Study On The Silk Printing And Dyeing Wastewater Treatment By Combined Micro-electrolysis/BAF Processes

The dyeing and printing wastewater is one of the hard-deal industrial wastewater in china because its difficult degradation,organic ingredients complex chromaticity. At present,is commonly used in biological and chemical treatment,but there is one color and CODcr difficult to remove,as well as produce secondary pollution.How to dispose the dyeing and printing wastewater with economical and effective processing technology has become a universal problem concerned by the environmental protection industry today.This article analyzes the characteristics and the nature of the printing and dyeing wastewater briefly,and summarizes the related treatment method used in this type wastewater at home and abroad at present.The article takes the wastewater of line of embroidery in dyeing section as the object of research,the wastewater is got from certain printing and dyeing company in Zhejiang.We bring forward Iron filings micro-electrolysis / BAF technology to deal with the waste water,aiming at the wastewater characteristics of poor biochemical character,high-color,complex composition.From micro-electrolysis static beaker experiment,we study the affect factor and the best reaction conditions of using micro-electrolysis to pretreatment the wastewater by the numbers,the results show that:1.PH value of micro-electrolysis process's influence is significant,The results show that,when the PH value is in the range of 3 to 9,pH value,the smaller,the better to deal with.However,taking into account the actual project,pH value is too low will increase the running costs,it will also cause a certain degree of corrosion to equipment.It is therefore proposed to control the pH value of 4 to 5。2.reaction time will not only affect the results,but also has an impact in the consumption of filler.The appropriate reaction time should be able to ensure the treatment effect,and also can not waste filler.Reaction time is too short,the response inadequate and can not achieve the desired effect,The retention time is too long will increase solubility of iron in the wastewater,emerge the phenomenon of color back., in addition,it will increase the investment in equipment。3.the quantity of Iron filings of micro-electrolysis's influence is more obvious. Single-factor data of experiment shows,the removal rate of CODcr increases with the increasing of the dosage of iron filings,when the dosage is greater than 8% (8g/100ml wastewater),CODcr removal rate will no longer get a marked increase. This is because too much iron filings will cause that the wastewater and the filler's contact area will be limited by response system.The use of iron filings is inadequate. In addition,with the acid's rapidly consuming,the reaction will be weakened.The removal rate of the color rapidly increases with the increasing of the iron filings dosage.But when the dosage is greater than 10%,the removal rate reduces on the contrary.4.It can be drawn from the static orthogonal experiment that:the order of impacting on the color removal rate is reaction time(B)＞pH value(A)＞iron filings dosage(C),the best level combination is A₁B₃C₃,that is,PH value of wastewater before treatment is 4,reaction time is 70min,iron filings dosage is 10%;the order of impacting on the color removal rate is pH value(A)＞reaction time(B)＞iron filings dosage(C),the best level combination is A₁B₄C₄,that is,PH value of wastewater before treatment is 4,reaction time is 80min,iron filings dosage is 12%.On the comprehensive comparison of the level of various factors,we can see the appropriate operating parameters of the Iron filings micro-electrolysis is that PH value is 4, reaction time is 70min,iron filings dosage is 10%.At the normal temperature,in the conditions of that,PH value is 4,reaction time is 70min,iron filings dosage is 10%,aeration volume is 10L/min,we carry out small-scale micro-electrolysis dynamic experiment.After 10 days' observation in a row,we can see that the water is generally stable.The water after treatment maintain the pH value of about 5.1,color removal rate of 88%,CODcr removal rate of 67%. The B/C of the water after treatment is 0.32,which increases 65.6%comparing with the water before treatment's.It creates a good condition for biological and chemical processing following.Through the pretreatment of iron filings micro-electrolysis,color and heavy metals content of the wastewater drop,biodegradability of the wastewater improves. The experiment proves that BAF is effective and easy to use to deal with the wastewater.Technology of COD_cr,SS,NH₃-N removal efficiency achieves 81.2%,87.8%,89.1%separately.After a month's observation,we can see that the quality of the water after treatment of system is stable.Wastewater indicators can reach the first standard of wastewater discharge standard(GB8978-1996).