Maleic anhydride wastewater treatment process

Abstract

The invention relates to the technical field of sewage treatment, in particular to a maleic anhydride wastewater treatment process which comprises the following steps: calculating according to a COD actual value of maleic anhydride wastewater to be treated and obtaining a COD calculated value; calculating and obtaining the adding amount of hydrogen peroxide according to the COD calculation value; calculating and obtaining the adding amount of ferrous sulfate according to the adding amount of hydrogen peroxide; adjusting the pH value of the maleic anhydride wastewater to be treated to 2.5-3; adding 20% of ferrous sulfate according to the calculated adding amount of the ferrous sulfate, and mixing the ferrous sulfate with the maleic anhydride wastewater to be treated; adding 30% of hydrogen peroxide according to the calculated adding amount of the hydrogen peroxide, and enabling the hydrogen peroxide to react with ferrous sulfate; adjusting the pH value of the effluent of the Fenton reaction to 4.5-5.5; and 10 ppm to 20 ppm of polyacrylamide is added. On the premise of ensuring the treatment effect, the dosage of two medicaments is reduced, and the cost is saved.

Description

A maleic anhydride wastewater treatment process Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically a maleic anhydride wastewater treatment process. Background Technology

[0002] In the chemical production field, maleic anhydride is an important organic chemical raw material, widely used in unsaturated polyester resins, pesticides, coatings, and many other industries. However, its production process inevitably generates wastewater, and this wastewater is relatively large in volume and causes serious pollution, affecting the overall economic benefits of chemical plants.

[0003] Fenton oxidation is a popular process in many wastewater treatment plants for treating maleic anhydride wastewater. Ferrous sulfate combined with hydrogen peroxide is widely used as the Fenton reagent in practical maleic anhydride wastewater treatment. Theoretical calculations often use a 2:1 molar ratio of hydrogen peroxide to ferrous sulfate for the Fenton process. However, in actual reagent dosing, this parameter leads to reagent waste, and the dosing is not tailored to the specific influent water quality. Furthermore, the relationship between the influent water, ferrous sulfate, and hydrogen peroxide has not been investigated. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a maleic anhydride wastewater treatment process. The Fenton oxidation method is used to treat maleic anhydride wastewater. The amount of hydrogen peroxide does not need to be added excessively. The amount of hydrogen peroxide to be added can be calculated from the COD. Then, based on the hydrogen peroxide and ferrous sulfate, the amount of hydrogen peroxide and ferrous sulfate to be added is calculated. The corresponding Fenton reagent is added to achieve the removal of COD from the wastewater. The amount of two reagents added is reduced while ensuring the treatment effect, thus saving costs.

[0005] To achieve the above objectives, the present invention provides a maleic anhydride wastewater treatment process, comprising: calculating and obtaining a calculated COD value based on the actual COD value of the maleic anhydride wastewater to be treated; calculating and obtaining the dosage of hydrogen peroxide based on the calculated COD value; calculating and obtaining the dosage of ferrous sulfate based on the dosage of hydrogen peroxide; adjusting the pH value of the maleic anhydride wastewater to be treated to 2.5-3; adding 20% ​​ferrous sulfate according to the calculated dosage and mixing it with the maleic anhydride wastewater to be treated; adding 30% hydrogen peroxide according to the calculated dosage to react with the ferrous sulfate; adjusting the pH value of the Fenton reaction effluent to 4.5-5.5; and adding 10ppm-20ppm of polyacrylamide.

[0006] Furthermore, the calculated COD value is 5% to 20% of the actual COD value.

[0007] Furthermore, the ratio of the amount of hydrogen peroxide added to the calculated COD value is 0.03% to 0.06%.

[0008] Preferably, the ratio of the amount of hydrogen peroxide added to the calculated COD value is 0.03%.

[0009] Preferably, the ratio of the amount of hydrogen peroxide added to the calculated COD value is 0.06%.

[0010] Furthermore, the ratio of the amount of hydrogen peroxide added to the molar ratio of ferrous sulfate is 0.2 to 1.

[0011] The beneficial effects of this invention are as follows: the calculated COD value is obtained based on the actual COD value, and then the theoretical COD data used when adding hydrogen peroxide is obtained. The hydrogen peroxide consumption is adjusted synchronously according to the actual water quality changes, and then the ferrous sulfate dosage is obtained. The ferrous sulfate dosage is less than the conventional dosage, thus realizing the precise addition of Fenton reagent for different water qualities. Attached Figure Description

[0012] Figure 1 shows the effect of changing the COD dosing ratio on the COD removal rate of maleic anhydride wastewater; Figure 2 shows the effect of changing the molar ratio of hydrogen peroxide to ferrous sulfate on the COD removal rate of maleic anhydride wastewater; Figure 3 shows that the supernatant becomes clear after treating maleic anhydride wastewater by changing the ratio of ferrous sulfate to hydrogen peroxide. Detailed Implementation

[0013] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0014] Example 1: The calculated COD value was obtained based on the actual COD value of the maleic anhydride wastewater to be treated. The actual measured COD value of the maleic anhydride wastewater was 50,000 mg / L; the calculated COD value was 5% to 20% of the actual COD value. The dosage of hydrogen peroxide was calculated based on the calculated COD value, and a calculated COD value of 10,000 mg / L was obtained by using 20% ​​of the actual COD value. The calculation of the hydrogen peroxide dosage was based on the ratio of the hydrogen peroxide dosage to the calculated COD value of 0.03%. That is, according to the calculation, the dosage of hydrogen peroxide for treating 500 ml of maleic anhydride wastewater is 5 ml; which can meet the requirement of 5 ml × 30% / (10000 × 500 ml × 10). -3 =0.03%.

[0015] The amount of ferrous sulfate added was calculated based on the amount of hydrogen peroxide added. The molar ratio of hydrogen peroxide to ferrous sulfate added was 0.46, and the amount of ferrous sulfate added was 132 ml. In this example, ferrous sulfate heptahydrate was used, which satisfies (5 ml × 30% / 34) / (132 ml × 20% / 278) = 0.46, where 0.46 is the molar ratio.

[0016] Add appropriate liquid alkali to the maleic anhydride wastewater to adjust the pH to 2.5; add 20% ferrous sulfate according to the calculated dosage and mix it with the maleic anhydride wastewater; add 30% hydrogen peroxide according to the calculated dosage to react with the ferrous sulfate; add an appropriate amount of liquid alkali to adjust the pH of the Fenton reaction effluent to 4.5, add 10 ppm of polyacrylamide (PAM), and remove pollutants by flocculation and flotation.

[0017] As shown in Figure 1, the COD removal rate was 50.1% after treatment.

[0018] Example 2: The COD of the maleic anhydride wastewater to be treated was calculated and obtained. The measured COD of the maleic anhydride wastewater was 50,000 mg / L. The amount of hydrogen peroxide to be added was calculated based on the COD value. Using 20% ​​of the actual COD value, the calculated COD was 10,000 mg / L. The ratio of the hydrogen peroxide dosage to the calculated COD was 0.06%. Based on the calculation, to treat 500 ml of maleic anhydride wastewater, the hydrogen peroxide dosage was 10 ml, which meets the requirement of 10 ml × 30% / (10,000 × 500 ml × 10). -3 =0.06%.

[0019] The amount of ferrous sulfate added was calculated based on the amount of hydrogen peroxide added. The molar ratio of hydrogen peroxide to ferrous sulfate was 0.93, and 132 ml of ferrous sulfate was added. In this example, ferrous sulfate heptahydrate was used, which satisfies (10 ml × 30% / 34) / (132 ml × 20% / 278) = 0.93, where 0.93 is the molar ratio.

[0020] Add an appropriate amount of liquid alkali to adjust the pH of the maleic anhydride influent to 2.5; add 20% ferrous sulfate according to the calculated dosage and mix it with the maleic anhydride wastewater; add 30% hydrogen peroxide according to the calculated dosage to react with the ferrous sulfate; adjust the pH of the Fenton reaction effluent to 4.5-5.5, add 10 ppm of polyacrylamide (PAM), and remove pollutants by flocculation and flotation.

[0021] As shown in Figure 2, the COD removal rate was 47.7% after treatment.

[0022] The diagram shows the COD removal rate for different conditions.

[0023] As shown in Figure 1, under the condition of fixed Fenton reagent (molar ratio of hydrogen peroxide to ferrous sulfate of 1), the effect of the dosage ratio (the ratio of the calculated COD value to the actual COD value, i.e. the dosage ratio) on the COD removal rate was investigated for different calculated COD values, i.e. 5%, 10%, 20%, and 30% of the actual COD value of maleic anhydride wastewater.

[0024] As shown in Figure 2, with a fixed dosage ratio of 20%, the effect of different hydrogen peroxide / ferrous sulfate molar ratios on COD removal rate was investigated. The effect of dosage ratio on COD of maleic anhydride wastewater was also investigated. If the dosage ratio is too large, the cost will increase accordingly. Considering the overall cost of reagent addition, the optimal molar ratio range is 0.2-1.

[0025] As shown in Figure 3, from left to right, these are the liquid states after flocculation corresponding to hydrogen peroxide / ferrous sulfate molar ratios of 0.5, 1, 2, 4, and 8.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] In this invention, unless otherwise explicitly specified and limited, "above" or "below" a second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of a second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. It should be noted that when an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "above," "below," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

Claims

1. A maleic anhydride wastewater treatment process, characterized in that: The process includes calculating the COD value based on the actual COD value of the maleic anhydride wastewater to be treated; calculating the dosage of hydrogen peroxide based on the COD value; calculating the dosage of ferrous sulfate based on the dosage of hydrogen peroxide; adjusting the pH value of the maleic anhydride wastewater to be treated to 2.5-3; adding 20% ​​ferrous sulfate according to the calculated dosage and mixing it with the maleic anhydride wastewater; adding 30% hydrogen peroxide according to the calculated dosage to react with the ferrous sulfate; adjusting the pH value of the Fenton reaction effluent to 4.5-5.5; and adding 10ppm-20ppm of polyacrylamide.

2. The maleic anhydride wastewater treatment process according to claim 1, characterized in that: The calculated COD value is 5% to 20% of the actual COD value.

3. The maleic anhydride wastewater treatment process according to claim 1, characterized in that: The ratio of the amount of hydrogen peroxide added to the calculated COD value is 0.03% to 0.06%.

4. The maleic anhydride wastewater treatment process according to claim 3, characterized in that: The ratio of the amount of hydrogen peroxide added to the calculated COD value is 0.03%.

5. The maleic anhydride wastewater treatment process according to claim 3, characterized in that: The ratio of the amount of hydrogen peroxide added to the calculated COD value is 0.06%.

6. The maleic anhydride wastewater treatment process according to claim 1, characterized in that: The molar ratio of the amount of hydrogen peroxide added to the amount of ferrous sulfate added is between 0.2 and 1.

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