Transformation Characteristics And Accumulation And Cotrol Regulation Of Chromogenic Organics In Printing And Dyeing Wastewater During Recycling

In view of the high content of organic matter,large emissions and serious pollution in printing and dyeing wastewater,higher requirements have been put forward for the recycling of printing and dyeing wastewater in many parts of the country,and stricter standards for COD and chroma of effluent have been put forward.However,in the process of recycling,Here exists a series of pollution on general.With the increase of recycling times,there must be the gradual enrichment of chromogenic organic matter.Therefore,it is very important to control the enrichment of chromogenic organic matter.In this subjection,the pilot-scale experiment system of the combination of the dual-step ozone induced flotation process and biological system developed by our research group was used to treat simulated printing and dyeing wastewater.The transformation characteristics,enrichment and control characteristics of chromogenic organic compounds in the process of recycling of printing and dyeing wastewater were studied.Using the combined system between biochemical and air flotation,physichemical indexes and liquid chromatography analysis were determined.The distribution,transformation and mass balance of dyes in the process of biological system operation were obtained.Subsequently,the conventional physichemical indexes and organic matter characteristics were measured by the dual-step ozone induced flotation process(DOIF),and the transformation characteristics of reactive red M-3BE in the recycling process were analyzed.The results showed that reactive red M-3BE was degraded gradually by ozone flotation process,and the degradation rule of reactive red dyes was deduced.It is that,theazo double bond of chromogenic group(-N=N-)and the nitrogen-hydrogen bond of chromogenic group(-NHR)were broken firstly,then the vinyl sulfone active group and chromogenic group of benzene ring and naphthalene ring were degraded,and the structure of naphthalene ring and pyrogalloxazine was further opened,finally,forming some substances which contain the benzene ring.In order to further explore the enrichment rule of chromogenic organic matter in the recycling process of printing and dyeing wastewater,the combined system between biochemical-air flotation was used to treat artificial simulated printing and dyeing wastewater.The conventional physichemical indexes and organic matter characteristics were determined.It was found that the light intensity of high-cyclic aromatic proteins and soluble microbial metabolites decreased gradually under the treatment of biological system,but the effect of DAF process on the removal of organic matters was not obvious.With the increase of recycling times,the content of unsaturated bonds of organic compounds increased,soluble microbial metabolites,aromatic substances and the index of each fraction gradually enriched,and enriched chromogenic organic substances in the printing and dyeing wastewater contained a large number of aromatic substances,such as benzene ring and naphthalene ring,and small molecular inorganic substances.In order to reduce the negative impact of organic matter enrichment on the reuse of reclaimed water and improve the recycling efficiency of printing and dyeing wastewater,the combined system between biochemical and the dual-step ozone induced flotation process(biochemical-DOIF)was used to treat artificial simulated printing and dyeing wastewater.The conditions of water distribution,operation parameters during operation were consistent with those of biochemical-DAF system,and the conventional physichemical indexes and organic matter characteristics were determined.The control characteristics of enriched chromogenic organic matter were analized.The results show that the effluent chroma of DOIF system increases from 8 times to 32 times,while that of DAF system increases from12 times to 120 times,indicating that DOIF system can effectively reduce the chroma of secondary effluent.The cumulative rate of COD in effluent of DOIF system is about 0.45mg/L·d,which is 91.3% lower than the DAF system.From the point of recycling,DOIF system can effectively reduce the influence of phenylnaphthalene ring aromatic substances on biological system,control the enrichment of high-cyclic aromatic proteins and solublemicrobial by-products,increase the running time of biological system by 2.5 times,and effectively reduce the impact of enrichment of chromogenic organic substances on biological system.