Wastewater treatment method based on activated sludge to quickly and significantly reduce COD

Abstract

The present invention discloses a wastewater treatment method for rapidly and substantially reducing COD based on activated sludge, wherein the treatment method is to transport the wastewater to be treated that meets the requirements into a closed reaction device arranged with biological fillers, add activated sludge after being acclimated with the wastewater to be treated, and control the pressure in the reaction device to be 0.02-0.1Mpa and the temperature to be 30-35°C under aeration, so that the wastewater stays in the reaction device for 12-48h for biological oxidation treatment. The wastewater treatment method of the present invention can realize the efficient treatment of COD in wastewater, so as to reduce the high level of COD to a lower level in a relatively short time, and the treatment method has strong impact resistance, low cost, and small investment, and has obvious environmental benefits and broad application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a wastewater treatment method for rapidly and significantly reducing COD based on activated sludge. Background Art

[0002] Biological wastewater treatment is a method of removing organic pollutants from wastewater by utilizing the metabolic effects of microorganisms. It mainly includes the following categories: activated sludge method, biological pond method, anaerobic biological treatment method, biofilm method, and contact oxidation method. Among them, the activated sludge method is an aerobic biological treatment method for wastewater. This method is to continuously mix and culture wastewater and various microbial communities under artificial oxygenation conditions to form activated sludge, and utilize the biological coagulation, adsorption and oxidation effects of activated sludge to decompose and remove organic pollutants in wastewater.

[0003] In practical applications, based on the microbial characteristics of activated sludge, when treating organic wastewater according to conventional processes, there are upper limits for the content of pollutants in the wastewater to be treated. Usually, COD≤10000mg / L, ammonia nitrogen content less than 500mg / L, and phosphorus content less than 50mg / L (the specific limits will vary depending on the treatment process and wastewater quality, but there will not be a big difference). If the COD, ammonia nitrogen, phosphorus and other contents of the wastewater to be treated significantly exceed the upper limit of the treatment range, it will have a great impact on the microbial population in the activated sludge, directly reduce the activity of the microorganisms, and even cause inactivation and paralysis of the treatment system. In addition, in the conventional activated sludge biochemical treatment process, the wastewater treatment time is long and the degradation of pollutants is limited. For example, the aerobic treatment process requires that the wastewater generally stay for 24~72h to reduce the influent COD from 1000~3000mg / L to about 300~500mg / L, and then discharge it into the sewage treatment plant for further treatment. If the COD exceeds the load and the effluent exceeds the standard, it is difficult to meet the timely treatment requirements of a large amount of highly polluted wastewater. Due to the above limitations, when treating biochemical wastewater with high COD and high pollutants (such as production wastewater generated by fermentation and food industries), it is impossible to directly use the activated sludge method for treatment. It is necessary to first treat it through coagulation sedimentation, oxidation treatment or filtration adsorption and other means before performing activated sludge biological oxidation. This not only increases the treatment cost, but may also introduce new pollution and increase the difficulty of wastewater treatment. Summary of the invention

[0004] In order to solve the problems of limited treatable COD content and slow COD treatment speed in the existing activated sludge method for treating organic wastewater, the present invention provides a wastewater treatment method based on activated sludge for rapidly and significantly reducing COD.

[0005] To achieve the above-mentioned purpose, the wastewater treatment method for rapidly and substantially reducing COD based on activated sludge provided by the present invention is to transport the wastewater to be treated that meets the requirements into a closed reaction device arranged with biological fillers, add activated sludge that has been acclimated with the wastewater to be treated, and control the pressure in the reaction device to be 0.02-0.1Mpa and the temperature to be 30-35°C under aeration, so that the wastewater stays in the reaction device for 12-48 hours for biological oxidation treatment; the wastewater to be treated must meet the following requirements:

[0006] (1) The B / C value (ratio of biochemical oxygen demand (BOD5) to chemical oxygen demand (COD)) of the wastewater to be treated is greater than 0.3;

[0007] (2) When the COD of the wastewater to be treated is between 10,000 and 15,000 (inclusive) mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 350 mg / L, the total phosphorus content is required to be above 50 mg / L, and the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥4 mg / L;

[0008] When the COD of the wastewater to be treated is between 15000 and 22000 (including 22000) mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 500 mg / L, the total phosphorus content is required to be above 70 mg / L, and the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥ 6 mg / L;

[0009] When the COD of the wastewater to be treated is 22000~30000 (including 30000) mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 650 mg / L, the total phosphorus content is required to be above 90 mg / L, and the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥8 mg / L;

[0010] When the COD of the wastewater to be treated is 30,000~50,000 (including 50,000) mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 850 mg / L, and the total phosphorus content is required to be above 120 mg / L. At the same time, the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥10 mg / L.

[0011] The wastewater treatment method of the present invention is based on the activated sludge method, breaks the conventional restrictions on COD, ammonia nitrogen and total phosphorus in wastewater, and controls the ammonia nitrogen concentration and total phosphorus content in the wastewater to match the COD and reach a certain range under pressurized and aerated conditions, so as to promote the rapid reproduction of the microbial community in the activated sludge and improve the biological activity, thereby achieving substantial degradation of organic pollutants, so that the COD of the wastewater is reduced from tens of thousands to thousands within a relatively short period of time of 12 to 48 hours, thereby completing substantial and rapid removal of the COD of the wastewater, and providing a convenient, effective and efficient treatment method for highly polluted biodegradable wastewater.

[0012] As a limitation of the above technical solution, the volume of activated sludge added is 10% to 20% of the volume of the wastewater to be treated, wherein the volume of activated sludge is calculated based on the amount of activated sludge after centrifugal treatment.

[0013] As a limitation of the above technical solution, when the COD of the wastewater to be treated is between 10,000 and 15,000 mg / L, the volume of activated sludge added is 10% to 12% of the volume of the wastewater to be treated;

[0014] When the COD of the wastewater to be treated is between 15000 and 22000 mg / L, the volume of activated sludge added is 12% to 14% of the volume of the wastewater to be treated;

[0015] When the COD of the wastewater to be treated is between 22,000 and 30,000 mg / L, the volume of activated sludge added is 14% to 16% of the volume of the wastewater to be treated;

[0016] When the COD of the wastewater to be treated is between 30,000 and 50,000 mg / L, the volume of activated sludge added is 16% to 20% of the volume of the wastewater to be treated.

[0017] As a limitation of the above technical solution, the COD of the wastewater to be treated with a COD of 10,000-50,000 mg / L is reduced to 1,000-5,000 mg / L after biological oxidation treatment.

[0018] The wastewater treatment method based on activated sludge of the present invention can directly treat highly polluted wastewater with COD as high as 10,000 to 50,000 mg / L, which is greatly improved compared with the treatment limit of COD by conventional activated sludge method. Moreover, after only 12 to 48 hours of treatment time, the COD of the wastewater can be greatly reduced to 1,000 to 5,000 mg / L, which has significant application value for the treatment of highly polluted biodegradable wastewater.

[0019] As a limitation of the above technical scheme, it is required that the ammonia nitrogen concentration of the wastewater during the biological oxidation treatment process is not less than 50 mg / L, and the total phosphorus content is not less than 10 mg / L; when the initial ammonia nitrogen concentration, the initial total phosphorus content of the wastewater to be treated, and any of the ammonia nitrogen concentration and the total phosphorus content of the wastewater during the biological oxidation treatment process do not meet the requirements, ammonia nitrogen or phosphorus shall be added in time to make all indicators meet the requirements.

[0020] As a limitation of the above technical solution, it is required that the initial ammonia nitrogen concentration of the wastewater to be treated is not higher than 2000 mg / L.

[0021] As a limitation of the above technical solution, the wastewater treatment method based on activated sludge to rapidly and significantly reduce COD includes the following treatment steps:

[0022] a. The wastewater to be treated enters the buffer tank, where the ammonia nitrogen concentration and total phosphorus content are regulated, the pH is adjusted to 7-8 after homogenization, and then pumped into the biological oxidation reaction device, where biological fillers are arranged and activated sludge domesticated for the wastewater to be treated is added;

[0023] b. Introduce compressed air into the reaction device for distribution and aeration, control the pressure, temperature and dissolved oxygen in the reaction device, and allow the wastewater to stay in the reaction device for 12 to 48 hours for biological oxidation treatment. During the biological oxidation treatment process, monitor the pressure in the reaction device and the dissolved oxygen, ammonia nitrogen concentration and total phosphorus content of the wastewater and adjust them in time to meet the requirements;

[0024] c. After the biological oxidation treatment is completed, the effluent from the reaction device is filtered, and the filtrate is discharged to the subsequent treatment system, and then discharged to the industrial wastewater treatment pipeline after meeting the standards; the subsequent treatment includes at least one of oxidation treatment, ammonia nitrogen removal treatment, and phosphorus removal treatment.

[0025] Oxidation treatment includes LDO low-temperature wet catalytic oxidation treatment, electrocatalytic oxidation, Fenton oxidation, etc. Ammonia nitrogen removal treatment can be carried out by air stripping method, zeolite deamination method, etc. Phosphorus removal treatment includes chemical precipitation method, adsorption method, etc.

[0026] Since the initial pollutant content of the wastewater is very high and the ratio of ammonia nitrogen and total phosphorus content has been increased, it is generally still unable to meet the requirements for direct discharge to the industrial wastewater treatment system after biological oxidation treatment. However, the pollutants and the degree of pollution at this time are within the range that is easy to handle. Combined with existing commonly used oxidation treatment, ammonia nitrogen removal treatment, phosphorus removal treatment and other methods, the emission standards can be met, thereby simplifying the treatment process and reducing treatment costs.

[0027] The activated sludge-based wastewater treatment method of the present invention is further improved to optimize the wastewater treatment effect.

[0028] As a limitation of the above technical solution, the ammonia nitrogen concentration of the wastewater is increased by adding urea and / or ammonium sulfate; the total phosphorus content of the wastewater is increased by adding potassium dihydrogen phosphate and / or dipotassium hydrogen phosphate.

[0029] As a limitation of the above technical solution, if the initial ammonia nitrogen concentration of the wastewater to be treated is higher than 2000 mg / L, it is necessary to first use ammonia nitrogen removal treatment to reduce the initial ammonia nitrogen concentration to less than 2000 mg / L.

[0030] In order to maintain the activity of activated sludge and enable the biological oxidation treatment to proceed normally, the initial ammonia nitrogen concentration of the wastewater needs to be controlled within 2000 mg / L.

[0031] As a limitation of the above technical solution, if the wastewater to be treated contains volatile organic matter, the tail gas is collected from the top of the reaction device and discharged to the waste gas treatment system.

[0032] In summary, the wastewater treatment method of the present invention is a breakthrough based on the activated sludge method. According to the content of organic pollutants in the wastewater to be treated, i.e., the COD range, the content ratio of C, N, and P in the wastewater is controlled under aeration and a certain pressure and temperature conditions, and the dissolved oxygen of the wastewater is increased at the same time. Under the synergy of various conditions, the microorganisms in the activated sludge are prompted to enhance the utilization rate of oxygen, improve the metabolism and proliferation rate, thereby achieving efficient treatment of COD in the wastewater, so as to reduce the high level of COD to a lower level in a relatively short time. The wastewater treatment method has a high COD removal rate, strong impact resistance of the activated sludge, low cost, small investment, and has obvious environmental benefits and broad application prospects. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0034] The chemical raw materials involved in the embodiments and comparative examples are all typical products purchased on the market.

[0035] The water quality in the examples and comparative examples was tested using the standard methods and instruments shown in Table 1 below.

[0036] Table 1. Standard methods and instruments for water quality testing

[0037]

[0038] Example 1

[0039] A production process wastewater from a cellulose production plant was treated. The pollutant content in the wastewater was tested before treatment. The test results are shown in Table 2 below.

[0040] Table 2. Pollutant content of cellulose production wastewater before treatment in Example 1

[0041]

[0042] Since the COD of the cellulose wastewater is very high, it cannot be directly discharged into the sewage treatment plant in the park where the production plant is located for treatment, which will seriously exceed the bearing capacity of the biochemical system of the sewage plant. The wastewater must first be subjected to the following activated sludge-based biological oxidation treatment.

[0043] (I) Use the cellulosic wastewater to be treated to domesticate the activated sludge.

[0044] Activated sludge was taken from the wastewater treatment biochemical pool of the cellulose production plant and domesticated step by step. First, 8L of nutrient solution with COD 5000mg / L (prepared with glucose, ammonium sulfate / urea, and potassium dihydrogen phosphate at a carbon-nitrogen-phosphorus ratio of 100:5:1) was mixed with 2L of diluted wastewater to be treated (COD diluted to 5000mg / L) as the culture medium, and about 1L of centrifuged activated sludge was added. Aeration (dissolved oxygen at 2-5 mg / L) culture, when COD drops to about 80% (i.e. COD drops to 4000mg / L), stop aeration and sedimentation, discard the supernatant, add new culture solution, at this time the proportion of diluted wastewater to be treated in the culture solution is increased to 40% for aeration culture, COD drops to about 80%, sedimentation, then discard the supernatant, add new culture solution, at this time the proportion of diluted wastewater to be treated in the culture solution is increased to 60%, and so on to 80%, 100%, after the diluted wastewater to be treated is completely cultured, the dilution multiple is gradually reduced, and the influent COD is increased (i.e. the initial dilution is to about COD5000mg / L, then 10000mg / L, 15000mg / L...) until the initial concentration of the wastewater to be treated.

[0045] (ii) Treat cellulosic wastewater using activated sludge.

[0046] Since the ratio of ammonia nitrogen concentration to COD content in the wastewater to be treated does not meet the requirements, the initial ammonia nitrogen concentration in the wastewater is increased by artificial feeding (urea / ammonium sulfate) to make it greater than 850 mg / L; then 10L of wastewater is transported to a closed reaction tank equipped with biological fillers (commercially available biological fillers are acceptable), and the activated sludge that has been tamed in the previous step is added to the reaction tank, with an initial addition amount of 16% (i.e., 10L of wastewater is added with 1.6L of activated sludge after centrifugation, and the water content of the activated sludge after centrifugation is 75~85%w / w). The pressure in the reaction tank is controlled at 0.02~0.1Mpa, and the dissolved oxygen in the wastewater is controlled to be ≥10mg / L by adjusting the ventilation and aeration volume, stirring speed and pressure in the tank for wastewater treatment. During this period, samples are taken regularly to test COD, ammonia nitrogen, total phosphorus and other data. The results are shown in Table 3 below.

[0047] Table 3 Monitoring data of cellulose production wastewater treatment process in Example 1

[0048]

[0049] After 32 hours of treatment, the COD of the wastewater dropped to 8592 mg / L, and the dissolved oxygen rebounded. After the treatment was continued for 40 hours, the COD decline slowed down significantly, indicating that most of the remaining substances were poorly biodegradable. The treatment was stopped, and the discharged water was filtered to remove the sludge. The filtrate entered the LDO low-temperature wet catalytic oxidation treatment equipment for catalytic oxidation treatment. The COD of the wastewater before and after treatment is shown in Table 4 below.

[0050] Table 4. COD content of cellulose production wastewater after treatment in Example 1

[0051]

[0052] After LDO low-temperature wet catalytic oxidation treatment, the difficult-to-degrade substances are decomposed into small molecules, and the COD of the wastewater is reduced to below 500 mg / L, meeting the requirements for entering the park's sewage treatment plant. After mixing with other wastewater in the plant, it is discharged into the park's sewage treatment plant.

[0053] Example 2

[0054] A process wastewater from a biological fermentation enterprise was treated. The pollutant content in the wastewater was tested before treatment. The test results are shown in Table 5 below.

[0055] Table 5. Pollutant content of fermentation wastewater before treatment in Example 2

[0056]

[0057] For the wastewater, the activated sludge was gradient acclimated with the fermentation wastewater to be treated, and the specific acclimation operation was the same as that in Example 1.

[0058] The fermentation wastewater is treated by activated sludge.

[0059] Since the total phosphorus content in the wastewater to be treated is low, the initial total phosphorus content in the wastewater is increased to be greater than 100 mg / L by artificially feeding potassium dihydrogen phosphate / dipotassium hydrogen phosphate; 10L of wastewater is transported to a closed reaction tank equipped with biological fillers, and the activated sludge after acclimatization in the previous step is added to the reaction tank, with an initial addition amount of 12% (i.e., 10L of wastewater is added with 1.2L of activated sludge after centrifugation). The pressure in the reaction tank is controlled at 0.02~0.06Mpa, and the dissolved oxygen in the wastewater is controlled to be ≥6mg / L by adjusting the ventilation and aeration volume, stirring speed and pressure in the tank for wastewater treatment. During this period, samples are taken regularly to test COD, ammonia nitrogen, total phosphorus and other data. The results are shown in Table 6 below.

[0060] Table 6. Monitoring data of fermentation wastewater treatment process in Example 2

[0061]

[0062] After 28 hours of treatment, the COD of the wastewater dropped to 4138, and the treatment was stopped. After the discharged water was filtered, the filtrate entered the LDO low-temperature wet catalytic oxidation treatment equipment for treatment to further reduce the COD content of the wastewater. The COD of the wastewater before and after treatment is shown in Table 7 below.

[0063] Table 7. COD content of fermentation wastewater after treatment in Example 2

[0064]

[0065] After LDO low-temperature wet catalytic oxidation treatment, the COD of the wastewater drops to below 500 mg / L and is discharged into the plant's biochemical system for mixed treatment with other wastewater.

[0066] Example 3

[0067] A production wastewater from a food industry was treated. The pollutant content in the wastewater was tested before treatment. The test results are shown in Table 8 below.

[0068] Table 8 Pollutant content of food production wastewater before treatment in Example 3

[0069]

[0070] For this wastewater, the activated sludge was domesticated with the food wastewater to be treated, and the specific domestication operation was the same as in Example 1.

[0071] Use activated sludge to treat food wastewater.

[0072] Since the initial ammonia nitrogen and total phosphorus concentrations of the wastewater did not meet the requirements, the initial ammonia nitrogen and total phosphorus concentrations in the wastewater were increased by artificial feeding (urea / ammonium sulfate and potassium dihydrogen phosphate / dipotassium hydrogen phosphate), and then 10L of wastewater was transported to a closed reaction tank equipped with biological fillers, and the activated sludge after domestication in the previous step was added to the reaction tank, with an initial addition amount of 14% (i.e., 10L of wastewater was added with 1.4L of activated sludge after centrifugation). The pressure in the reaction tank was controlled at 0.02~0.08Mpa, and the dissolved oxygen in the wastewater was controlled to be ≥8mg / L by adjusting the ventilation and aeration volume, stirring speed and pressure in the tank for wastewater treatment. During this period, samples were taken regularly to test COD, ammonia nitrogen, total phosphorus and other data. The results are shown in Table 9 below.

[0073] Table 9 Monitoring data of food production wastewater treatment process in Example 3

[0074]

[0075] After 28 hours of treatment, the COD of the wastewater dropped to 5023 mg / L, and the treatment was stopped. After the discharged water was filtered, the filtrate entered the LDO low-temperature wet catalytic oxidation treatment equipment for treatment to further reduce the COD content of the wastewater. The COD of the wastewater before and after treatment is shown in Table 10 below.

[0076] Table 10, COD content of food production wastewater after treatment in Example 3

[0077]

[0078] After LDO low-temperature wet catalytic oxidation treatment, the COD of the wastewater is reduced to below 500 mg / L and is directly discharged into the conventional sewage system for treatment.

[0079] Comparative Example 1

[0080] The cellulose wastewater of Example 1 is directly treated by using activated sludge under pressurized conditions. The difference from Example 1 is that the wastewater is not subjected to matching requirements for COD, ammonia nitrogen and total phosphorus. The specific operation is as follows.

[0081] 10L of untreated cellulose wastewater (without adjustment or pretreatment) was directly transported to a closed reaction tank equipped with biological fillers, and domesticated activated sludge was added. The initial addition amount was 16% (same as Example 1). The pressure in the system was controlled to be 0.02-0.1Mpa. The aeration volume, stirring speed and pressure were adjusted to control the dissolved oxygen to ≥10mg / L for wastewater treatment. During the treatment, samples were taken regularly to detect COD, ammonia nitrogen, total phosphorus and other data. The results are shown in Table 11.

[0082] Table 11. Monitoring data of cellulose production wastewater treatment process in comparative example 1

[0083]

[0084] During the treatment of cellulose wastewater, no nitrogen source was added. It can be seen from the test data that the degradation rate of pollutants in the wastewater was significantly slower. After 28 hours of treatment, the COD of the wastewater was still at a high value of 30301 mg / L, and the dissolved oxygen began to rise at this time. Even if the treatment continued, the COD no longer decreased significantly, and extending the time had little effect on COD removal.

[0085] Comparative Example 2

[0086] The fermentation wastewater of Example 2 is directly treated by using activated sludge under pressurized conditions. The difference from Example 2 is that the wastewater is not subjected to matching requirements for COD, ammonia nitrogen and total phosphorus. The specific operation is as follows.

[0087] 10L of fermentation wastewater to be treated (without adjustment or pretreatment) was directly transported to a closed reaction tank equipped with biological fillers, and domesticated activated sludge was added. The initial addition amount was 12% (same as Example 2). The pressure in the system was controlled to be 0.02-0.06Mpa. The aeration volume, stirring speed and pressure were adjusted to control the dissolved oxygen to be ≥6mg / L for wastewater treatment. During the treatment, samples were taken regularly to detect COD, ammonia nitrogen, total phosphorus and other data. The results are shown in Table 12.

[0088] Table 12, Comparative Example 2 Fermentation Wastewater Treatment Process Monitoring Data

[0089]

[0090] During the treatment of fermentation wastewater, no phosphorus was added. It can be seen from the test data that the pollutants in the wastewater are degraded slowly. After 24 hours of treatment, the COD of the wastewater was at a high value of 14860 mg / L, and the dissolved oxygen began to rise at this time. After that, even if the treatment continued, the COD no longer decreased significantly, and there was little effect on COD removal.

[0091] Comparative Example 3

[0092] The food wastewater of Example 3 was directly treated under pressurized conditions using activated sludge. The difference from Example 3 was that the wastewater was not subjected to matching requirements for COD, ammonia nitrogen, and total phosphorus, and when the ammonia nitrogen concentration of the wastewater was lower than 50 mg / L and the total phosphorus content was lower than 10 mg / L during the treatment process, the corresponding ammonia nitrogen and phosphorus were not added. The specific operations are as follows.

[0093] 10L of food wastewater to be treated (without adjustment or pretreatment) is directly transported to a closed reaction tank equipped with biological fillers, and the activated sludge after acclimation in the previous step is added to the reaction tank, with an initial addition amount of 14% (same as Example 3). The pressure in the reaction tank is controlled at 0.02-0.08Mpa, and the dissolved oxygen in the wastewater is controlled to be ≥8mg / L by adjusting the ventilation aeration volume, stirring speed and pressure in the tank for wastewater treatment. During this period, samples are taken regularly to detect COD, ammonia nitrogen, total phosphorus and other data. The results are shown in Table 13 below.

[0094] Table 13 Monitoring data of food production wastewater treatment process in comparative example 3

[0095]

[0096] In this comparative example, the ammonia nitrogen and total phosphorus contents were low, and no nitrogen and phosphorus were supplemented. The COD removal rate was slow during the process, and MLSS decreased and dissolved oxygen increased in the later stage. After 28 hours of treatment, the COD of the wastewater dropped to 14297 mg / L, which was significantly different from Example 3.

[0097] Comparative Example 4

[0098] The food wastewater of Example 3 was treated by the activated sludge method under non-pressurized conditions, and the specific operations are as follows.

[0099] After adding ammonia nitrogen and phosphorus, 10L of food wastewater to be treated was transported to a closed reaction tank equipped with biological fillers, and the domesticated activated sludge was added with an initial addition amount of 14% (same as Example 3). The aeration volume and stirring speed were adjusted according to conventional aeration conditions to treat the wastewater. During the treatment, samples were taken regularly to detect COD, ammonia nitrogen, total phosphorus and other data. The results are shown in Table 14.

[0100] Table 14. Monitoring data of food production wastewater treatment process in comparative example 4

[0101]

[0102] After 36 hours of treatment, the COD of the wastewater dropped to 17625 mg / L. The dissolved oxygen in the treatment process remained at a low level. Even if the combined dosage of C, N, and P was controlled, the COD removal rate was slow and the efficiency was low according to conventional aeration treatment.

[0103] In summary, the wastewater treatment method of the present invention can achieve efficient treatment of COD in wastewater, so as to reduce high-level COD to a lower level in a relatively short time. In addition, the treatment method has strong impact resistance, low cost, and small investment, and has obvious environmental benefits and broad application prospects.

Claims

1. A wastewater treatment method based on activated sludge to rapidly and substantially reduce COD, characterized in that: The treatment method is to transport the wastewater to be treated that meets the requirements into a closed reaction device equipped with biological fillers, add activated sludge that has been acclimated with the wastewater to be treated, and control the pressure in the reaction device to 0.02~0.1Mpa and the temperature to 30~35℃ under aeration to allow the wastewater to stay in the reaction device for 12~48h for biological oxidation treatment. The wastewater to be treated must meet the following requirements: (1) The B / C value of the wastewater to be treated is greater than 0.3; (2) When the COD of the wastewater to be treated is between 10,000 and 15,000 mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 350 mg / L, the total phosphorus content is required to be above 50 mg / L, and the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥ 4 mg / L; When the COD of the wastewater to be treated is between 15000 and 22000 mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 500 mg / L, the total phosphorus content is required to be above 70 mg / L, and the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥ 6 mg / L; When the COD of the wastewater to be treated is 22000~30000mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 650mg / L, the total phosphorus content is required to be above 90mg / L, and the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥8mg / L; When the COD of the wastewater to be treated is 30,000-50,000 mg / L, the initial ammonia nitrogen concentration of the wastewater is required to be above 850 mg / L, the total phosphorus content is required to be above 120 mg / L, and the dissolved oxygen of the wastewater in the biological oxidation treatment process is controlled to be ≥10 mg / L; It is also required that the ammonia nitrogen concentration of the wastewater during the biological oxidation treatment process shall not be less than 50 mg / L, and the total phosphorus content shall not be less than 10 mg / L; when the initial ammonia nitrogen concentration, initial total phosphorus content of the wastewater to be treated, and any of the ammonia nitrogen concentration and total phosphorus content of the wastewater during the biological oxidation treatment process do not meet the requirements, ammonia nitrogen or phosphorus shall be added in time to make all indicators meet the requirements.

2. The wastewater treatment method for rapidly and substantially reducing COD based on activated sludge according to claim 1, characterized in that: The volume of activated sludge added is 10%~20% of the volume of wastewater to be treated.

3. The wastewater treatment method for rapidly and substantially reducing COD based on activated sludge according to claim 2 is characterized in that: When the COD of the wastewater to be treated is between 10,000 and 15,000 mg / L, the volume of activated sludge added is 10% to 12% of the volume of the wastewater to be treated; When the COD of the wastewater to be treated is between 15000 and 22000 mg / L, the volume of activated sludge added is 12% to 14% of the volume of the wastewater to be treated; When the COD of the wastewater to be treated is between 22,000 and 30,000 mg / L, the volume of activated sludge added is 14% to 16% of the volume of the wastewater to be treated; When the COD of the wastewater to be treated is between 30,000 and 50,000 mg / L, the volume of activated sludge added is 16% to 20% of the volume of the wastewater to be treated.

4. The wastewater treatment method for rapidly and substantially reducing COD based on activated sludge according to claim 3 is characterized by: The COD of the wastewater to be treated with a COD of 10000~50000 mg / L is reduced to 1000~5000 mg / L after biological oxidation treatment.

5. The wastewater treatment method for rapidly and substantially reducing COD based on activated sludge according to claim 1, characterized in that: The initial ammonia nitrogen concentration of the wastewater to be treated is required to be no higher than 2000 mg / L.

6. The method for treating wastewater by rapidly and substantially reducing COD based on activated sludge according to any one of claims 1 to 5, characterized in that: The processing steps include: a. The wastewater to be treated enters the buffer tank, where the ammonia nitrogen concentration and total phosphorus content are regulated, the pH is adjusted to 7-8 after homogenization, and then pumped into the biological oxidation reaction device, where biological fillers are arranged and activated sludge domesticated for the wastewater to be treated is added; b. Introduce compressed air into the reaction device for distribution and aeration, control the pressure, temperature and dissolved oxygen in the reaction device, and allow the wastewater to stay in the reaction device for 12 to 48 hours for biological oxidation treatment. During the biological oxidation treatment process, monitor the pressure in the reaction device and the dissolved oxygen, ammonia nitrogen concentration and total phosphorus content of the wastewater and adjust them in time to meet the requirements; c. After the biological oxidation treatment is completed, the effluent from the reaction device is filtered, and the filtrate is discharged to the subsequent treatment system, and then discharged to the industrial wastewater treatment pipeline after meeting the standards; the subsequent treatment includes at least one of oxidation treatment, ammonia nitrogen removal treatment, and phosphorus removal treatment.

7. The wastewater treatment method for rapidly and substantially reducing COD based on activated sludge according to claim 6, characterized in that: The ammonia nitrogen concentration of the wastewater is increased by adding urea and / or ammonium sulfate; the total phosphorus content of the wastewater is increased by adding potassium dihydrogen phosphate and / or dipotassium hydrogen phosphate.

8. The wastewater treatment method for rapidly and substantially reducing COD based on activated sludge according to claim 6, characterized in that: If the initial ammonia nitrogen concentration of the wastewater to be treated is higher than 2000 mg / L, it is necessary to first use ammonia nitrogen removal treatment to reduce the initial ammonia nitrogen concentration to less than 2000 mg / L.

9. The wastewater treatment method for rapidly and substantially reducing COD based on activated sludge according to claim 6, characterized in that: If the wastewater to be treated contains volatile organic matter, the tail gas is collected from the top of the reaction device and discharged to the waste gas treatment system.

Images