Study On Optimization Of Treatment And Reuse Technology Of Synthetic Leather Substrates Wastewater

The development of productivity of synthetic PU leather and itssubstrates enhanced local economy dramatically in Zhejiang province, butat the same time, it also brought heavy stress of water pollution. It isnecessary to develop an economical, practical and high efficiencytechnology for treatment and reuse of wastewater from synthetic leathersubstrates industry.At first, the characteristics of dyeing technics and its wastewater wereanalyzed in this paper. After contrasting the methods of dyeing wastewatertreatment at home and abroad, a combined technics of "Coagulation—Biochemical reaction—Flotation—Bio-active carbon(BAC)—Ion-exchange" was chosen to treat dyeing wastewater of synthetic leathersubstrates. Moreover, based on the detailed investigation about quality andquantum of dyeing wastewater from a synthetic leather substrate company,experiment of coagulation, study on optimal control of biochemicalreaction, laboratory-scale and pilot-scale research of deep treatment byBAC were carried out in this paper. The results showed that at first coagulating sedimentation, the optimal dosage of FeSO₄ was 1.4g/L andthe optimal pH was 11.5. At secondary coagulating sedimentation, theoptimal dosage of Al₂(SO₄)₃ was 1.3g/L. In order to improve biochemicalperformance of the dyeing wastrwater, it was necessary to regulate pH toabout 8 by acid or hydrolysis—acidification. In addition, the experimentresults of BAC technology in deep treatment demonstrated that upfolwmode, the concentration of COD less than 300mg/L, the speed of filteringless than 2 m/h were suitable process parameters, and the period ofbackwashing of filter was about 60 h. After deep treatment, the wastewaterwas reused in the rinse process of substrates production. The qualityindicaters of the substrates and its synthetic PU leather satisfyed therequirements.Aaccoding to the benefit analyse, we can conclude that thetechnology for treatment and reuse of wastewater from synthetic leathersubstrates industry have environmental and economical profitability,which is good for application and popularization.