Pendimethalin wastewater treatment system

Abstract

The invention relates to the technical field of pendimethalin wastewater treatment, in particular to a pendimethalin wastewater treatment system which comprises a first reaction tank, the upper end of the first reaction tank is provided with a wastewater inlet and a feeding port, and a discharging port in the lower end of the first reaction tank is connected with the inlet end of a first filter press; a discharge liquid of the first filter press is pumped to a feed port at the upper end of a second reaction tank, a discharge port at the lower end of the second reaction tank is connected with an inlet end of a second filter press, and a discharge liquid of the second filter press is pumped to an inlet end of a multi-stage oxidation reaction tank; the outlet end of the multi-stage oxidation reaction tank is connected with the inlet end of the third filter press, according to the pendimethalin wastewater treatment system, the number of the reaction tanks in the multi-stage oxidation reaction tank can be adjusted according to the content of pollutants in wastewater in the treatment process, and it is guaranteed that the fluctuation range of the effluent quality is small, and the treatment effect is stable.

Description

Technical Field

[0001] The present invention relates to the technical field of pendimethalin wastewater treatment, in particular to a pendimethalin wastewater treatment system. Background Art

[0002] Pendimethalin is a selective herbicide widely used in agricultural production, effectively controlling annual grasses and broadleaf weeds. Due to its high weed control performance, it is produced and used in large quantities worldwide. Its production process involves multiple chemical reactions, such as nitrification, reduction, and condensation, which generate significant amounts of wastewater.

[0003] Pendimethalin wastewater typically contains nitric acid and various organic compounds. Nitric acid concentrations in wastewater typically range from 1% to 5%. Direct neutralization with sodium hydroxide produces explosive sodium nitrate waste salts, which require third-party disposal, resulting in high costs and high risks. Furthermore, changes in production batches or process adjustments can lead to variations in nitric acid concentrations, organic compound types, and content, further complicating treatment.

[0004] However, existing wastewater treatment systems are mostly designed with fixed treatment processes and parameters, lacking the ability to adapt to fluctuations in water quality. When water quality fluctuates significantly, the treatment system struggles to quickly adjust operating parameters, leading to unstable treatment results and substandard effluent quality. Therefore, we propose a pendimethalin wastewater treatment system to address these issues. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a pendimethalin wastewater treatment system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A pendimethalin wastewater treatment system includes a first reaction tank, wherein the upper end of the first reaction tank is provided with a wastewater inlet and a feeding port, the discharge port at the lower end of the first reaction tank is connected to the inlet end of a first filter press, the discharge liquid of the first filter press is pumped to the feed port at the upper end of a second reaction tank, the discharge port at the lower end of the second reaction tank is connected to the inlet end of a second filter press, the discharge liquid of the second filter press is pumped to the inlet end of a multi-stage oxidation reaction tank, and the outlet end of the multi-stage oxidation reaction tank is connected to the inlet end of a third filter press;

[0008] It also includes a drying tower, which is used to dry the filter cake produced by the second filter press. A feeding pipe is connected between the discharge port of the drying tower and the feed port of the second reaction tank.

[0009] Preferably, the multi-stage oxidation reaction tank includes 2-5 reaction tanks, and the reaction tanks are connected in series.

[0010] Preferably, a feed port is provided at the upper end of each reaction tank of the multi-stage oxidation reaction tank.

[0011] Preferably, a magnetic separator is provided between the discharge port of the drying tower and the inlet end of the second reaction tank.

[0012] Preferably, the gas phase outlet of the first reaction tank is connected to the inlet of the first dryer, and the outlet of the first dryer is connected to the inlet of the denitration system.

[0013] Preferably, the gas phase outlet end of the second reaction tank is connected to the inlet end of the absorption tower, the gas phase outlet end of the absorption tower is connected to the inlet end of the second dryer, and the outlet end of the second dryer is connected to the inlet end of the denitration system.

[0014] Preferably, the absorbent in the absorption tower is deionized water.

[0015] Preferably, the filter cakes produced by filtration by the first filter press and the third filter press are sent for solid waste treatment.

[0016] Preferably, the filter cake produced by the second filter press is recycled 2-5 times and then sent to solid waste treatment. After the filter cake is recycled many times, the iron hydroxide adhering to the carbon powder will increase. When the mass of the carbon powder is less than 30% of the mass of the remaining filter residue, the filter residue is transported to solid waste treatment equipment for treatment.

[0017] The beneficial effects of the present invention are:

[0018] 1. The pendimethalin wastewater treatment system can adjust the number of reaction tanks in the multi-stage oxidation reaction tank according to the content of pollutants in the wastewater during the treatment process, ensuring that the fluctuation range of the effluent water quality is small and the treatment effect is stable.

[0019] 2. During the use of the pendimethalin wastewater treatment system, ferrous oxide or ferrous hydroxide is first added to the first reaction tank to adjust the pH of the wastewater to neutral. Then, the pH of the discharge liquid from the second reaction tank is adjusted to 2-5 using an inorganic acid, and an iron-carbon mixture is added to carry out an oxidation-reduction reaction. The discharge liquid from the second reaction tank is transported to a multi-stage oxidation reaction tank, and hydrogen peroxide is added to carry out multi-stage catalytic oxidation of organic matter, which can effectively reduce the COD of the wastewater.

[0020] 3. In the second reaction tank of the pendimethalin wastewater treatment system, an iron-carbon mixture generates a galvanic cell effect in the solution, with iron as the negative electrode and carbon as the positive electrode, which can quickly reduce nitrate to nitrogen oxides or ammonia, efficiently and quickly treating the nitrate. At the same time, iron ions and ferrous ions can eventually generate corresponding hydroxides for precipitation. When the reaction in the second reaction tank starts, the pH of the primary filtrate is first adjusted to a weakly acidic state with an inorganic acid. This can, on the one hand, increase the reaction rate inside the second reaction tank, and on the other hand, remove iron hydroxides attached to the surface of carbon powder when the iron-carbon mixture is recycled, thereby ensuring that the carbon powder can smoothly participate in the reaction.

[0021] 4. In the multi-stage oxidation reaction tank of the pendimethalin wastewater treatment system, hydrogen peroxide can be added once or multiple times, which can effectively reduce the COD of the wastewater, while reducing the use of hydrogen peroxide and improving the treatment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic flow chart of a pendimethalin wastewater treatment system proposed in the present invention.

[0023] In the figure: 1 first reaction tank, 2 first filter press, 3 second reaction tank, 4 second filter press, 5 third reaction tank, 6 fourth reaction tank, 7 fifth reaction tank, 8 third filter press, 9 drying tower, 10 magnetic separator, 11 first dryer, 12 absorption tower, 13 second dryer, 14 denitrification system. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0025] Reference Figure 1 A pendimethalin wastewater treatment system comprises a first reaction tank 1, wherein the upper end of the first reaction tank 1 is provided with a wastewater inlet and a feeding port, the discharge port at the lower end of the first reaction tank 1 is connected to the inlet end of a first filter press 2, the discharge liquid of the first filter press 2 is pumped to the feed port at the upper end of a second reaction tank 3, the discharge port at the lower end of the second reaction tank 3 is connected to the inlet end of a second filter press 4, the discharge liquid of the second filter press 4 is pumped to the inlet end of a multi-stage oxidation reaction tank, and the outlet end of the multi-stage oxidation reaction tank is connected to the inlet end of a third filter press 8;

[0026] The drying tower 9 is also included, and the drying tower 9 is used to dry the filter cake produced by the filtration of the second filter press 2 . A feeding pipe is connected between the discharge port of the drying tower 9 and the feed port of the second reaction tank 3 .

[0027] The multi-stage oxidation reaction tank includes 2-6 reaction tanks, and the reaction tanks are connected in series.

[0028] In this embodiment, the multi-stage oxidation reaction tank is provided with three reaction tanks: a third reaction tank 5, a fourth reaction tank 6, and a fifth reaction tank 7; the filtrate of the second filter press 4 enters from the feed port at the upper end of the third reaction tank 5, the discharge liquid of the third reaction tank 5 is pumped to the feed port at the upper end of the fourth reaction tank 6, the discharge liquid of the fourth reaction tank 6 is pumped to the feed port at the upper end of the fifth reaction tank 7, and the discharge liquid of the fifth reaction tank 7 is connected to the inlet end of the third filter press 8. A feeding port is provided at the upper end of each reaction tank of the multi-stage oxidation reaction tank.

[0029] A magnetic separator 10 is provided between the discharge port of the drying tower 9 and the inlet end of the second reaction tank 3 .

[0030] The gas phase outlet end of the first reaction tank 1 is connected to the inlet end of the first dryer 11 , and the outlet end of the first dryer 11 is connected to the inlet end of the denitration system.

[0031] The gas phase outlet of the second reaction tank 3 is connected to the inlet of the absorption tower 13, the gas phase outlet of the absorption tower 13 is connected to the inlet of the second dryer 14, and the outlet of the second dryer 14 is connected to the inlet of the denitration system.

[0032] The absorbent in the absorption tower 13 is deionized water. The ammonia generated by the reaction in the second reaction tank 3 is absorbed by the absorption tower 13, and the unabsorbed NO is transported to the denitrification system.

[0033] The filter cakes produced by the first filter press 2 and the third filter press 8 are sent to solid waste treatment.

[0034] The filter cake produced by the second filter press 2 is recycled 2-5 times and then sent to solid waste treatment. After the filter cake is recycled many times, the iron hydroxide adhering to the carbon powder will increase. When the mass of the carbon powder is less than 30% of the mass of the remaining filter residue, the filter residue will be transported to the solid waste treatment equipment for treatment.

[0035] Example: The feed port at the upper end of the third reaction tank 5, the discharge liquid of the third reaction tank 5 is pumped to the feed port at the upper end of the fourth reaction tank 6, the discharge liquid of the fourth reaction tank 6 is pumped to the feed port at the upper end of the fifth reaction tank 7, and the discharge liquid of the fifth reaction tank 7 is connected to the inlet end of the third filter press 8

[0036] Example: Using the pendimethalin wastewater from a pesticide factory as the water to be treated, the initial pH is 0.4, the initial COD is 16721 mg / L, and the initial NO3 - The concentration is 24635mg / L, and the treatment volume is 2m 3 The specific processing steps are as follows:

[0037] Step 1, primary pH adjustment and solid-liquid separation: transport the wastewater to the first reaction tank 1, add ferrous hydroxide to the first reaction tank 1, adjust the pH of the wastewater to neutral, and obtain a primary filtrate after filtering through a first filter press 2;

[0038] Step 2, micro-electrolysis reaction treatment: the primary filtrate is pumped to the second reaction tank 3, the pH of the primary filtrate is adjusted to 2 with 30% hydrochloric acid, and an iron-carbon mixture is added to the second reaction tank 3, wherein the mass of iron powder is 200 kg, the mass of carbon powder is 400 kg, and the iron-carbon mass ratio is 1:2, and an oxidation-reduction reaction is carried out. The reaction end point is when bubbles stop, and the secondary filtrate is filtered through a second filter press 4 to obtain a secondary filtrate;

[0039] Step 3, multi-stage catalytic oxidation: the secondary filtrate is introduced into three reactors connected in series (a third reactor 5, a fourth reactor 6, and a fifth reactor 7; the secondary filtrate enters from the feed port at the upper end of the third reactor 5, the discharge liquid of the third reactor 5 is pumped to the feed port at the upper end of the fourth reactor 6, the discharge liquid of the fourth reactor 6 is pumped to the feed port at the upper end of the fifth reactor 7, and the discharge liquid of the fifth reactor 7 is connected to the inlet end of the third filter press 8), and 836 kg of hydrogen peroxide is added. The hydrogen peroxide is added in three times, with the input amount of the third reactor 5 being 436 kg, the input amount of the fourth reactor 6 being 260 kg, and the input amount of the fifth reactor 7 being 140 kg. After reaction in the last reactor, the filtrate is filtered and discharged through the third filter press 8. The residence time of each reactor is 60 minutes.

[0040] In step 1, the pH of the wastewater is first adjusted to neutral by ferrous oxide or ferrous hydroxide, which can precipitate some solid waste (calcium, magnesium ions, etc.) to prevent these solid wastes from mixing into the iron-carbon mixture of step 2. When the solid waste is deposited on the surface of the carbon powder, it will cause the carbon powder to be deactivated in advance, affecting the number of cycles of the iron-carbon mixture. The treatment of step 1 can effectively reduce the amount of solid waste generated. At the same time, during the use of ferrous oxide or ferrous hydroxide, a small amount of nitrate can be reduced, and the iron ions generated by adjusting the pH can be conveniently removed in the subsequent step 2 (without introducing new impurities).

[0041] In step 2, the iron-carbon mixture generates a galvanic cell effect in the solution, with iron as the negative electrode and carbon as the positive electrode, which can quickly reduce nitrate to nitrogen oxides or ammonia, and efficiently and quickly treat the nitrate. At the same time, iron ions and ferrous ions can eventually generate corresponding hydroxides for precipitation. In step 2, the pH of the primary filtrate is first adjusted to a weak acidity with an inorganic acid. On the one hand, this can increase the reaction rate of step 2. On the other hand, when the iron-carbon mixture is recycled, the iron hydroxide attached to the surface of the carbon powder can be removed, thereby ensuring that the carbon powder can smoothly participate in the reaction.

[0042] In step 3, multi-stage catalytic oxidation of organic matter in the wastewater is performed using hydrogen peroxide, which can effectively reduce the COD of the wastewater, while reducing the amount of hydrogen peroxide used and improving the treatment efficiency.

[0043] After being processed by this system, the final NO3 - When the concentration drops below 10 mg / L, the COD removal rate reaches over 90%.

[0044] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A pendimethalin wastewater treatment system, comprising a first reaction tank (1), characterized in that: The upper end of the first reaction tank (1) is provided with a wastewater inlet and a feeding port, the discharge port at the lower end of the first reaction tank (1) is connected to the inlet end of the first filter press (2), the discharge liquid of the first filter press (2) is pumped to the feed port at the upper end of the second reaction tank (3), the discharge port at the lower end of the second reaction tank (3) is connected to the inlet end of the second filter press (4), the discharge liquid of the second filter press (4) is pumped to the inlet end of the multi-stage oxidation reaction tank, and the outlet end of the multi-stage oxidation reaction tank is connected to the inlet end of the third filter press (8); It also includes a drying tower (9) for drying the filter cake produced by the second filter press (2). A feeding pipe is connected between the discharge port of the drying tower (9) and the feed port of the second reaction tank (3).

2. A pendimethalin wastewater treatment system according to claim 1, characterized in that: The multi-stage oxidation reaction tank includes 2-6 reaction tanks, and the reaction tanks are connected in series.

3. A pendimethalin wastewater treatment system according to claim 2, characterized in that: The upper end of each reaction tank of the multi-stage oxidation reaction tank is provided with a feeding port.

4. A pendimethalin wastewater treatment system according to claim 1, characterized in that: A magnetic separator (10) is provided between the discharge port of the drying tower (9) and the inlet end of the second reaction tank (3).

5. The pendimethalin wastewater treatment system according to claim 1, characterized in that: The gas phase outlet of the first reaction tank (1) is connected to the inlet of the first dryer (11), and the outlet of the first dryer (11) is connected to the inlet of the denitration system.

6. The pendimethalin wastewater treatment system according to claim 1, characterized in that: The gas phase outlet end of the second reaction tank (3) is connected to the inlet end of the absorption tower (13), the gas phase outlet end of the absorption tower (13) is connected to the inlet end of the second dryer (14), and the outlet end of the second dryer (14) is connected to the inlet end of the denitration system.

7. A pendimethalin wastewater treatment system according to claim 6, characterized in that: The absorbent in the absorption tower (13) is deionized water.

8. The pendimethalin wastewater treatment system according to claim 1, characterized in that: The filter cakes produced by the filtration of the first filter press (2) and the third filter press (8) are sent to solid waste treatment.

9. The pendimethalin wastewater treatment system according to claim 1, characterized in that: The filter cake produced by the second filter press (2) is recycled 2-5 times and then sent to solid waste treatment.

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