Nutrient removal via nitrite from reject water and polyhydroxyalkanoate ( PHA ) storage during nitrifying conditions

BACKGROUND Nutrient removal via nitrite was investigated in a sequencing batch reactor ( SBR ) treating reject water produced from the anaerobic digestion of sewage sludge and the subsequent dewatering process. The polyhydroxyalkanoate ( PHA ) storage capacity of the biomass obtained under nitrifying (nitritation) and non‐nitrifying aerobic conditions was investigated in batch reactors for biomass taken from the SBR . RESULTS In situ activity tests showed that the nitritation rate was not affected by the type of external organic carbon source that was added (i.e. propionic acid ‐ HPr and sludge fermentation liquid ‐ SFL ). In contrast, the specific nitrite uptake rate ( sNUR ) and the specific phosphate uptake rate ( sPUR ) via nitrite were much higher when SFL was applied compared with HPr (22.39 ± 1.08 mgN g − 1 VSS h −1 and 3.41 ± 1. 71mgP g − 1 VSS h −1 when SFL was added compared with 7.80 ± 1. 23mgN g − 1 VSS h −1 and 1.09 ± 0. 12mgP g − 1 VSS h −1 when HPr was added). The majority of phosphorus removal was attributed to the normal growth of biomass rather than the activity of phosphorus accumulating organisms ( PAOs ). The PHA yield was 0.65–0.67 C‐mmol PHA /C‐mmol short chain fatty acid ( SCFA ) when nitrification was inhibited, and 0.60–0.63 C‐mmol PHA /C‐mmol SCFA when nitritation also occurred. CONCLUSION The PHA yield was not adversely affected under nitrifying conditions, demonstrating that nitritation can be integrated with the production of PHA . © 2014 Society of Chemical Industry