Phosphate removal from municipal wastewater by alginate-like exopolymers hydrogels recovered from aerobic granular sludge.

This worked assessed the potential of alginate-like exopolymers (ALE) hydrogels recovered from aerobic granular sludge (AGS) in removing compounds commonly present in municipal wastewater. Batch sorption experiments were performed with ALE hydrogels at different operating conditions. Results showed that ALE hydrogels can only remove phosphate, at removal efficiencies of up to 90.8% and practical loadings of 1.22 ± 0.07 mg PO43--P/g TSALE. Phosphate removal was observed even in the presence of competing ions. Moreover, neutral to acidic pH values strongly impaired the phosphate removal (28.9 ± 0.8% at pH = 6.00), while basic pH at around 8.50 was the most favourable (up to 90.8% at pH = 8.67). However, ALE hydrogels contributed to the increase in COD, total nitrogen and total phosphorus in the bulk liquid, what suggests that ALE need to be further tailored. Therefore, this study demonstrates that ALE represent a relevant approach for the recovery of phosphates from municipal wastewater.