Research On The Purification Of Direct Black-19 Dyeing Wastewater

Dyeing industry is one of the major pollution sources.The waste water of it meanly from the processing of desizing,scouring,mercerizing and dyeing and characterized by large amount,darkness and complexity.As a result,the comprehensive management became the problem to be solved.With the high decolourization ratio,large handling capacity,low cost,less investment,less space necessity and the high performance,the flocculation method is widely applied.Also,it can be used individually and combined with other ways.The technique of ultrafiltration is gradually applied to pollutant processing because of the energy economic efficiency,low costing in concentration process,no impurity in whole process,high purity of the product,compaction of the equipment,stability,convenience in maintains.Some kinds of dyeing waste water,which is hard to handle,are addressed by flocculation separately.Because the improvement of the method is small in extra process,we use the ultrafiltration as supplement.From the testing,we can conduct the conclusion that for the waste water sample 1,dyed by the Black-19,the processed pollutant can reach the national standard only with simple flocculation method.The optimum result was obtained when 300mg/L flocculants were added.The CODcr(Chemical oxygen demand)of the supernatant is 38mg/L and the chromaticity is 35 times when PFS(Polymeric ferric sulfate)was added.Meanwhile,the CODcr of the supernatant is 56mg/L and the chromaticity is 30 times when the other floccutant PAC(Polymeric aluminium chloride)was added.Both of the applying of the two kinds of flocculants can satisfy the national waste water release standard.But the two approaches focused on different target.For the waste water sample 2,the relatively complex flocculation method was used.Under the condition of 900mg/L PFS added,PH being 11,speed of blending the combination liquid being 500r/min and 1.5min,speeding of blending the flocculation being 100r/min and 20mins,the CODcr of the supernatant is 86mg/L and the removal rate of it is 94.2%and the chromaticity is 45 times and the removal rate of the chromaticity is 90%.At the same time,under the best condition of PAC added,the CODcr of the supernatant is 138mg/L and the chromaticity is 30 times.Although the CODcr of the waste water supernatant reaches the standard processed by the PFS,the one handled by the PAC won't.Consequently,the prime floccutant is PFS.For the sample 3,it was addressed by the complicated coupled flocculating ultrafiltration method.PFS was exclude.Under the condition of 500mg/L PAC added,PH being 10,speed of blending the combination liquid being 500r/min and 1.5min,speeding of blending the flocculation being 100r/min and 15mins,the CODcr of the supernatant is 392mg/L and the removal rate of it is 71.6%and the chromaticity is 55 times and the removal rate of the chromaticity is 87.8%.The result needed extra ultrafiltration as post treatment to satisfy the national standard.Under the pressure of 0.4MPa and the duration of 30min,the CODcr is 74mg/L and the removal rate of it is 94.6%and the chromaticity is 13 times and the removal rate of the chromaticity is 97.1%.The sample 3 can satisfy the standard.The pollution of the filter is an inevitable result after the filter separative process.After the contrastive test between acidulous and alkalescent handling,the conclusion can be conduct that washed by the HClO with PH of 6,the membrane flux was recovered to 97%.