Preparation Of Novel Iron-carbon Micro-electrolysis Filler And Its Performance Of Phosphorus Removal

Iron-carbon micro-electrolysis is a wastewater treatment process basing on the corrosion of iron,which is also called internal electrolysis.Iron-carbon micro-electrolysis technology can simultaneously remove pollutants from water,such as phosphorus,COD and heavy metals,and has been widely studied and applied.The current commercial filler is a physical mixture of solid particles or powders,which is based on iron-based materials(iron scraps or iron powder)and solid carbon-based materials(carbon powder,coal,activated carbon,etc.)and is prepared by physical mixing or by roasting(regularization).When applied in wastewater treatment,commercial filler shows disadvantage of slow reaction rate and low pollutant removal efficiency.And iron carbon filler is easy to passivate and compact after long-term use,which leads to frequent replacement of fillers and increases operating costs.The above problems restrict the promotion and application of micro-electrolysis technology.A novel preparation process of iron-carbon micro-electrolytic filler is proposed to overcome these issues.This paper establishes a micro-scale iron-carbon micro-electrolysis system by depositing carbon particles on the surface of iron substrates.It is the new bonding mode of iron-carbon that increases the number of micro-primary cells per unit volume and the contact between iron and carbon.The efficient removal of sewage pollutants is achieved.This thesis includes three aspects:technical principle,process optimization and application performance.And the preparation and application of novel iron-carbon micro-electrolytic filler have been investigated.The major findings are listed as following:(1)Preparation and characterization of new micro-electrolytic fillers.Using tar as carbon source and sponge iron as iron-based material,a novel process was proposed to prepare iron-carbon filler.Preparation procedures of the novel process include homogenizing,carbonizing and forming.The products are characterized by SEM-EDS and XRD and Elemental analyzer.The results show that,carbon are deposited on the surface and internal pores of sponge iron during carbonizing process,increasing the contact between iron and carbon.The content of elemental iron in the filler increases after deep reduction,contributing to increase of the number of micro-primary batteries.Finally,the new filler exhibited excellent phosphorus removal performance compared to conventional iron-carbon filler(Fe/C).(2)The preparation conditions are optimized.The carbonization and forming parameters optimization experiments of new fillers were carried out by single factor method.Optimal parameters are obtained by investigating the effect of ratio of tar to sponge iron,carbonization/roasting temperature and holding time on the carbonization/roasting process.When mass ratio of tar to sponge iron,carbonizing temperature,holding time,binder mass fraction,roasting temperature and time are set as 0.3,950 ?,0 min,30%,900 ? and 90 min,respectively,the synthetic Fe-C filler will exhibit an optimized phosphorus removal performance,giving a removal efficiency as high as 98%,which meets with discharge standard of phosphorous-contained sewage.(3)Treatment of wastewater by novel micro-electrolytic filler.Novel iron carbon fillers were prepared under optimized conditions and were used to treat dewatering filtrate from sludge hydrothermal-anaerobic digestion and industrial wastewater.The effect of operating conditions on the removal of phosphorus and COD by fillers was investigated by single factor method.The results show that phosphorus and COD can be removed simultaneously.The removal performance of the filler on the contaminant can be effectively improved by increasing the solid-liquid ratio and aeration rate,reducing the initial pH,and prolonging the reaction time.After treatment under optimal evaluation conditions,the effluent phosphorus meets with discharge standard of phosphorous-contained sewage.