Floating islands

Van den Berg Garden Village, DH Environmental Consulting and Envirowise have just introduced floating islands here. These islands, manufactured from a patented concept mimicking nature, are not only an attractive addition to any water feature in a landscape, they also act as highly efficient floating water treatment wetlands. Sometimes, all a polluted pond or dam needs is a little love from an island - a floating treatment wetland.

Load soil onto loofah-like mesh pf plastic (made from recycled carpet and water bottles), plant it, float it, and let it grow. The plant roots become home to biofilms that gobble nitrates and phosphates, denying those nutrients to algal blooms. Microorganisms eat the biofilms, fish eat them, and the water gradually gets cleaner. They also remove a host of nasty chemical and pharmaceutical pollutants.

They can also be used, to great effect, in natural swimming pools.

More on floating islands

In the last half-century, there has been a rediscovery of the wetland as nature’s primary tool to clean water. Many variations of constructed wetland have been implemented, with varying degrees of success, to clean all kinds of contaminated water, from wastewater and stormwater to drinking water. It used to be assumed that plants were the major contributor to this cleaning task. But recently, biofilm-creating microbes have been found to play a dominant role as observed by Dr Otto Stein of the Center for
Biofilm Research at Montana State University: “The majority of wetland transformations are due to microbial activity”. This awareness has given rise to a new form of constructed wetland, the floating wetland, known variously as floating islands, floating treatment wetlands or even floating emergent wetlands, which maximize the ability for microbes to thrive by providing massive areas of inert surface on which biofilms can form.

A Floating Treatment Wetland (FTW) consists of emergent wetland vegetation growing on a mat or structure floating on the surface of a body of water. The plant stems remain above the water level, while their roots grow down through the buoyant structure and into the water column. In this way, the plants grow in a hydroponic manner, taking their nutrition directly from the water column. Beneath the floating mat, a hanging network of roots, rhizomes and attached biofilm is formed. This hanging root/biofilm network provides an active surface area for biochemical processes, as well as physical processes such as filtering and entrapment. Thus, the general FTW design objective is to maximize the contact between the root/biofilm network and the polluted water passing through the system.

BioHaven Floating Islands

BioHaven® Floating Islands provide the most significant development in artificial wetland technology. For the first time it is now possible to substantially increase the biological working surface ('biofilm') in existing wetland environments, augmenting the treatment capacity without the need for additional land area. BioHavens create opportunities for continuous wetland function, irrespective of water levels and flow rates. The option to install BioHavens as a functional component of new wetlands allows for a smaller wetland footprint as well as the ability to sequestrate dissolved nutrients and pollutants that would be difficult to achieve with conventional wetland systems.

BioHavens provide a wide range of options for the functional beautification of both natural and artificial wetlands, maturation and ornamental ponds, dams and other waterbodies. The options are limitless. These floating islands may not only be planted with either aquatic or terrestrial plants, they may also be used for growing cut flowers or vegetables, i.e. providing income or food security in addition to improved water quality. Larger versions, with recirculation devices and other features, can be added to existing wastewater treatment plants to cope with meeting effluent treatment needs. The options are endless.

For more information, go to the DH Environmental Consulting website