Study On Treatment Of High Concentration Emulsified Wastewater

Oily emulsified wastewater is a sort of commonly-seen industrial wastewater.It has a few characteristics such as wide varieties,complicated component,high COD(chemical oxygen demand),low biodegradability.It is harmful to co-environment if it is discharged to environment without proper treatment.It is difficult for some traditional methods like single physical or chemical method to reach efficiency degradation.So this kind of wastewater is often treated with multistage methods,like coagulation-air floating,coagulation-absorption,absorption-Fenton.These methods can reach efficiency degradation.However,they are comparatively expensive and complicated.Thus,it is imperative to find a effective,simple,and cheap solution.Considering the advantages and disadvantages of some individual technology,the study took waste cutting fluid and waste fluorescent fluid as targets.It investigated the optimal condition of treating these two kinds of wastewater and the multistage method that was develop in this study showed great potentials in terms of the cost and simplicity.A multistage process(antiphase demulsification/ coagulation/ sponge-iron Fenton)was introduced in the disposal of waste cutting fluid.Single factors,like dilution times,dosage of demulsifier,pH value,and dosage of PAM(polyacrylamide)were studied,and a(4 factors,3 levels)orthogonal test and condition of Fenton were investigated.The results of single factor experiment are listed as following: 2 times dilution,concentration of demulsifier(D03)= 0.3 ‰,pH = 8,concentration of PAM =0.05 ‰,COD = 6203.5 mg/L,COD removal rate=95.06 %;results of orthogonal test illustrated the different significance of 4 factors on COD removal rate: dilution time>dosage of demulsifier> pH> dosage of PAM;under the optimal conditions of Fenton(retention time=60 min,pH=3,concentration of H2O2=16 ml/L),COD removal rate is99.2 %;when diluted 3 time or more,mother flood diluted by recycling water gets the same COD removal rate as by tap water.According to the current prices of the agents,the cost of disposal for 1 ton waste cutting fluid is 38.86 RMB which is lower than thecost of other methods mentioned in previous studies.An ‘One step method' was introduced the disposal of waste fluorescent fluid.Single factors,like dilution times,demulsifier choice,stirring methods,retention time,pH value,and dosage of coagulant,were studied,and a(3 factors,5 levels)orthogonal test and a(3 factors,5 levels)respond-surface design test were investigated.The results of single factor experiment are listed as following: demulsifier(DGW-1)was chosen,both non-stop stirring and discontinuous stirring reached good COD removal rate,retention time=8-15 min,pH=6-10,concentration of DGW-1?2 ‰,COD removal rate ?95 %;results of orthogonal test illustrated the different significance of3 factors on COD removal rate: concentration of coagulant> pH> retention time;results of respond-surface not only testify for results of orthogonal test,but also show the optimal conditions: pH=8,dosage of DGW-1=3 ‰,retention time=8 min 30 s;when the concentration of mother flood is below 2000 mg/L,mother flood diluted by recycling water gets the same COD removal rate as by tap water.In addition,the respond-surface design predicted that this process could guarantee that the outlet meets the category B of GB 8978-2002 and cut the cost by up to 14.24 %,which is2.65 million RMB,if 120,000 tons waste fluorescent water treated per year.Therefore,this process has great economic potential.