One Photocatalytic Oxidation Reactor Treating Phenolic Wastewater Biodegradation

It is one of available methods that recalcitrant and inhibitory organic wastewater is treated by photocatalyst, but some compounds would be only changed under the photocatalysis, but not mineralized fully sometime, or although some could be mineralized fully but usually not feasible due to cost considerations. In this case, biological treatment is necessary as post treatment in order to let the compound to be innocuity. Intimate coupling photocatalytic-biological treatment, i.e. photocatalysis will be combined with biodegradation to be integrative, will be applied for treatment of trichlorophenol in this project. Several scientific questions will be explained in this project, for example, we want to know if TiO₂ catalyst and biofilm can be integrated efficiently, there is different for mechnism and kinetics of 2,4,6-TCP degradation under coupling photocatalysis and biodegradation from only photocatalysis and biodegradation separately based on this experiment. The key object on coupling TiO₂ and biofilm will be realized with lighter porous ceramic carrier with coated TiO₂ and biofilm at the same time during the project.2,4,6-TCP and phenol removal rates and mineralization were respectively compared under four strategies, that were alone photocatalytic oxidation, photocatalitic oxidation after biodegradation, and simultaneous photocatalitic oxidation and biodegradation.The results show that: in the batch experiment of the degradation of 2,4,6-TCP, the same concentration of 2,4,6-TCP solution in the photocatalytic degradation rate is higher than the biodegradation rate, lower than photocatalytic/biological methods. When the concentration of 2,4,6-TCP is in 10-30 mg/L, with the increase of initial concentration, 2,4,6-TCP degradation rate is rising. With the degradation of 2,4,6-TCP, the concentration of 2,4,6-TCP is reduced in solution, Cl- is concentration, the quality of Cl is about one in the third in 2,4,6-TCP. It can be explained that the molecular structure of 2,4,6-TCP is broken in the reaction progress, a Cl takes off from the benzene ring and forms of other intermediate products.The experiment of intermittent and continuous are used to treat the mixed solution of phenol and 2,4,6-TCP. In batch conditions, the photocatalytic/biological integrated combination is the best for removing mixture. For the degradation of phenol in solution, integrated is the best, biological followed, photocatalytic oxidation is the worst.In continuous operation, The rate of removal of phenol and 2,4,6-TCP with the integrated combination of methods is higher than a single photocatalytic oxidation and biodegradability.COD average removal rate is the highest, reaching 90%. In the same concentration of the mixture, the longer residence time, the higher remove rate of phenol and 2,4,6-TCP.2,4,6-TCP and phenol solution in several different steps in the coupling and photocatalytic/biological degradation of integrated combination comparative analysis shows that:photocatalytic/biological integration combination is the best in removing 2,4,6-TCP and phenol. Removal rate of COD of is also the best. In the several different coupling methods, the shorter photocatalytic pretreatment do, the longer the biological do, the better mineralization is.Feasibility of coupling photocatalysis and biodegradation will be proved theoretically by 2,4,6-TCP and phenol degradation, which will be a base for novel photobiocatalyst applied for recalcitrant wastewater.