Rougher, wetter, weaker: Multiscale evidence and mechanisms of tetramethylammonium hydroxide-induced anammox granule...

The treatment of semiconductor wastewater containing tetramethylammonium hydroxide (TMAH) presents a formidable challenge to anammox resilience yet the mechanisms governing irreversible sludge deterioration remain obscure. This study elucidates a deterioration pathway driven fundamentally by the disintegration of the granular structural architecture rather than immediate metabolic inhibition. Long-term exposure induced a transition toward a rougher and hydrophilic phenotype where surface roughness increased five-fold and water contact angles declined significantly. Mechanistically this physical unraveling was triggered by the dismantling of the hydrophobic extracellular polymeric substances network characterized by a plummeting protein/polysaccharide ratio and the depletion of tryptophan-like substances. Fourier transform infrared analysis confirmed the disruption of hydrogen bonding and the loss of hydrophobic moieties which compromised the cohesive scaffold. This microenvironmental collapse precipitated a distinct abundance-activity decoupling where the genomic abundance of Candidatus Kuenenia remained robust at 37.73% yet its functional vitality was severely impaired as evidenced by plummeting intracellular ATP and heme c levels. Concurrently the selective washout of filamentous skeleton-forming Chloroflexota and adhesion-promoting Pseudomonas further accelerated the structural fragmentation. These findings establish that the integrity of the hydrophobic EPS protein network is the prerequisite for sustaining anammox resilience against alkaline organic toxicity.