Comparison of phosphorus recovery through pre-anaerobic-digestion brushite precipitation and post-anaerobic-digestion struvite crystallization

Sludge streams in water resources recovery facilities present promising opportunities of nutrient recovery. Brushite precipitation and struvite crystallization are two feasible methods of phosphorus recovery. This study evaluated the performance of CalPrex and AirPrex pilot tests in terms of treatment process, phosphorus release and recovery strategy, and impacts on solids treatment processes. Both CalPrex and AirPrex pilot units were designed at the same hydraulic loading. The performance of dewaterability of acidogenically digested sludge and the methanogenic digested sludge were compared. The phosphorus removal and recovery potentials were evaluated between brushite precipitation and struvite crystallization. This study showed that both brushite precipitation and struvite crystallization are viable options for phosphorus recovery in water resources recovery facilities.