Nitrogen and phosphorus removal in a denitrifying phosphorus removal process in a sequencing batch reactor with a forced anoxic phase

Abstract

The objective of this study was to establish such operating conditions in a sequencing batch reactor (SBR) that will enable the achievement of the highest possible share of denitrifying P removal in nutrient elimination. Two different operating strategies for SBRs were analysed. Both of these strategies used a forced anoxic phase in the SBR treatment cycle. The first one was based on an intermittent aeration, which led to periodic occurrence of anoxic conditions when the uptake of P-PO4(3-) could occur. The second strategy was based on mimicking the A2O process and forcing an anoxic phase straight after an anaerobic phase. The experiments were performed in a laboratory reactor operating at a maximum fill of 26.8-27.7 litres and a constant temperature of 18 degrees C. It was found that a SBR configuration with intermittent aeration did not allow the achievement of significant denitrifying P removal, despite the DPAO/PAO ratio being equal to 50.5%. Almost the entire load of orthophosphates was being removed in aerobic conditions right after the anaerobic phase, even though this aerobic period lasted only 20 minutes. However, a SBR with a forced anoxic phase occurring after an anaerobic phase and created by an introduction of NO(x) rich stream of wastewater guaranteed the highest DPAO/PAO ratio of 82.8% and the highest share of denitrifying P removal (above 80%) in the total removal of phosphorus.

The role of external carbon sources at each stage of an A2/O process for simultaneously removing nitrogen and phosphorus

“…With increasing nitrate recycling ratios, and thereby increasing the reaction time, a second release of phosphorus was recorded. This finding was previously highlighted by Podedworna et al [19], who noted increasing reaction times to correlate to a possible second release of phosphorus. Our results show that effluent concentrations at Stage 5 were higher than those at Stage 3.…”

“…This finding was previously highlighted by Podedworna et al . , who noted increasing reaction times to correlate to a possible second release of phosphorus. Our results show that effluent concentrations at Stage 5 were higher than those at Stage 3.…”

A Novel Process for Nutrients Removal and Phosphorus Recovery From Domestic Wastewater by Combining BNR With Induced Crystallization

“…At the steady state, in the BNR-IC system, when the COD, TN, NH 4 -N and P concentrations of 250 mg L A typical key phosphorus biochemical transformation, namely anaerobic P release and anoxic P uptake, was observed through a cycle batch test (2 h of anaerobic and 4 h anoxic) performed at the end of 55 days, as shown in Figure 3. The variations of carbon, nitrogen and phosphorus concentrations during a whole anaerobic-anoxic cycle were similar to what is typically observed in EBPR systems (Podedworna, Żubrowska-Sudoł 2012), strongly suggesting that DPAO was predominant in the BNR-IC process. In this process, the anaerobic P release rate and anoxic P uptake rate were 8.47 mg P (g MLSS) -1 and 11.13 mg P (g MLSS) -1 , presenting a good P biochemical transfer performance indicated by the ratio of anoxic P uptake to anaerobic P release (1.3), thereby creating a preferable condition that could support the growth of DPAO in the BNR-IC system (Guerrero et al 2012a).…”

Effect of the Aeration Strategy on NOB Suppression in Activated Sludge and Biofilm in a Hybrid Reactor with Nitrification/Denitrification

“…Table 2 presents concentration values of pollutants in influent and effluent from the IFAS-MBSBBR and the mean efficiency of removal of organic compounds, nitrification, and denitrification determined for particular stages of the experiment. nd-not detected, 1 -values calculated in accordance with the methodology provided in the [30].…”