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• O 2 -supply capacity significantly impacts LAS metabolic pathway in a membrane biofilm reactor. • All three O 2 -supply capacities achieved high removal rates of LAS and nitrogen. • Aerobic mineralization + aerobic NO- 3-n respiration achieved high LAS removal under sufficient O 2 . • Aerobic and anaerobic NO- 3-n respiration is important in efficient LAS removal with low O 2 -supply. • Four aerobic and two anaerobic LAS metabolic pathways were detected at restricted O 2 condition. Linear alkylbenzene sulfonate (LAS) can be thoroughly mineralized within sufficient oxygen (O 2 ), but which is energy intensive and may causes serious foaming problem. Although cometabolism can achieve efficient LAS removal within a wide range of O 2 dosages, how O 2 dosage systematically affects LAS metabolic pathway is still unclear. Here, membrane aerated biofilm reactor (MABR) enabled accurate O 2 delivery and bulk dissolved oxygen (DO) control. MABR achieved efficient removal of LAS (>96.4 %), nitrate (>97.8 %) and total nitrogen (>96.2 %) at the three target DO conditions. At high DO condition (0.6 mg/L), LAS was efficiently removed by aerobic mineralization (predominant) coupled with aerobic denitrification biodegradation with the related functional enzymes. Pseudomonas, Flavobacterium, Hydrogenophaga , and Pseudoxanthomonas were dominant genus contributing to four possible LAS aerobic metabolic pathways. As O 2 dosage reduced to only 29.7 % of the demand for LAS mineralization, O 2 facilitated LAS activation, benzene-ring cleavage and a portion of respiration. NO 3 - -N respiration-induced anaerobic denitrification also contributed to ring-opening and organics mineralization. Desulfomicrobium and Desulfonema related two possible anaerobic metabolic pathways also contributed to LAS removal. The findings provide a promising strategy for achieving low-cost high LAS-containing greywater treatment.
Wei et al. (Thu,) studied this question.