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Transitioning from chemically assisted to fully biological nutrient removal is essential for sustainable treatment of industrial wastewaters, yet the mechanisms underlying microbial and morphological sludge transitions under real feedwater conditions remain poorly understood. This study investigated enhanced biological phosphorus removal (EBPR) in sequencing batch reactors (SBRs) fed with starch-rich potato-processing wastewater (PPW). Three reactors were operated for 180 days with distinct inocula: conventional activated sludge, PAO-enriched sludge, and a non-EBPR reference. Reactor performance, hydrolytic enzyme activity, sludge morphology, and microbial community dynamics were evaluated using batch assays, enzyme profiling, 16S rRNA sequencing, and FISH. Conventional sludge (SBR2) was successfully enriched into PAO-dominated communities within 60–90 days, achieving up to 97% COD, 93% TN, and 97% TP-removal, comparable to the pre-enriched inoculum (SBR3). Hydrolytic capacity proved decisive, with amylase activity in SBR2 increasing by >120%, linking starch degradation to phosphorus cycling. Morphological shifts from loose flocs to dense, partially granulated aggregates improved settleability (SVI₃₀ 120% increase) linked starch hydrolysis to P cycling • Flocs densified into stable, partially granulated sludge with good settling • EBPR reduced microbial diversity but increased functional robustness
Göttert et al. (Sat,) studied this question.