Enhanced hydrolyzed polyacrylamide removal from water by an aerobic biofilm reactor-ozone reactor-aerobic biofilm reactor hybrid treatment system: Performance, key enzymes and functional microorganisms

[Display omitted] •The AOA hybrid treatment system was feasible to treat HPAM-containing wastewater.•No AM monomer was detected in the effluent of the AOA hybrid treatment system.•The activities of key enzymes involved in HPAM biodegradation was measured.•Functional microorganisms in two ABRs were investigated by Illumina MiSeq sequencing.•The relationships between keystone microorganisms and functions of ABRs were linked. Degradation of hydrolyzed polyacrylamide-containing (HPAM-containing) wastewater was investigated in a lab-scale aerobic-ozonic-aerobic hybrid treatment system. When the HPAM concentration was 500 mg L−1 and the ozone dose was 25 g O3/g TOC, the HPAM removal rate reached 90.79%. Experimental results obtained from gel permeation chromatography (GPC) and rheometer indicated that the refractory HPAM was decomposed into small-molecule compounds. High performance liquid chromatography (HPLC) analysis showed that there was no acrylamide (AM) in the effluent of the system. Microbial communities in two aerobic biofilm reactors (ABRs) were analyzed by Illumina MiSeq Sequencing, which indicated that norank_f_Cytophagaceae, Meiothermus, Bacillus, etc. were keystone functional bacterial genera and Methanobacterium, norank_p_Bathyarchaeota, norank_c_Marine_Group_Ⅰ, etc. were dominant functional archaeal groups. To our knowledge, this is the first study to treat HPAM-containing wastewater using an aerobic-ozonic-aerobic hybrid process. Good removal efficiencies and presence of functional microorganisms demonstrated that the hybrid treatment system was practical for treating HPAM-containing wastewater.