Reed bed treatment systems are
self-contained, artificially engineered, wetland ecosystems.
They are designed to optimise the microbiological, chemical and
physical processes naturally occurring in the Reed Bed. Wetland
plants, such as reeds, transfer atmospheric oxygen down through
their roots in order to survive in waterlogged conditions. This
creates both aerobic and anaerobic soil conditions, allowing an
extraordinary microbial species diversity to flourish.
These bacteria and fungi can use organic pollutants as a food
source, breaking down a wide range of organic chemical products.
So, chemicals are not simply stored in the reed bed; they are
actually degraded into harmless components. Other contaminants,
such as metals, are transformed from a toxic, mobile state and
fixed in the soil via complex chemical reactions. The soil's
adsorption capacity also provides a buffer for peak or shock
The complexity of microbial life and powerful reactions within
the root zone of the soil based Reed Bed result in an
extraordinary water cleaning capability. This capability is
often far less constrained than in many chemical or physical
wastewater treatment systems.
The Role of Plants
The specially selected
plant species within the Reed Bed have three main functions:
· They provide the means for secondary restructuring of the soil
system. The very extensive root and rhizome system creates
channels for the water to pass through and also keeps the soil
open through the constant growth and die back of the root
· The roots of the aquatic plant introduce atmospheric oxygen
down into the body of soil, providing an environment which
encourage an extraordinary quantity of species diversity of
micro-organisms to flourish around the plant roots. These are
needed for the effective breakdown of many types of compounds,
such as the oxidation of ammonia to nitrate - the first step in
the biological breakdown of this compound.
· The plants are capable of taking up a certain amount of
nutrient from the wastewater themselves.