Study On The Mechanism Of Contamination Removal And Kinetics In Constructed Rapid Infiltration Biological Filter

Constructed Rapid Infiltration biological Filter (CRI for short) system is a new sewage treatment technology that was developed on the traditional Rapid Infiltration (RI for short) system,which used natural river sand and artificial filters as the main infiltration media instead of crude soil, because they had better permeability.This system solved some problems of RI system,those were low hydraulic loading, large used area,so the hydraulic loading improved and used area reduced. And CRI has some advantages,which are simple equipment,easy operation management,low-cost of infrastructure investment and operation management, low energy consumption and good purification effect. But CRI technology needs to be researched more on the types and forms of microorganisms in the system, removal mechanism and the migration law of the pollutants,better removal effectiveness and operating management,and so on.In this thesis,the operation factors of the system and the removal mechanism of the organic matter, nitrogen and phosphorus were analyzed systematical;and the reaction kinetics were explored initially as the its characteristics.Which was good for improving the system's removal effectiveness,and can optimize the theory parameters during engineering design,then there is important theoretical and practical significance for treating wastewater using this treatment technology.In the wet-dry ratio experiment, when the hydraulic loading was 1.0m/d, the removal effect of the device were discussed under the condition of wet-dry ratio as 1/1,1/2,1/3,1/4.The experimental results indicated that removal effect of the organic pollutants was impacted greatly, less for that of nitrogen and phosphorus.The wet-dry ratio of 1/2 was chosen to be the best.During the hydraulic loading test,made the wet-dry ratio as 1/2, the factor to operating performance of the system was discussed under different hydraulic loading,and showed that 1.0m/d was the best hydraulic loading. Under the best condition, the effluent concentration of COD,NH3-N and PO43--P was 40mg/L,1.0 mg/L and 0.039mg/L respectively,which were superior to Discharge standard of pollutants for municipal wastewater treatment plant(GB18918-2002).The system's non-biological and biological degradation mechanism for organic pollutants and nutrient elements was revealed through the simulation of constructed rapid infiltration biofilter. It was shown that the organic pollutant removal by the system was fulfilled under the synergetic action of non-biological and biological mechanism,and biological action prevailed in degradation of organic pollutants; In the system, nitrification action prevailed in nitrogen conversion, while denitrification effect was relatively weaker. while non-biological mechanism prevailed in phosphorus degradation with biological mechanism as auxilary.During the reaction kinetics test,we could see that ratio C/C0 of the outlet concentration and influent concentration had a negative exponential relationship with the ratio y of distance monitoring points to the in water end and the effective height of the device.