In the completely autotrophic nitrogen removal over nitrite (CANON) process, the conflicting oxygen requirements of anammox and ammonium-oxidizing bacteria often lead to retardation in anammox activity. However, our study achieved stable nitrogen removal with a maximum capacity of 1096 g-N/m3/d in a 20 m3 CANON reactor under long-term intensive aeration. The anammox bacteria unusually distributed in the outer layer of the biofilm and demonstrated remarkable oxygen tolerance. Their activity only declined by 18.5 % under 2.0 mg/L of dissolved oxygen. When anammox bacteria encountered oxygen exposure, they adopted some strategies. Metatranscriptomics revealed that Candidatus Kuenenia, the dominant anammox species in our system, downregulated its gene expressions involved in carbon metabolism and oxidative phosphorylation. This may reduce electron leakage that combines with O2, thereby minimizing the generation of reactive oxygen species (ROS). By contrast, the secretion of extracellular proteins and conversion of O2·− were upregulated to eliminate ROS promptly. This behavior endowed Ca. Kuenenia with a unique oxygen detoxification pathway: O2·− were initially converted to H2O2 by superoxide dismutase SOD2 and superoxide reductase dfx (major role), followed by reduction to H2O via non-heme chloroperoxidase cpo (a newly recognized mechanism in the oxygen detoxification of anammox) and catalase katE. These results expanded the current knowledge of anammox alleviating oxidative stress.@en

Scour leads to the loss of soil around monopile foundations for offshore wind turbines, which affects their structural safety. In this paper, the effect of scour on the lateral behaviour of monopiles was extensively investigated using finite element analysis, and calibration and comparison were undertaken using centrifuge tests. Piles with three slenderness ratios, i.e., 3, 5 and 8, were studied by keeping the diameter constant and varying the embedment length. Three scour types (local narrow, local wide and global) and four scour depths (0.5D, 1D, 1.5D and 2D; D signifies the pile diameter) were considered in this investigation. The results indicate that the lateral resistance of the pile is the greatest in the case of local narrow scour, followed by that in the cases of local wide scour and global scour. When the scour depth is larger than 1D, the influence of the scour type on the pile lateral bearing behaviour is insignificant. The influence of the scour type and scour depth on the pile lateral bearing behaviour is broadly similar for piles with slenderness ratios of 3, 5 and 8. However, the piles featured with smaller embedment lengths show a larger decrease rate in their lateral capacity, which means the effect of scour should cause more concern on small slenderness ratio monopiles.@en