Landfill leachate pretreatment method and application thereof

Abstract

The invention relates to a landfill leachate pretreatment method and application thereof, and the landfill leachate pretreatment method comprises the following steps: carrying out a crushing step, a reaction step and a granulation step on landfill leachate in sequence to complete pretreatment. When the landfill leachate pretreatment method is applied to the aspect of landfill leachate, the pretreatment efficiency of the landfill leachate can be improved, the hydraulic retention time is short, and the utilization rate of water resources can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a landfill leachate pretreatment method and application thereof. Background Art

[0002] Landfill leachate is a mixture of infiltrated rainwater, water produced by biodegradation of garbage, and inherent water in garbage, which contains a large amount of dissolved organic matter, salts, and heavy metal ions. In addition, the content of salinity, ammonia nitrogen, humic acid and other substances in landfill leachate is high, and it contains a variety of harmful substances, including a variety of anilines and aromatic compounds. Therefore, landfill leachate is a wastewater with high color, strong odor, complex components of pollutants, high concentration of pollutants, and large changes in water quality and quantity. If landfill leachate is directly incorporated into the urban sewage treatment plant for treatment, it is easy to cause the collapse of the original municipal sewage system, and in severe cases, it will cause serious damage to the environment.

[0003] At present, the pretreatment processes for landfill leachate at home and abroad mainly include: adsorption method, coagulation sedimentation method, biological method, advanced oxidation method, etc. Among them, the simplest method is the traditional coagulation sedimentation method. Compared with other pretreatment processes, traditional coagulation can remove more types of pollutants and has extremely low comprehensive costs. It can maximize the removal efficiency by simply changing the water quality conditions, water flow shear force, dosing time and dosing amount. However, traditional coagulation as a pretreatment process for landfill leachate has problems such as poor turbidity removal effect, loose flocs, and low water resource recovery rate. Summary of the invention

[0004] In order to solve at least one of the above technical problems, the present invention provides a landfill leachate pretreatment method and application thereof; the pretreatment efficiency of landfill leachate can be improved, and the hydraulic retention time is short, which can improve the utilization rate of water resources.

[0005] As one aspect, the present invention provides a method for pretreating landfill leachate, which comprises: subjecting the landfill leachate to a crushing step, a reaction step and a granulation step in sequence to complete the pretreatment.

[0006] In some embodiments of the present invention, the stirring rate of the crushing step is 1000-3000 r / min, for example, it can be 1003 r / min, 1296 r / min, 1498 r / min, 1683 r / min, 1853 r / min, 2198 r / min, 2539 r / min, 2798 r / min, 2979 r / min, etc.; and / or, the time of the crushing step is 20-60 min, for example, it can be 29 min, 37 min, 43 min, 49 min, 52 min, 56 min, 59 min, etc.

[0007] In some embodiments of the present invention, the reaction step includes: after adding the coagulant, adjusting the pH with an alkaline solution, reacting for 5-20 minutes, which can be 8 minutes, 11 minutes, 13 minutes, 16 minutes, 17 minutes, 19 minutes, etc.; wherein, at the end of the reaction step, the pH value of the leachate is 11-13, for example, it can be 11.3, 11.6, 11.9, 12.1, 12.3, 12.6, 12.9, etc.

[0008] In some embodiments of the present invention, the concentration of the coagulant is 500-5000 mg / L, for example, it can be 568 mg / L, 638 mg / L, 729 mg / L, 1239 mg / L, 2178 mg / L, 2997 mg / L, 3408 mg / L, 3957 mg / L, 4618 mg / L, 4937 mg / L, etc.; and / or the concentration of the alkaline solution is 1-5 mol / L, for example, it can be 1.3 mol / L, 1.6 mol / L, 1.9 mol / L, 2.1 mol / L, 2.9 mol / L, 3.3 mol / L, 3.9 mol / L, 4.3 mol / L, 4.9 mol / L, etc.

[0009] In some embodiments of the present invention, the coagulant is polyaluminium chloride; and / or the alkaline solution is sodium hydroxide solution or potassium hydroxide solution.

[0010] In some embodiments of the present invention, the stirring rate of the reaction step is 100-1000 r / min, for example, it can be 129 r / min, 248 r / min, 376 r / min, 497 r / min, 598 r / min, 687 r / min, 789 r / min, 897 r / min, 923 r / min, 987 r / min, etc.

[0011] In some embodiments of the present invention, the granulation step includes: adding a flocculant to the landfill leachate for granulation to obtain pretreated landfill leachate.

[0012] In some embodiments of the present invention, the concentration of the flocculant is 10-50 mg / L; for example, it can be 13 mg / L, 19 mg / L, 23 mg / L, 29 mg / L, 33 mg / L, 39 mg / L, 43 mg / L, 49 mg / L, etc.

[0013] In some embodiments of the present invention, the stirring rate of the granulation step is 20-60r / min, for example, it can be 23r / min, 29r / min, 34r / min, 39r / min, 47r / min, 53r / min, 57r / min, 59r / min, etc.; and / or the reaction time of the granulation step is 30-60min, for example, it can be 33min, 39min, 43min, 47min, 51min, 53min, 56min, 59min, etc.; and / or the flocculant is polyacrylamide.

[0014] As another aspect, the present invention provides an application of the above-mentioned landfill leachate pretreatment method in treating landfill leachate.

[0015] The technical solution of the embodiment of the present invention has the following advantages:

[0016] The method for pretreating the landfill leachate of the embodiment of the present invention is sequentially subjected to the pretreatment process of the crushing step, the reaction step and the granulation step, and the chemical oxygen demand (COD) in the landfill leachate can be removed by 20-30%, the turbidity (NTU) removal rate is 80-95%, and the solid suspended matter (SS) removal rate is 80-95%. Among them, the crushing step is to crush and homogenize the original particles in the landfill leachate; the reaction step is to make the crushed homogenized particles complex the pollutants in the leachate under the action of the agent; the granulation step is to aggregate and grow the floccules generated in the reaction step again to generate granular sludge. Such a method is 20-30% higher than the traditional coagulation method, and provides an efficient pretreatment method for the subsequent further treatment of the landfill leachate. In addition, compared with the traditional coagulation method for pretreating landfill leachate, the granulation coagulation method provided by the present invention can improve the pretreatment efficiency of landfill leachate, and the hydraulic retention time is short, which can improve the utilization rate of water resources. This is because there are a large number of metal ions in the leachate, which can provide a nucleation basis for the aggregation of flocs. At the same time, under the action of high pH, ​​the net capture and sweeping coagulation can improve the pollutant removal rate. In addition, the regulation of hydraulic conditions can compress and dehydrate the flocs, making them more compact, and ultimately increase the sedimentation rate of the flocs, reducing the overall reaction hydraulic retention time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 is a macroscopic schematic diagram of landfill leachate that has not been treated by the landfill leachate pretreatment method according to an embodiment of the present invention;

[0020] Figure 2 This is a macroscopic schematic diagram of landfill leachate treated by the landfill leachate pretreatment method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0023] According to an embodiment of the present invention, a method for pretreating landfill leachate is provided. The method for pretreating landfill leachate comprises: subjecting the landfill leachate to a crushing step, a reaction step and a granulation step in sequence to complete the pretreatment.

[0024] The landfill leachate pretreatment method of the embodiment of the present invention can remove 20-30% of COD, 80-95% of turbidity and 80-95% of SS in the landfill leachate through the pretreatment process; it provides an efficient pretreatment method for the subsequent further treatment of landfill leachate. In addition, compared with the traditional coagulation method for pretreating landfill leachate, the granulation coagulation method provided by the present invention can improve the pretreatment efficiency of landfill leachate, and the hydraulic retention time is short, which can improve the utilization rate of water resources.

[0025] In some embodiments of the present invention, the landfill leachate pretreatment method is implemented in three steps, namely a crushing step, a reaction step and a granulation step.

[0026] In some embodiments of the present invention, the crushing step specifically includes: wherein, the stirring rate is 1000-3000r / min, the time is 20-60min, and no other parameters need to be adjusted, the purpose is to crush and homogenize the original particles in the leachate; after completion, enter the reaction step.

[0027] In some embodiments of the present invention, the reaction step specifically includes: performing the reaction step after the rapid crushing step is completed, adding a coagulant at the beginning of the reaction step, preferably polyaluminium chloride (PAC), the amount of the coagulant added is generally 500-5000mg / L (specifically determined according to the actual pollutant concentration in the landfill leachate), and then using an alkaline solution to adjust the pH value, wherein the alkaline solution is 1-5mol / L, and the alkaline solution can be a sodium hydroxide or potassium hydroxide solution. The addition of the alkaline solution must be controlled by a peristaltic pump to control the dosing rate so that the pH value of the landfill leachate reaches 11-13 at the end of the reaction step, and the stirring rate during the entire reaction step is 100-1000r / min, and the reaction time is 5-20min.

[0028] In some embodiments of the present invention, the granulation step specifically includes: the stirring rate of the granulation step is 20-60r / min, and the reaction time is 30-60min; wherein, a certain amount of flocculant is added at the beginning of the granulation step, preferably polyacrylamide (PAM), the type of polyacrylamide (PAM) can be cationic or anionic, and the dosage concentration is 10-50mg / L.

[0029] According to an embodiment of the present invention, there is provided an application of the above-mentioned landfill leachate pretreatment method in treating landfill leachate.

[0030] In order to further illustrate the effect of the present invention, specific embodiments are used for illustration below.

[0031] Example 1

[0032] This embodiment provides a method for pretreating landfill leachate.

[0033] The landfill leachate pretreatment method of this embodiment is implemented in three steps:

[0034] (1) Crushing step: wherein the stirring rate is 1000-3000 r / min, the time is 20-60 min, and no other parameters need to be adjusted, the purpose is to crush and homogenize the original particles in the landfill leachate. After completion, the reaction step is entered.

[0035] (2) Reaction step: After the rapid crushing step is completed, the reaction step is carried out. At the beginning of the reaction step, a coagulant is added, preferably polyaluminium chloride (PAC), and the addition amount is generally 500-5000 mg / L (determined according to the actual pollutant concentration in the landfill leachate). Then, an alkaline solution is used to adjust the pH value, wherein the alkaline solution is 1-5 mol / L, and the alkaline solution can be a sodium hydroxide or potassium hydroxide solution. The addition of the alkaline solution must be controlled by a peristaltic pump to achieve a pH value of 11-13 at the end of the reaction step, and the stirring rate during the entire reaction step is 100-1000 r / min, and the reaction time is 5-20 min.

[0036] (3) Granulation step: In this process, the stirring rate is 20-60 r / min, and the reaction time is 30-60 min. A certain amount of polyacrylamide (PAM) is added at the beginning of the granulation step. The type of polyacrylamide (PAM) can be cationic or anionic, and the dosage concentration is 10-50 mg / L.

[0037] In the landfill leachate pretreatment method of this embodiment, after the pretreatment process, the COD in the landfill leachate can be removed by 20-30%, the turbidity removal rate is 80-95%, and the SS removal rate is 80-95%.

[0038] Figure 1 is a macroscopic schematic diagram of landfill leachate that has not been treated by the landfill leachate pretreatment method according to an embodiment of the present invention; Figure 2 This is a macroscopic schematic diagram of landfill leachate treated by the landfill leachate pretreatment method according to an embodiment of the present invention.

[0039] according to Figure 1 and Figure 2 From the data analysis, it can be seen that the looseness of the leachate flocs treated by the leachate pretreatment method is reduced.

[0040] Example 2

[0041] This embodiment provides an application of the above-mentioned landfill leachate pretreatment method in treating landfill leachate, and the specific experimental operation steps are as follows:

[0042] The landfill leachate pretreatment method of this embodiment is implemented in three steps:

[0043] (1) Crushing step: The stirring rate is 1000 r / min and the time is 20 min. No other parameters need to be adjusted. The purpose is to crush and homogenize the original particles in the landfill leachate. After completion, the reaction step is entered.

[0044] (2) Reaction step: After the rapid crushing step is completed, the reaction step is performed. At the beginning of the reaction step, a flocculant is added, preferably polyaluminium chloride (PAC), with an addition amount of 500 mg / L, and then an alkaline solution is used to adjust the pH value, wherein the alkaline solution is 1 mol / L, and the alkaline solution can be a sodium hydroxide or potassium hydroxide solution. The addition of the alkaline solution must be controlled by a peristaltic pump to achieve a pH value of 11 in the landfill leachate at the end of the reaction step, and the stirring rate during the entire reaction step is 100 r / min, and the reaction time is 5 min.

[0045] (3) Granulation step: In this process, the stirring rate is 20 r / min and the reaction time is 30 min. At the beginning of the granulation step, a certain amount of polyacrylamide (PAM) is added, which can be cationic or anionic, and the dosage concentration is 10 mg / L.

[0046] In the landfill leachate pretreatment method of this embodiment, after the pretreatment process, the COD in the landfill leachate can be removed by 25%, the turbidity removal rate is 85%, and the SS removal rate is 90%.

[0047] Example 3

[0048] This embodiment provides an application of the above-mentioned landfill leachate pretreatment method in treating landfill leachate, and the specific experimental operation steps are as follows:

[0049] The landfill leachate pretreatment method of this embodiment is implemented in three steps:

[0050] (1) Crushing step: wherein the stirring rate is 3000 r / min, the time is 60 min, and no other parameters need to be adjusted. The purpose is to crush and homogenize the original particles in the landfill leachate; after completion, the reaction step is entered.

[0051] (2) Reaction step: After the rapid crushing step is completed, the reaction step is performed. At the beginning of the reaction step, a flocculant is added, preferably polyaluminium chloride (PAC), with an addition amount of 5000 mg / L, and then an alkaline solution is used to adjust the pH value, wherein the alkaline solution is 5 mol / L, and the alkaline solution can be a sodium hydroxide or potassium hydroxide solution. The addition of the alkaline solution must be controlled by a peristaltic pump to achieve a pH value of 13 in the landfill leachate at the end of the reaction step, and the stirring rate during the entire reaction step is 1000 r / min, and the reaction time is 20 min.

[0052] (3) Granulation step: In this process, the stirring rate is 60 r / min and the reaction time is 60 min. At the beginning of the granulation step, a certain amount of polyacrylamide (PAM) is added, which can be cationic or anionic, and the dosage concentration is 50 mg / L.

[0053] In the landfill leachate pretreatment method of this embodiment, after the pretreatment process, 30% of COD in the landfill leachate can be removed, the turbidity removal rate is 95%, and the SS removal rate is 95%.

[0054] Comparative Example 1

[0055] This comparative example provides an application of the landfill leachate pretreatment method not following the above-mentioned landfill leachate treatment method, and the specific experimental operation steps are as follows:

[0056] First, a certain amount of PAC was directly added to the leachate, and the mixture was rapidly stirred at a speed of 300 r / min for 1 min. Then a certain amount of NaOH was directly added to adjust the pH to 12, and then a certain amount of PAM was added, and the mixture was allowed to stand for 30 min to terminate the reaction.

[0057] In the landfill leachate pretreatment method of this comparative example, after the pretreatment process, 10% of COD in the landfill leachate can be removed, 50% of turbidity can be removed, and 60% of SS can be removed.

[0058] In summary, the method for pretreating landfill leachate according to the embodiment of the present invention is a coagulation method with delayed stirring and granulation, which is used for pretreating and removing suspended solids (SS), chemical oxygen demand (COD) and turbidity (NTU) in landfill leachate; it improves the pretreatment effect of traditional coagulation on landfill leachate. Specifically, the method for pretreating landfill leachate according to the embodiment of the present invention can remove 20-30% of COD in landfill leachate, the removal rate of turbidity is 80-95%, and the removal rate of SS is 80-95%. It is 20-30% higher than the traditional coagulation method, and provides an efficient pretreatment method for the subsequent further treatment of landfill leachate. In addition, compared with the traditional coagulation method for pretreating landfill leachate, the granulation coagulation method provided by the present invention can improve the pretreatment efficiency of landfill leachate, and the hydraulic retention time is short, which can improve the utilization rate of water resources.

[0059] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0060] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments described herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for pretreating landfill leachate, characterized in that: The landfill leachate pretreatment method comprises: subjecting the landfill leachate to a crushing step, a reaction step and a granulation step in sequence to complete the pretreatment.

2. The method for pretreating landfill leachate according to claim 1, characterized in that: The stirring rate of the crushing step is 1000-3000r / min; And / or, the crushing step is performed for 20-60 minutes.

3. The method for pretreating landfill leachate according to claim 1 or 2, characterized in that: The reaction steps include: after adding a coagulant, adjusting the pH with an alkaline solution and reacting for 5-20 minutes; Wherein, the pH value of the landfill leachate at the end of the reaction step is 11-13.

4. The method for pretreating landfill leachate according to claim 3, characterized in that: The concentration of the coagulant is 500-5000 mg / L; And / or, the concentration of the alkaline solution is 1-5 mol / L.

5. The method for pretreating landfill leachate according to claim 3 or 4, characterized in that: The coagulant is polyaluminium chloride; And / or, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

6. The method for pretreating landfill leachate according to any one of claims 3 to 5, characterized in that: The stirring rate of the reaction step is 100-1000 r / min.

7. The method for pretreating landfill leachate according to any one of claims 1 to 6, characterized in that: The granulation step comprises: adding a flocculant into the landfill leachate for granulation to obtain the pretreated landfill leachate.

8. The method for pretreating landfill leachate according to claim 7, characterized in that: The concentration of the flocculant is 10-50 mg / L.

9. The method for pretreating landfill leachate according to claim 7 or 8, characterized in that: The stirring rate of the granulation step is 20-60r / min; And / or, the reaction time of the granulation step is 30-60 min; And / or, the flocculant is polyacrylamide.

10. Use of the landfill leachate pretreatment method according to any one of claims 1 to 9 in treating landfill leachate.

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