Abstract:
Increased treatment capability is required on small sewage treatment works to meet ammonium
consents that are tightening to effluent concentrations of below 5 mg[Ammonical nitrogen (mg/L)]
and in some cases as
low as 0.5mg[Ammonical nitrogen (mg/L)]
Optimisation of existing assets is preferential over the addition or
expansion of the works to minimise associated costs and energy usage. Many small works in the UK
currently employ horizontal sub-surface flow constructed wetlands (HSSF CWs) that have
restricted capability to nitrify due to limited oxygen transfer and as such artificial aeration has been
proposed as a potential upgrade technology. To assess the performance of the technology, full-
scale sites were monitored in terms of ammonium and solids removal and hydraulic
characterisation over 3 years. Supporting pilot studies were carried out to assess the effect of
aeration on the planted vegetation and to determine optimum transfer efficiencies.
Cont/d.
