Have you ever used floating wetlands? We had, but mostly they were built primarily of plastic, are imported from overseas and cost an exorbitant amount.
To test whether we could build a cost effective and simple to make floating wetland, we teamed up with Toi consulting and Ecoquest to further develop Element Environmental’s prototype bamboo floating wetland.
With funding from MBIEs curious minds science and innovation fund as well as loads of energy from Te Kauwhata College teachers and students, we were able to teach students how to build these wetlands and help them create their own floating island network.
Figure 1 – The bamboo floating raft, which is built and launched. This raft is yet to have jute, soil and plants installed.
How did we go about building a bamboo floating wetland?
As part of the project, we created two “how to” video resources for the students, a short time-lapse video and a longer form video as a teaching aid.
Video 1 - Timelapse of how we made the floating wetland
Video 2 - Full teachers aid instructions on how to build bamboo floating wetlands.
How did the students go at building a floating wetland?
They did a wonderful job at their first set of rafts (figure 2). Using innovative techniques, they lashed the wetlands together to create a much larger structure. The beauty of doing it this way means that the wetland complex can be added to over time.
Figure 2 – The Te Kauwhata College students’ rafts. They are also testing the effectiveness of using manuka in a floating wetland to see if their anti-bacterial properties can further treat the water.
Will Bamboo Become an Alternative to Plastic Based Wetlands?
We will keep monitoring the progress of these wetlands to see how they function over time. So far we have found that they are easy and cost effective to construct. Costs are kept very low for us as we have a nearby supply of large bamboo.
We think that bamboo is a versatile and sustainable material that has many benefits when used in floating wetlands. It has several properties that make it an ideal material for use in floating wetlands. First, it is a fast-growing plant that can grow up to 91 cm per day, making it an abundant and renewable resource. Second, bamboo has a high strength-to-weight ratio, which makes it an ideal material for constructing floating structures. Third, bamboo has a natural resistance to water and decay, which makes it durable and long-lasting.
With its many benefits, bamboo could be an excellent choice for use in floating wetlands and should be considered in future wetland restoration and construction projects.
Floating Wetland Function and Construction
Floating wetlands, which can also be called floating treatment wetlands or floating islands, are usually man-made structures that mimic natural wetlands, designed to improve water quality, habitat, and aesthetics in bodies of water such as lakes, ponds, and stormwater retention ponds. Some efforts have also been undertaken to create floating wetlands in small rivers and agricultural drains.
Floating wetlands can also be used to treat rural diffuse pollution, which is a significant problem in many parts of the world, including New Zealand. Diffuse pollution refers to the contamination of water resources from multiple sources, often stemming from agricultural activities such as livestock farming and fertiliser use.
Floating wetland construction
Floating wetlands consist of a buoyant base, commonly made of recycled materials, which supports a variety of wetland plants and roots that dangle below the water's surface. The plants take up nutrients, help drop sediment from the water column and the roots provide habitat for aquatic organisms.
In studies like our one above, floating wetlands have also been made from biodegradable materials, which offer the added benefit of reducing environmental impact and waste. Biodegradable materials used in floating wetlands often include coconut coir, jute, and other natural fibres.
Biodegradable floating wetlands have been used in a variety of locations, including urban areas and rural waterways, with positive results. For example, in India, biodegradable floating wetlands made of coconut coir have been used to treat wastewater in urban areas, providing a sustainable and cost-effective solution for improving water quality.
Overall, biodegradable floating wetlands offer a sustainable and environmentally friendly alternative to traditional materials, with the added benefit of supporting plant growth and wildlife habitats. As such, they are likely to continue to gain popularity in the future as an effective solution for improving water quality and restoring wetland ecosystems.
Why are floating wetlands so useful?
Modern application of floating wetlands inare often undertaken for water quality improvement: Floating wetlands have been shown to improve water quality by removing excess nutrients, such as nitrogen and phosphorus. These nutrients can cause harmful algal blooms, deplete oxygen levels, and negatively impact aquatic life. The plants in the floating wetlands take up these nutrients, asnd enable additional denitrification in the root zone, limiting nutrient concentrations (figure 3).
Floating wetlands provide habitat for aquatic organisms such as fish, birds, and invertebrates. The plants and roots create a sheltered environment for these organisms to thrive.
Aesthetic Improvement: Floating wetlands can improve the aesthetic appeal of bodies of water by adding greenery and natural features to otherwise barren or developed areas. They can also provide a habitat for wildlife, making the area more attractive to visitors.
Cost-Effective: Floating wetlands can be a cost-effective solution for improving water quality in bodies of water that would otherwise require expensive dredging or chemical treatments. They can also be installed in areas where traditional wetlands cannot be easily created, such as in urban environments.
What are floating wetland limitations?
Floating wetlands require regular maintenance, such as removing dead plants and replacing them with new ones. If the plants become too overgrown, they may sink, which can be detrimental to the health of the aquatic organisms living in the wetland.
Floating wetlands have a limited capacity to remove pollutants from the water. They may not be suitable for large bodies of water or areas with high levels of pollutants.
Floating wetlands may be vulnerable to extreme weather events such as storm events, floods, or strong winds. If the wetland is not secured properly, it may become detached or damaged.
Floating wetlands are a promising tool for improving water quality and providing habitat for aquatic organisms. Bamboo provides a sustainable and versatile material that has several properties making it an ideal material for use in floating wetlands. These biodegradable materials, alongside other natural materials like coconut coir and jute, have also been used in the construction of floating wetlands, offering a sustainable and environmentally friendly alternative to traditional materials. While floating wetlands have some limitations, such as the need for regular maintenance, their benefits outweigh their drawbacks in many applications, making them a promising tool for addressing water quality issues in bodies of water in New Zealand.