Comparison of the treatment efficiency of aerobic granular sludge with bacterial-algal symbiotic aerobic granular sludge on wastewater containing dibutyl phthalate and the effect of DBP on the system processing of traditional pollutants

Dibutyl phthalate (DBP), a widely used plasticizer, is frequently detected in aquatic environments and poses risks to ecosystems and human health due to its endocrine-disrupting toxicity. This study compared the removal efficiency of DBP by bacterial-algal symbiotic aerobic granular sludge (ABGS) and conventional aerobic granular sludge (AGS) in parallel sequencing batch reactors. Under low DBP concentration (0.5 mg/L), ABGS achieved 99.6% removal, significantly higher than AGS (54%). ABGS also exhibited better tolerance to high DBP loads (5-10 mg/L) and faster recovery after stress removal. The presence of microalgae enhanced photosynthetic oxygen production, increased EPS secretion, and improved sludge structural stability. DBP removal involved both adsorption (pseudo-first-order and pseudo-second-order kinetics) and biodegradation (up to 27% at 30°C). Microbial analysis revealed enrichment of DBP-degrading genera (Thauera, Flavobacterium) in ABGS. These findings demonstrate that ABGS is a promising low-carbon biotechnology for treating DBP-contaminated wastewater.