Biological Denitrification by MABR and ANAMMOX Process
Date Issued
2008
Date
2008
Author(s)
Feng, Yu-Jou
Abstract
In the last decade, some new biological nitrogen removal processes have been developed to reduce operational costs related to the oxygen and organic carbon source requirements. Many studies focused on the development of autotrophic nitrogen elimination technology such as combination of partial nitrification and the Anammox process, which is regarded as a promising new method for removing nitrogen from wastewater or groundwater with a low C/N ratio and a fairly large quantity of ammonium.n this study, a combined partial nitrification MABR－Anammox system was developed to achieve a condition wherein only approximately one-half of ammonium is converted to nitrite, followed by the Anammox process to ensure total nitrogen removal. In addition, a molecular biotechnology method was applied to identify the bacterial community of the biofilm and the acclimated biomass.he experimental results showed that the developed membrane aeration bioreactor is an efficient, economical system to achieve 50% partial nitrification for ammonium-rich wastewater. The open-ended silicone tube in this bioreactor provided a large specific surface area for oxygen transfer and biofilm attachment. An appropriate initial alkalinity was also an important factor to achieve stable partial nitrification. Bicarbonate that serves carbon and alkalinity sources was added into the wastewater only once from the beginning. There is no need for pH adjustment by adding a base or an acid throughout the reaction if the initial alkalinity is appropriately controlled. Furthermore, an appropriate ammonium surface loading resulted in approximately 50% partial nitrification within a short period of time by adjusting the tube’s length in accordance with the range of initial ammonium loading. As mentioned above, the MABR system developed in this study is very stable and easy to operate. This system has great flexibility for partial nitrification, making it an ideal pretreatment system for Anammox.egarding the acclimation of Anammox biomass, the concentrated activated sludge collected from a local municipal WWTP was used as seed sludge. The macroscopic appearance of the enriched biomass remained a light brown color after cultivation under appropriate conditions for about 4 months. Additionally the settling efficiency of the biomass was very remarkable; the consumption of ammonium and nitrite resulted in the production of N2 and a small amount of nitrate. Anammox is denitrification of nitrite with ammonium as the electron donor to yield nitrogen gas, in which reaction nitrite is consumed faster than ammonium. The batch experimental results showed that the maximum anammox reaction rate occurred when the nitrite concentration ranged from 60 to 70 mg-N/L, whereas the activity was inhibited when higher than 80 mg-N/L.ith regard to cell-immobilization technique, the PVA-alginate sodium nitrate method was proven appropriate for enriched anammox biomass because the nitrogen removal activity of immobilized anammox beads was quite satisfactory. This approach demonstrated that the established immobilization technique offers a promising way to granulate valuable anammox biomass, to protect these microorganisms against the unfavorable surroundings, and to efficiently retain anammox activity in the reactor. Therefore, the problems encountered in conventional bioprocesses for nitrogen elimination such as solid-liquid separation and biomass washout could be solved simultaneously.
Subjects
partial nitrification
MBR
ANAMMOX
biological denitrification
Type
thesis
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