Effect Of Bamboo Charcoal On The Performance Of Anammox Reactor And Its Mechanism

The anaerobic ammonia oxidation (Anammox) process is a biological nitrogen removal technology in which ammonia is oxidized to nitrogen gas with nitrite as the electron acceptor. The advantages of Anammox process are shorter pathway of nitrogen, higher nitrogen removal loading, no requirement of external organic matter and smaller production of excess sludge. Therefore, Anammox process has become a potential sustainable nitrogen removal biotechnology. However, the shortcomings of Anammox process, for example, unstable running and incomplete nitrogen removal, are hindering the Anammox process application in engineering. Studies have shown that a carrier’s addition helps to overcome the defects of Anammox process. As a biochar, bamboo charcoal is not only having a high surface area and high hydrophobicity as traditional carriers, but increasing the number of microorganisms and enhancing the microbial activity. Therefore, bamboo charcoal is a potantial material of carriers. Accordingly, this thesis used bamboo charcoal as a carrier of Anammox reactor, and comparing the influence between bamboo charcoal and spherical plastic on Anammox reactors; investigated the different impacts of different addition levels and different particle sizes of bamboo charcoal on performance of Anammox reactors; analysed the mechanism of impact of bamboo charcoal on Anammox reaction, explored the feasibility of bamboo charcoal as a carrier of Anammox reactor. The main results of this thesis are as follows:(1) Bamboo charcoal and spherical plastic were used as the carriers of two Anammox-UASB reactors, to study the effects of different carriers on performance of Anammox reactors. The results showed that BC reactor was slightly higher TN removal efficiency than SP reactor, and nitrate concentration of effluent in BC reactor was remarkably smaller than SP reactor. The different physical and chemical properties of these two carriers are the main reasons for these differences. After180days of operating, Anammox biofilms formed on the surface of bamboo charcoal and spherical plastic, but biofilm on bamboo charcoal surface was relatively looser. The majority of Anammox bacteria in these two Anammox biofilm reactors are both Brocadia sp.40. In summary, bamboo charcoal is more beneficial to be used as a carrier in Anammox-UASB reactor than spherical plastic.(2) Bamboo charcoal was used as the carrier of Anammox-UASB reactors to study the impact of different addition levels and different particle sizes of bamboo charcoals on performance of reactors. The results show that differences of selected addition levels and particle sizes of bamboo charcoal did not influence on the performance of Anammox reactors significantly. The main reasons for no different performance of Anammox-UASB reactors, which packed with different addition levels and particle sizes of bamboo charcoal, may be less bamboo charcoal’s additon.(3) Serum bottle test was carried out to study the impact and mechanism of bamboo charcoal on nitrate metabolic in Anammox sludge. Studies have shown that adding bamboo charcoal to Anammox sludge has significantly reduced the amount of nitrate production. Material balance analysis showed that the dissimilatory nitrate reduction to ammonium (DNRA) is an important nitrate metabolism pathway in Anammox sludge. Higer DNRA’s activity of Anammox sludge caused by bamboo charcoal is the main reasons for much more nitrate removement.