Mitigation of eutrophication caused by wastewater discharge: A simulation-based approach

Mitigation of eutrophication, intensified by excessive nutrient load discharge in wastewaters regulated by restrictive legal requirements, remains one of today's most important global problems. Despite implementation of the Water Framework Directive, the Urban Wastewater Directive and the HELCOM recommendations, the actual condition of surface water is still not satisfactory. In response to the above, the study presents an alternative approach for surface water protection against eutrophication based on the selection of appropriate nutrient removal technologies. An activated sludge model simulation was used to enable the identification of environmentally justified nutrient removal systems with lowest eutrophication potential of treated wastewater conditioned by bioavailable nutrient forms content. Based on the outcome of the study, the 3-stage Bardenpho system was identified as the most efficient for bioavailable phosphorus removal, while the Johannesburg system proved to have the highest efficiency for bioavailable nitrogen removal. The proposed eutrophication mitigation approach underlines the need for a reconsideration of current legal regulations which ignore nutrient bioavailability and key eutrophication limiting factors.

Automated summary

The study proposes an alternative approach for surface water protection against eutrophication based on the selection of appropriate nutrient removal technologies, using an activated sludge model simulation to identify environmentally justified nutrient removal systems. The 3-stage Bardenpho system was found to be most efficient for bioavailable phosphorus removal, while the Johannesburg system was most efficient for bioavailable nitrogen removal. This highlights the need for a reconsideration of current legal regulations that do not take into account nutrient bioavailability and key eutrophication limiting factors.