Simultaneous Recovery of Carbon, Nitrogen, and Phosphorous from Waste Activated Sludge: Influence of pH in Anaerobic Fermentation.

Recovery of carbon, nitrogen, and phosphorus resources can be accomplished through treatment of the anaerobic fermentation supernatant from waste activated sludge (WAS). However, the anaerobic fermentation process is significantly influenced by pH values. In this article, thickened sludge from a secondary sedimentation tank of a wastewater treatment facility in Zhengzhou was used to conduct a batch test to examine the effect of pH values between 5.0 and 11.0 on the recovery efficiency of carbon, nitrogen, and phosphorus in sludge fermentation liquid. The results showed that the production of volatile fatty acids and the total suspended solids degradation rate of sludge reached the highest levels at pH 10.0, with 2481.35 mg/L and 54.11%, respectively, which was 1.45 times higher than the results of the unadjusted pH group. The highest efficiency of nitrogen and phosphorus recovery in the supernatant of anaerobic fermentation was achieved at pH 10.0, with the mole ratio of Mg2+/NH4+-N of 1.5 and the mole ratio of PO43−/ NH4+-N of 1.0, yielding 96.55%. The actualization of sludge resource usage and the recovery of carbon, nitrogen, and phosphorus resources from WAS could be achieved simultaneously in this study. [ABSTRACT FROM AUTHOR]