Rapid Enrichment And The Nitrogen Removal Performance Of Anammox Bacteria Based On Basalt Fiber Biocarrier

In recent years,the problem of ammonia nitrogen pollution in water bodies has become increasingly prominent,which has had an adverse impact on the ecological environment and human health.Therefore,the development of new nitrogen removal technology becomes particularly important.Anaerobic ammonia oxidation?ANAMMOX?technology is a new type of biological nitrogen removal technology with broad application prospects and high energy efficiency.However,the bottleneck of this technology is that the growth of anammox bacteria is slowly and the growth conditions are severe,which seriously restricts the development and application of the ANAMMOX process.Thus,rapid enrichment of anammox bacteria is a key issue for the development of ANAMMOX technology.In view of this,this paper conbines cell fixation technology and biofilm carrier technology.First,cell fixation technology was used to pre-cultivate anaerobic ammonia oxidation mixture to obtain suspended anammox enrichment culture;And then use it as the inoculated sludge of ANAMMOX reactor filled with a novel basalt fiber?BF?bio-carrier,which was compared with non-woven bio-carrier to investigate the feasibility of novel BF bio-carrier for rapid enrichment of anammox bacteria.Finally,the nitrogen removal performance of the ANAMMOX reactor based on BF bio-carrier was investigated by matrix removal kinetic models and matrix inhibition kinetic models.The main contents and results of this study are as follows:?1?Pre-cultivation of suspended anammox bacteria based on cell fixation technologyThe anaerobic ammonia oxidation mixture was embedded and fixed with sodium alginate?SA?.SA-immobilized anaerobic ammonia oxidation gel beads were pre-cultured to obtain the suspended anammox enrichment culture,which was used as the inoculated sludge of ANAMMOX reactor.The results showed that the 16S rRNA gene copy number of anammox bacteria inside SA-immobilized anaerobic ammonia oxidation gel beads increased from 2.74×10⁶ copies/gel-bead to1.32×10⁷copies/gel-bead after 17 days of pre-cultivation,successfully achieving the rapid proliferation of suspended anammox bacteria.?2?Enrichment efficiency of anammox bacteria in ANAMMOX reactors based on umbrella-shaped BF,cushion-shaped BF and non-woven bio-carriersThe non-woven,cushion-shaped BF and umbrella-shaped BF bio-carriers were filled in ANAMMOX reactors,and named WFB,DBF and SBF reactors in turn.The nitrogen removal performance and the anammox bacteria enrichment effect of the ANAMMOX reactor filled with noval BF bio-carrier were investigated and compared with the non-woven bio-carrier to explore the advantages of novel BF bio-carrier.The results show that the three ANAMMOX reactors have successfully started and have good nitrogen removal performance.The anammox gene copy numbers in SBF,DBF and WFB reactors are 3.59×10¹⁰ copies/g dry.sludge,3.33×10¹⁰ copies/g dry.sludge and 2.87×10¹⁰ copies/g dry.sludge,respectively,and the dominant bacteria in SBF,DBF and WFB reactors are Candidatus Kuenenia.Therefore,the concentration of anammox bacteria enriched in the SBF reactor is greater than that of WFB and DBF reactors,and BF bio-carrier is an efficient and environmentally friendly bio-carrier for anammox enrichment,especially umbrella-shaped BF bio-carrier.?3?Reaction kinetics in ANAMMOX reactors based on umbrella-shaped BF,cushion-shaped BF and non-woven bio-carriersDifferent matrix removal models and matrix inhibition models were used to investigate the matrix removal kinetics and matrix inhibition kinetics in SBF,DBF and WFB reactors,respectively.The results show that the modified Stover-Kincannon model and Haldane model are suitable for describing the matrix removal kinetics and matrix inhibition kinetics of three ANAMMOX reactors,respectively.In the modified Stover-Kincannon model fitting results,the U_max and K_B of the SBF reactor are the largest among three reactors.In the Haldane model fitting results,the ammonia nitrogen inhibition constant K_i of the SBF reactor is also the largest,but there was no obvious difference in nitrite nitrogen inhibition constant K_i of three reactors.Therefore,the SBF reactor has the best nitrogen removal potential and a higher inhibitory concentration in ammonia nitrogen inhibition,but it dose not have obvious advantage in nitrite nitrogen removal.