteria and anaerobic ammonia oxidizing bacteria, stable and appropriate effluent of the nitrosation reactor is supplied to a subsequent anaerobic ammonia oxidation process, and the performance of the anaerobic ammonia oxidation reactor is improved. The process provided by the invention is simple to operate and stable in performance, and effectively realizes high-efficiency low-consumption denitrification of the sludge anaerobic digestion biogas slurry and removal of organic matters.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater denitrification, and in particular to a device and process for denitrifying biogas slurry by anaerobic digestion of sludge based on micron-grade diatomaceous earth powder. Background Art

[0002] As a byproduct of sewage treatment, the output of sludge is also rising sharply. Anaerobic digestion technology is a treatment technology that can achieve sludge reduction, stabilization, harmlessness and resource utilization. Anaerobic digestion technology is a process in which anaerobic microorganisms degrade and stabilize organic matter under anaerobic conditions to form biogas and fertilizers for nutrient recovery in agriculture and gardens.

[0003] The solid content of conventional sludge anaerobic digestion technology is about 3% to 5%, which makes the equipment bulky and the construction cost investment high. Therefore, the current hot spot of technical research is the anaerobic digestion technology of high-solid sludge (the solid content of the incoming sludge is about 10%). While increasing the processing load and biogas production, this technology also solves the above-mentioned problems of conventional anaerobic digestion. However, a large amount of anaerobic digestion liquid rich in ammonia nitrogen and organic matter is also produced during the anaerobic digestion of high-solid sludge, which needs to be treated before being discharged into the receiving water body, which brings pressure and challenges to the conventional denitrification treatment process of the sewage treatment plant. Therefore, the efficient denitrification of sludge anaerobic digestion liquid has become one of the bottleneck problems in digestate treatment.

[0004] Anaerobic ammonium oxidation, a new denitrification pathway discovered and confirmed in the 1990s, has significant advantages over traditional nitrification-denitrification biological denitrification technology. This process can save 60% of aeration energy consumption, does not require a carbon source, and has low residual sludge production, and has been applied in the treatment of traditional anaerobic digestion liquid. However, compared with ordinary sludge anaerobic digestion liquid, high-solid anaerobic digestion liquid has higher concentrations of ammonia nitrogen and organic matter, and is more difficult to treat. At the same time, it is difficult to maintain stable operation in the nitrite process; in the anaerobic ammonium oxidation process, the functional bacteria have a long doubling period and the process starts slowly, which limits the promotion and application of this process.

[0005] Adding biological carriers to sewage treatment systems and forming biofilms has been proven to be an effective way to increase the amount of functional microorganisms and achieve deep reduction of pollutants. Reducing the size of the carriers or even using powder carriers can further shorten the biofilm period and improve sewage treatment performance. Currently, sewage treatment processes based on powder carriers have demonstrated good removal capabilities in real sewage treatment systems, but related research and applications are still blank in the treatment of high-ammonia nitrogen wastewater. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of difficult efficient enrichment and slow biofilm formation of autotrophic denitrification functional bacteria in the prior art, and to overcome the defect of difficult coordinated denitrification regulation in a one-stage autotrophic denitrification process.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a device for denitrification of biogas sludge by anaerobic digestion of sludge based on micron-sized diatomaceous earth powder, the device comprising:

[0008] Influent biogas pool 1, nitrite reactor 2, intermediate water pool 3, carrier recovery device I 4, anaerobic ammonium oxidation reactor 5, carrier recovery device II 6;

[0009] The influent biogas slurry pool 1 is connected to the nitrite reactor 2 via a peristaltic pump Ⅰ1.1;

[0010] The nitrification reactor 2 is provided with a mechanical stirrer Ⅰ2.1, an air pump 2.2, a gas flow meter 2.3, an aeration plate 2.4, an online monitor for dissolved oxygen and pH 2.5, a constant temperature water bath system Ⅰ2.6, a water inlet Ⅰ2.7, a water outlet Ⅰ2.8, a constant temperature layer water inlet Ⅰ2.9 and a constant temperature layer water outlet Ⅰ2.10;

[0011] The intermediate water tank 3 is connected to the anaerobic ammonium oxidation reactor 5 via a peristaltic pump II 3.1;

[0012] The carrier recovery device I4 is provided with a peristaltic pump III4.1 and a peristaltic pump IV4.2;

[0013] The anaerobic ammonia oxidation reactor 5 is provided with a mechanical stirrer II 5.1, a pH online monitor 5.2, a water inlet II 5.3, a water outlet II 5.4, a constant temperature layer water inlet II 5.5, a constant temperature layer water outlet II 5.6, a constant temperature water bath system II 5.7 and an air outlet 5.8;

[0014] The carrier recovery device II6 is provided with a peristaltic pump V6.1 and a peristaltic pump VI6.2.

[0015] The second aspect of the present invention provides a process for denitrification of biogas sludge by anaerobic digestion of sludge based on micron-sized diatomaceous earth powder, the process being carried out in the device described in the first aspect of the present invention and comprising the following steps:

[0016] S1: Inoculate sewage plant sludge in the nitrification reactor 2, wherein the sludge concentration in the nitrification reactor (2) after inoculation is 4500-5500 mg / L, and add 1.5-3.5 g / L of micron-grade diatomaceous earth powder;

[0017] In the inlet biogas slurry pool 1, the ammonia nitrogen concentration, COD concentration, and pH value of the thermal hydrolysis anaerobic digestion biogas slurry are adjusted, and then the biogas slurry enters the above-mentioned nitrite reactor 2 through the peristaltic pump 11.1 and the water inlet 12.7 for the first treatment, and the water is discharged after the treatment is completed;

[0018] S2: The water obtained in step S1 enters the intermediate water tank 3 through the water outlet I 2.8 to be diluted to an ammonia nitrogen concentration of 50-100 mg / L, and then enters the anaerobic ammonium oxidation reactor 5 for the second treatment;

[0019] The anaerobic ammonium oxidation reactor (5) has been inoculated with anaerobic ammonium oxidation granular sludge in advance, and after inoculation, the sludge concentration in the anaerobic ammonium oxidation reactor 5 is 5000-6000 mg / L, and 1.0-3.0 g / L of the micron-sized diatomaceous earth powder is added;

[0020] And in the second treatment process, the anaerobic ammonium oxidation reactor 5 is in a continuous flow operation mode.

[0021] Preferably, in step S1, the ammonia nitrogen concentration, COD concentration and pH value of the thermal hydrolysis anaerobic digestion slurry are adjusted in the influent slurry pool 1 so that the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration in the effluent water of the nitrite reactor 2 is 1:1.1 to 1:1.32.

[0022] Further preferably, in step S1, during the first treatment process, the operating temperature of the nitrification reactor 2 is 25-35°C, the pH in the reactor is 7.5-8.0, and the operating mode is anaerobic.

[0023] More preferably, in step S1, the conditions of the first treatment are satisfied: stirring speed is 100-250 rpm, stirring time is 4-6 h, aeration time is 6-10 h, standing water time is 30-60 min, and dissolved oxygen in the aeration section is controlled at 0.5-1.0 mg / L.

[0024] Preferably, in step S1, the nitrification reactor 2 discharges sludge during the aeration stage, once every 5 to 10 days, and the discharged sludge enters the carrier recovery device I 4. After running at 150 to 350 r / min for 5 to 15 minutes, the lower sedimentation carrier is refluxed and the upper floc sludge is discharged.

[0025] Preferably, in step S2, the conditions of the second treatment at least meet the following conditions: the operating temperature is 30-40°C, the pH is controlled at 7.8-8.0, the inlet ammonia nitrogen concentration is gradually increased from 50-100 mg / L to 500-550 mg / L, and the hydraulic retention time is gradually increased from 8-10 h to 30-40 h.

[0026] Preferably, in step S2, the anaerobic ammonium oxidation reactor 5 discharges sludge once every 20 to 30 days, and the discharged sludge enters the carrier recovery device II 6. After running at 150 to 250 r / min for 5 to 10 minutes, the lower sedimentation carrier is refluxed and the upper floc sludge is discharged.

[0027] The device and process provided by the present invention have at least the following excellent effects:

[0028] (1) The present invention realizes the rapid enrichment of functional microorganisms and the shortening of the process startup cycle by constructing a two-stage nitrite-anaerobic ammonium oxidation high-efficiency and low-consumption denitrification system based on micron-sized diatomite powder. Diatomite powder increases the abundance of ammonia-oxidizing bacteria and anaerobic ammonium-oxidizing bacteria, and the nitrite reactor supplies the subsequent anaerobic ammonium oxidation process with stable and suitable effluent, thereby improving the performance of the anaerobic ammonium oxidation reactor. The process provided by the present invention is simple to operate and has stable performance, and effectively realizes the high-efficiency and low-consumption denitrification and removal of organic matter in the anaerobic digestion of sludge.

[0029] (2) The present invention proposes a device and process for denitrification of anaerobic digestion of sludge and biogas slurry based on micron-sized diatomaceous earth powder. Through the addition of micron-sized diatomaceous earth, microorganisms can be quickly attached and the sludge concentration in the system can be increased. During the nitritation process, the diatomaceous earth powder promotes the enrichment of ammonia oxidizing bacteria and inhibits nitrite oxidizing bacteria, thereby achieving stable nitritation, and the effluent characteristics are suitable for anaerobic ammonia oxidation reaction. During the anaerobic ammonia oxidation process, the diatomaceous earth powder promotes the formation of anaerobic ammonia oxidation granular sludge, enhances the retention capacity of functional microorganisms, and improves the stability of autotrophic denitrification performance; the addition of micron-sized diatomaceous earth realizes the rapid start-up and stable and efficient denitrification of the two-stage nitritation-anaerobic ammonia oxidation process, effectively solving the problem of efficient and low-consumption denitrification of anaerobic digestion of sludge and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a diagram of the device for denitrification of biogas sludge by anaerobic digestion of sludge based on micron-sized diatomaceous earth powder according to the present invention.

[0031] Description of Reference Numerals

[0032] 1. Influent biogas pool 2. Nitrite reactor 3. Intermediate water pool

[0033] 4. Carrier recovery device I 5. Anaerobic ammonium oxidation reactor 6. Carrier recovery device II

[0034] 1.1. Peristaltic pump Ⅰ 2.1. Mechanical stirrer Ⅰ 2.2. Air pump

[0035] 2.3, Gas flow meter 2.4, Aeration plate 2.5, Dissolved oxygen and pH online monitor 2.6, Constant temperature water bath system Ⅰ 2.7, Water inlet Ⅰ 2.8, Water outlet Ⅰ

[0036] 2.9, Constant temperature layer water inlet Ⅰ2.10, Constant temperature layer water outlet Ⅰ3.1, Peristaltic pump Ⅱ

[0037] 4.1. Peristaltic pump III 4.2. Peristaltic pump IV 5.1. Mechanical agitator II

[0038] 5.2. pH online monitor 5.3. Water inlet Ⅱ 5.4. Water outlet Ⅱ

[0039] 5.5. Constant temperature layer water inlet Ⅱ 5.6. Constant temperature layer water outlet Ⅱ 5.7. Constant temperature water bath system Ⅱ

[0040] 5.8, air outlet 6.1, peristaltic pump V 6.2, peristaltic pump VI DETAILED DESCRIPTION

[0041] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0042] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials are all commercially available.

[0043] In the following examples, unless otherwise specified, the total volume of the nitrification reactor 2 is 4.0 L and the effective volume is 3.5 L;

[0044] The effective volume of the anaerobic ammonium oxidation reactor is 4.0L;

[0045] Carrier: micron-sized diatomaceous earth powder, with an average particle size of 20 μm;

[0046] The average particle size of anaerobic ammonium oxidation granular sludge after screening is 1.0-2.0 mm.

[0047] Example 1

[0048] This example is used to provide a high-efficiency and low-consumption deammoniation process for anaerobic digestion of sludge based on micron-sized diatomaceous earth powder, and the process Figure 1 The method is carried out in the device shown, and comprises the following steps:

[0049] S1: The sludge from the secondary sedimentation tank of a sewage plant in Shanghai was inoculated in the nitrification reactor 2. After the inoculation, the sludge concentration in the nitrification reactor 2 was 5022±58 mg / L, and 2.0 g / L of micron-grade diatomaceous earth powder was added;

[0050] In the influent biogas slurry pool 1, the ammonia nitrogen concentration of the thermal hydrolysis anaerobic digestion biogas slurry is adjusted to 2500±123 mg / L and the COD concentration is adjusted to 3000±50 mg / L by dilution, and the pH value of the thermal hydrolysis anaerobic digestion biogas slurry is adjusted to 7.5-8.0 by adding alkalinity (such as sodium bicarbonate), and then the biogas slurry enters the above-mentioned nitrite reactor 2 through the peristaltic pump I1.1 and the water inlet I2.7 for the first treatment, and the water is discharged after the treatment is completed;

[0051] In the first treatment process, the operating temperature of the nitrite reactor 2 is 32±1°C, the pH in the reactor is 7.5±0.3, and the operating mode is anaerobic; the conditions of the first treatment are as follows: the stirring speed is 150rpm, the stirring time is 5h, the aeration time is 8h, the standing water time is 30min, and the dissolved oxygen in the aeration section is controlled to be 0.5-1.0mg / L;

[0052] The nitrite reactor 2 discharges sludge during the aeration stage, once every 5 to 10 days, and 1.0L of sludge is discharged into the carrier recovery device I 4. After running at 300r / min for 10min, the lower sedimentation carrier is refluxed and the upper floc sludge is discharged. After the nitrite reactor 2 runs stably, the ammonia nitrogen concentration in the effluent is 500 to 550mg / L, and the nitrite nitrogen concentration is 600 to 700mg / L.

[0053] S2: The water obtained in step S1 enters the intermediate water tank 3 through the water outlet I 2.8 to be diluted to an ammonia nitrogen concentration of 50 mg / L, and then enters the anaerobic ammonium oxidation reactor 5 for the second treatment;

[0054] The anaerobic ammonium oxidation reactor 5 has been inoculated with anaerobic ammonium oxidation granular sludge in advance. After inoculation, the sludge concentration in the anaerobic ammonium oxidation reactor 5 is 6000 mg / L, and 1.5 g / L of the micron-grade diatomaceous earth powder is added;

[0055] In the second treatment process, the anaerobic ammonium oxidation reactor 5 is in a continuous flow operation mode, the operating temperature is 35±1°C, the pH is controlled at 7.8-8.0, the influent ammonia nitrogen concentration is gradually increased from 50 mg / L to 500-550 mg / L in a gradient of 100 mg / L, and the hydraulic retention time is gradually increased from 8 h to 40 h;

[0056] The anaerobic ammonium oxidation reactor 5 discharges sludge once every 25 days, and 1L of sludge is discharged into the carrier recovery device II 6. After running at 150r / min for 5min, the lower layer of sedimentation carriers is refluxed and the upper layer of floc sludge is discharged.

[0057] The test results show that after 60 days of continuous operation of the process, the effluent ammonia nitrogen concentration is 0-8 mg / L, nitrite nitrogen concentration is 5-15 mg / L, nitrate nitrogen concentration is 10-40 mg / L, COD concentration is 500-700 mg / L, and the total nitrogen removal rate reaches more than 90%.

[0058] Comparative Example 1

[0059] The method of Example 1 is followed, except that in step S1 and step S2, after the sludge is inoculated, no micron-sized diatomaceous earth carrier is added to the nitrite reactor 2 and the anaerobic ammonium oxidation reactor 5, and the remaining steps and parameters are the same as those of Example 1.

[0060] Comparative Example 2

[0061] The method of Example 1 is followed, except that in step S1 and step S2, after the nitrite reactor 2 and the anaerobic ammonia oxidation reactor 5 are inoculated with sludge, a centimeter-sized polyethylene suspension carrier with a volume ratio of 30% is used to replace the micron-sized diatomaceous earth carrier, and the remaining steps and parameters are the same as those of Example 1.

[0062] Comparative Example 3

[0063] The method of Example 1 is followed, except that in step S1, the sludge discharged from the nitrite reactor 2 is not treated by the carrier recovery device I 4 but is directly discharged; in step S2, the sludge discharged from the anaerobic ammonia oxidation reactor 5 is not treated by the carrier recovery device II 6 but is directly discharged, and the remaining steps and parameters are the same as those of Example 1.

[0064] The ammonia oxidizing bacteria abundance, anaerobic ammonia oxidizing bacteria abundance and total nitrogen removal rate of the above embodiments and comparative examples are summarized, and the results are shown in Table 1.

[0065] Table 1

[0066] serial number Ammonia oxidizing bacteria abundance (%) Abundance of anaerobic ammonium oxidizing bacteria (%) Total nitrogen removal rate / % Example 1 15.2～23.1％ 12.2～19.8％ >90％ Comparative Example 1 2.3～4.5％ 0.5～1.2％ 45±5％ Comparative Example 2 5.4～9.5％ 4.2～6.7％ 58±4％ Comparative Example 3 5.6～10.1％ 8.2～10.5％ 65±7％

[0067] It can be seen from the results in Table 1 that the device and method using the embodiments of the present invention have significantly higher ammonia oxidizing bacteria abundance, anaerobic ammonia oxidizing bacteria abundance and total nitrogen removal rate.

[0068] By comparing Example 1 and Comparative Example 1, it can be seen that, compared with the conventional activated sludge process, the addition of the micron-sized diatomaceous earth powder of the present invention effectively enriches the functional microorganisms and improves the denitrification performance.

[0069] By comparing Example 1 and Comparative Example 2, it can be seen that, compared with the common centimeter-level polyethylene suspension carrier, the micron-level diatomaceous earth of the present invention increases the abundance of functional microorganisms and improves the denitrification performance.

[0070] By comparing Example 1 and Comparative Example 3, it can be seen that the setting of the carrier recovery device can realize the recovery of micron-sized diatomaceous earth powder while optimizing the bacterial community structure and improving the denitrification performance.

[0071] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A device for denitrification of biogas sludge by anaerobic digestion of sludge based on micron-sized diatomite powder, characterized in that: The device comprises: Influent biogas slurry pool (1), nitrite reactor (2), intermediate water pool (3), carrier recovery device I (4), anaerobic ammonium oxidation reactor (5), carrier recovery device II (6); The influent biogas slurry pool (1) is connected to the nitrite reactor (2) via a peristaltic pump I (1.1); The nitrification reactor (2) is provided with a mechanical stirrer I (2.1), an air pump (2.2), a gas flow meter (2.3), an aeration plate (2.4), an online monitor for dissolved oxygen and pH (2.5), a constant temperature water bath system I (2.6), a water inlet I (2.7), a water outlet I (2.8), a constant temperature layer water inlet I (2.9) and a constant temperature layer water outlet I (2.10); The intermediate water tank (3) is connected to the anaerobic ammonium oxidation reactor (5) via a peristaltic pump II (3.1); The carrier recovery device I (4) is provided with a peristaltic pump III (4.1) and a peristaltic pump IV (4.2); The anaerobic ammonia oxidation reactor (5) is provided with a mechanical stirrer II (5.1), a pH online monitor (5.2), a water inlet II (5.3), a water outlet II (5.4), a constant temperature layer water inlet II (5.5), a constant temperature layer water outlet II (5.6), a constant temperature water bath system II (5.7) and an air outlet (5.8); The carrier recovery device II (6) is provided with a peristaltic pump V (6.1) and a peristaltic pump VI (6.2).

2. A sludge anaerobic digestion biogas denitrification process based on micron-sized diatomite powder, characterized in that: The process is carried out in the apparatus of claim 1 and comprises the following steps: S1: Inoculating sewage sludge in a nitrite reactor (2), wherein the sludge concentration in the nitrite reactor (2) after inoculation is 4500-5500 mg / L, and adding 1.5-3.5 g / L of micron-grade diatomaceous earth powder; In the inlet biogas slurry pool (1), the ammonia nitrogen concentration, COD concentration and pH value of the thermal hydrolysis anaerobic digestion biogas slurry are adjusted, and then the biogas slurry enters the above-mentioned nitrite reactor (2) through the peristaltic pump I (1.1) and the water inlet I (2.7) for the first treatment, and the water is discharged after the treatment is completed; S2: The water obtained in step S1 enters the intermediate water tank (3) through the water outlet I (2.8) to be diluted to an ammonia nitrogen concentration of 50-100 mg / L, and then enters the anaerobic ammonium oxidation reactor (5) for the second treatment; The anaerobic ammonium oxidation reactor (5) has been inoculated with anaerobic ammonium oxidation granular sludge in advance, and after inoculation, the sludge concentration in the anaerobic ammonium oxidation reactor (5) is 5000-6000 mg / L, and 1.0-3.0 g / L of the micron-sized diatomaceous earth powder is added; Furthermore, during the second treatment process, the anaerobic ammonium oxidation reactor (5) is in a continuous flow operation mode.

3. The method according to claim 2, wherein: In step S1, in the inlet biogas slurry pool (1), the ammonia nitrogen concentration, COD concentration and pH value of the thermal hydrolysis anaerobic digestion biogas slurry are adjusted so that the ratio of the ammonia nitrogen concentration to the nitrite nitrogen concentration in the effluent of the nitrite reactor (2) is 1:1.1 to 1:1.

32.

4. The method according to claim 2 or 3, wherein: In step S1, during the first treatment process, the operating temperature of the nitrification reactor (2) is 25-35°C, the pH in the reactor is 7.5-8.0, and the operating mode is anaerobic.

5. The method according to claim 2 or 3, wherein: In step S1, the conditions of the first treatment are as follows: the stirring speed is 100-250 rpm, the stirring time is 4-6 hours, the aeration time is 6-10 hours, the standing water time is 30-60 minutes, and the dissolved oxygen in the aeration section is controlled at 0.5-1.0 mg / L.

6. The method according to claim 2 or 3, wherein: In step S1, the nitrification reactor (2) discharges sludge during the aeration stage, once every 5 to 10 days. The discharged sludge enters the carrier recovery device I (4), and after running at 150 to 350 r / min for 5 to 15 minutes, the lower layer of sedimentation carriers is refluxed and the upper layer of floc sludge is discharged.

7. The method according to claim 2 or 3, wherein: In step S2, the conditions of the second treatment at least meet: the operating temperature is 30-40°C, the pH is controlled at 7.8-8.0, the influent ammonia nitrogen concentration is gradually increased from 50-100 mg / L to 500-550 mg / L, and the hydraulic retention time is gradually increased from 8-10h to 30-40h.

8. The method according to claim 2 or 3, wherein: In step S2, the anaerobic ammonium oxidation reactor (5) discharges sludge once every 20 to 30 days. The discharged sludge enters the carrier recovery device II (6). After running at 150 to 250 r / min for 5 to 10 minutes, the lower layer of sedimentation carriers is refluxed and the upper layer of floc sludge is discharged.

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