Research On Pretreating Of Dye Intermediate Wastewater By Fenton+Coagulation Process

Dye intermediate wastewater, which is hard to be degraded due to its highconcentration and the complication of organic components, is a kind of typicalpersistent organic pollutants. This subject studied the pretreatment of dyeintermediate wastewater, which comes from a Chemical limited company (CompanyCo. Ltd) of Jiangxi province, with Fenton oxidation and coagulation-sedimentation.The optimum reaction parameters were studied and determined through the testin laboratory. First, the method of Fenton oxidation treatment was used. The impacton COD and chroma by influence factors were studied. According to orthogonal test,the primary and secondary sequence of main factors was dosage of H2O2, dosage ofFeSO4·7H2O, pH, reaction time. Then, optimum conditions were determined bysingle factor experiment. The results showed that at the optimum conditions ofdosage of H2O2(concentrations was30%) was80ml/L, dosage of FeSO4·7H2O was10g/L, pH value4, settling time of1hour, the COD of raw water reduced from22222mg/L to6111mg/L, the removal rate of COD was72.5%；the colority Originalwater reduced from2500times to1200times, the removal rate of chroma was52%.Finally, the coagulation-sedimentation experiment of water comes from Fentonwas tested. Compared the removal efficiency of three kinds of agents: polyacrylamide(PAM) and polymeric ferric sulfate (PFS) and polyaluminium chloride (PAFC), PAMwas selected be the flocculant of our test. Single factor experiment showed that thebest coagulation conditions: PH was8, the dose of PAM(concentration of1perthousand) was8ml/L, the precipitation time was60min. By coagulation reactions,COD reduced from6111mg/L to3117mg/L,the colority reduced from1200times to270times, the removal rate of COD, Color were49%,77.5%.Bases on the result, the total removal rates of COD and chroma were86%and89.2%. The B/C was raised to0.42, which indicated the biodegradability was highlyimproved. Fenton oxidation with coagulation-sedimentation process was accountedan efficient method of pretreatment of dye intermediate wastewater.