Denitrifying phosphorus removal in a step-feed CAST with alternating anoxic-oxic operational strategy.
A bench-scale cyclic activated sludge technology (CAST) was operated to study the biological phosphorus removal performance and a series of batch tests was carried out to demonstrate the accumulation of denitrifying polyphosphate-accumulating organisms (DNPAOs) in CAST system. Under all operating conditions, step-feed CAST with enough carbon sources in influent had the highest nitrogen and phosphorus removal efficiency as well as good sludge settling performance. The average removal rate of COD, NH4+-N, PO4(3-)-P and total nitrogen (TN) was 88.2%, 98.7%, 97.5% and 92.1%, respectively. The average sludge volume index (SVI) was 133 mL/g. The optimum anaerobic/aerobic/anoxic (AOA) conditions for the cultivation of DNPAOs could be achieved by alternating anoxic/oxic operational strategy, thus a significant denitrifying phosphorus removal occurred in step-feed CAST. The denitrification of NOx(-)-N completed quickly due to step-feed operation and enough carbon sources, which could enhance phosphorus release and further phosphorus uptake capability of the system. Batch tests also proved that polyphosphate-accumulating organisms (PAOs) in the step-feed process had strong denitrifying phosphorus removal capacity. Both nitrate and nitrite could be used as electron acceptors in denitrifying phosphorus removal. Low COD supply with step-feed operation strategy would favor DNPAOs accumulation.
Ma
Juan
J
Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China. majuan@emails.bjut.edu.cn
Peng
Yongzhen
Y
Wang
Shuying
S
Wang
Li
L
Liu
Yang
Y
Ma
Ningping
N
D019149:Bioreactors; D009584:Nitrogen / Q000302:isolation & purification / Q000378:metabolism; D010758:Phosphorus / Q000302:isolation & purification* / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*
D010758:Phosphorus; D009584:Nitrogen