Constructed Wetlands and Reed-Beds: Mature Technology for the Treatment of Wastewater from Small Populations

This paper reviews the design and performance of constructed wetlands for the treatment of domestic sewage. Horizontal-flow systems have now become accepted for secondary treatment where only BOD and SS consents are required. However, in recent years there has been increasing interest in systems such as vertical-flow and hybrid systems which are capable of achieving good nitrification. These systems have a greater and more reliable capability for oxygen transfer. As yet, there are only a few systems of this type in the UK, but the number is likely to increase. The paper describes the performance of (a) secondary and tertiary treatment systems, and (b) sludge-drying reed-beds.