| The characteries of landfill leachate, with a significant specificity, depend on type of disposal, stability and moisture of solid waste, hydrology, meteorology and temperature of landfill site, landfill age and decomposition stages of solid waste;"Standard for pollution control on the landfill site of municipal solid waste"(GB16889-2008) regulate strict controlling over effluent concentration of leachate pollutants, those factors pose a challenge for landfill leachate to be treated by biological technology. The Fenton process, non-selectively reacted with organic compounds, can be used to degrade pollutants into harmless substances under mild conditions and considered to be an alternative technology for landfill leachate treatment.To study effect of combined technology of sonication, photo and Fenton, the optimization of sonication and Fenton were firstly studied, then the technologies assisted by sonication and photo were used to improve removal of leachate, the aim of this research was found to a new approach to get best removal by comparison of various combinations process and the kinetic model of treatment leachate effluents by Fenton process was built finally.The highest COD removal was achieved by80KHz sonication in this study and the mineralization of organic matter mainly achieved at the first60min according to the variation of COS and AOS. Low initial pH, low initial concentration, higher temperature and assisted aeration were beneficial for improving COD removal efficiency. The highest NH3-N removal was achieved by50KHz sonication in this research. Higher pH and assisted aeration can improve the NH3-N removal, the initial concentration have little influence on NH3-N removal. The higher intensities of UV-vis and EEM spectra were induced from breaking down high molecular weight organics into lower ones by sonication. That the variation of special parameters of UV-vis were in accord with the shift of peaks in EEM spectra or Pi,n by FRI were affected by initial pH, initial concentration, ultrasound frequency and reaction time.The Fenton, US-Fenton, photo-Fenton and US-photo-Fenton processes were proved to be highly effective for treatment of landfill leachate. And they are similar in the following points:The degradation of leachate were got in the first30min, especially dramatically changed in the first10min and slowly after30min; the same phenomenon were appeared for AOS and COS, which meant that the dramatic chemical reaction were reacted and reaction intermediates were generated in the first30min. The best TOC removal was got at pH3. The economic TOC removal was existed for all researched Fenton-related processes. That the TOC removal were affected slightly when the dosage of H2O2excess2Dth for Fenton process and1Dth for the other. The best oxidation removal of leachate were got at [H2O2]/[Fe2+] molar ratio of4for photo-Fenton and5for the other. The TOC removal were increased with dosing times of H2O2while there are slight different in different process of dosing times of Fe2+. The TOC removal were increased with the initial concentration of leachate. The temperature had a slight effect on TOC removal for all process. The UV254removal were higher than TOC removal for all processes.The leachate pretreated by US/Fe2+was equal to be treated by Fenton process containing little amount of H2O2. The TOC removal were affected by initial pH, initial concentration of Fe2+and temperature. The TOC removal was increased with S/V value increase in photo-Fenton. The order of TOC removal for the same leachate under unified parameters were US-photo-Fenton> US/photo-Fenton> US-Fenton> photo-Fenton>Fenton>US/Fe2+>US>UV.Under the following conditions:H2O23655-10965mg·L-1, FeSO41200-28800mgFe·L-1,12-30?and pH3.0, the kinetic reaction equation of leachate treatment by Fenton process between5min and30min of reaction was fitted as follows:... |
PDF Full Text Request