Two-phase mud film efficient synchronous nitrogen and phosphorus removal process

Abstract

The invention belongs to the field of sewage treatment, and discloses a two-phase mud film efficient synchronous nitrogen and phosphorus removal process. By integrating biological denitrification and chemical phosphorus removal technologies and adopting a two-phase treatment unit, efficient and synchronous removal of nitrogen and phosphorus in sewage is realized. According to the process, a biological treatment procedure of denitrifying bacteria and nitrifying bacteria under an anaerobic and aerobic alternating condition is utilized, and ammonia nitrogen and nitrate nitrogen in sewage are effectively removed by controlling reaction conditions and formation of a mud film. Meanwhile, ferric salt and polyaluminum chloride flocculants are used for chemical precipitation, phosphate ions form insoluble precipitates by adjusting the pH value and the adding amount, and activated carbon or a zeolite adsorption material is combined for adsorption, so that phosphorus is further removed. The method has the advantages of high treatment efficiency, low operation cost, simplicity and convenience in operation and wide applicability, and an efficient, economic and environment-friendly solution is provided for sewage treatment.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment, and in particular relates to a two-phase mud membrane high-efficiency synchronous denitrification and dephosphorization process. Background Art

[0002] Sewage usually contains a large amount of nitrogen and phosphorus nutrients. If it is not effectively treated, it will lead to eutrophication of water bodies, which will in turn cause algae to reproduce in large numbers, forming red tides or algal blooms, destroying the balance of water ecology, affecting the water landscape and human health. In addition, after nitrogen and phosphorus-containing wastewater is discharged into the water body, the organic matter produced by degradation will consume the dissolved oxygen in the water, further leading to the death of aquatic organisms and destroying the stability of the water ecosystem.

[0003] The removal of nitrogen and phosphorus is an important part of sewage treatment. Nitrogen removal is mainly achieved through biological denitrification processes, including nitrification and denitrification. The nitrification process oxidizes ammonia nitrogen into nitrate nitrogen, and the denitrification process reduces nitrate nitrogen to nitrogen gas, thereby achieving nitrogen removal. However, the biological denitrification process has high requirements for environmental conditions, requires strict control of dissolved oxygen concentration, temperature and pH parameters, has a long reaction time, and is easily interfered by external factors. Phosphorus removal is mainly achieved through biological phosphorus removal and chemical precipitation. Biological phosphorus removal removes phosphorus through the excessive absorption of polyphosphate bacteria, but the process is complicated and requires high operating conditions. The chemical precipitation method forms an insoluble precipitate by adding flocculants (such as iron salts and aluminum salts) to react with phosphate ions, but in the case of high phosphorus concentration, a large amount of flocculants need to be added, the treatment cost is high, and the chemical sludge produced needs further treatment.

[0004] In existing sewage treatment technologies, nitrogen and phosphorus removal are usually carried out separately, resulting in complex process flows, high equipment investment and operating costs, and large land occupation. It is difficult to simultaneously meet the increasingly stringent emission standards and the requirements of sewage treatment plants for treatment efficiency and economy. Traditional biological denitrification and phosphorus removal processes face many challenges in practical applications, such as insufficient internal carbon sources in the biological denitrification process, low denitrification efficiency, and phosphorus reflux during biological phosphorus removal. Although chemical phosphorus removal can achieve a high removal effect in a short period of time, it requires a large dosage, high operating costs, and the need to solve the problems of reagents and sludge disposal.

[0005] Therefore, there is an urgent need for a new sewage treatment process that can efficiently and simultaneously achieve nitrogen and phosphorus removal to address the shortcomings of existing technologies, improve treatment efficiency, reduce operating costs, simplify the operation process, reduce floor space, and meet more stringent emission standards. Summary of the invention

[0006] The present invention integrates biological denitrification and chemical phosphorus removal technologies and adopts a two-phase treatment unit to achieve efficient and simultaneous removal of nitrogen and phosphorus in sewage. The nitrogen removal unit utilizes the biological treatment process of denitrifying bacteria and nitrifying bacteria under anaerobic and aerobic alternating conditions to effectively remove ammonia nitrogen and nitrate nitrogen in sewage by controlling reaction conditions and mud film formation. The phosphorus removal unit further removes phosphorus by adding iron salts and polyaluminium chloride flocculants combined with activated carbon or zeolite adsorption materials for chemical precipitation and adsorption.

[0007] The specific technical solutions are as follows:

[0008] A two-phase mud membrane high-efficiency synchronous dephosphorization and nitrogen removal process, the two-phase mud membrane is composed of a nitrogen removal unit and a phosphorus removal unit coupled in an interactive manner. The nitrogen removal unit is composed of sulfur autotrophic denitrifying bacteria, nitrifying bacteria, diatomaceous earth and polyethylene network carriers; the phosphorus removal unit is composed of iron salt (FeSO, FeS2) or polyaluminium chloride (PAC) as flocculants and activated carbon or zeolite as adsorption materials. The dephosphorization and nitrogen removal process includes the following processes:

[0009] (1) Denitrification treatment: The sewage first enters the nitrogen removal unit, and the reaction conditions are controlled as follows: the dissolved oxygen concentration in the reactor is between 0.2 and 2 mg / L, the temperature is controlled at 20-30°C, and the reaction time is 6-12 hours. The sewage is first introduced into the anaerobic zone, where denitrifying bacteria reduce nitrate nitrogen to nitrogen gas under anaerobic conditions. Subsequently, the sewage flows into the aerobic zone, where nitrifying bacteria oxidize ammonia nitrogen to nitrate nitrogen under sufficient oxygen supply.

[0010] (2) Phosphorus removal: After nitrogen removal, the wastewater enters the phosphorus removal unit. The reaction conditions are controlled as follows: pH range is 6.5-7.5, and the reaction time is 30-60 minutes. Phosphorus is removed by chemical reduction or adsorption.

[0011] (3) Sedimentation and filtration: The wastewater after the reaction enters the sedimentation tank, where the flocculated sediment settles, and the clear liquid passes through the filtration device to further remove suspended matter and residual phosphorus.

[0012] (4) Post-treatment effluent: The wastewater after denitrification and phosphorus removal is subsequently treated to meet discharge standards or reuse requirements.

[0013] In some embodiments, the bacteria in the nitrogen removal unit are denitrifying bacteria (such as Paracoccus denitrificans) and nitrifying bacteria (such as Nitrosomonas europaea and Nitrobacter winogradskyi) that are resistant to high ammonia nitrogen and nitrate nitrogen concentrations.

[0014] In some embodiments, the mud film preparation method of the nitrogen removal unit is to use a polyethylene network and diatomaceous earth mixed carrier, the pore size of the carrier is 0.1-1.0 mm, placed in a reactor, and the aeration intensity is adjusted to make bacteria adhere to the surface of the carrier to form a stable mud film.

[0015] In some embodiments, a plurality of mud membrane carriers are arranged inside the nitrogen removal unit reactor, and the structure is designed to alternate anaerobic and aerobic zones. By adjusting the aeration equipment and aeration mode, the sewage is circulated between the anaerobic and aerobic zones for 3 to 5 times.

[0016] In some of the embodiments, the concentration of the flocculant in the phosphorus removal unit using iron salt (FeSO4, FeS2) or polyaluminium chloride (PAC) as a flocculant is 100-200 mg / L.

[0017] In some of the embodiments, the particle size of the activated carbon or zeolite used as the adsorption material in the nitrogen removal unit is 0.5-2 mm, and the dosage is 10-20 g / L.

[0018] In some of the embodiments, the phosphorus removal unit uses a stirred reactor to ensure uniform distribution of the flocculant and the adsorbent material.

[0019] In some embodiments, the reaction conditions are monitored and controlled in the following manner:

[0020] (1) Online monitoring: By installing online monitoring instruments for ammonia nitrogen, nitrate nitrogen and total phosphorus, the nitrogen and phosphorus concentrations in sewage can be monitored in real time.

[0021] (2) Automatic control: PLC control system is used to automatically adjust the exposure intensity, flocculant dosage and temperature to ensure stable operation of the process.

[0022] The present invention has the following advantages

[0023] (1) Through the combination of two-phase mud membrane, chemical precipitation and adsorption, nitrogen and phosphorus can be removed simultaneously and efficiently, simplifying the process flow.

[0024] (2) Combining the advantages of biological treatment and chemical treatment, it reduces the consumption of chemicals and energy and reduces operating costs.

[0025] (3) Online monitoring and PLC control system are used to automatically adjust process parameters to ensure stable operation of the process and reduce the difficulty of operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Microscopic photographs of wastewater before and after treatment in Example 1.

[0027] Figure 2 Microscopic photographs of wastewater before and after treatment in Example 2. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the technical implementation method of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in combination with the technical process steps, specific implementation conditions and materials in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] (1) Denitrification treatment: The sewage first enters the nitrogen removal unit, and the reaction conditions are controlled as follows: the dissolved oxygen concentration in the reactor is between 0.2 mg / L, the temperature is controlled at 20°C, and the reaction time is 6 hours. The sewage is first introduced into the anaerobic zone. Under anaerobic conditions, Paracoccus denitrifying bacteria reduce nitrate nitrogen to nitrogen gas for emission. Subsequently, the sewage flows into the aerobic zone. With sufficient oxygen supply, Nitrosomonas europaea nitrifying bacteria oxidize ammonia nitrogen to nitrate nitrogen. By adjusting the aeration equipment and aeration method, the sewage is circulated between the anaerobic zone and the aerobic zone three times.

[0031] (2) Phosphorus removal: After nitrogen removal, the wastewater enters the phosphorus removal unit. The phosphorus removal unit uses FeSO and complex aluminum chloride as flocculants, and the concentration of the flocculant is 100 mg / L. The reaction conditions are controlled as follows: pH is 6.5 and the reaction time is 30 minutes. Phosphorus is removed by combining chemical reduction and adsorption.

[0032] (3) Sedimentation and filtration: The wastewater after the reaction enters the sedimentation tank, where the flocculated sediment settles, and the clear liquid passes through the filtration device to further remove suspended matter and residual phosphorus.

[0033] (4) Post-treatment effluent: The wastewater after denitrification and phosphorus removal is subsequently treated to meet discharge standards or reuse requirements.

[0034] Microscopic photos of the treated sewage before and after treatment Figure 1 shown.

[0035] Example 2

[0036] (1) Denitrification treatment: The sewage first enters the nitrogen removal unit, and the reaction conditions are controlled as follows: the dissolved oxygen concentration in the reactor is between 0.5 mg / L, the temperature is controlled at 23°C, and the reaction time is 8 hours. The sewage is first introduced into the anaerobic zone. Under anaerobic conditions, Paracoccus denitrifying bacteria reduce nitrate nitrogen to nitrogen gas for emission. Subsequently, the sewage flows into the aerobic zone. With sufficient oxygen supply, Nitrosomonas europaea nitrifying bacteria oxidize ammonia nitrogen to nitrate nitrogen. By adjusting the aeration equipment and aeration method, the sewage is circulated between the anaerobic zone and the aerobic zone 4 times.

[0037] (2) Phosphorus removal: After nitrogen removal, the wastewater enters the phosphorus removal unit. The phosphorus removal unit uses FeS2 and complex aluminum chloride as flocculants, and the concentration of the flocculant is 130 mg / L. The reaction conditions are controlled as follows: pH is 7 and the reaction time is 40 minutes. Phosphorus is removed by combining chemical reduction and adsorption.

[0038] (3) Sedimentation and filtration: The wastewater after the reaction enters the sedimentation tank, where the flocculated sediment settles, and the clear liquid passes through the filtration device to further remove suspended matter and residual phosphorus.

[0039] (4) Post-treatment effluent: The wastewater after denitrification and phosphorus removal is subsequently treated to meet discharge standards or reuse requirements.

[0040] Microscopic photos of the treated sewage before and after treatment Figure 1 shown.

[0041] Example 3

[0042] (1) Denitrification treatment: The sewage first enters the nitrogen removal unit, and the reaction conditions are controlled as follows: the dissolved oxygen concentration in the reactor is between 0.1 mg / L, the temperature is controlled at 25°C, and the reaction time is 10 hours. The sewage is first introduced into the anaerobic zone. Under anaerobic conditions, Paracoccus denitrifying bacteria reduce nitrate nitrogen to nitrogen gas for emission. Subsequently, the sewage flows into the aerobic zone. With sufficient oxygen supply, Nitrosomonas europaea nitrifying bacteria oxidize ammonia nitrogen to nitrate nitrogen. By adjusting the aeration equipment and aeration method, the sewage is circulated between the anaerobic zone and the aerobic zone for 5 times.

[0043] (2) Phosphorus removal: After nitrogen removal, the wastewater enters the phosphorus removal unit. The phosphorus removal unit uses FeS2 and complex aluminum chloride as flocculants, and the concentration of the flocculant is 150 mg / L. The reaction conditions are controlled as follows: pH is 7 and the reaction time is 50 minutes. Phosphorus is removed by combining chemical reduction and adsorption.

[0044] (3) Sedimentation and filtration: The wastewater after the reaction enters the sedimentation tank, where the flocculated sediment settles, and the clear liquid passes through the filtration device to further remove suspended matter and residual phosphorus.

[0045] (4) Post-treatment effluent: The wastewater after denitrification and phosphorus removal is subsequently treated to meet discharge standards or reuse requirements.

[0046] Example 4

[0047] (1) Denitrification treatment: The sewage first enters the nitrogen removal unit, and the reaction conditions are controlled as follows: the dissolved oxygen concentration in the reactor is between 2 mg / L, the temperature is controlled at 30°C, and the reaction time is 12 hours. The sewage is first introduced into the anaerobic zone. Under anaerobic conditions, the denitrifying bacteria Nitrobacter winogradskyi reduce nitrate nitrogen to nitrogen gas for emission. Subsequently, the sewage flows into the aerobic zone. With sufficient oxygen supply, the nitrifying bacteria Nitrobacter winogradskyi oxidize ammonia nitrogen to nitrate nitrogen. By adjusting the aeration equipment and aeration method, the sewage is circulated between the anaerobic zone and the aerobic zone 5 times.

[0048] (2) Phosphorus removal: After nitrogen removal, the wastewater enters the phosphorus removal unit. The phosphorus removal unit uses FeS2 and complex aluminum chloride as flocculants, and the concentration of the flocculant is 200 mg / L. The reaction conditions are controlled as follows: pH is 7.5 and the reaction time is 60 minutes. Phosphorus is removed by combining chemical reduction and adsorption.

[0049] (3) Sedimentation and filtration: The wastewater after the reaction enters the sedimentation tank, where the flocculated sediment settles, and the clear liquid passes through the filtration device to further remove suspended matter and residual phosphorus.

[0050] (4) Post-treatment effluent: The wastewater after denitrification and phosphorus removal is subsequently treated to meet discharge standards or reuse requirements.

[0051] Example 5

[0052] Monitoring and control of reaction conditions:

[0053] (1) Online monitoring: By installing online monitoring instruments for ammonia nitrogen, nitrate nitrogen and total phosphorus, the nitrogen and phosphorus concentrations in sewage can be monitored in real time.

[0054] (2) Automatic control: PLC control system is used to automatically adjust the exposure intensity, flocculant dosage and temperature to ensure stable operation of the process.

[0055] Technical personnel should note that although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention, and any modification using the inventive concept will be included in the scope of protection of this patent.

Claims

1. A two-phase mud membrane high-efficiency synchronous denitrification and phosphorus removal process, characterized by: The two-phase mud membrane is composed of a nitrogen removal unit and a phosphorus removal unit that are interactively coupled; the nitrogen removal unit is composed of sulfur autotrophic denitrifying bacteria, nitrifying bacteria, diatomaceous earth and polyethylene network carriers; the phosphorus removal unit is composed of iron salt (FeSO, FeS2) or polyaluminium chloride (PAC) as flocculants and activated carbon or zeolite as adsorption materials; the denitrification and phosphorus removal process includes the following processes: S1. Denitrification treatment: The sewage first enters the nitrogen removal unit, and the reaction conditions are controlled as follows: the dissolved oxygen concentration in the reactor is between 0.2 and 2 mg / L, the temperature is controlled at 20-30°C, and the reaction time is 6-12 hours. The sewage is first introduced into the anaerobic zone, where denitrifying bacteria reduce nitrate nitrogen to nitrogen gas for emission under anaerobic conditions. Subsequently, the sewage flows into the aerobic zone, where nitrifying bacteria oxidize ammonia nitrogen to nitrate nitrogen under sufficient oxygen supply. S2. Phosphorus removal: After nitrogen removal, the wastewater enters the phosphorus removal unit. The reaction conditions are controlled as follows: pH range is 6.5-7.5, and the reaction time is 30-60 minutes. Phosphorus is removed by chemical reduction or adsorption. S3. Sedimentation and filtration: The wastewater after reaction enters the sedimentation tank, where the flocculated sediment settles, and the clear liquid passes through the filtration device to further remove suspended matter and residual phosphorus. S4. Post-treatment effluent: The wastewater after denitrification and phosphorus removal is subsequently treated to meet the discharge standards or reuse requirements.

2. A two-phase mud membrane synchronous denitrification and dephosphorization process as claimed in claim 1, characterized in that: The bacteria in the nitrogen removal unit are denitrifying bacteria (such as Paracoccus denitrificans) and nitrifying bacteria (such as Nitrosomonas europaea and Nitrobacter winogradskyi) that are resistant to high ammonia nitrogen and nitrate nitrogen concentrations.

3. A two-phase mud membrane synchronous denitrification and dephosphorization process as claimed in claim 1, characterized in that: The method for preparing the mud film of the nitrogen removal unit is to use a polyethylene network and diatomaceous earth mixed carrier, the pore size of the carrier is 0.1-1.0 mm, place it in a reactor, and adjust the aeration intensity to make bacteria adhere to the surface of the carrier to form a stable mud film.

4. A two-phase mud membrane synchronous denitrification and dephosphorization process as claimed in claim 1, characterized in that: The nitrogen removal unit reactor is provided with a plurality of mud membrane carriers, and is designed to have an alternating structure of anaerobic and aerobic zones. By adjusting the aeration equipment and aeration mode, the sewage is circulated between the anaerobic and aerobic zones for 3 to 5 times.

5. A two-phase mud membrane synchronous denitrification and dephosphorization process as claimed in claim 1, characterized in that: In the phosphorus removal unit, iron salt (FeSO4, FeS2) or polyaluminium chloride (PAC) is used as a flocculant, and the concentration of the flocculant is 100-200 mg / L.

6. A two-phase mud membrane synchronous denitrification and phosphorus removal process as claimed in claim 1, characterized in that: The particle size of the activated carbon or zeolite used as the adsorption material in the nitrogen removal unit is 0.5-2 mm, and the dosage is 10-20 g / L.

7. A two-phase mud membrane synchronous denitrification and dephosphorization process as claimed in claim 1, characterized in that: The phosphorus removal unit adopts a stirring reactor to ensure uniform distribution of flocculants and adsorbent materials.

8. A two-phase mud membrane synchronous denitrification and dephosphorization process as claimed in claim 1, characterized in that: The monitoring and control mode of the reaction conditions is: S5. Online monitoring: By installing online monitoring instruments for ammonia nitrogen, nitrate nitrogen and total phosphorus, the concentrations of nitrogen and phosphorus in sewage can be monitored in real time. S6. Automatic control: PLC control system is used to automatically adjust the exposure intensity, flocculant dosage and temperature to ensure stable operation of the process.

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