Highlights
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Two upflow microaerobic sludge reactors were constructed to treat MFPW.
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Aerobic and anaerobic activated sludge (S) were the inocula, respectively.
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Aerobic S was easier being accumulated than anaerobic S, only feasible for low NLR.
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The accumulated anaerobic AS was feasible for treating MFPW with higher NLR.
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An increased loading rate changed microbial community structure and removal load.