Integrated Process For Advanced Treatment And Reuse Of Printing And Dyeing Wastewater

Because the quality of printing and dyeing wastewater is complex, the reuse of waste water is difficult to achieve by single technology. Therefore, various methods need to be organically combined and combined process for comprehensive treatment. Xiaojun, Wang, and so on [18] ozone combined with biological treatment of printing and dyeing wastewater, ozone oxidation of wastewater B/C increased from 0.18 to 0.36, COD COD and chroma removal rate has also been improved. Huang Ruimin, et al. [19] the dyeing wastewater of knitted cotton fabric was treated by combined process of coagulation decolorization biological aerated filter and ion exchange. The effluent color was removed to less than 10 times, COD<20 mg/L, SS below 2 mg/L and turbidity below 3 NTU. Guo Zhaohai et al. [6] studied the effect of O3 oxidation and biofilter combined process on printing and dyeing wastewater. It was found that the O3- biofilter combination technology played a synergistic role in chemical oxidation, adsorption and biodegradation, and had the advantages of low operation cost, no concentrated liquid and less residual sludge. Single technology for advanced treatment is difficult to solve problems such as decolorization, COD reduction, salt removal and so on. The combination of various single technologies can achieve better results. It can also ensure the full use of the advantages of various technologies and improve the removal rate of pollutants.

The composition of printing and dyeing wastewater is complex, such as membrane technology. Printing and dyeing wastewater It is necessary to choose suitable pretreatment process to prevent colloid and organic matter in waste water. Suspended solids And so on, causing pollution to the membrane. A., Bes-Pi, and so on [20]. The combination of O3 and NF was used to treat the printing and dyeing wastewater after biochemical treatment, and O3 was used to oxidize organic pollutants which cause membrane fouling. All indexes of the effluent can meet the reuse standard. M., Marcucci, and so on [21] aimed at physicochemical pretreatment of straight row wastewater in the workshop, and then treated by flocculation sedimentation, O3 oxidation and UF for subsequent deep treatment, the chroma removal rate of the whole process was 93%, and the COD removal rate was 66%. The problem of membrane fouling limits the application of membrane technology in printing and dyeing wastewater treatment. O3 membrane oxidation and other pretreatment methods are used to control membrane fouling, thus increasing the service life of membrane and reducing the cost of treatment.

Many studies abroad have proved that combining different membrane separation technologies to form integrated membrane technology is an important direction for advanced treatment of printing and dyeing wastewater. M. Marcucci et al. [21] treat the printing and dyeing wastewater after sand filtration and UF treatment, then use NF or RO for advanced treatment. Experiments show that NF or RO is feasible for advanced treatment, and RO effluent can be used in any printing and dyeing process. NF is not as good as RO in desalting and removing minerals, but the running cost is lower than RO.

　　 Zhejiang The "ozone catalytic oxidation +CMF+ RO" advanced treatment process was developed in the US environment, and a 1500 m3/d printing and dyeing wastewater membrane treatment reuse demonstration project was built. The O3 catalytic oxidation system is mainly used to remove the COD and the chroma of the biodegradable organic pollutants in water. The removal rates can reach up to 30%~40% and 90% respectively. Ozone catalytic oxidation effluent into the continuous ultrafiltration (CMF) system, stable effluent quality, COD stabilized at about 40 mg/L, <0.4 turbidity NTU, pollution index (SDI) <3. After reverse osmosis treatment, the effluent COD<10 mg/L, electrical conductivity <10.5 S/cm, SS SS and chroma were 0, meeting the recommended quality standard for advanced reuse water. The whole process is treated by separate treatment, grading and reuse, and the wastewater reuse rate reaches more than 75% of the total treatment volume.

All these studies indicate the future development direction of wastewater advanced treatment technology, that is, to make full use of a variety of process and technology integration to improve the degree of wastewater treatment, and to achieve the goal of recycling wastewater is the ultimate goal.