Study On Regenerated Papermaking Wastewater Advanced Treatment By Pre-coagulation-Fenton Oxidation

As one of the paper’s regenerated papermaking in city of Xinmi, becouse of its original wastewater treatment process equipment aging and the implementation of new national emission standards for papermaking wastewater, the wastewater discharges of non-compliance issues seriously effect its nomal prduction and operation.With the wastewater treatment of this paper mill as the resaerch object, This thesis deeply studied the advanced treatment process of pre-coagulation-Fenton oxidation.In the pre-coagulation tests, coagulant by comparing several wastewater coagulation tests to determine the three kinds of coagulant in wastewater CODCr removal:Al2(SO4)3is the best, PAC followed, FeCl3is the worst. Al2(SO4)3and PAM mixed use can improve the coagulation effect. When Al2(SO4)3dosage to400mg/L, PAM (2g/L) dosage of0.5mL/L, treatment effect reachs the best, The CODCr removal rate is about48.8%, wastewater’s CODcr from500mg/L decreased to about265mg/L.In the Fenton oxidation treatment experiments, Through orthogonal experiments and single-factor test,we can know that:the main factors affecting the Fenton oxidation treatment effect and their primary and secondary relationship is:the dosage of H2O2> the dosage of FeSO4·7H2O>initial pH> reaction time. The optimulu operating conditions for Fenton oxidation is that:the dosage of H2O2is8mmol/L,the dosage of FeSO4·7H2O is6mmol/L, initial pH is4, reaction time.is40min. Under these conditions, the wastewater’s CODCr can be removed from265mg/L to76mg/L, the removal rate is about71.3%.In the system after Fenton oxidation reaction,the residual H2O2’s concentration is about33mg/L, calculated by the linear regression equation,it has a positive impact of about16.8mg/L to system’s CODCr. Elevated temperature and adjust the pH to alkaline could not effectively improve the decomposition rate of the low concentration H2O2, and so these two methods is not suitable to eliminate low concentrations of H2O2in wastewater. Finally, on the understanding of the degradation of organic matter in the oxidation reaction process, we know that the system’s TOC and CODcr dose not show a good linear relationship. After oxidation treatment, the cracking of the aromatic ring structure of the part of the lignin fragments in the wastewater are converted into a organics of the aliphatic carboxylic acids.