Proceedings

Implementation of the Water Framework Directive seems likely to require extensive moves to 3 mg/l
95%-ile ammonia Consents and 2 mg/l average total-P Consents, usually at the same works. At works
using chemical P-removal, metals consents from 1 to 4 mg/l (upper tier) will correspondingly result.
Data from supported growth systems is presented to show that Rotating Biological Contactors (RBCs) can
comfortably achieve these ammonia levels. In conjunction with reed beds the low levels of solids required
to comply with metals consents are also achievable, but less reliably.

Data from works with P-Consents introduced under the Habitats Directive and the CROW Act is presented
to show that the impact on nitrification is poorly predictable, and that ammonia performance can
improve or degrade, even at nominally similar works.