Advanced Treatment Of Dyeing Wastewater By BAF: Study And Practice

With the development of dyeing industry,the problems such as water consumption and wastetwater discharge become more serious,so it is important to strengthen the advanced treatment of dyeding wastewater and promote the wastetwater reuse.This work studied the advanced treatment of dyeding wastewater by biological aerated filter process(BAF),and start-up method and running Characteristics of this process were investigated.The effect of environmental factors, operation parameters,and backwashing program on pollutants removal was researched. Furthermore,the dagradation of major pollutants was studied using GC-MS technology.Based on these works,an engineering project was performed and the practical effect of advanced treatment of deying wastewater by BAF was obtained.The main results were as follows:1.BAF reactor could be started up by two-stage method,including batch flow and continuous flow stages,and COD_Cr removal rate could reach 70%in three months. When the reactor had stoped running for one month,the formed biological film still exhibited good activity,and just 3～5 days were needed to started up the reactor again.2.BAF process exhibited excellent performance in the advanced treatment of dyeing wastewater.When the gas-water ratios was 4:1 and hydraulic loading was 0.31m³/(m²Â·h),the COD_Cr value of effluent could be fixed around 64 mg/L,and the concentration of NH₄⁺-N was too low to be detectived.3.Combined backwashing method was adopted in the expriments,and the optimum backwashing effect was obtained when backwashing intensity of gas was 10～15L/(m²Â·s),and water intensity was 5～6L/(m²Â·s).4.The pollutants in wastewater included butylated hydroxytoluene,cedrol, pHthalic acid,and alkanes with a straight chain form nine to twenty seven.All the pollutants could be biological degraded in BAF,but butylated hydroxytoluene and cedrol,as two major pollutants,still had 65.0%and 39.2%retention,respectively.5.Based on the experiment results,a BAF project was designed for dyeing waterwater advaced treatment with a water quantity of 3000m³/d.The BAF system showed fine ability on the wastewater advaced treament,and the effluent could be directly reused.