| Nitrogenous compounds(ammonium,nitrite,nitrate etc.)are major threat as pollution in wastewater bodies.The destruction of these compounds is known nitrogen removal,which is carried out by micro unicellular engines know microorganisms.After multiple discoveries of the biological wastewater processes for nitrogen catabolism,the anammox process has attracted more attention due to its exclusive potential of nitrogen removing efficiency from wastewaters.Anammox bacteria directly convert ammonium and nitrite into nitrogen gas in the absence of oxygen.This degredation process is called anammox process.Anammox process in nature contributes 70%of nitrogen into the atmosphere from the oceans.Anammox bacteria are slow grower and have relative low abundance as compared to other microorganisms.Therefore,many research studies have conducted to enhance the growth rate and improve its nitrogen removal efficiency by applying physical and chemical parameters to optimized anammox system.Fe microbial oxidation is playing important role in nitrification and denitrification for anammox system as a co-factor for heme containing enzymes and provide energy to the anammox bacteria by offering electrons.Secondly,recently research has payed attention towards secondary signaling system which controls important cellular regulatory roles such as,biofilm,adhesion,cell-cell progression,EPS,aggregation,motility and virulence,etc.There is only a few reported work on the understanding of signaling system for anammox bacteria.Therefore,it is important to study from both aspects by improving anammox system.This doctoral thesis is based on the effect of Fe on anammox bacteria to improve the nitrogen removal of wastewater and the molecular research of cGMP signaling bifunctional protein.Therefore,this research is divided into two parts.The first part covers the effects of high and low Fe supplementation on the anaerobic ammonia oxidation system.The second part determines the functional role of cGMP signaling protein in anammox bacteria,specifically into Ca.Brocadia sinica for the first time.The main dissertation work of this research is briefly described as follow:Fe is often used in wastewater treatment and is an important part of the anaerobic ammonia oxidation system.In this study,the effect of Fe on the anammox system with Fe concentrations of 0,1,and 5 mM in the reactor was studied.The removal efficiency of nitrogen and nitrogen removal rates were significantly changed at start-up time,at 1 mM Fe after 63 days,and at the reactor,the removal efficiency was 94%,and the removal rates were 81.5 g N m-3d-1 correspondingly.The extracellular polymeric substances-EPS were also enhanced and the Fe relationship was also linear.The 16S metagenomic study displayed that Fe improved the anammox bacteria-Candidatus Brocadia's relative abundances rather than control.RT-qPCR results also showed that Fe oxidation triggered the centralized metabolism by increasing the regulation of major functional genes in anammox bacteria(hdh and hao).We observed that there have been variations in ammonium removal efficiency and nitrites removal across all the reactors,that might be due to the difference between the functional genes and Candidatus brocadia abundance in the sludge,since Ca Brocadia greatly influences anaerobic ammonium oxidation.The appropriate quantity of Fe is added to the sludge,improving the ARE and NRE.Overall,when the anammox consortium meets a suitable amount of Fe,the system may be quickly enhanced even at high concentrations. |
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