| With the development of the economy and society,water shortage and water environment pollution have become prominent problems that affect national economic development.To alleviate the problem,the developments of sewage treatment technology for industrial wastewater,domestic sewage,commercial sewage,and other fields have been enhanced,especially the study on synergic efficiency of the filler and reactor.Removal of nitrogen and phosphorus is the crucial step for biological sewage treatment technology.The leading causes of water eutrophication and water pollution attribute to the present of nitrogen,phosphorus,and other harmful substances which can be effectively reduced by nitrogen and phosphorus removal technology.At present,heterotrophic denitrification technology is widely used by most of sewage treatment plants,which not only results in high costs but also significant carbon emissions.Based on the sulfur-autotrophic denitrification sewage treatment process,a rectangular sulfur-autotrophic fluidized bed reactor with narrow slot cone distribution plate for the sulfur-autotrophic bioactive filler was studied in the present work.The flow characteristics inside the reactor,distribution plate,and reactor structure on flow characteristics were studied via numerical simulation,aiming to provide technical reference for the engineering application of sulfur-autotrophic denitrification technology and the upgrading of sewage treatment plants.The conclusions are as follows:(1)Based on the principle of sulfur autotrophic denitrification,the sulfur autotrophic bioactive filler synthesized with elemental sulfur and boron mud as raw materials has good removal efficiency on total nitrogen and total phosphorus in synthetic sewage,with removal efficiency of 99.5% and 50.4%,respectively.(2)A fluidized sulfur autotrophic reactor was designed for sulfur autotrophic bioactive filler,and the effects of the distribution plate structure on the flow characteristics in the reactor were investigated by numerical simulation method.The results show that velocity distribution in the reactor is found to have high uniformity,with a velocity variation coefficient of 0.24.Moreover,the particles can be fluidized to a height of 900 mm,and promoted to form efficient annular nuclear flow in the reactor,so that the start-up time of the reactor is reduced to 15 s.(3)The optimizations of the inlet,pressure chamber,and distribution plate of the fluidized sulfur autotrophic reactor were investigated by numerical simulation.And the results show that the uniformity of velocity distribution of fluidizing medium in the reactor is improved by the water inlet structure of DN300.Otherwise,a pre-distributor with a length of 60 mm connecting column is added in the booster chamber,which can further improve the uniformity of velocity distribution of the fluidizing medium and reduce the coefficient of velocity variation to 0.22,and as a result,the fluidizing dead zones at the corner of the reactor wall are eliminated.Furthermore,the slit hole conical distribution plate is distributed perpendicular to the central axis,with an angle of 120° and an opening rate of 71%,which can further improve the stability of the bed and reduce the particle volume fraction near the wall,contributing to an enhanced uniformity of particle distribution. |
