Study On The Treatment Performance Of Ship Traffic Wastewater By Anammox And Its Effect On Cresol And Its Removal Mechanism

As an efficient biological nitrogen removal technology,anammox（anammox）process can be used as a new way to treat nitrogen-containing oily wastewater produced in ship transportation.Compared with traditional nitrogen removal technology,anammox has the advantages of high efficiency,low consumption and no residual sludge,so it has a broad application prospect.Three groups of laboratory scale upflow anammox reactors running in parallel were constructed to study the relationship between the operation performance of granular sludge-biofilm anammox process and the characteristics of biofilm/granular sludge,the structure of functional bacteria and functional genes.On this basis,the influence characteristics of cresol on different anammox process performance,functional genes and functional bacteria as well as the process characteristics of cresol removal were explored to provide technical support for the removal of nitrogen and phenolic substances from wastewater containing nitrogen and oil.The main conclusions obtained include:（1）Run granular sludge reactor R₁（control）,granular sludge coupled multi-faceted hollow column filler（PHCF）carrier biofilm reactor R₂,and granular sludge coupled PHCF and comet fiber filler（CFC）carrier biofilm reactor R₃.Study on stability of granular sludk-carrier biofilm anammox process,activity of biofilm/granular sludge,nitrogen removal functional bacteria community and nitrogen removal functional genes.The experimental results showed that all the reactors could maintain stable operation,and the denitrification performance was ranked as R₃>R₂>R₁from high to low,but there was little difference.The proportion of granular sludge with particle size greater than 1mm in R₁,R₂and R₃reactors was 47%,50%and 51%,respectively.The presence of biofilm promoted the enrichment of An AOB,especially in reactor R3,which was more obvious under the coupling effect of PHCF and CFC biofilm,but the promotion effect of PHCF was not obvious.（2）Remove the PHCF biofilm,run the granular sludge reactor R₁and R₂and the granular sludge coupled CFC carrier biofilm reactor R₃,and improve the operation performance of the anaerobic ammox reactor by gradually reducing the HRT.The TN removal rates of R₁,R₂and R₃were increased to 81.88%,82.50%and 85.50%,and the corresponding NRR had little difference.The relative abundance of Planctomycetes in R₁,R₂,R₃particulate sludge and R₃carrier biofilm was 45.16%,44.24%,66.94%and 58.33%,respectively,which were dominant.The dominant genera of these reactors were Candidatus＿Brocadia,Candidatus＿Jettenia,Candidatus＿Kuenenia and Lautropia.The relative abundance Candidatus＿Brocadia,Candidatus＿Jettenia and Candidatus＿Kuenenia in reactor R₃was significantly increased due to the influence of carrier biofilm.（3）On the basis of the anammox reactor mentioned in（2）,the effects of cresol on the operating performance of anammox system,nitrogen removal functional bacteria and functional genes were studied,and the process mechanism of cresol degradation was explored.The experimental results showed that the addition of cresol inhibited the nitrogen removal performance of anammox system,and the inhibition effect decreased with the increase of p-cresol concentration.At the same time,the system was able to remove part of the cresol.When 38.80mg/L was added,the cresol removal rates of R₂and R₃were 33%and 39%,respectively,and when 72.04mg/L was added,the removal rates of R₂and R₃were 34%and 26%,respectively.When 123.43mg/L para-cresol was added,the removal rates of R₂and R₃were 35%and 36%,respectively.Under the influence of cresol,in the granular sludge and carrier biofilm of the reactor,floxomycetes was no longer the dominant phylum,and the activity of anaerobic ammox bacteria decreased,and the relative abundance in the granular sludge and biofilm was very low.The relatively high abundance in granular sludge and carrier biofilm is Acidobacteria and some of its bacteria,which is presumed to be caused by the metabolites of para-cresol to some fatty acids.Further analysis showed that p-cresol was ring-opened under the action of Pseudomonas in the system,cracking into adiadienoic acid,further degradation into 3-hydroxybutyric acid,and finally degradation into carbon dioxide and water.