Floating Wetlands

Posted on May 29, 2014

Effluent Ponds are a necessary evil of Dairy Farming. 
They are a source of pollution, smell and visible unattractiveness if not managed well.

Kauri Park Nurseries has developed a unique floating wetland system which can be used to remove pollutants from an effluent pond. The plants are planted on the floating wetland and send their roots into the water taking up nitrogen, phosphates and potassium.

Planting the perimeter and swales

It is desirable to plant wetland plants and Phormium species around the perimeter of the pond and larger shrub type natives on the bank edges.

Overflow swales should be fenced off and planted in Carex and Phormium species.

How Kauri Park’s floating 
wetland system works

The floating wetland, which can be used in any water environment requiring treatment, provides a base for plants and vegetation to grow. As the roots spread down through the fibrous structure of the floating media, a vast activated surface area is created for microbes and bacteria to establish to take on their role of bio-remediation, that is, the use of micro-organisms to remove pollutants.

The microbes and bacteria, which do not swim, and are UV sensitive, adhere to the roots and microscopic root hairs of the plants, and within the fibrous structure of the floating media itself, secreting sticky extracellular proteins and forming biofilms. It is within these biofilms which microbes and bacteria trap and digest organic matter and nutrients in waste water, including total suspended solids, biochemical oxygen demand (BOD), nitrogen and phosphorus.

All of the plants are bedded into the floating media so there is no issue with plants clogging the effluent pond.

The floating wetland remains on the surface of the pond, visually hiding the pond while at the same time constantly removing pollutants and minimising odour.

Pollutant Removal Capacity

To give an idea of the potential pollutant removal capacity of a floating wetland treatment system, an area of 100m2 of floating media planted with wetland species, will remove approximately 73kg Nitrogen and 37kg Phosphorus per annum.

The floating wetlands work better at the later stages of water treatment before water is released into the waterway.

This pollutant removal capacity is likely to be lower than the incoming levels of pollutants, so for most systems the floating wetland will not be the only method of pollutant extraction.

The key advantages of a floating wetland system are aesthetic improvement of the effluent ponds, odour reduction and partial treatment of the water.