Succession of bacterial community in anaerobic–anoxic–aerobic (A²O) bioreactor using sludge fermentation liquid as carbon source

To analyze the effect of sludge fermentation liquid on succession of bacterial community as carbon source, a three-month-long experiment was conducted in anaerobic–anoxic–aerobic process at room temperature. Experimental results showed that the removal efficiencies of total nitrogen and total phosphorus were improved to 84.7 and 94.3% from 64.5 and 54.2% at flow ratio of fermentation liquid and municipal wastewater, 1:35. Meanwhile, the principal component analysis demonstrated that significant shifts of bacterial community were observed with fermentation liquid addition. In particular, fermentation liquid appeared to be selective for the phosphorus-removal bacteria Gammaproteobacteria, denitrifying bacteria Comamonas sp., nitrogen-removal bacteria Betaproteobacteria, and denitrifying phosphate accumulating organisms Sphingobacterium, indicating simultaneous nitrification and denitrification, and denitrifying dephosphatation might be present after fermentation liquid addition.