Does ferric dosing for phosphorus removal upset the nutrient balance for biological sewage treatment processes?: PRESENTATION ONLY
Youdan, J., Healey, S., Walker, H. and Whittle, I., Wessex Water, UK
(free)
Abstract:
During AMP6 Wessex Water have been undertaking a phosphorus removal, catchment permitting trial looking at innovative ways to permit the removal of phosphorus. This often involves removing phosphorus at sewage treatment works using ferric dosing, often ahead of the primary settlement stage. It was thought that high levels of ferric dosing to remove phosphorus would upset the nutrient balance of the nitrogen, phosphorus and carbon which may negatively impact on ammonia removal across the biological processes.
This piece of works investigates three sites and aims to understand if the increased ferric dosing has had an impact on the nutrient balance and ultimately on the ammonia concentrations in the final effluent. The results indicate that despite the expectation (based on literature and operational experience) for nutrient stripping to have occurred and therefore a negative impact on nitrification to have taken place, this was not the case and no statistical difference was seen before and after the increases in ferric dosing, for two of the three sites. The third site showed that the differences in nutrient ratios were statistically different before and after the increases in ferric dosing, although the ammonia concentrations within the final effluent were not impacted.
