Identification and evaluation of SND in a full-scale multi-channel oxidation ditch system under different aeration modes

Abstract

h i g h l i g h t sSND was observed in a multi-channel OD at very low DO of 0.10-0.25 mg L À1 . SND was identified by micro-environment characteristics within tiny flocs. The highest SND occupied 44.1% of influent nitrogen mass by NMB analysis. The maximum SND efficiency was 79% with SND rate of 5.09 mg L À1 h À1 . a r t i c l e i n f o t r a c tSimultaneous nitrification and denitrification (SND) was evidently observed in a full-scale multi-channel oxidation ditch (OD), especially occurring within the outer channel under microaerophilic conditions. The optimum average dissolved oxygen (DO) concentration for SND was 0.25 mg L À1 with 79% SND efficiency and 5.09 mg L À1 h À1 SND rate, leading to 74.9% overall TN removal efficiency. Small sized flocs consisting of more nitrifying bacteria enhanced nitrification in favor of SND due to less oxygen diffusion limitation inside flocs than larger flocs under micro-aerated conditions. SND was also identified by co-existing of nitrifying and denitrifying bacteria as well as some microaerophilic microorganisms based on molecular biology analysis. Nitrogen mass balances (NMB) quantitatively demonstrated that the highest SND efficiency accounted for 44.1% of influent nitrogen mass. Above valuable findings might deeply reveal SND as a principal mechanism of nitrogen removal in a multi-channel OD from macro-to micro-scale.

The settling behaviour of an activated sludge with simultaneous nitrification and dentrification

“…V hs (X) = 11.304•e -0.408·Xtssi (2) These data is consistent with the generally accepted estimated values. For the point II the value X TSS -ex (ESS) was measured and DSS/FSS tests were made.…”

“…It involves physical and microbiological interactions of components of activated sludge [1,2]. According to preliminary studies, a stable process of simultaneous nitrification and denitrification is preceded by an adaptation of the biomass to operating conditions [3].…”

Optimal Surface Aeration Control in Full-Scale Oxidation Ditches through Energy Consumption Analysis

“…In a full-scale Orbal oxidation ditch, the low DO scenario (0.25 mg·L −1 ) was realized with satisfactory nitrification [40]. Moreover, reducing aeration intensity also results in lower emissions of aerosol or hazardous gas from the reactors.…”

Organic substrate transformation and sludge characteristics in the integrated anaerobic anoxic oxic–biological contact oxidation (A2/O–BCO) system treating wastewater with low carbon/nitrogen ratio

“…Anthrone method was used to test the glycogen (GLY). Table 2 The FISH [25,26] was used to observe the functional PAOs and nitrifiers in activated sludge (the A 2 /O reactor) and biofilms (the BCO reactor) ( Table 2). At least 30 images were taken for each sample.…”