Method and system for treating vacuum circulating wastewater

Abstract

The present invention provides a method and system for treating vacuum circulating wastewater, and relates to the technical field of wastewater treatment. The treatment method comprises calculating a wastewater coefficient k according to wastewater conditions, detecting an influent COD value, calculating aeration intensity or aeration time required for wastewater in a wastewater biochemical treatment tank according to the wastewater coefficient k, and improving the treatment efficiency of vacuum circulating wastewater by adjusting aeration time and aeration intensity. The treatment method has a simple process structure, saves floor space, improves the treatment effect of COD, saves energy and reduces emissions, and reduces operating costs.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method and system for treating vacuum circulating wastewater. Background Art

[0002] Vacuum circulating wastewater comes from a wide range of sources. It is produced in industries such as mechanical processing, electronics, metallurgy, surface coating, chemical industry, textiles, and daily life. During the working process of the vacuum circulation system, the sucked gas often contains volatile organic matter and oil. It is necessary to drain and replenish water to make the system run normally, so vacuum circulating wastewater is produced. The characteristics of this wastewater are: the system is decentralized, the drainage volume is small, and it is difficult to collect and treat it centrally. Because the main pollutants of drainage are organic matter and oil, a matching horizontal flow oil separation treatment equipment is usually set up to remove oil by using the density difference between oil and water. However, because some well-soluble oils and other dissolved volatile organic matter will cause the oxygen transfer rate in water to decrease, the self-purification of the water body is hindered, resulting in poor treated water quality and failure to meet the standards. Therefore, it is necessary to effectively treat all types of vacuum circulating wastewater to prevent substandard wastewater from being discharged into natural water bodies. The effective treatment of vacuum circulating wastewater is of great significance for protecting resources, maintaining ecological balance, and promoting economic development.

[0003] Chinese patent CN216584388U discloses a wastewater treatment device based on SBR-MBBR process, comprising a wastewater pool, the wastewater pool is used to place wastewater; a filter screen, the filter screen is arranged in the wastewater pool, and the periphery of the filter screen is connected to the wastewater pool to form a decanting area and a reaction area; a decanter, the decanter is connected to the wastewater pool, and the decanter is arranged in the decanting area; a functional suspension carrier, the functional suspension carrier is arranged in the reaction area The functional suspension carrier is used to be dispersed in the wastewater, and the specific surface area of ​​the functional suspension carrier is ≥800; an aerator assembly, the aerator assembly includes an original aerator and a perforated aerator, the original aerator and the perforated aerator are both arranged at the bottom of the wastewater pool, and the original aerator and the perforated aerator are both arranged corresponding to the functional suspension carrier; an original agitator, the original agitator is arranged at the reaction zone, and the original agitator is connected to the wastewater pool. The equipment can reduce the operating cost of wastewater.

[0004] Patent application CN 114604964A discloses a micro-aerobic EGSB and SBR-MBBR combined treatment coupling process for Chinese medicine residue wastewater, comprising the following steps: starting the micro-aerobic EGSB reactor to gradually acclimate the sludge in a manner that the COD concentration of the influent gradually increases; starting the acclimatization of the MBBR reactor with the micro-aerobic EGSB effluent for dilution, and gradually increasing the activity of the microorganisms in the SBR-MBBR reactor on the metabolic degradation of organic matter in the micro-aerobic effluent in a manner that the COD concentration gradually increases; the raw water tank pumps the sewage into the micro-aerobic EGSB reactor through an inlet pump, the effluent of the EGSB reactor enters a storage tank, and the sewage in the storage tank is pumped into two groups of SBR-MBBRs operating under different dissolved oxygen concentrations by the inlet pump.

[0005] For vacuum circulating wastewater, there are usually problems with collection difficulty and high cost. Therefore, there is an urgent need for a wastewater treatment method with simple process, low cost, green and low-carbon. Summary of the invention

[0006] The purpose of the present invention is to solve the above-mentioned problems of difficulty and high cost in collecting vacuum circulating wastewater, and provide a method and system for treating vacuum circulating wastewater, which can adjust the aeration intensity and aeration time in the wastewater biochemical treatment tank by introducing the wastewater coefficient k. Under the premise that the vacuum circulating wastewater meets the discharge standard, the treatment efficiency is improved, energy consumption is saved, and the cost is reduced.

[0007] In order to solve the existing technical problems, the present invention provides a method for treating vacuum circulating wastewater, comprising the following steps: S1, after the wastewater enters the collection tank, the chemical oxygen demand (COD) of the wastewater is detected; according to the wastewater coefficient k, the aeration intensity q or the aeration time T is calculated according to Formula 1:

[0008] q×T=k×COD 进 ×γ (Formula 1)

[0009] Among them, aeration intensity: q (%), aeration time: T (hr),

[0010] COD 进 : Dichromate index of influent water (COD cr ), γ is the insurance coefficient.

[0011] S2. When the wastewater biochemical treatment tank completes the drainage of the previous treatment batch and reaches the water collection level M, the wastewater in the collection tank is pumped into the oil-water separator, and the wastewater enters the wastewater biochemical treatment tank after oil separation, and stops entering the wastewater biochemical treatment tank until the preset liquid level H of the wastewater biochemical treatment tank is reached. S3. After the wastewater enters the wastewater biochemical treatment tank, the circulation valve is opened, and the anoxic operation is started through hydraulic stirring; after the anoxic operation is completed, the circulation valve is closed, the air intake regulating valve is opened, and the aeration intensity q is calculated according to the reference aeration time T by formula 1, and aeration aerobic operation is performed; if the calculated q>100%, the aeration intensity q takes a value of 100%, and the aeration time is calculated by formula 1.

[0012] S4. After the aerobic operation is completed, close the air inlet regulating valve and carry out sedimentation and stratification.

[0013] S5. After sedimentation is completed, the biochemically treated water will be directly discharged if it meets the discharge standards. If it does not meet the standards, it will be filtered and then discharged or returned to the wastewater biochemical treatment tank for further treatment.

[0014] Further, the wastewater coefficient k is calculated according to the following formula:

[0015] k = reference aeration intensity × reference time / reference COD,

[0016] The reference aeration intensity (%) is the ratio of the aeration volume to the maximum air volume that can be provided under the reference COD of the influent and the reference time, and the maximum air volume that can be provided is the maximum aeration volume required to achieve the treatment purpose.

[0017] Furthermore, the benchmark COD value is a value between 50% and 70% of the maximum COD value of the wastewater to be treated.

[0018] Furthermore, in step S1, the aeration intensity q is calculated by formula 1 according to the reference aeration time T; when the aeration intensity q is 60% or less, the aeration intensity is taken as 60%, and the aeration time T is reduced accordingly to meet the requirements of energy saving and environmental protection.

[0019] Furthermore, the wastewater biochemical treatment tank is filled with a functional suspension carrier, the functional suspension carrier is used to be dispersed in the wastewater, and microorganisms are attached to the functional suspension carrier.

[0020] Furthermore, the insurance coefficient γ is 1.05-1.2.

[0021] Furthermore, a fluidized bed is arranged in the wastewater biochemical treatment tank, and a swirling water flow is generated inside the fluidized bed through circulating water and aeration, so that the functional suspended carrier swirls in the water.

[0022] The present invention also provides a vacuum circulating wastewater treatment system, including a collection tank, an oil-water separator, a wastewater biochemical treatment tank, a biochemical treatment drainage pump, a filter and an inlet and outlet water controller, and also includes a control system. The control system can adjust the aeration intensity and aeration time of the wastewater biochemical treatment tank according to Formula 1 through the measured COD value, and realize the process of "water inlet-anoxic-aerobic-sedimentation-water outlet" in stages.

[0023] Furthermore, the wastewater biochemical treatment tank contains retained treated water for diluting and buffering the sewage.

[0024] Furthermore, a functional suspension carrier is arranged in the wastewater biochemical treatment tank, and the functional suspension carrier is a three-dimensional hollow structure for attaching microorganisms.

[0025] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art, as an example:

[0026] 1. It has the characteristics of anti-shock load of Moving-Bed Biofilm Reactor (MBBR) and Sequencing Batch Reactor Activated Sludge Process (SBR), high efficiency of removing organic matter of MBBR, and simple structure and space saving of SBR.

[0027] 2. It does not need to set up special drainage equipment like SBR, and it can also avoid the characteristic of MBBR that mud and water are difficult to separate, thus improving the COD treatment effect.

[0028] 3. It has achieved miniaturization, no need to add chemicals during the treatment process, and no secondary waste is generated; it does not require a decanter or a sedimentation tank, has extremely low operating costs, reduces carbon emissions, and meets higher emission requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A block diagram of a vacuum circulating wastewater treatment method provided in an embodiment of the present invention.

[0030] Figure 2 A process flow chart of a vacuum circulating wastewater treatment system provided in an embodiment of the present invention.

[0031] Description of reference numerals:

[0032] 100-Vacuum cycle wastewater treatment system;

[0033] 110-collecting tank, 111-liquid level meter, 112-COD meter;

[0034] 120-oil-water separator; 130-wastewater biochemical treatment tank, 131-liquid level detector, 132-automatic circulation valve 1, 133-automatic circulation valve 2, 134-air intake regulating valve; 135-automatic drain valve, 140-biochemical treatment drain pump, 141-bypass drain valve, 142-filter valve;

[0035] 150-Filter canister. DETAILED DESCRIPTION

[0036] The following is a further detailed description of a vacuum circulating wastewater treatment method and system disclosed in the present invention in conjunction with the accompanying drawings and specific embodiments.

[0037] Figure 1 A block diagram of a method for vacuum circulating wastewater treatment provided in an embodiment of the present invention. Figure 2 Process flow chart of the vacuum circulating wastewater treatment system provided by the embodiment of the present invention. Figure 1 and Figure 2 As shown, S1, vacuum cycle wastewater enters the collection tank 110 for temporary storage in batches, and the liquid level meter 111 is used to limit the water intake of each batch. The COD meter 112 is used to test the COD of the wastewater, and the test results will be transmitted to the control system.

[0038] As an example but not limitation, the vacuum circulating wastewater is divided into 2-3 batches according to the total amount to be treated and placed into the collection tank 110.

[0039] In actual operation, the COD value range of the wastewater is estimated, and a benchmark COD needs to be determined. Preferably, the benchmark COD is a value between 50% and 70% of the maximum COD value of the wastewater to be treated. The benchmark COD here is used to calculate the wastewater coefficient k of the wastewater to be treated.

[0040] The value of the wastewater coefficient k is calculated by formula 2 as follows:

[0041] k = reference aeration intensity x reference time / reference COD (Formula 2).

[0042] According to the wastewater coefficient k, the aeration intensity q or aeration time T is calculated according to formula 1:

[0043] q×T=k×COD 进 ×γ (Formula 1)

[0044] Among them, aeration intensity: q (%), aeration time: T (hr), COD 进 : Dichromate index of influent water (COD cr ), γ is the insurance coefficient;

[0045] Preferably, the insurance coefficient γ is 1.05-1.2, preferably 1.1.

[0046] S2, when the wastewater biochemical treatment tank 130 completes the last treatment batch and the liquid level after drainage reaches the water collection level M, the wastewater in the collection tank 110 is pumped into the oil-water separator 120. The wastewater is separated from the oil, and some water-insoluble organic pollutants are separated from the water layer. The wastewater after oil separation enters the wastewater biochemical treatment tank 130, and the water intake stops after reaching the preset liquid level H of the wastewater biochemical treatment tank 130.

[0047] Preferably, a liquid level detector 131 is provided in the wastewater biochemical treatment tank to control the wastewater liquid level in the wastewater biochemical treatment tank.

[0048] S3, after the wastewater biochemical treatment tank 130 stops inflowing water, it enters the anoxic operation process. Figure 2 As shown, the automatic circulation valve 132 and the automatic circulation valve 133 are opened, and the other automatic valves are closed, and the biochemical treatment drainage pump 140 is running. The wastewater biochemical treatment tank 130 is hydraulically stirred inside, and anoxic operation is started, and the time of anoxic operation is set according to the actual situation of the wastewater.

[0049] After the anoxic operation process is completed, the wastewater biochemical treatment tank 130 enters the aerobic operation process. At this time, the automatic circulation valve 132 and the automatic circulation valve 133 are closed. The preset aeration time T is used as an example but not limited to the reference aeration time T, which is usually set to 6 hours. The aeration intensity q value is calculated according to Formula 1. The air intake regulating valve 134 is opened for aeration, and the aeration flow rate is detected according to the air intake flow meter FIQ, and the corresponding q value is reached.

[0050] If the calculated q>100%, the aeration intensity q is taken as 100%, and the aeration time T is recalculated according to formula 1.

[0051] S4, after the aeration time T ends, the aerobic operation ends. The air inlet regulating valve 134 is closed, and the wastewater in the wastewater biochemical treatment tank 130 enters the natural sedimentation and stratification process. Different sedimentation times are preset according to the actual situation of the wastewater.

[0052] S5, after the sedimentation process is completed, the automatic drain valve 135 is opened, the bypass drain valve 141 is opened, and the biochemical treatment drainage pump 140 starts to run for drainage. If the influent COD exceeds the design range, the bypass drain valve 141 is closed, the filter valve 142 is opened, and the treated wastewater enters the filter tank for filtration or flows back to the wastewater biochemical treatment tank for further treatment to enhance the treatment effect.

[0053] Preferably, the wastewater biochemical treatment tank 130 is filled with a functional suspension carrier, and the functional suspension carrier is used to disperse in the wastewater. As an example but not limitation, the functional suspension carrier is a three-dimensional hollow filler, which serves as a carrier of microorganisms.

[0054] Preferably, the microorganisms growing inside the three-dimensional hollow filler are facultative bacteria, forming a denitrification environment, and the microorganisms growing outside are aerobic bacteria, which undergo aerobic and nitrification reactions. The process has rich bacterial species and is resistant to shock loads.

[0055] The wastewater biochemical treatment tank 130 is provided with a fluidized bed, and a swirling water flow is generated inside the fluidized bed through circulating water and aeration, so that the suspended three-dimensional hollow fillers swirl in the water.

[0056] As an example but not limitation, during normal operation, the aeration method is central aeration or unilateral aeration, and a swirling water flow is generated inside the wastewater biochemical treatment tank 130.

[0057] In actual operation, the aeration intensity q is usually determined by formula 1 based on the benchmark aeration time T; when the calculated aeration intensity q is 60% or less, the aeration intensity q is taken as 60%, and the aeration time T is recalculated by formula 1 accordingly. This can better save energy and achieve the purpose of energy saving and emission reduction.

[0058] Example 1

[0059] The vacuum circulating wastewater from a factory was treated to meet discharge standards.

[0060] Original wastewater situation: The company currently has 2 sets of vacuum circulation equipment, which are respectively in 2 different production workshops, namely 1# production line and 2# production line. After oil separation, they are mixed with other cleaning wastewater and discharged. The wastewater volume of each set is 3m 3 / d, the maximum instantaneous water volume is 0.5m 3 / h. The characteristics of the wastewater quality are: 1) small water volume and scattered drainage points; 2) the wastewater contains volatile organic compounds and oils.

[0061] project Wastewater quality range Emission standards pH 4～6 6～9 SS,mg / L 200-500 ＜400 CODCr,mg / L 600～1600 ＜500 BOD5,mg / L 200-800 ＜350

[0062] Table 1 Wastewater quality table

[0063] Calculate the wastewater coefficient k:

[0064] k = reference aeration intensity × reference time / reference COD = 78 × 6 / 1200 = 0.39

[0065] The base time is calculated as 6 hours; Base COD: according to the influent COD cr 75% of the maximum value of 1600 is calculated as 1200 mg / L, and the baseline aeration intensity is 78%.

[0066] The preset aeration time is 6 hours, and the applicable aeration intensity q is calculated according to formula 1:

[0067] q×T=k×COD 进 ×γ (Formula 1)

[0068] Preferably, the aeration intensity: q (%) is generally set at 60 to 100. The aeration time: T (hr) is generally set at 4 to 10 hr, and the value of γ is 1.05.

[0069] COD 进 : Influent COD cr , generally not more than 2 times of the benchmark COD;

[0070] In this embodiment, as COD 进 As the value changes, the aeration intensity also changes, as shown in the following table:

[0071] <![CDATA[COD 进 (mg / L)]]> 786 1000 1215 1520 q(％) 53.6 68.25 82.9 100 T(hr) 6 6 6 6.22

[0072] Table 2 Relationship between aeration intensity and wastewater COD value

[0073] In this embodiment, the anoxic operation time is preset to 2 hours, and the aerobic operation time is preset to 6 hours. 进 When it is 1520 mg / L, the aeration intensity q exceeds 100%. At this time, the aeration time T needs to be extended. The aeration intensity is set to 100%. After extending the aeration time, the treatment requirements can be met.

[0074] When COD 进 When it is 786 mg / L, the aeration intensity calculated by the benchmark aeration time is 53.6%. At this time, the aeration intensity can be taken as 60%. The aeration time T calculated by formula 1 is 5.36 hours, which can better save energy and reduce emissions.

[0075] After the anoxic-aerobic operation is completed, the wastewater enters the sedimentation process, and the preset sedimentation time is 1.5 hours. When the wastewater is discharged, it is subjected to enhanced treatment through the filter tank, and the treatment results are shown in the following table:

[0076] The test results of treated water quality are as follows:

[0077] <![CDATA[COD 进 ]]> mg / L 786 1000 1215 1420 <![CDATA[COD 出 ]]> mg / L 242 285 339 372

[0078] Table 3 Water quality treatment results

[0079] The wastewater was treated in two batches using the vacuum circulating wastewater treatment method. After treatment, the wastewater successfully met the predetermined discharge standard.

[0080] Preferably, the entire treatment process of "water intake → anoxic → aerobic → sedimentation → drainage" can be automatically realized through the control system. The process can be adaptively adjusted according to different vacuum cycle wastewater qualities to achieve the predetermined discharge standard.

[0081] By way of example and not limitation, the retention time of wastewater in an oil-water separator and / or filter may be determined based on the degree of oil-water separation or sedimentation rate of the specific wastewater.

[0082] Example 2

[0083] The organic evaporation and condensation wastewater from a factory was reused.

[0084] project Evaporation condensate water quality Biochemical treatment standards pH 6.5～9 6～9 <![CDATA[COD 进 ,(mg / L)]]> 500-900* ＜150

[0085] Table 4 Water quality of wastewater to be treated

[0086] Wastewater quality characteristics:

[0087] 1) The amount of water is small; 2) The wastewater contains volatile organic compounds.

[0088] According to the water quality of the wastewater to be treated, the benchmark COD value is set to 600 mg / L, the benchmark aeration intensity is 78%, and the benchmark aeration time is 6 hours. The wastewater coefficient k is calculated as follows:

[0089] k = reference aeration intensity × reference time / reference COD = 78 × 6 / 600 = 0.78

[0090] According to k value, influent COD 进 , γ is taken as 1.1, and the aeration intensity and aeration time are calculated by formula 1:

[0091]

[0092]

[0093] Table 5 Relationship between aeration intensity and wastewater COD value

[0094] In this embodiment, when the COD of the influent 进 When the concentration exceeds 700 mg / L, the aeration intensity q>100%, and the aeration intensity is calculated as 100%.

[0095] Specifically, the anoxic operation time is preset to 1.5 hours, the aerobic operation time changes accordingly with the influent COD value, and the sedimentation time is preset to 1.5 hours. The effluent is discharged after enhanced treatment by the filter tank 150. The water quality test results after treatment are shown in the following table:

[0096] project Water quality data <![CDATA[COD 进 (mg / L)]]> 563 <![CDATA[COD 出 (mg / L)]]> 74 <![CDATA[COD Cr Removal rate]]> 86.9％ <![CDATA[COD Cr Treatment standard mg / L]]> ＜150

[0097] Table 6 Water quality treatment results

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating vacuum circulating wastewater, characterized in that: The following steps are involved: S1. After the wastewater enters the collection tank, the chemical oxygen demand (COD) of the wastewater is tested, and the aeration intensity q or aeration time T is calculated according to the wastewater coefficient k according to formula 1: q×T=k×COD 进 ×γ (Formula 1) Among them, aeration intensity: q, aeration time: T, COD 进 : Dichromate index COD of influent cr , γ is a safety coefficient, and the safety coefficient γ is 1.05-1.2; The wastewater coefficient k is calculated according to the following formula: k = reference aeration intensity × reference time / reference COD (Formula 2), The reference aeration intensity is the ratio of the aeration volume to the maximum air volume that can be provided under the reference COD of the influent and the reference time, and the maximum air volume that can be provided is the maximum aeration volume required to achieve the treatment purpose; the reference COD value is a value between 50% and 70% of the maximum COD value of the wastewater to be treated; S2. When the wastewater biochemical treatment tank completes the drainage of the previous treatment batch and reaches the water collection level M, the wastewater in the collection tank is pumped into the oil-water separator, and the wastewater enters the wastewater biochemical treatment tank after oil separation, and stops entering the wastewater biochemical treatment tank after reaching the preset liquid level H of the wastewater biochemical treatment tank; S3. After the wastewater enters the wastewater biochemical treatment tank, the circulation valve is opened, and the anoxic operation is started through hydraulic stirring; after the anoxic operation is completed, the circulation valve is closed, the air inlet regulating valve is opened, and the aeration intensity q is calculated according to the reference aeration time T by formula 1, and the aeration aerobic operation is performed; if the calculated q>100%, the aeration intensity q is taken as 100%, and the aeration time is calculated by formula 1; In step S1, the aeration intensity q is calculated by formula 1 according to the reference aeration time T; when the aeration intensity q is 60% or less, the aeration intensity is taken as 60%, and the aeration time T is reduced accordingly to meet the requirements of energy saving and environmental protection; S4. After the aerobic operation is completed, close the air inlet regulating valve to carry out sedimentation and stratification; S5. After sedimentation is completed, the biochemically treated water will be directly discharged if it meets the discharge standards. If it does not meet the standards, it will be filtered and then discharged or returned to the wastewater biochemical treatment tank for further treatment.

2. The method for treating vacuum circulating wastewater according to claim 1, characterized in that: The wastewater biochemical treatment tank is filled with a functional suspension carrier, which is used to be dispersed in the wastewater, and microorganisms are attached to the functional suspension carrier.

3. The method for treating vacuum circulating wastewater according to claim 1, characterized in that: A fluidized bed is arranged in the wastewater biochemical treatment tank, and a swirling water flow is generated inside the fluidized bed through circulating water and aeration, so that the functional suspended carrier swirls in the water.

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