Bioavailability of Phosphorus Species in Secondary Effluents

Phosphorus (P) is a limiting nutrient responsible for the eutrophication of surface waters and marine coasts. Wastewater treatment technologies are being stressed to achieve low P effluents and national effluent P limits are expected in the coming years. This research investigates how different P-species contribute to bioavailable phosphorus (BAP) in secondary effluent using bioassays and the standard algal species Raphidocelis subcapitata. Results show that all P-species contributed to BAP, soluble reactive phosphorus and soluble acid hydrolysable phosphorus have high bioavailabilities, and there is no significant correlation between BAP and the P-species analyzed. BAP is an important parameter in determining effluent contributions to eutrophication. This research demonstrates that certain P-species may be used to approximate BAP for faster analysis compared to the bioassay method.