Nitrogen removal from sludge reject water by a two-stage oxygen-limited autotrophic nitrification denitrification process

Abstract

Nitrogen removal from sludge reject water was obtained by oxygen-limited partial nitritation resulting in nitrite accumulation in a first stage, followed by autotrophic denitrification of nitrite with ammonium as electron donor (similar to anaerobic ammonium oxidation) in a second stage. Two membrane-assisted bioreactors (MBRs) were used in series to operate with high sludge ages and subsequent high volumetric loading rates, achieving 1.45 kg N m(-3) day(-1) for the partial nitritation MBR and 1.1 kg N m(-3) day(-1) for the anaerobic ammonium oxidation MBR. Biomass retention in the nitritation stage ensured flexibility towards loading rate and operating temperature. Nitrite oxidisers were out-competed at low oxygen and high free ammonia concentration. Biomass retention in the second MBR prevented wash-out of the slowly growing bacteria. Nitrite and ammonium were converted to dinitrogen gas in a reaction ratio of 1.05, thereby maintaining nitrite limitation to assure process stability. The anoxic consortium catalysing the autotrophic denitrification process consisted of Nitrosomonas-like aerobic ammonium oxidizers and anaerobic ammonium oxidizing bacteria closely related to Kuenenia stuttgartiensis. The overall removal efficiency of the combined process was 82% of the incoming ammonium according to a total nitrogen removal rate of 0.55 kg N m(-3) day(-1), without adding extra carbon source.

Sequencing Batch Reactor for Wastewater Treatment: Recent Advances

“…The process eliminates the requirements of aeration and exogenous organic carbon sources compared to the traditional nitrification-denitrification process of nitrogen removal. However, slow growth rate of the anammox bacteria and toxicity issues forced the early development of the process with biofilms, granulation, and suspended biomass reactors [9][10][11]. The process requires the combination of two processes, nitritation and anammox reaction, which, in engineered systems, can either be separated in time or space.…”

Rapid Screening of Ammonia Oxidizing Bacteria in the Sewage

“…Studies have shown that the composition and diversity of microbial communities is important in nitrogen transformation and removal processes [9], [10]. The process of nitrificationdenitrification is a microbial process which comprises of two phases [11]. The first, known as nitrification, is an aerobic process carried out by Gram-negative, in which ammonium is oxidized to nitrite (NO 2 − ) by means of ammonia oxidizing bacteria (AOB).…”

Modelación matemática del proceso de nitrificación en dos etapas. Desarrollo de metodologías de calibración del modelo para un reactor SHARON y un proceso de fangos activados

“…Se han definido diferentes concentraciones de OD para llevar a cabo la nitrificación parcial, que van desde 0.3 a 2.5 mg/l (Wyffels et al 2004a(Wyffels et al , 2004b. Altas concentraciones de OD (> 2 mg/l) podrían convertir la nitrificación parcial en completa, mientras que concentraciones inferiores a 0.5 mg/l puede reducir considerablemente la tasa de nitrificación.…”