Study On Pollution Control Technology Of High Salt Wastewater In Printing And Dyeing Industry

The high concentration of salt in the waste water will make the soil compaction along the receiving water,break the balance of the water ecological,and even environmental degradation.In view of the high-salt phenomenon existing in the wastewater discharge process of the printing and dyeing industry,through investigation and testing of some printing and dyeing companies in Shandong Province,the reasons for the high salt content of dyeing wastewater and reasons for high salt were analyzed,and proposed the technical regulations for recycling,clean production,end treatment of waste water.Through investigation,it was found that the salts in the printing and dyeing wastewater mainly come from the addition of dyes and auxiliaries in the production process,as well as the neutralization treatment of alkaline wastewater from the desizing and mercerization processes in the production process.A printing and dyeing company mainly engaged in the production of cotton textile products is the main research object,through the addition of salt in its production process,the transformation of the conventional sewage treatment process,to solve the problems arising in the conventional sewage treatment process,and the subsequent process of desalination.The study provided conditions for developing technical regulations for the desalination of dyeing and printing wastewater.Puts forward salt-controlled cleaner production processes,such as fiber modification process,short liquor dyeing process,low temperature dyeing process,short process dyeing process,biological enzyme treatment technology and supercritical carbon dioxide dyeing process,etc.to reduce inorganic salt dosing and use;select appropriate dyes,use new reactivedyes,use low-salt,environmentally friendly new dyes,etc.;select suitable additives,use other salt substitutes instead of anhydrous sodium sulfate,add cationic additives,use new additives Etc.;increase the reuse rate of wastewater,increase the use of recycled water,etc.Aiming at the source of waste water and the concentration of pollutants,a set of conventional sewage treatment processes was proposed,and for the problems of large production volume and unstable water production in the conventional sewage treatment of a certain printing and dyeing plant,the treatment process was reformed.Through the modification of the treatment process,Master air flotation machine and mixed sedimentation tanks are added to the conventional sewage treatment process,so that the effluent COD concentration is reduced from the original 190 mg/L to about 70 mg/L to 190 mg/L;other indicators of effluent such as ammonia nitrogen,SS,etc.are also reduced.The effluent before the transformation has been reduced to achieve a better effluent effect,solving the problems of sludge swelling and high moisture content in the sludge.In the desalting stage,the effluent turbidity of the secondary settling tank was removed by the MBR process.The turbidity-removed wastewater passes through a two-stage nanofiltration system and a softening system,followed by a DTRO system,and finally undergoes four-effect evaporation for salt curing.The solidified salt is disposed of in accordance with the requirements of the environmental protection department.In this desalination system,some of the reclaimed water produced is used for production,and some of it is used for greening,flushing toilets,etc.After the desalination system,the total amount of salt in the discharged wastewater is less than 1600 mg/L.