The Research On The Advanced Treatment Of Printing And Dyeing Waetewater By Adsorption-Catalytic Ozonation Process

Printing and dyeing wastewater is one kind of refractory industrial wastewater.Due to the complex composition,strong toxicity and poor biodegradability,it is hard to satisfy the wasterwater discharge standard.Recently,the national industrial wastewater discharge standards were enhanced step by step,which resulted in the enormous pressure on the printing and dyeing enterprises.To solve this problem,developing high efficient and low cost advanced treatment processes is undoubtedly the best choice.Advanced treatment was carried out in the present study with the wastewater from a printing and dyeing factory in Wuxi as the research object.Adsorption combined with catalytic ozonation was chosen as the advanced treatment process.The main contents of the study are as follows:Firstly,the target wastewater was analyzed comprehensively.It is shown that the COD value was in the range of 160²30mg·L^-1 and the BOD₅ value 52⁷5mg·L^-1.There is still a big gap between the value and the discharge standard.The presence of aromatics and unsaturated fatty hydrocarbons in wastewater was indicated by UV analysis.About 22kinds of organic pollutants in wastewater were detected by GC-MS analysis,such as azo,heterocyclic,halogenated and aromatics hydrocarbons.Secondly,the wastewater was pre-treated by coagulation process.The coagulation effect of aluminum sulfate,polyaluminum chloride and polyferric sulfate was compared.As a result,polymerized ferric sulfate showed the best effect and 1000ppm was the appropriate dosage.In addition,a series of adsorption materials such as activated carbon?AC?,molecular sieve and zeolite were used to adsorb organic pollutants from wastewater.Granular activated carbon and mordenite can reduce the value of COD and UV₂₅₄ in wastewater.In consideration of the economic factors,granular activated carbon was selected as the adsorbent and catalyst support in the following ozonation process.At last,the manganese was supported on the granular activated carbon to prepare the Mn@AC catalyst of the ozonation process.Adsorption process combined with catalytic ozonation process achieved a great treatment efficiency.Effect of catalyst amount,ozone amount,pH value and ionic concentration on the wastewater treatment efficiency was investigated.The Mn@AC catalyst was characterized by SEM,BET,XPS,ICP and strength tests.And the stability of the Mn@AC catalyst was evaluated preliminarily.The organic matters were effectively removed from the printing and dyeing wastewater by the adsorption combined with catalytic ozonation process.The value of COD and BOD₅ reached the national discharge standard.The number of species of detected organic matter was reduced to 15 after the advanced treatment process.Some cyclic hydrocarbons experienced ring opening process.The molecular structure of most of the organic matters became simpler.As a result,adsorption combined with catalytic ozonation process has a broad application prospect in the deep treatment of printing and dyeing wastewater.