CN110818036A - A method for strengthening iron-carbon micro-electrolysis combined with persulfate for advanced treatment of papermaking wastewater - Google Patents

Abstract

A method for strengthening iron-carbon micro-electrolysis combined with persulfate for advanced treatment of papermaking wastewater, comprising the following steps: step 1: detecting the main water quality indicators of the effluent from the secondary sedimentation tank of a sewage treatment station in a paper mill; step 2: taking 400 mL of wastewater in a 500 mL beaker, Adjust pH to 2～9, add iron powder, activated carbon and K ₂ S ₂ O ₈ in turn, and carry out aeration; Step 3: react at normal temperature for 2～3h, take an appropriate amount of solution to adjust pH=9～9.5, and then in Centrifuge at 3500r/min for 30min, and take the supernatant to detect its COD and chromaticity. The invention adds aeration on the basis of iron-carbon micro-electrolysis combined with persulfate, which can not only improve the treatment effect of the original system on papermaking wastewater, but also alleviate the problem of iron-carbon hardening in the later stage of the reaction.

Description

A method for strengthening iron-carbon micro-electrolysis combined with persulfate for advanced treatment of papermaking wastewater

technical field

The invention relates to the field of advanced treatment of papermaking wastewater, in particular to a method for strengthening iron-carbon micro-electrolysis combined with persulfate for advanced treatment of papermaking wastewater.

Background technique

The wastewater pollutants produced in the pulping and papermaking process are complex in composition, deep in color, difficult to handle, and large in discharge, which is one of the main sources of environmental pollution. At present, pulp and papermaking wastewater is generally treated by primary physicochemical and secondary biochemical treatment, but the effluent quality still has problems such as high COD content and deep chromaticity, and it is difficult to meet the requirements of GB3544-2008 Pulp and Paper Industry Water Pollutant Discharge Standard. Therefore, it is of great significance and broad application prospects for environmental protection and the development of the paper industry to carry out advanced treatment research on the secondary effluent of pulp and papermaking wastewater to further reduce the COD content of the effluent and improve the quality of the effluent. Common advanced treatment methods include physicochemical method, biochemical method and advanced oxidation method. Among them, physical and chemical methods include coagulation, adsorption and membrane separation; biochemical methods include aerobic biochemical methods and anaerobic biochemical methods; advanced oxidation methods include advanced oxidation methods based on sulfate radicals (SO ₄ ^- ·), Fenton oxidation, ozone oxidation, photocatalytic oxidation, electrochemical oxidation, etc. ^[3] . Although the traditional advanced treatment method has a certain treatment effect, it also has the problems of low efficiency, secondary pollution and high cost. Compared with traditional water treatment methods, advanced oxidation technology has the advantages of strong oxidation capacity, non-selective oxidation process, thorough reaction, continuous operation and small footprint, especially for pulping with complex components and high advanced treatment requirements. The treatment of papermaking wastewater has great application value.

The new advanced oxidation technology based on sulfate radicals is a water treatment technology that has developed rapidly in recent years to treat refractory organic pollutants. Persulfate (PS) is dissolved in water to ionize the persulfate ion S ₂ O ₈ ^2- . S ₂ O ₈ ^2- has strong oxidizing property and is relatively stable at room temperature. Its redox potential is E ₀ =2.01V, but it has a slow oxidation rate of organic matter and has little removal effect. However, under the activation conditions of UV, ultrasound, heat and transition metals, persulfate ions can generate SO ₄ ^- ·, SO ₄ ^- · has a strong oxidizing ability. Among the persulfate activation methods, transition metal activation is simple, and the pollutant removal effect is good. Among them, Fe ²⁺ activates persulfate to generate sulfate radicals, which is the most favored by researchers. But in the process of activating persulfate by metal ions to generate SO ₄ ^- ·, the speed is faster, which reduces the utilization rate of SO ₄ ^- ·.

Iron-carbon micro-electrolysis combined with advanced persulfate oxidation technology is a new method proposed in recent years. Fe ²⁺ and [H] with high chemical activity are generated by the iron-carbon micro-electrolysis reaction. These substances can not only directly destroy the carbon chain of organic pollutants, ^but also can activate persulfate to produce strongly oxidizing SO ₄ ^－ · . At the same time, the original Fe ⁰ in the system can continuously reduce Fe ³⁺ to form Fe ²⁺ , and the generated Fe ²⁺ can continue to activate persulfate. However, in practical applications, there are still problems such as poor treatment effect and hardening of iron-carbon materials to reduce the pollutant removal effect. Therefore, how to improve the effect of iron-carbon micro-electrolysis combined with persulfate in advanced treatment of papermaking wastewater is an important research direction.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a kind of method for strengthening iron-carbon micro-electrolysis combined persulfate advanced treatment of papermaking wastewater, adding aeration on the basis of iron-carbon micro-electrolysis combined persulfate, not only The treatment effect of the original system on papermaking wastewater can be improved, and the problem of iron and carbon hardening in the later stage of the reaction can be alleviated.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for strengthening iron-carbon micro-electrolysis combined with persulfate advanced treatment of papermaking wastewater, comprising the following steps:

Step 1: Detect the main water quality indicators of the effluent from the secondary sedimentation tank of the sewage treatment station of the paper mill;

Step 2: take 400 mL of waste water into a 500 mL beaker, adjust the pH to 2-9, add iron powder, activated carbon and K ₂ S ₂ O ₈ in sequence, and conduct aeration;

Step 3: react at room temperature for 2 to 3 hours, take an appropriate amount of solution and adjust to pH=9 to 9.5, then centrifuge at 3500 r/min for 30 minutes, and take the supernatant to detect its COD and chromaticity.

In the second step, the dosage of K ₂ S ₂ O ₈ is preferably 2.5-15 mM, and the best is 7.5 mM; the iron-to-carbon ratio is 1:1, 2:3, 1:2, and the best is 2:3 ; The total dosage of iron and carbon is preferably 0.3 to 0.7g, and the best is 0.6g; the aeration volume is preferably 0.2 to 0.6L/min, and the best is 0.4L/min;

In the second step, the iron is selected from 100 mesh zero-valent iron; the activated carbon is granular activated carbon with a particle size of 0.9-3 mm.

The present invention has the following beneficial technical effects:

1. The present invention increases aeration on the basis of iron-carbon micro-electrolysis combined with persulfate, which can not only reduce the hardening of iron-carbon, but also enhance the corrosion effect of micro-electrolysis and improve the overall processing capacity under oxygenation conditions.

2. The present invention uses K ₂ S ₂ O ₈ as the oxidant. Compared with the commonly used H ₂ O ₂ , K ₂ S ₂ O ₈ is more stable, and is more convenient for transportation and storage in practical applications; and it is cheap and easy to popularize and use.

3. Compared with the traditional Fenton technology, the persulfate advanced oxidation technology adopted in the present invention has a wider range of pH adaptation, less iron sludge output, and better effect in treating high-concentration organic wastewater.

Description of drawings

Fig. 1 is a simple schematic diagram of the reaction device of the present invention.

Figure 2 is a schematic diagram of the treatment effect under aerated and non-aerated conditions.

Figure 3 is a schematic diagram of the effect of different aeration amounts on the treatment effect.

Detailed ways

Embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings:

As shown in Figure 1, a method for strengthening iron-carbon micro-electrolysis combined with persulfate advanced treatment of papermaking wastewater, comprising the following steps:

Step 1: Detect the main water quality indicators of the effluent from the secondary sedimentation tank of the sewage treatment station of the paper mill.

Step 2: Take 400mL of wastewater into a 500mL beaker, adjust the pH to 2-9, add iron powder, activated carbon and K ₂ S ₂ O ₈ in sequence, the dosage of K ₂ S ₂ O ₈ is 2.5-15mM, and the ratio of iron to carbon is 2.5 to 15 mM. 1:1, 2:3, 1:2, the total dosage of iron and carbon is 0.3~0.7g; and aeration is performed, and the aeration rate is set to 0.2~0.6L/min;

Table 1 Main water quality indicators

Step 3: react at room temperature for 2 to 3 hours, take an appropriate amount of solution and adjust to pH=9 to 9.5, then centrifuge at 3500 r/min for 30 minutes, and take the supernatant to detect its COD and chromaticity.

Example 1

Step 1: Take 400 mL of waste water into two beakers A and B (500 mL) respectively, adjust the pH to 5, and add iron (0.24 g), activated carbon (0.36 g) and K ₂ S ₂ O ₈ (0.812 g) in turn.

Step 2: A is the aeration group: the aeration volume is set to 0.4L/min; B is the non-aerated group: placed under a six-joint agitator for stirring, and the rotational speed is set to 240r/min.

Step 3: After 2.5 hours of reaction, take an appropriate amount of solution to adjust to pH=9～9.5, then centrifuge at 3500r/min for 30min, and take the supernatant for detection. The results are shown in Figure 2. The COD removal rate in the aeration group was 73%, and the color removal rate was 98%; the COD removal rate in the non-aerated group was 62.5%, and the color removal rate was 91%. Under the same conditions, the COD and chromaticity removal rates of the aerated group were higher than those of the non-aerated group.

Example 2

Step 1: Take 400 mL of waste water into a 500 mL beaker, adjust the pH to 5, and add iron (0.24 g), activated carbon (0.36 g) and K ₂ S ₂ O ₈ (0.812 g) in sequence.

Step 2: The aeration volume is set to 0.2L/min, 0.4L/min, 0.6L/min.

Step 3: After 2.5 hours of reaction, take an appropriate amount of solution to adjust to pH=9～9.5, then centrifuge at 3500r/min for 30min, and take the supernatant for detection. The results are shown in Figure 3, and the COD removal rates were 65%, 72.6%, and 64.2%, respectively. The best aeration rate is 0.4L/min.

Example 3

Step 1: Take 400mL of wastewater into a 500mL beaker, and adjust the pH to 2, 3, 5, 7, and 9.

Step 2: Iron (0.24g), activated carbon (0.36g) and K ₂ S ₂ O ₈ (0.812g) were added in sequence, and the aeration rate was set to 0.4L/min.

Step 3: After 2.5 hours of reaction, take an appropriate amount of solution to adjust pH=9～9.5, then centrifuge at 3500r/min for 30min, take the supernatant for detection, the COD removal rates are 61%, 67%, 73.6%, 50%, respectively. %, 36%. The initial pH is around 5 for the best treatment.

Claims (3)

1. A method for strengthening advanced treatment of papermaking wastewater by combining iron-carbon micro-electrolysis with persulfate is characterized by comprising the following steps:

the method comprises the following steps: detecting main water quality indexes of effluent of a secondary sedimentation tank of a sewage treatment station of a paper mill;

step two: taking 400mL of wastewater into a 500mL beaker, adjusting the pH to 2-9, and sequentially adding iron powder, activated carbon and K₂S₂O₈And aeration is carried out;

step three: reacting for 2-3 h at normal temperature, taking a proper amount of solution, adjusting the pH value to 9-9.5, centrifuging for 30min at 3500r/min, and taking supernatant for detecting COD and chroma.

2. The method for the advanced treatment of the papermaking wastewater by combining the strengthening iron-carbon micro-electrolysis with the persulfate according to claim 1, wherein in the second step, K is₂S₂O₈The amount of the addition is preferably 2.5 to 15 mM; the iron-carbon ratio is 1:1, 2:3 and 1: 2; the total dosage of the iron and carbon is preferably 0.3-0.7 g; the aeration rate is preferably 0.2 to 0.6L/min.

3. The method for the advanced treatment of the papermaking wastewater by the combination of the reinforced iron-carbon micro-electrolysis and the persulfate according to claim 1, wherein in the second step, the iron is zero-valent iron with a 100-mesh size; the activated carbon is granular activated carbon, and the particle size is 0.9-3 mm.

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