A treatment agent and treatment method for kitchen waste leachate

Abstract

The present invention belongs to the technical field of sewage treatment, and specifically discloses a treatment agent for kitchen waste leachate, which comprises modified zeolite, lipase and protease; the modified zeolite is zeolite with magnetite nanoparticles deposited on the surface, and the content of magnetite is 10-30 Wt.%. The present invention also provides the application of the treatment agent in the full aerobic treatment process of kitchen waste leachate, which can achieve the synchronous removal of COD Cr , ammonia nitrogen, total nitrogen and total phosphorus during the aerobic treatment process. In particular, the synchronous removal effect of ammonia nitrogen and total nitrogen can reach more than 90%.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular, a treatment agent is used for the preparation and application of improving the full aerobic treatment of food waste leachate. Background Art

[0002] According to the China Statistical Yearbook, the amount of food waste in China shows an increasing trend year by year. A large amount of food waste will produce food waste leachate with a thick and stinking odor after stacking, biochemical degradation or compaction treatment. Among them, this liquid contains a large amount of organic substances such as proteins, sugars, and lipids, high ammonia nitrogen, and is extremely easy to rot and stink and breed pathogenic bacteria. If not effectively treated, it is easy to pollute the surrounding environment and groundwater, and can cause the spread of diseases in severe cases. At present, the main treatment method for food waste leachate is the biological method, which has the advantages of low operating cost, high treatment efficiency, and no secondary pollution. The biological method includes aerobic biological method and anaerobic biological method.

[0003] However, in the current process of treating food waste leachate by biological methods, anaerobic fermentation is the mainstream method, but anaerobic fermentation is mainly used for high-load food waste leachate, and generally needs to be used in combination with other reactors to achieve a better overall synchronous treatment effect. The aerobic treatment also cannot achieve a better synchronous removal effect, and is easily inhibited by high grease and high protein during operation.

[0004] Therefore, for the treatment method of food waste leachate, there is currently a need for a method to synchronously remove COD, ammonia nitrogen, total phosphorus, and total nitrogen from food waste leachate. Summary of the Invention

[0005] Aiming at the problems of complex composition of food waste leachate and difficulty in synchronously removing COD, ammonia nitrogen, total phosphorus, and total nitrogen, the first object of the present invention is to provide a treatment agent for food waste leachate, aiming to provide a treatment agent that can effectively synchronously remove COD, ammonia nitrogen, total phosphorus, and total nitrogen from food waste leachate.

[0006] The second object of the present invention is to provide a method for treating food waste leachate based on the above treatment agent.

[0007] The composition of food waste leachate is complex and the removal is difficult, especially it is difficult to synchronously remove COD, ammonia nitrogen, total phosphorus, and total nitrogen. In view of this problem, the present invention provides the following solutions:

[0008] A treatment agent for food waste leachate, comprising modified zeolite, lipase and protease;

[0009] The modified zeolite is zeolite with magnetite nanoparticles deposited on the surface, and the content of magnetite is 10-30 Wt.%.

[0010] The present invention innovatively discovers that the combination of the modified medical stone, lipase, and protease can achieve synergy, significantly solve the problem of difficult treatment of kitchen waste leachate, and achieve the simultaneous removal of COD, ammonia nitrogen, total phosphorus, and total nitrogen.

[0011] In the present invention, in the modified medical stone, the magnetite nanocrystals are uniformly deposited on its surface, and it has good treatment effects. Moreover, when it is used in combination with lipase and protease, it can further induce enzymatic reactions, thereby synergistically improving the simultaneous removal effects of COD, ammonia nitrogen, total phosphorus, and total nitrogen in kitchen waste leachate.

[0012] In the present invention, the medical stone, water-soluble ferrous salt, and water-soluble iron salt are mixed in liquid phase to obtain a solution, and then an alkali solution is added dropwise for deposition reaction to obtain the modified medical stone.

[0013] The research of the present invention discovers that, innovatively using the medical stone as an induction substrate and combining it with the alkali precipitation method can induce the nucleation and deposition of magnetite on the surface of the medical stone, improve the phase, and moreover, help to construct active sites, improve its own catalytic ability, and also help to improve the enzymatic reactions of protease and lipase.

[0014] Preferably, the water-soluble ferrous salt is at least one of ferrous chloride, ferrous sulfate, ferrous nitrate, and ferrous acetate;

[0015] Preferably, the water-soluble iron salt is at least one of ferric chloride, ferric sulfate, and ferric nitrate;

[0016] Preferably, the molar ratio of Fe 2+ to Fe 3+ in the solution is 1-3:1.

[0017] Preferably, the mass ratio of the medical stone to the water-soluble ferrous salt is 2-4:1. The research of the present invention discovers that at this preferred ratio, the simultaneous removal effects of COD, ammonia nitrogen, total phosphorus, and total nitrogen in kitchen waste leachate can be further synergistically improved.

[0018] Preferably, the alkali solution is an aqueous solution of at least one of NH3·H2O, NaOH, and KOH, and its solute concentration is preferably 1-3 mol / L;

[0019] Preferably, the pH during the deposition process and at the end of deposition is 9-11.

[0020] Preferably, the deposition reaction time is 2-3 h.

[0021] In the present invention, both the lipase and the protease are enzymes that have been activated. The activation method can be well-known in the industry. In the present invention, it is preferred to activate the enzyme by placing it in a phosphate buffer solution.

[0022] In the present invention, the dosage ratios of the modified zeolite, lipase and protease in the treatment agent for kitchen waste leachate can be adjusted as needed. For example, the weight ratio of the modified zeolite, lipase and protease is 1: 0.05-0.52: 0.02-0.13.

[0023] In the present invention, the treatment agent can be used in a solid state or in a solution state.

[0024] The preparation steps of the treatment agent described in the present invention include:

[0025] S1: Activate the lipase and protease respectively;

[0026] S2: Modify the zeolite; the steps are as follows:

[0027] Soak the original zeolite in distilled water, wash it and dry it, crush the zeolite with a pulverizer, and sieve it for later use; put ferrous chloride, ferric chloride and the sieved zeolite into a beaker, and add deionized water; add a sodium hydroxide solution dropwise to the above suspension, and stir at room temperature; after the reaction is completed, separate the solid and liquid to obtain the modified zeolite. The molar ratio of Fe 2+ and Fe 3+ in the reaction solution is 1-3: 1; the mass ratio of zeolite to ferrous chloride is 2-4: 1; the molar concentration of the alkali solution is 1-3 mol / L; the pH of the deposition process and the deposition end point is 9-11; the reaction stirring time is 2-3 h.

[0028] S3: Compound the activated lipase, protease and modified zeolite according to the volume ratio.

[0029] Mix the lipase and protease according to the volume ratio of 2-4: 1, and dissolve 5-9 g of modified zeolite in the mixed solution of lipase and protease.

[0030] The present invention also provides a method for treating kitchen waste leachate, in which the treatment agent is placed in the kitchen waste leachate for a fully aerobic reaction to obtain treated effluent.

[0031] The present invention has found that thanks to the use of the treatment agent, it is possible to synergistically improve the simultaneous removal effects of COD Cr , ammonia nitrogen, total phosphorus and total nitrogen in the kitchen waste leachate.

[0032] In the present invention, there is no special requirement for the content of the pollutants in the kitchen waste leachate. For example, the COD CrCOD is greater than or equal to 500 mg / L, ammonia nitrogen is greater than or equal to 20 mg / L, and total nitrogen is greater than or equal to 120 mg / L;

[0033] Preferably, in the kitchen waste leachate, the COD Cr is 500 - 12000 mg / L, ammonia nitrogen is 20 - 500 mg / L, total phosphorus is 1 - 5.2 mg / L, and total nitrogen is 120 - 800 mg / L.

[0034] In the present invention, the dosage of the treatment agent can be adjusted according to the pollution situation. Preferably, the dosage of the treatment agent is 50 - 300 ppm;

[0035] Preferably, the dissolved oxygen concentration during the treatment process is 1 - 5 mg / L;

[0036] Preferably, the concentration of sludge during the treatment process is 5 - 15 g / L;

[0037] Preferably, after the fully aerobic reaction treatment, membrane filtration is carried out to obtain the treated effluent.

[0038] The present invention also provides the application of the treatment agent in the fully aerobic treatment process of kitchen waste leachate. The treatment agent prepared by the method is added to the reactor at the initial stage of the reaction, and aeration reaction is carried out for 1 - 3 d to obtain the effluent. The effluent passes through a 0.45 μm membrane, and the COD Cr , ammonia nitrogen, total phosphorus and total nitrogen of the kitchen waste leachate before and after biochemical treatment are measured according to the national standard. The absorbance in the ultraviolet region before and after biochemical treatment is measured by using an ultraviolet-visible spectrophotometer, and the removal rates of COD Cr , ammonia nitrogen, total phosphorus and total nitrogen are calculated. The effluent result after adding the treatment agent is analyzed by three-dimensional fluorescence spectroscopy.

[0039] Advantages and positive effects of the invention:

[0040] (1) The present invention combines the modified zeolite, lipase and protease, which can achieve synergy, can significantly solve the problem that the kitchen waste leachate is difficult to treat, and can achieve the simultaneous removal of COD Cr , ammonia nitrogen, total phosphorus and total nitrogen.

[0041] (2) In view of the characteristics and treatment difficulties of the kitchen waste leachate, the present invention innovatively combines based on the components of the treatment agent, which can induce and promote the activities of protease-lipase. Moreover, it can increase the oxygen transport amount, improve the biocompatibility, and is beneficial to the microbial film formation and reproduction, thereby synergistically improving the simultaneous treatment effects of COD, ammonia nitrogen, total phosphorus and total nitrogen.

[0042] (3) Using the treatment agent prepared by the present invention to promote the biochemical degradation of the kitchen waste leachate, for COD CrThe food waste leachate with a COD content of 250 - 12000 mg / L, an ammonia nitrogen content of 100 - 300 mg / L, and a total nitrogen content of 8000 - 20000 mg / L can enable the synchronous removal of COD, Cr ammonia nitrogen, total nitrogen, and total phosphorus during the aerobic treatment process. In particular, the synchronous removal effect of ammonia nitrogen and total nitrogen can reach over 90%. Description of the Drawings

[0043] [Appendix Figure 1 is the SEM image of untreated zeolite (left figure) and the modified zeolite prepared in Example 1 (right figure). It can be seen that magnetite nanoparticles are deposited on its surface.

[0044] [Appendix Figure 2 is the ultraviolet-visible spectrogram of the food waste leachate in Example 2 after adding the composite auxiliary agent during the biochemical process. During the reaction process, as time prolongs, the absorbance in the ultraviolet region gradually decreases, indicating that the concentration of organic matter in the food waste leachate decreases, and both the aromaticity and the degree of conjugation decrease.

[0045] [Appendix Figure 3 is the fluorescence spectrum change of the food waste leachate in Example 2 after adding the composite auxiliary agent during the biochemical process. The continuous degradation of microbial by-products and the rapid formation of humic acid-like and fulvic acid-like organic substances are the main transformation trends during the reaction stage.

[0046] [Appendix Figure 4 is the fluorescence region integral map of the regions divided in the three-dimensional fluorescence spectrum. It can be seen from the figure that during the initial treatment process, a small part of aromatic proteins are rapidly decomposed by microorganisms; at the same time, a large amount of humic acid-like substances are formed; and the microbial by-products decrease significantly.

[0047] [Appendix Figure 5 is the microbial community situation in the sludge of the food waste leachate after adding the composite auxiliary agent. Analyzing the community composition at the phylum level, adding the treatment agent (B-II) significantly increases the Proteobacteria during the aerobic treatment process, while the microbial communities during the aerobic treatment processes with the addition of ordinary zeolite (B-I) and without any additives (B) do not change much.

[0048] [Appendix Table 7] is the microbial Alpha diversity analysis of the sludge of the food waste leachate after adding the composite auxiliary agent,

[0049] The Chao index indicates the size of the number of species to a certain extent. The larger its value, the more species there are. It can be seen that B-II has the largest number of species. Detailed Embodiments

[0050] The technical solutions adopted in this application are introduced in detail below with reference to examples. The background information on some of the materials and experimental instruments involved in the experiments is introduced as follows:

[0051] Experimental materials:

[0052] Both lipase and protease were purchased from Nanjing Aoduofuni Biotechnology Co., Ltd.;

[0053] The zeolite came from Mengyin, Shandong;

[0054] The leachate of food waste was taken from a garbage transfer station in Xiangxiang, Hunan. The water quality conditions were: COD Cr was 50 - 12000 mg / L, ammonia nitrogen was 20 - 500 mg / L, total phosphorus was 1 - 5.2 mg / L, and total nitrogen was 60 - 800 mg / L.

[0055] Partial detection methods and standards:

[0056] The COD of the food waste leachate before and after degradation was determined according to HJ / T 399 - 2007 Cr ; the ammonia nitrogen of the food waste leachate before and after degradation was determined using HJ535 - 2009; the total nitrogen of the food waste leachate before and after degradation was determined using GJ 11894 - 89.

[0057] Examples 1 - 9

[0058] I. The treatment agent provided by this application has the following specific preparation method.

[0059] (1) Activate lipase and protease as follows:

[0060] Add 2 g of lipase to a 100 mL stoppered conical flask, add 50 mL of phosphate buffer solution (0.05 mol / L), place it in a constant temperature oscillator, shake to evenly disperse the enzyme in the buffer solution, control the temperature at 25 - 30 °C, and activate the enzyme for 30 min;

[0061] Add 2 g of protease to a 100 mL stoppered conical flask, add 50 mL of phosphate buffer solution (0.05 mol / L), place it in a constant temperature oscillator, shake to evenly disperse the enzyme in the buffer solution, control the temperature at 25 - 30 °C, and activate the enzyme for 30 min;

[0062] (2) Soak the raw zeolite in distilled water for 24 h, wash it and dry it, then crush the zeolite with a pulverizer and sieve it through a 200 - mesh sieve for standby; according to Fe 2+ 、Fe 3+Weigh ferrous chloride and ferric chloride in a molar ratio of 1 to 3:1, and the mass ratio of zeolite to ferrous chloride is 2 to 4:1; add 100 mL of deionized water; add 1 to 3 mol / L sodium hydroxide solution to the above suspension until the pH reaches 9 - 11, then stop adding the alkali solution, and stir at room temperature for 2 to 3 h; after the reaction is completed, separate the solid and liquid to obtain the modified zeolite.

[0063] (3) Mix the lipase and protease in step (1) evenly according to a volume ratio of 2 to 4:1. Add 5 to 9 g of the modified zeolite to 100 mL of the enzyme solution mixed evenly by volume ratio, which can be used as a treatment agent in the treatment process of kitchen waste leachate.

[0064] Second, for the biological aerobic treatment of kitchen waste leachate, investigate the influence of the treatment agent on the biochemical process

[0065] The influent water for this experiment is taken from kitchen waste leachate. The influent COD is about 12000 mg / L, ammonia nitrogen is about 400 mg / L, total nitrogen is about 600 mg / L, total phosphorus is about 5.2 mg / L, the dissolved oxygen is controlled at 2.5 mg / L, the pH is in the range of 7 - 7.5, and the sludge concentration is controlled at 10 g / L. Pour the prepared 100 ppm enzyme mixed solution into the reactor (the reaction volume is 2 L), take out the water after 2 d of treatment, and calculate the removal rates of COD, ammonia nitrogen, and total nitrogen after biochemical treatment (see Table 1).

[0066] Table 1 Investigate the treatment effect of different treatment agent ratios on kitchen waste leachate

[0067]

[0068]

[0069] Examples 10 - 16

[0070] Prepare the enzyme mixture and modified zeolite according to Example 2, and investigate the degradation of kitchen waste leachate under different reaction conditions (see Table 2).

[0071] Table 2 Investigate the removal effect of different conditions on kitchen waste leachate

[0072]

[0073] Examples 17 - 19

[0074] Add the treatment agent prepared in Example 7 in an amount of 100 ppm to the reactor to treat kitchen waste leachate with different water qualities (see Table 3).

[0075] Table 3 Investigate the treatment of different kitchen waste leachates by the treatment agent

[0076]

[0077]

[0078] Comparative Examples 1-2

[0079] Dolomite and montmorillonite were used to replace medical stone in the same way as in Example 1 for modification, and the mixed solution with the enzyme was used as the treatment agent. 100 ppm of the treatment agent was added to the kitchen waste leachate, and after treatment for 2 days, the water was taken out to calculate the removal rates of COD, ammonia nitrogen, total nitrogen and total phosphorus after biochemical treatment (see Table 4).

[0080] Table 4 Treatment of different kitchen waste leachates with treatment agents prepared from different ores

[0081]

[0082] Comparative Examples 3-4

[0083] The influent COD of the kitchen waste leachate was about 12000 mg / L, ammonia nitrogen was about 400 mg / L, total nitrogen was about 600 mg / L, and total phosphorus was about 1-5.2 mg / L; the dissolved oxygen was controlled at 2-4 mg / L, the PH was in the range of 7-7.5, and the sludge concentration was controlled at 10 g / L. Only the combination of lipase and modified medical stone and only the treatment agent of protease and modified medical stone were added to the kitchen waste leachate. The enzyme solution was 20 g / L, 100 ppm of the treatment agent was added, and after treatment for 2 days, the water was taken out to calculate the removal rates of COD, ammonia nitrogen, total nitrogen and total phosphorus after biochemical treatment (see Table 5).

[0084] Table 5 Treatment of kitchen waste leachate with different enzyme additions

[0085]

[0086]

[0087] Comparative Example 5

[0088] The influent water quality of the kitchen waste leachate was the same as that in Example 3. Lipase and protease were mixed evenly at a volume ratio of 2:1. 6.7 g of medical stone and 2.3 g of Fe3O4 were added to 100 mL of the enzyme solution mixed evenly by volume ratio to prepare a treatment agent. 100 ppm of the treatment agent was added to the kitchen waste leachate, and after treatment for 2 days, the water was taken out to calculate the removal rates of COD, ammonia nitrogen, total nitrogen and total phosphorus after biochemical treatment (see Table 6).

[0089] Table 6 Biochemical effect of the treatment agent prepared by mixing ordinary medical stone and Fe3O4 on kitchen waste leachate

[0090]

[0091] Comparative Example 6

[0092] The influent quality of the kitchen waste leachate was the same as that in Example 4. Lipase and protease were mixed evenly at a volume ratio of 4:1. Ferrous chloride and ferric chloride were weighed according to a molar ratio of Fe 2+ 、Fe 3+ of 2:1. The mass ratio of zeolite to ferrous chloride was 2:1. Stir at room temperature for 2 - 3 h. After the reaction was completed, solid-liquid separation was carried out to obtain modified zeolite. 7 g of the modified zeolite was added to 100 mL of the enzyme solution mixed evenly by volume to obtain a treatment agent. 100 ppm of the treatment agent was added to the kitchen waste leachate, and after treatment for 2 d, the water was taken out and the removal rates of COD, ammonia nitrogen, total nitrogen and total phosphorus after biochemical treatment were calculated (see Table 7).

[0093] Table 7 Biochemical effects of the treatment agent prepared by ordinary addition of Fe 2+ and Fe 3+ on kitchen waste leachate

[0094]

[0095]

[0096] Comparative Examples 7 - 8

[0097] Compared with Example 1, the difference was only the weight ratio of zeolite:FeCl2, that is, the content of magnetite in the modified zeolite was controlled, and other operations and parameters were the same as those in Example 1.

[0098] Table 8 Treatment effects of the treatment agent prepared by changing the key innovation points on kitchen waste leachate

[0099]

[0100] It can be seen that by using the method of the present invention, the comprehensive removal effect of kitchen waste leachate can be synergistically improved.

[0101] Comparative Example 9

[0102] For the kitchen waste leachate (the same as in Example 1), after directly treating for 2 d without adding any substances, the water was taken out and the removal rates of COD, ammonia nitrogen and total nitrogen after biochemical treatment were calculated (see Table 6).

[0103] Table 6 Investigation of the treatment of different kitchen waste leachates without adding a treatment agent

[0104]

[0105] Table 7 Indicator table of sample diversity and abundance

[0106]

[0107] In summary, based on the above examples and comparative examples, it can be seen that adding a treatment agent composed of lipase, protease and zeolite can simultaneously improve the removal rates of COD Cr , ammonia nitrogen, total nitrogen and total phosphorus.

Claims

1. A treatment agent for kitchen waste leachate, characterized in that, It includes modified picrolite, lipase and protease; The modified picrolite is picrolite with magnetite nanoparticles deposited on its surface, and the content of magnetite is 10 - 30 Wt.%; Mix picrolite, water-soluble ferrous salt and water-soluble ferric salt in liquid phase to obtain a solution, and then dropwise add an alkali solution to carry out a deposition reaction to obtain the modified picrolite; Fe in the solution 2+ and Fe 3+ have a molar ratio of 1 to 3:1; the mass ratio of zeolite to water-soluble ferrous salt is 2 to 4:

1.

2. The treatment agent for kitchen waste leachate according to claim 1, characterized in that, The water-soluble ferrous salt is at least one of ferrous chloride, ferrous sulfate, ferrous nitrate, and ferrous acetate.

3. The treatment agent for kitchen waste leachate according to claim 1, characterized in that, The water-soluble ferric salt is at least one of ferric chloride, ferric sulfate, and ferric nitrate.

4. The treatment agent for kitchen waste leachate according to claim 3, characterized in that, The alkali solution is an aqueous solution of at least one of NH₃·H₂O, NaOH, and KOH.

5. The treatment agent for kitchen waste leachate according to claim 4, characterized in that, The solute concentration of the alkali solution is 1 - 3 mol / L.

6. The treatment agent for kitchen waste leachate according to claim 1, characterized in that, The pH during the deposition process and at the end point of deposition is 9 - 11.

7. The treatment agent for kitchen waste leachate according to claim 1, characterized in that, The time of the deposition reaction is 2 - 3 h.

8. The treatment agent for kitchen waste leachate according to claim 1, characterized in that, Both the lipase and protease are enzymes that have been activated.

9. The treatment agent for kitchen waste leachate according to any one of claims 1 to 8, characterized in that, The weight ratio of the modified picrolite, lipase and protease is 1:0.05 - 0.52:0.02 - 0.

13.

10. A treatment method for kitchen waste leachate, characterized in that, Place the treatment agent described in any one of claims 1 - 9 into the leachate of food waste for a fully aerobic reaction to obtain treated effluent.

11. The treatment method for kitchen waste leachate according to claim 10, characterized in that, In the kitchen waste leachate, the COD Cr is greater than or equal to 500 mg / L, ammonia nitrogen is greater than or equal to 20 mg / L, total phosphorus is greater than or equal to 1 mg / L, and total nitrogen is greater than or equal to 120 mg / L.

12. The treatment method for kitchen waste leachate according to claim 11, characterized in that, In the kitchen waste leachate, the COD Cr is 500~12000 mg / L, ammonia nitrogen is 20~500 mg / L, total phosphorus is 1~5.2 mg / L, and total nitrogen is 120~800 mg / L.

13. The treatment method for kitchen waste leachate according to any one of claims 10 to 12, characterized in that, The dosage of the treatment agent is 50 - 300 ppm.

14. The treatment method for kitchen waste leachate according to claim 13, characterized in that, The dissolved oxygen concentration during the treatment process is 1 - 5 mg / L.

15. The treatment method for kitchen waste leachate according to claim 13, characterized in that, The concentration of sludge during the treatment process is 5 - 15 g / L.

16. The treatment method for kitchen waste leachate according to claim 13, characterized in that, After the fully aerobic reaction treatment, carry out membrane filtration to obtain the treated effluent.

Images