Experimental Study On Improving The Effect Of Anaerobic Ammonium Oxidation Treatment By Mixing Mass Transfer

In many engineering fields,it is necessary to improve the engineering efficiency by means of the mass transfer process,in which the mixing mass transfer is adapted to the biochemical reaction mass transfer process in the solid-liquid two-phase fluid.The mixing mass transfer under the stirring flow field is characterized by its good transfer effect on both solid particles and liquid substances.Anammox bacteria have strict requirements on environmental factors and long generation cycle,so the mass transfer factor is especially important in the reaction process.Therefore,the experimental study of mixing and mass transfer under different sludge concentrations has certain engineering application guidance significance for improving the degradation efficiency of ANAMMOX.In this paper,the flow field distribution and the concentration distribution of activated sludge under the mixing were studied,and the size,installation height and stirring speed range of the stirring blade were determined under the certain sludge concentration.The initiation and influence factors of ANAMMOX were studied,especially the promotion of the mixing mass transfer in the stirred flow field on ANAMMOX reaction.At last,the laboratory continuous simulation of two stages of Anammox under stirred flow field was carried out.Main work is as follows: using the CFD simulation analysis of the mechanical mixing flow field inside the reactor,the effects of experimental analysis of the mixing flow field distribution of sludge concentration along the reactor height,identified in 150 mm in length,liquid level height 280 mm,and dry matter concentration of 5 g/L square agitation tank,when the impeller diameter of 70 mm,80 mm from bottom height,stirring speed 120 RPM,solidliquid mixed effect is best.By gradually increasing the concentration of influent substrate and shortening the hydraulic residence time,the anaerobic ammonium oxidation(ANAMMOX)bacteria were enriched and cultured in the complete mixed anaerobic reactor.The ANAMMOX system was successfully started on the 56 th day,and the total operation time from startup to enrichment was 162 days.It was observed by scanning electron microscope that the concentrated ANAMMOX granular sludge was mostly of compact spherical structure.Through high-throughput sequencing analysis,the diversity of the biological community decreased during the start-up process.In the mature ANAMMOX sludge,Fusarium and Proteobacteria were in the majority,and the ANAMMOX bacteria enriched in the test was Candidatus Kuenenia.Batched experiments were conducted to analyze the effects of different shear speeds on the denitrification performance of ANAMMOX bacteria under different sludge concentrations.It was determined that the best denitrification effect was achieved when the rotating speed was 140 rpm,and the activated sludge structure and microbial system began to be damaged when the rotating speed was 150 rpm.Anammox test was carried out in the stirred flow field,and it was determined that the mechanical stirring speed should be 120 rpm in the completely mixed bioreactor.The improved anaerobic baffle reactor was designed by itself,and the test for the treatment of simulated slaughtering and meat processing wastewater was carried out by starting partial nitrosation-anammox system.The nitrogen degradation efficiency was improved by gradually increasing the stirring speed,and the total nitrogen removal rate reached 91%.Figures: 41,Tables: 12,References:83.