Neptune Project Deliverable D1.2

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Neptune Project Deliverable D1.2

Strategies to improve nutrient removal

Several EU member states have yet to satisfy the stringent nutrient removal requirement of the Urban Waste Water Directive (1991) for sensitive areas. An environmental engineer working in the field of wastewater treatment is faced with increasing demands on the treatment efficiency. With the new European Water Framework Directive (EWFD, 2000/60/CE) there is a shift in paradigm from emission-based wastewater treatment plant (WWTP) effluent limits to an immission-based (from the river perspective) approach. Water policies in Europe and the world have shifted towards “demand management” and therefore have to incorporate new technologies in treatment and reuse. They prime the protection of aquatic ecosystems and point towards sustainable development. As a side-effect, even small plants have to fulfill the highest effluent limits if discharging into small water bodies. If we look into North America or Australia we see a trend to extremely low effluent limits, e.g. for total nitrogen as low as 3 mg N/L for sensitive
areas. Moreover, recent evidence is showing that WWTP are on the verge of a second upgrading round not only for the increase in the legislation requirements but also considering that some of the WWTP constructed in the 80’s and 90’s are becoming saturated because of population and industry growth. An important role is given to the WWTPs to reduce the urban contamination of rivers to very low levels and therefore nutrient removal in biological treatment has to be improved and optimized.