Abstract
Removal of nutrients from pretreated black water is difficult during the biological nutrient removal process, owing to the lack of carbon sources. To improve nitrogen and phosphorus removal, this study explored optimal operating strategies in a plant-scale multistage activated sludge-membrane bioreactor system for black water treatment. The results showed that the nutrient removal efficiency was highly dependent on the regulation of dissolved oxygen (DO) levels and sludge concentrations. The decreased DO levels (0.6–0.7 mg O2/L) in aerobic zones O3–O5 and the increased sludge concentrations (10.5 g/L) enhanced simultaneous nitrification and denitrification (SND), thereby improving the nitrogen removal efficiency from 82.4 % to 94.3 %. Additionally, when the nitrates were mostly reduced in the aerobic zones, phosphorus removal significantly increased from 29.6 % to 75.7 %. High-throughput sequencing analyses revealed a continuous increase in bacterial diversity during the entire operation period to adapt to the black water properties. Although the proportion of nitrogen- and phosphorus-removing bacteria decreased under oxygen-limited conditions, nitrogen removal efficiency was guaranteed via the SND pathway. The bacterial relative abundances could be partially or fully recovered by appropriately adjusting the DO levels and sludge concentrations.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call