Leveraging side-stream sludge fermentation for phosphorus recovery in wastewater treatment systems

• Side stream enhanced biological P removal process (S2EBPR) useful for P recovery. • Better P-removal for S2EBPR (98 %) than anaerobic/anoxic/oxic configuration (86 %) • S2EBPR facilitates successive P-recovery steps by producing a P-enriched effluent. • Up to 40 % of the total P input to the plant can be recovered as soluble P. • Longer residence time in the side stream sludge fermenter gives better results. This study proposes the integration of a new P-recovery strategy through the use of a side stream enhanced biological P removal (S2EBPR) process. To evaluate this alternative, a 150 L pilot-scale anaerobic/anoxic/aerobic (A 2 O) plant was operated with a side-incorporated reactor (10 or 23 L) to work as an anaerobic side stream sludge fermenter (SSSF). The P removal performance and possible P-recovery under different hydraulic residence time in the SSSF were evaluated. The integration of the SSSF in the A 2 O configuration provided an excellent 98 % P-removal and allowed to create in the SSSF a stream with a very high soluble phosphate concentration (up to 196.5 ± 10.9 mgP/L). The supernatant of the wasted activated sludge (WAS) discharged from the SSSF contained as soluble phosphate up to 40 % of the total P input to the plant.