About Reed Beds

Two different basic types of reed-beds have been developed and used for the treatment of polluting waste water effluents over the last 20 years or so:

• Horizontal flow reed-beds
• Vertical flow reed-beds

From these in more recent years a third type of reed bed system, that is highly efficient, has evolved:

• Combination vertical and horizontal flow reed beds

Horizontal Flow Reed-Bed Systems:

Horizontal flow reed beds work particularly well for low strength effluents, or effluents that have undergone some form of pre-treatment.

Whilst not effective in reducing ammonia they will almost always reduce BOD (Biochemical Oxygen Demand) and SS (Suspended Solids) levels. These systems play an invaluable role in tertiary treatment and for the polishing of effluents.

A typical application would be to treat the discharge from a package sewage treatment plant which is unable to meet the discharge consent standard required.

Vertical Flow Reed-Bed Systems:

Vertical flow reed-bed systems are much more effective than horizontal flow reed-beds not only in reducing BOD and SS levels but also in reducing ammonia levels and eliminating smells. They can be considerably smaller and will also cope with much stronger effluents.

Combination Systems:

Multi-stage reed-bed systems, incorporating one or two stages of vertical flow followed by one or more stages of horizontal flow, and large single stage vertical flow reed-beds, when properly designed, are used for example, for the full treatment of domestic sewage - black and grey water - and, sludge, if required.

TYPICAL FEATURES OF A COMBINATION REED-BED SYSTEM WITH TWO DOWNFLOW STAGES AND ONE HORIZONTAL

Cress Water's systems can be designed to accommodate virtually any situation - from flat sites to steep rocky slopes. On sloping sites gravity can be used, whereas one or two pumping stages may be required on flat sites, to move the effluent through the reed-beds.

Reed-bed systems do not require a lot of space. The most effective "combination reed-bed systems", usually sized at about 2 sq.m. per person equivalent for sewage treatment, have a remarkably small footprint.