System and process method for treating sewage based on polyaluminum chloride

Abstract

The invention relates to a system and process method for treating sewage based on polyaluminum chloride, the system comprises a stock solution barrel, a stirring tank and a stirring barrel, the stirring tank and the stirring barrel are connected through a first pipeline, and the stock solution barrel is connected to the first pipeline through a second pipeline. The method comprises the following steps: adding a flocculating agent, acid and alkali into raw water in a stirring tank to adjust the pH value, and outputting clear water from a first pipeline; outputting the proportioned polyaluminum chloride to the first pipeline from the second pipeline through a flow pump; stirring and fusing clear water and polyaluminum chloride in a stirring barrel; and the fused solution passes through the stirring barrel and is output to a sedimentation tank through a third pipeline for natural sedimentation. According to the method, a clear precipitation environment is provided for polyaluminum chloride by adopting a method of adding a medicament into clear water after stirring precipitation and reserving sufficient stirring precipitation time, and the implementation of the scheme does not influence the efficiency of stirring precipitation in the early stage, and meanwhile, the efficiency of aluminum ion precipitation in sewage in the later stage is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a system and process for treating sewage based on polyaluminium chloride. Background Art

[0002] Removing aluminum ions from wastewater treatment is a comprehensive requirement for environmental safety, human health, process stability, and regulatory compliance, in order to reduce the negative impact on subsequent equipment and ecosystems. Commonly used methods in existing technologies are to directly filter aluminum ions from wastewater through reverse osmosis membranes, or to directly add polyaluminum chloride to the pre-stage sedimentation mixing tank to assist in the precipitation of aluminum ions in wastewater. However, both methods have the following disadvantages: (1) Direct filtration and removal through reverse osmosis membrane: This method is similar to forced filtration through a sieve, which can cause frequent clogging of the reverse osmosis membrane. Once clogged, it needs to be promptly chemically cleaned and removed, which can easily damage the reverse osmosis membrane. The purchase cost of the reverse osmosis membrane is high, which will increase the cost of sewage treatment. Repeated chemical cleaning will reduce the effective operating efficiency of the equipment, reduce water treatment output, and increase labor costs.

[0003] (2) Directly adding polyaluminium chloride to the mixing tank: Directly adding polyaluminium chloride can affect the sedimentation rate of the previous stage, thereby increasing sedimentation time and reducing wastewater treatment efficiency. This method ignores or fails to verify the impact of adding polyaluminium chloride directly to the mixing tank on the sedimentation rate, and does not test the clear water quality environment required for polyaluminium chloride to improve the efficiency of aluminum ion precipitation in wastewater. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a system and process method for treating sewage based on polyaluminum chloride to solve one or more problems in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A system for treating sewage based on polyaluminium chloride comprises a stock liquid barrel, a stirring tank and a stirring barrel, wherein the stirring tank and the stirring barrel are connected via a first pipeline, and the stock liquid barrel is connected to the first pipeline via a second pipeline.

[0006] Furthermore, the system also includes a flow pump, which is arranged in the second pipeline and acts on the raw liquid barrel.

[0007] Furthermore, the system also includes a sedimentation tank, and the stirring barrel is connected to the sedimentation tank via a third pipeline.

[0008] Furthermore, the height of the connection between the first pipeline and the stirring barrel is lower than the height of the connection between the third pipeline and the stirring barrel.

[0009] A process method is applied to the above-mentioned system for treating wastewater based on polyaluminium chloride, comprising the following steps: Add flocculant, acid and alkali to the raw water in the mixing tank to adjust the pH value and output clean water through the first pipeline; Outputting the proportioned polyaluminium chloride in the second pipeline to the first pipeline through a flow pump; Stir clean water and polyaluminium chloride in a mixing bucket; The fused solution is output to the sedimentation tank through the third pipeline through the stirring barrel for natural sedimentation.

[0010] Furthermore, flocculants, acid and alkali are added to the raw water in the stirring tank to adjust the pH value to be controlled at 6.5-7.5.

[0011] Furthermore, the concentration of polyaluminium chloride after mixing is controlled to be 100-130 mg / m 3 .

[0012] Furthermore, the stirring and fusion time in the stirring barrel is 2 minutes.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are as follows: The present invention fully considers and verifies the water quality environment required for improving the precipitation efficiency of polyaluminium chloride. Therefore, a method of adding a reagent to clear water after stirring and settling and reserving sufficient stirring and settling time is adopted to provide a clear precipitation environment for polyaluminium chloride. The implementation of this scheme does not affect the efficiency of the early stirring and settling, while improving the efficiency of aluminum ion precipitation in the subsequent sewage. In addition, the present invention adopts a natural precipitation method, which has extremely low maintenance cost compared with reverse osmosis direct filtration and is simpler and more convenient to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of a system and process method for treating sewage based on polyaluminium chloride according to an embodiment of the present invention is shown.

[0015] Figure 2 A schematic flow chart of a system and process method for treating wastewater based on polyaluminium chloride according to an embodiment of the present invention is shown.

[0016] Markings in the attached figure: 1. Raw liquid barrel; 2. Mixing tank; 3. Mixing barrel; 4. First pipeline; 5. Second pipeline; 6. Flow pump; 7. Sedimentation tank; 8. Third pipeline. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following is a further detailed description of a system and process method for treating sewage based on polyaluminum chloride proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings adopt a very simplified form and all use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification, so that people familiar with this technology can understand and read them, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the efficacy and purpose that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention.

[0018] See also Figure 1 and Figure 2 The polyaluminium chloride-based wastewater treatment system of this embodiment includes a stock liquid tank 1, a stirring tank 2, and a stirring tank 3. The stock liquid tank 1 is used to store the proportioned polyaluminium chloride. The stirring tank 2 serves as a pre-precipitation container, capable of separating the sediment and clean water. The stirring tank 3 serves as a stirring device to stir the clean water and polyaluminium chloride separated in the stirring tank 2. The stirring tank 2 and the stirring tank 3 are connected by a first pipeline 4. The stock liquid tank 1 is connected to the first pipeline 4 via a second pipeline 5, and then the polyaluminium chloride and clean water both flow from the first pipeline 4 into the stirring tank 3.

[0019] Furthermore, the system also includes a flow pump 6, which is arranged in the second pipeline 5 and acts on the raw liquid barrel 1, and then controls the delivery rate and volume of polyaluminum chloride in the raw liquid barrel 1 through the flow pump 6 to ensure the stability of the process and the processing efficiency.

[0020] Furthermore, the system also includes a sedimentation tank 7, and the stirring barrel 3 is connected to the sedimentation tank 7 via a third pipeline 8. After precipitation in the sedimentation tank 7, clean water and sediment are further separated. In this embodiment, the addition of polyaluminum chloride is controlled at a position between the water outlet of the front-stage sedimentation, i.e., the water outlet of the stirring tank 2, and the sedimentation tank 7 of the rear stage, to ensure the clarity of the produced water, because the front-stage sedimentation has removed most of the suspended matter and particles, ensuring that only target pollutants such as soluble aluminum ions remain in the clean water output by the stirring tank 2. If polyaluminum chloride is directly added to turbid water, polyaluminum chloride will preferentially combine with suspended matter rather than aluminum ions, resulting in waste of reagents and reduced precipitation efficiency. In addition, adding polyaluminum chloride to the front-stage sedimentation, i.e., after the precipitation of the stirring tank 2, can give polyaluminum chloride and aluminum ions sufficient mixing reaction time before the clean water enters the sedimentation tank 7 of the rear stage.

[0021] Furthermore, the height of the connection between the first pipe 4 and the stirring barrel 3 is lower than the height of the connection between the third pipe 8 and the stirring barrel 3. This arrangement ensures that the clean water produced by the stirring tank 2 and the polyaluminum chloride added by the stock liquid barrel 1 are stirred and blended in the stirring barrel 3 and then enter from the bottom and exit from the top, ensuring that they are completely and evenly mixed.

[0022] The process method of this embodiment is applied to the above-mentioned system for treating wastewater based on polyaluminium chloride, and includes the following steps: Step 1: Add flocculant, acid, and alkali to the raw water in the mixing tank 2 to adjust the pH value and output the clean water through the first pipeline 4. The adjusted pH value is controlled to 6.5-7.5 to optimize the chemical reaction conditions, ensure the efficient function of the polyaluminum chloride added later, and ensure the stability of the process flow.

[0023] Step 2: Output the proportioned polyaluminium chloride in the second pipeline 5 to the first pipeline 4 through the flow pump 6, and the concentration of the proportioned polyaluminium chloride is controlled to be 100-130 mg / m 3 If the concentration is too low, the precipitation rate of aluminum ions in the water will be low. If the concentration is too high, excess polyaluminum chloride will float in the water, affecting the cleanliness of the water and causing secondary pollution to the treated water.

[0024] Step 3: Stir clean water and polyaluminium chloride in the stirring barrel 3. The stirring time in the stirring barrel 3 is 2 minutes to make polyaluminium chloride evenly dispersed in the clean water, avoiding excessively high local concentrations resulting in unreacted reagent residues or excessively low concentrations resulting in insufficient precipitation efficiency.

[0025] Step 4: The fused solution is output to the sedimentation tank 7 through the third pipeline 8 via the stirring tank 3 for natural sedimentation. The clean water separated after sedimentation in the sedimentation tank 7 flows into the filtration and reverse osmosis system to remove other ionic components, while the precipitate separated by the sedimentation tank 7 and the precipitate separated in the stirring tank 2 are both sent to the plate filter for filtration.

[0026] After demonstration tests, it was found that adding polyaluminium chloride to the clean water produced by the pre-precipitation stage, i.e. the mixing tank 2, and then stirring it thoroughly and evenly before flowing it into the sedimentation tank 7, achieved a very good aluminum ion precipitation effect. After precipitation, a large amount of soluble aluminum ions in the water enter the subsequent reverse osmosis membrane, which greatly reduces the blockage of the reverse osmosis membrane and effectively improves the yield, as shown in Table 1: Table 1 The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0027] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A system for treating sewage based on polyaluminium chloride, characterized in that: The system includes a raw liquid barrel, a stirring tank and a stirring barrel. The stirring tank and the stirring barrel are connected via a first pipeline, and the raw liquid barrel is connected to the first pipeline via a second pipeline.

2. A system for treating sewage based on polyaluminium chloride as claimed in claim 1, characterized in that: The system further comprises a flow pump, which is arranged in the second pipeline and acts on the raw liquid barrel.

3. A system for treating sewage based on polyaluminium chloride as claimed in claim 2, characterized in that: The system further comprises a sedimentation tank, and the stirring barrel is connected to the sedimentation tank via a third pipeline.

4. A system for treating sewage based on polyaluminium chloride as claimed in claim 3, characterized in that: The height of the connection between the first pipeline and the stirring barrel is lower than the height of the connection between the third pipeline and the stirring barrel.

5. A process method, which is applied to a system for treating wastewater based on polyaluminium chloride according to any one of claims 1 to 4, characterized in that: The steps are as follows: Add flocculant, acid and alkali to the raw water in the mixing tank to adjust the pH value and output clean water through the first pipeline; Outputting the proportioned polyaluminium chloride in the second pipeline to the first pipeline through a flow pump; Stir clean water and polyaluminium chloride in a mixing bucket; The fused solution is output to the sedimentation tank through the third pipeline through the stirring barrel for natural sedimentation.

6. A process according to claim 5, characterized in that: The pH value of the raw water in the stirring tank is controlled to be 6.5-7.5 by adding flocculant, acid and alkali.

7. A process according to claim 6, characterized in that: The concentration of polyaluminium chloride after mixing is controlled to be 100~130mg / m 3 .

8. A process according to claim 7, characterized in that: The stirring and fusion time in the stirring barrel is 2 minutes.

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