Master’s thesis

Nitritation in mainstream conditions at Sjölunda WWTP


Today, the nitritation-anammox process has been implemented for nitrogen removal in warm and highly concentrated sludge liquors and industrial wastewaters at nearly 100 full-scale applications worldwide. The next challenge is to implement fully autotrophic nitrogen removal (i.e. nitritation-anammox) in the mainstream of municipal wastewater treatment plants. In 2012-2015, a pilot project called Manammox (Mainstream anammox) was operated at Sjölunda Wastewater Treatment Plant (WWTP) for investigating the possibility to implement the nitritation-anammox process in a one-stage moving-bed biofilm reactor (MBBR). The pilot successfully maintained the anammox bacteria in the mainstream. However, the nitrite-oxidising bacteria (NOB) was not fully repressed, which is a prerequisite for an implementation of the process.
During 2016, a new project called Nanammox (Nitritation-anammox) will be performed. Nanammox is a one-year pilot project of a two-stage MBBR system investigating the potential of nitrite-oxidising bacteria (NOB) repression in such a system at Sjölunda WWTP. During the spring the project will focus on dissolved oxygen (DO) competition among ammonia-oxidising bacteria (AOB) and NOB by adding sludge liquor to the mainstream to permanently and sequentially decrease the DO:NH4+ ratio.


The main aim of the master´s thesis is to find a suitable DO:NH4+ for successful NOB repression in the nitritation reactor of the Nanammox pilot plant at Sjölunda WWTP.


The student will be involved in the project group of the Nanammox project. Simple ex-situ laboratory batch tests will be used to specify for measuring endogenous, AOB and NOB activities. Variations of these activities should be coupled to the operational results of the pilot plant and thereafter the operational strategy of the pilot plant should be adjusted. All laboratory work will be performed at Sjölunda WWTP.


David Gustavsson, research leader at VA SYD/Sweden Water Research


Spring 2016


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