Process Study On Hydrothermal And Fenton Oxidation Treatment Of Paint Sludge

Paint sludge is characterized by high viscosity and difficulty of dewatering,which restricts its direct incineration treatment.Aimed at this problem,two new process routes were put forward in this paper in order to provide reference for minimization and recycling of paint sludge.The first process was a combined process of hydrothermal reduction of paint sludge and Fenton pretreatment of hydrothermal effluent.Under the optimum conditions(temperature=200?,water amount=10 g/g dry sludge,hydrothermal time=1.5 h),clear coat sludge,base coat sludge and primer sludge achieved solid reductions of 39.4%,31.1%,31.8%,and their dewatering abilities were improved.SEM,elemental analysis,infrared spectroscopy,thermogravimetry showed the products after hydrothermal treatment had better combustion properties,and the results also indicated that the mechanism of hydrothermal treatment involved decarboxylation and hydrolysis of ester bonds.When the solid reduction was 30%,the COD of hydrothermal effluent was about 2.5×104 mg/L,and the effluent needed Fenton-coagulation pretreatment.The process conditions were optimized by response surface method and single factor method.Under the optimum conditions(Fe2+/COD=0.15?H2O2/COD=2.5,temperature=50?,reaction time=3 h),COD removal of three hydrothermal effluents was 73-81%.The second process was direct treatment of paint sludge by Fenton reagents.The optimized conditions were that FeSO4 amount was 2.05%g/g dry sludge,H2O2 amount was 0.6 g/g dry sludge,temperature was 80?,reaction time was 3 h.Clear coat sludge,base coat sludge and primer sludge were treated under the above conditions,solid reductions were about 20%and overall reductions were 67.9%,48.2%,64.2%.CODs of the effluents after treatments were about 2000 mg/L,and the dewatering abilities of three products were improved to varying degrees.SEM and other analysis showed the products after Fenton treatment had better combustion properties,and the results also indicated the main mechanism of paint sludge by Fenton treatment was degradation of sodium carboxylate oligomer in water phase.