Study On Hydrazine/Dioxygen Wet Oxidation Of Pulp Bleaching And Chemical Pharmaceutical Wastewater

With the law of environmental proctection becoming more critical, more and more attentions were focused on the problems of water pollution. Sanitary and industrial wastewater are the main source of water pollution, and the industrial organic wastewater are very harmful to environment. Pulp bleaching and chemical pharmaceutical industry wastewater are the main industrial wastewater, which contains a lot of toixc organic compounds, including nitrobenzene, p-nitrophenol, chloroaniline, sulfadiazine, etc, all of them are acute toxicants to aquatic life, and are not conducive to the survival of microorganisms and enzymes. Furthermore, it is not easily decomposed by microorganisms, so that the polutions with high loads of COD and BOD are formed. In this thesis, several organic polluants and pulp bleaching wastewater (chlorination section) from Guangxi paper-making factory, were used as the study object, a new type of wet aerobic degradtion technology was used for the study of the degradation of the pulp bleaching wastewater and these model compounds. By this study, we hope we could provide the basis of theretical and technological for the treatment of pulp bleaching and chemical pharmaceutical industry wastewater.In this thesis, over ten of toxic organic polluants, including 4-chlorophenol, 2,4-dichlorophenol,2,4,6-trichlorophenol, p-nitrophenol,and nitrobenzene, are used as model compounds, in the presence of hydrazine in combination with oxygen, several parameters, such as reaction temperature, oxygen pressure, reaction time, and the pH value of solution on the degradation of these compounds are investigated. Under the degradation conditions, the removal rate of Total Organic Carbon (TOC) are reached to 35%to 86%, the main products are gas and small organic molecules, such as monocarboxide, dicarboxide, methanol, formic acid, acetic acid et.al.. Also, the residue of hydrazine in water is not detected. The hydrogen peroxide has been detected by analyzing the incomplete degradation phenol wasterwater. Finally, the degradation intermediate,1,2-diphenol was also detected by LC-MS. Based on these facts, in the degradation process, hydrazine heated under oxygen atmosphere may produce hydrogenperoxide, which degradated to hydroxyl radical, which is the active species for the degradation of organic compounds. Thus the wet aerobic oxidation degradation technology with hydrazine incombination with oxygen is envirometal benign method.Based on the degradation study of these model compounds, a broad spectrum of toxic organics was efficiently destroyed in the system. Furthermore, when this degradation system was applied to degradation of actual waste water of wood pulp bleaching with chlorine (COD: 1491 mg/L),77% COD decrease and 52% TOC mineralization of the wastewater were observed. In the paper, we investigate the effects of reaction temperature, reaction pressure and material feeding methods on the degradation. Finally, the COD decrease of the wastewater is up to 92%, and the TOC mineralization of the wastewater is up to 82%.In the paper, the treatment of wastewater is in the presence of dioxygen in combination with hydrazine hydrate, without metal salts and secondary pollution. After degradation reaction, the hydrazine was also decomposed into N2 and H2O instead of other harmful substances, and no hydrazine was remained. This oxidative degradation system is an almost green and ideal system.