Study on Decolorization of Wastewater Decolorizer CZTS-02 in Advanced Treatment of Middle-Stage Water

Abstract:

The turbidity and chromaticity removal efficiency of Henan XX Paper Company's external drainage was poor, which affects the environment. In order to meet the emission standards and not affect the environment, the advanced treatment is needed, but the cost is high. According to the actual situation of the paper mill, the wastewater decolorizer is used to treat the middle water, which developed by our company . The wastewater decolorizer is a colorless or light-colored transparent viscous liquid, belonging to an organic polymer compound, with a polymer spatial structure, which can produce a good adsorption bridge effect, making it have a good coagulation and sedimentation effect. The unique cationic groups in the molecular structure can be combined with the anionic groups of the color-developing substances in the wastewater to become insolubles and precipitate, thereby decolorizing the water. The sewage decolorizing agent developed by Zhengzhou Chengzhi Industrial Co., Ltd. has achieved good results in the treatment of middle-stage water.

1. Materials and Methods

1.1 Purpose of the experiment

The purpose of using wastewater decolorizer is to find a suitable scheme to reduce the turbidity and chroma of the effluent to the greatest extent.

1.2 Experimental materials

Polyferric sulfate (Fe³⁺), aluminum chloride (PAC), cationic polyacrylamide (CPAM), middle-stage water and external drainage were taken from Henan XX Paper Company. The wastewater decolorizer CZTS-02 was independently developed by Zhengzhou Chengzhi Industrial Co., Ltd.

1.3 Experimental procedure 

(1) Experimental process of middle water decolorization

Figure 1 experimental process of middle water decolorization

(2) Experimental method of decolorization of middle-stage water

Experimental design: Take 50 mL of the water to be treated, with a pH of 7-8. Firstly, add 2% of CZTS-02 sewage decolorant diluent 2.5‰-1% (original solution 50-200 ppm), stir for 5 minutes, then add an appropriate amount of 11% Fe³⁺ or 8% PAC made by XX Paper Company, stir for 5 minutes, Finally, 1‰ CPAM was added to promote solid-liquid separation. After the experimental water sample was treated with a water purification agent, the supernatant was filtered through a 300-mesh filter to detect its color and COD.

Experimental process: a total of 11 groups of schemes were carried out in the experiment. Firstly, the simulation experiment (1^#) was carried out according to the dosage of the agent provided by the person in charge of wastewater of XX paper company. In 50ml water body, the self-made Fe³⁺ of XX paper company was added, and the consumption was 3kg per ton of wastewater. Then, CPAM was added to make flocculation sedimentation and solid-liquid separation. Finally, two groups of water samples with better treatment effect were selected and sent to the laboratory for chroma and COD detection together with raw water and external drainage.

2. Experimental results and analysis

2.1 experimental results

Figure 2  Comparison of appearance effect of four groups of water samples

Table 1  Chromaticity and COD values of four groups of water samples

2.2 Experimental analysis

(1) In the current treatment scheme of wastewater treatment station of XX paper company, the COD was reduced from 565mg/L to 230mg/L, and the removal rate was 59.2%. The chroma was reduced from more than 5000 times to 530 times, and the removal rate was more than 89.4%.

(2) In the 7^# decolorization treatment plan, the consumption of CZTS-02 wastewater decolorizer per ton of water was 50ppm, the COD was reduced from 565mg/L to 162mg/L, and the removal rate reaches 71.3%. The chroma was reduced from 5000 times to 113 times, and the removal rate reached more than 97.7%. The COD removal rate increased by 12.1%, and the chroma decreased by 8.3%.

(3) In the 9^# decolorization treatment plan, the consumption of CZTS-02 wastewater decolorizer per ton of water was 100ppm, the COD was reduced from 565mg/L to 301mg/L, and the removal rate reaches 46.7%. The chroma was reduced from 5000 times to 118 times, and the removal rate reached more than 97.6%. The COD removal rate was reduced by 12.5%, and the chromaticity was reduced by 8.2 %.

3. Experimental conclusions

(1)The laboratory experiments have proved that the self-made flocculant Fe³⁺ + CPAM currently used in the wastewater treatment station of XX Paper Company was not efficient, and further optimization is necessary.

(2) On the basis of the existing scheme, the use of wastewater decolorizer CZTS-02 can significantly reduce the turbidity and chroma of the effluent from the advanced treatment, and the removal rate of COD can also be significantly improved.

(3) The results showed that the best combination of reagents optimized by the laboratory of Zhengzhou Chengzhi Industrial Co., Ltd. was wastewater decolorizer CZTS-02 + XX paper company's self-made Fe³⁺ + CPAM . The addition point of wastewater decolorizer CZTS-02 was after the secondary sedimentation tank effluent and before the addition of Fe³⁺ made by XX paper company.

(4) Recommended dosage for field pilot test: The addition range of wastewater decolorizer CZTS-02 is 50-200ppm per ton of water consumption, the addition range of Fe³⁺ with a concentration of 11% made by XX Paper Company is 7-10kg per ton of water consumption, and the addition range of CPAM is 2-5ppm, that is, the adding amount of 1‰ diluent is no more than 5kg per ton of wastewater.

(5) The operation effect of the sewage decolorizing agent CZTS-02 can be evaluated by continuously tracking the turbidity and chromaticity of the effluent from the external drainage pool, as well as the COD and SS of the external drainage.