Method for preparing biological carbon source by using waste emulsion

Abstract

The invention discloses a method for preparing a biological carbon source by using waste emulsion, and relates to the technical field of organic waste liquid treatment. The method comprises the following steps: S1, pretreating the waste emulsion, and removing suspended solids and colloidal substances to obtain a clear and transparent material; s2, performing reverse osmosis treatment on the clarified and transparent material, so that the content of macromolecular refractory substances in effluent is less than or equal to 5%; and S3, carrying out vacuum denitrification treatment and breakpoint chlorination reaction on the reverse osmosis effluent in S2 to remove ammonia nitrogen, wherein the reaction product is the biological carbon source. The reverse osmosis treatment has a remarkable interception effect on macromolecules, so that the content of macromolecular refractory substances in effluent is less than or equal to 5%, the biodegradability of the material is improved, the vacuum denitrification method is used as a main technical means for removing ammonia nitrogen in the raw material, and the residual ammonia nitrogen is completely removed by using a break point chlorination method; and finally, the requirement as a biological carbon source is met.

Description

Technical Field

[0001] The invention relates to the technical field of organic waste liquid treatment, and more specifically, to a method for preparing a biological carbon source by utilizing waste emulsion. Background Art

[0002] Waste emulsion is produced in the machinery manufacturing industry. A large amount of emulsion is used as a lubricant for cooling in metal cutting. After a period of use, the emulsion will become wastewater and become waste emulsion. With the rapid development of the machinery manufacturing industry, the amount of emulsion has increased rapidly. If it is not properly handled, it will pollute the environment. Waste emulsion often has a very high COD and has a certain biodegradability, and has the possibility of being prepared as a biological carbon source. Biological carbon sources are nutrients used to constitute the carbon source in microbial cells and metabolites. The research on using organic matter as an added carbon source has a history of twenty years. Many literatures have verified the effectiveness of common carbon sources (acetic acid, methanol, glucose), but the high prices of these carbon sources make it difficult to increase the cost of sewage treatment when they are used. The waste emulsion itself is rich in organic matter. As long as certain technical means are used to further improve its biodegradability and remove ammonia nitrogen, the waste emulsion can be turned into a biological carbon source to achieve the purpose of turning waste into treasure. Therefore, it is urgent to develop a method for effectively utilizing waste emulsion to prepare biological carbon sources.

[0003] The prior art discloses a high-concentration emulsion treatment method and treatment system, and the disclosed high-concentration emulsion treatment method is sequentially through collection treatment, acidification, primary coagulation and precipitation, secondary coagulation and precipitation, evaporation treatment, biochemical treatment, and second-stage biochemical treatment. However, the removal of ammonia nitrogen in this method is also through the biochemical A / O process. The biochemical technology not only removes ammonia, but also removes BOD, and the preparation of biological carbon sources requires the retention of BOD. Therefore, the existing emulsified waste liquid treatment method cannot realize the preparation of biological carbon sources using waste emulsion. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that the existing emulsified waste liquid treatment method cannot use the emulsion to produce a bio-carbon source, and to provide a method for using waste emulsion to produce a bio-carbon source, by overall control of process conditions to effectively recover the emulsified waste liquid to produce a bio-carbon source.

[0005] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a biocarbon source using waste emulsion comprises the following steps:

[0007] S1. Pre-treating the waste emulsion to remove suspended solids and colloidal substances to obtain a clear and transparent material;

[0008] S2. The clear and transparent material is subjected to reverse osmosis treatment so that the content of macromolecular refractory substances in the effluent is ≤5%;

[0009] S3. The reverse osmosis effluent in S2 is subjected to vacuum denitrification treatment and inflection point chlorination reaction to remove ammonia nitrogen, and the reaction product is the biological carbon source.

[0010] Among them, the macromolecular refractory substances in S2 are organic molecules with a molecular weight ≥150.

[0011] Among them, it should be noted that:

[0012] In the method of the present invention, waste emulsion is used as a raw material to prepare a biocarbon source. The waste emulsion contains a large amount of macromolecular difficult-to-degrade substances, including many kinds of substances, which have the common characteristics of large molecular weight, long molecular chain and difficulty in being degraded by microorganisms. The present invention has a significant interception effect on macromolecules through reverse osmosis treatment. The reverse osmosis membrane can intercept difficult-to-degrade macromolecules and pass through easily degradable small molecules. Theoretically, most of the organic molecules with a molecular weight greater than 150 will be intercepted when passing through reverse osmosis, and the interception rate is generally greater than 95%, so that the content of macromolecular difficult-to-degrade substances in the effluent is ≤5%, thereby improving the biodegradability of the material.

[0013] For high-ammonia nitrogen wastewater, commonly used processes include ammonia stripping towers, biochemical A / O processes, and anaerobic ammonia oxidation. Ammonia stripping towers are prone to odor leakage; biochemical technologies such as biochemical A / O processes and anaerobic ammonia oxidation not only remove ammonia, but also remove BOD, and the preparation of biological carbon sources requires the retention of BOD. Vacuum denitrification can retain its BOD while removing ammonia nitrogen, and it is not easy to produce odor leakage under negative pressure. In step S3, vacuum denitrification is used as the main technical means to remove ammonia nitrogen in the raw material, without adding chemical agents, and the vacuum ammonia nitrogen removal method is used to remove most of the ammonia nitrogen while achieving the concentration and enrichment of the raw material. The evaporated condensate can be recycled as ammonia water, and finally the feed liquid is pumped into the breakpoint chlorination reactor, and the remaining ammonia nitrogen is removed by the breakpoint chlorination method. After most of the ammonia nitrogen is removed by the vacuum ammonia removal method, only a small amount of sodium hypochlorite (breakpoint chlorination method) needs to be added to the raw material to reduce the ammonia nitrogen to the minimum, so that it finally meets the requirements as a biological carbon source; pH 6-9, COD≥156000ppm, B / C≥0.55, ammonia nitrogen value≤45ppm.

[0014] After using the technology of the present invention, hazardous waste disposal units that treat waste emulsions do not need to purchase additional carbon sources, and can achieve self-production and self-use of biological carbon sources internally.

[0015] In a specific embodiment, in order to achieve a better and more environmentally friendly denitrification effect, preferably, the ammonia nitrogen value after vacuum denitrification treatment in S3 is 100 to 200 ppm.

[0016] The vacuum denitrification of the present invention can be achieved by using a low-temperature evaporator. Preferably, the operating temperature of the vacuum denitrification treatment in S3 is 40 to 60° C., and the vacuum degree is -75 KPa to -95 KPa.

[0017] More preferably, the operating temperature of the vacuum denitrification treatment in S3 is 50°C and the vacuum degree is -95KPa.

[0018] In a specific embodiment, the waste emulsion pretreatment of the present invention can be filtered by tubular ultrafiltration membrane, preferably with a membrane surface flow rate of 3 to 5 m / s, and the suspended matter and colloidal substances can be more thoroughly removed by controlling the membrane surface flow rate to obtain a clear and transparent material. And the pretreatment of the raw material with tubular ultrafiltration membrane has less loss of effective ingredients, no phase change, no chemical change, mature technology and low energy consumption.

[0019] The pore size of the tubular ultrafiltration membrane may be a conventional pore size, and more preferably 30 nm.

[0020] In a specific embodiment, in order to achieve better retention of difficult-to-degrade macromolecules and make the effluent have better biodegradability, the reverse osmosis system of the present invention adopts a wide flow channel anti-pollution reverse osmosis membrane element. The operating pressure of the reverse osmosis treatment in S2 of the present invention is preferably 1.5-2.0 MPa, and more preferably 1.8 MPa.

[0021] In a specific embodiment, preferably, the pH value of the inflection point chlorination reaction in S3 is 6 to 7, and the reaction time is 0.5 to 2 hours.

[0022] The method for preparing biocarbon source from waste emulsion of the present invention can effectively recover the emulsified waste liquid and prepare it as biocarbon source, wherein the total nitrogen of the waste emulsion is 200-250 ppm and the ammonia nitrogen is 100-150 ppm.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The invention uses waste emulsion as a raw material to prepare a biological carbon source. The waste emulsion contains a large amount of macromolecular difficult-to-degrade substances. Reverse osmosis treatment has a significant interception effect on the macromolecular difficult-to-degrade substances, so that the content of macromolecular difficult-to-degrade substances in effluent is ≤5%, thereby improving the biodegradability of the material. A vacuum denitrification method is used as a main technical means for removing ammonia nitrogen in the raw material. The vacuum ammonia nitrogen removal method is used to remove most of the ammonia nitrogen while realizing the concentration and enrichment of the raw material. The breakpoint chlorination method is used to remove the remaining ammonia nitrogen, so that the waste emulsion can finally meet the requirements of being a biological carbon source; pH 6-9, COD ≥ 156000 ppm, B / C ≥ 0.55, and ammonia nitrogen value ≤ 45 ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0027] Example 1

[0028] A method for preparing a biocarbon source using waste emulsion, the process flow is as follows Figure 1 As shown, the following steps are included:

[0029] S1. First, the waste emulsion is pre-treated by a tubular ultrafiltration membrane to remove most of the suspended matter and colloidal substances, making the material clear and transparent. The tubular ultrafiltration membrane uses a 30nm pore size organic tubular ultrafiltration membrane and operates at a membrane surface flow rate of 4m / s;

[0030] S2. The output of the tubular ultrafiltration membrane enters the reverse osmosis system, and the interception effect of reverse osmosis on macromolecular refractory substances is used to further improve the biodegradability of the raw materials, so that the content of macromolecular refractory substances in the effluent is ≤5%. The reverse osmosis system uses a wide flow channel anti-pollution reverse osmosis membrane element with an operating pressure of 1.8Mpa;

[0031] S3. The reverse osmosis output is transported to the vacuum denitrification system, and most of the ammonia nitrogen in the raw material is removed by the removal effect of ammonia nitrogen under vacuum. The evaporated condensate can be recycled as ammonia water; finally, the feed liquid is pumped into the breakpoint chlorination reactor, and the remaining ammonia nitrogen is removed by the breakpoint chlorination method, so that it finally meets the requirements of being used as a biological carbon source.

[0032] The vacuum denitrification system can use a low-temperature evaporator to achieve vacuum denitrification. The operating temperature of the vacuum denitrification system is 50°C, the operating pH is about 9, the vacuum degree is -95kpa, and the reaction time is 1h. The condensate evaporated from the vacuum denitrification system can be recycled as ammonia water. The breakpoint chlorination reactor is used as a method for removing the remaining ammonia nitrogen after vacuum denitrification. The breakpoint chlorination method has a reaction pH of between 7 and a reaction time of 1h. The amount of sodium hypochlorite added is calculated based on the residual ammonia nitrogen concentration in the raw material.

[0033] Among them, the waste emulsion is the waste emulsion from a hazardous waste disposal unit, and the indicators are as follows:

[0034] Appearance: brown turbid emulsion; COD: 212357mg / L, B / C: 0.23, ammonia nitrogen concentration: 468mg / L, conductivity: 7369us / cm, pH: 7.3.

[0035] 5 tons of materials were treated in batches. After being filtered through tubular ultrafiltration membrane and reverse osmosis, the vacuum denitrification method was used to remove ammonia for 1 hour, and then the breakpoint chlorination method was used to react for 1 hour to obtain the product: 3.2 tons of carbon source, COD: 181324 mg / L, B / C: 0.57, ammonia nitrogen: 5.6 mg / L, conductivity: 69 us / cm, pH: 6.8. This carbon source was used as the carbon source for the sewage station whose wastewater process is A / O process. Ideal results have been achieved and the effluent quality meets the discharge standards. The specific test results are shown in Table 1.

[0036] Example 2

[0037] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the temperature of the vacuum denitrification treatment is 60°C.

[0038] Example 3

[0039] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the temperature of the vacuum denitrification treatment is 40°C.

[0040] Example 4

[0041] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the vacuum degree of vacuum denitrification treatment is -75KPa.

[0042] Example 5

[0043] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the operating pressure of the reverse osmosis treatment is 1.5 MPa.

[0044] Example 6

[0045] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the operating pressure of the reverse osmosis treatment is 2.0 MPa.

[0046] Example 7

[0047] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the pH value of the inflection point chlorination reaction in S3 is 7 and the reaction time is 0.5 h.

[0048] Example 8

[0049] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the pH value of the inflection point chlorination reaction in S3 is 6 and the reaction time is 2 hours.

[0050] Example 9

[0051] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the pretreatment in S1 adopts tubular ultrafiltration membrane filtration, and the operating membrane surface flow rate is 3m / s.

[0052] Example 10

[0053] A method for preparing a biocarbon source using waste emulsion is basically the same as Example 1, except that the pretreatment in S1 adopts tubular ultrafiltration membrane filtration, and the operating membrane surface flow rate is 5m / s.

[0054] The relevant carbon source COD value and carbon source B / C value test results of the bio-carbon source prepared by the method of preparing bio-carbon source using waste emulsion in the above Examples 1-10 are shown in Table 1.

[0055] The B / C value is the ratio of BOD to COD.

[0056] For specific BOD detection methods, please refer to HJ505-2009, and for COD detection methods, please refer to HJ / T399-2007.

[0057] Table 1. Biocarbon source indexes and application effluent indexes of Examples 1-10

[0058]

[0059]

[0060] Note: The above carbon sources are all added to the same sewage station. The water treatment process of the sewage station adopts the A / O process. When no biological carbon source is added, the total nitrogen in the effluent often exceeds 100ppm and cannot meet the takeover discharge standard. After adding the biological carbon source prepared by the present invention, the effluent ammonia nitrogen and total nitrogen can stably reach the takeover discharge standard. The above detection data 1-10 are the drainage monitoring data of the sewage station after adding the biological carbon source.

[0061] Comparative Example 1

[0062] A method for preparing a biocarbon source using waste emulsion comprises the following steps:

[0063] S1. First, the waste emulsion is pretreated by a tubular ultrafiltration membrane to remove most of the suspended matter and colloidal substances, making the material clear and transparent. The tubular ultrafiltration membrane uses a 30nm pore size organic tubular ultrafiltration membrane and operates at a membrane surface flow rate of 2m / s;

[0064] S2. The output of the tubular ultrafiltration membrane enters the reverse osmosis system, and the interception effect of reverse osmosis on macromolecular refractory substances is used to further improve the biodegradability of the raw materials, so that the content of macromolecular refractory substances in the effluent is ≤5%. The reverse osmosis system uses a wide flow channel anti-pollution reverse osmosis membrane element, and the operating pressure is 1.0Mpa;

[0065] S3. The reverse osmosis output is transported to the biochemical A / O process to remove ammonia nitrogen.

[0066] The waste emulsion is the waste emulsion from a hazardous waste disposal unit, and the indicators are the same as those in Example 1.

[0067] The product indicators obtained by treatment are as follows:

[0068] Carbon source 1.2 tons, COD: 138725mg / L, B / C: 0.37, ammonia nitrogen: 197mg / L, conductivity: 423us / cm, pH: 6.3.

[0069] It can be seen from the above that the carbon source obtained by removing ammonia nitrogen using the biochemical A / O process not only removes ammonia, but also removes BOD. The B / C value of the carbon source obviously cannot meet the requirement of ≥0.55. The preparation of the biological carbon source requires the retention of BOD. The method of preparing the biological carbon source using the waste emulsion of the present invention does not require the addition of chemical agents. The vacuum ammonia nitrogen removal method is used to remove most of the ammonia nitrogen while achieving the concentration and enrichment of the raw materials, reducing the ammonia nitrogen to a minimum, and ultimately meeting the requirements as a biological carbon source.

[0070] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a biocarbon source using waste emulsion, characterized in that: The steps include: S1. Pre-treating the waste emulsion to remove suspended solids and colloidal substances to obtain a clear and transparent material; S2. The clear and transparent material is subjected to reverse osmosis treatment so that the content of macromolecular refractory substances in the effluent is ≤5%; S3. The reverse osmosis effluent in S2 is subjected to vacuum denitrification treatment and inflection point chlorination reaction to remove ammonia nitrogen, and the reaction product is the biological carbon source. Among them, the macromolecular refractory substances in S2 are organic molecules with a molecular weight ≥150.

2. The method for preparing a biocarbon source using waste emulsion according to claim 1, characterized in that: The ammonia nitrogen value after vacuum denitrification treatment in S3 is 100-200 ppm.

3. The method for preparing a biocarbon source using waste emulsion according to claim 2, characterized in that: The operating temperature of the vacuum denitrification treatment in S3 is 40-60°C, and the vacuum degree is -75KPa--95KPa.

4. The method for preparing a biocarbon source using waste emulsion according to claim 3, characterized in that: The operating temperature of the vacuum denitrification treatment in S3 is 50°C and the vacuum degree is -95KPa.

5. The method for preparing a biocarbon source using waste emulsion according to claim 1, characterized in that: The pretreatment in S1 adopts tubular ultrafiltration membrane filtration, and the operating membrane surface flow rate is 3 to 5 m / s.

6. The method for preparing a biocarbon source using waste emulsion according to claim 5, characterized in that: The pore size of the tubular ultrafiltration membrane described in S1 is 30 nm.

7. The method for preparing a biocarbon source using waste emulsion according to claim 1, characterized in that: The operating pressure of the reverse osmosis treatment in S2 is 1.5 to 2.0 MPa.

8. The method for preparing a biocarbon source using waste emulsion according to claim 7, characterized in that: The operating pressure of the reverse osmosis treatment in S2 is 1.8 MPa.

9. The method for preparing a biocarbon source using waste emulsion according to claim 1, characterized in that: The pH value of the inflection point chlorination reaction in S3 is 6-7, and the reaction time is 0.5-2h.

10. The method for preparing a biocarbon source using waste emulsion according to any one of claims 1 to 9, characterized in that: The total nitrogen content of the waste emulsion is 200-250 ppm, and the ammonia nitrogen content is 100-150 ppm.

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