Phosphorus recovery from wastewater is an important approach for sustainable phosphorus use. Phosphorus recovery integrated into the anammox process could significantly minimize the operation cost and bring better biomass retention. In this work, a novel process combining anammox and hydroxyapatite (HAp) precipitation in an expanded bed reactor for simultaneous nitrogen removal and phosphorus recovery operated at 15°C was developed by applying specific Ca/P ratio and pH control. Performance of nitrogen removal and phosphorus recovery under different nitrogen loading and phosphorus loading rate was assessed in a continuous experiment. In this work, elementary analysis demonstrated the high phosphorus accumulation in sludge, and different analysis including Fluorescence in situ hybridization (FISH) and laser Raman microspectroscopy revealed the two layers structure with anammox biofilm attached to inorganic core of the granules. The results demonstrate that with proper control, anammox expanded bed reactor could be transformed into an efficient process to simultaneously remove nitrogen and recover phosphorus even at 15°C.
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