Synergistic Degradation Of Wastewater By Vacuum Ultraviolet(VUV) Coupled With Chemical Oxidation

Environmental problems have become the focus of our country now,especially water pollution,which has affected people's health and the normal development of our national economy.This paper adopts the vacuum ultraviolet(VUV)wastewater treatment coupled with chemical oxidation technology to degrade stimulated ciprofloxacin hydrochloride wastewater,and a series of experiments of UDMH wastewater and high-concentration azithromycin wastewater were carried out,and satisfactory results were obtained from the enlarged experiments of treating high-concentration azithromycin wastewater.In this paper,the catalytic wet peroxide oxidation(CWPO)combined with vacuum ultraviolet(VUV)irradiation was developed to treat the wastewater with high concentration of unsymmetrical dimethylhydrazine(UDMH),especially to decompose the main byproduct of UDMH decomposition,N-nitrosodimethylamine(NDMA).CuO-NiO-MgO/?-AlhO3 was used as the catalyst and H2O2 as the resources of ·OH.Fourier Transform Infra-Red spectroscopy(FT-IR),X-ray Powder Diffraction(XRD),Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray spectroscopy(EDS)were employed to evaluate the structure of catalyst.The catalytic activity such as the UDMH conversion,chemical oxygen demand(COD)and its removal efficiency,and the concentration of N-Nitrosodimethylamine(NDMA)were investigated in the treating process.The optimal conditions were obtained based on the results of single factor experiments including parameters possibly affecting the treatment performance such as the initial UDMH concentration,catalyst dosage,initial pH,H2O2 dosage and temperature.The comprehensive results indicated that CWPO/H2O2/VUV process presented flexibility to the reaction conditions with a high efficiency of UDMH conversion,COD removal and NDMA removal(100%in 20 min,95.02%in 30min and 100%in 20min).In addition,the possible formation mechanism of formaldehyde during the degradation process was carefully analyzed.Similarly,simulated ciprofloxacin hydrochloride wastewater and high-concentration azithromycin wastewater treated by vacuum ultraviolet(VUV)coupled by chemical oxidation achieved a good degradation.The process of degrading the high-concentration azithromycin wastewater is an exothermic process,and the degradation process is less affected by the solution pH,the biggest factor affecting the COD removal is H2O2 usage and the catalyst usage.In order to further explore the possibility of enlarged degradation of high-concentration azithromycin wastewater,the shaped CuO-NiO-MgO/?-Al2O3 was made and its life expectancy was researched.The experimental results showed that the efficiency of the catalyst is affected when the amount of wastewater treated was more than 580L,and the catalyst efficiency can be recovered after the reactivation.The enlarged experiment of high-concentration azithromycin wastewater showed after treated by 60 min,the COD concentration was reduced rapidly from 33100mg/L to 2243.6mg/L,achieving a removal rate of 93.22%.These results showed that vacuum ultraviolet(VUV)coupled by chemical oxidation as the pret-reatment method for high-concentration antibiotic wastewater is quite effective and efficient for improving the value of BOD/COD in a relatively short period of time.