The study heavily emphasizes bibliometric trends (e.g., the rise of anammox/comammox research) but fails to reconcile these trends with real-world implementation challenges. For instance:
*Why do the authors assert the superiority of novel processes like anammox and comammox when the data show China’s dominance in publications (56.2%), a country with full-scale adoption of these technologies remains limited due to high operational complexity and sensitivity to temperature?
*If “efficiency depends on wastewater type and bioreactor configuration” (as stated), why the analysis not address the glaring disconnect between academic output (e.g., 728 publications in 2022) and documented industrial scalability (e.g., <5% of global WWTPs use anammox)?
Moreover, the paper acknowledges N2O as a ” 200–300x more potent GHG than CO2″ yet optimistically frames DO control and heterotrophic denitrifiers as solutions. However:
*Given that N2O emissions are inherently tied to microbial metabolism (e.g., AOB denitrification under low DO), how can authors justify their conclusion that “effective completion of nitrification/denitrification decreases N2O accumulation” when even optimal systems emit N2O as an intermediate?
*The bibliometric data highlight “minimizing N2O” as a future trend, but the study ignores recent meta-analyses showing N2O emissions spike in anammox systems under variable loads (e.g., Sabba et al., 2018). Does this undermine the paper’s proposed “sustainable” nitrogen removal framework?