Global targets for sustainability, such as the Sustainable Development Goals (SDGs) set by the United Nations, seek to promote the environmental, social, and economic development in a manner that protects, preserves, and enhances our environment (Hák and Moldan, 2016). The use of a Nature-based Solution (NBS) for wastewater treatment offers a viable approach to achieve SDGs within the public sector. Constructed floating wetlands (CFWs) are one NBS that has a demonstrated capacity to improve the nutrient removal performance of wastewater treatment lagoons.
CFWs are a buoyant structure which can support plant growth, allowing plant roots to grow into the water column and uptake nutrients directly from the water source, similar to hydroponics. Two successful, global trials using CFWs to enhance wastewater lagoon systems have occurred in Queensland, Australia (Huth et al., 2021) and Alberta, Canada (Arslan, et al., 2023). Both studies demonstrated a significant uptake of nutrients by the plant species utilised, with Arslan et al. (2023) finding an improvement in water quality with the use of a CFW as opposed to without.
Based on the evidence and research presented on using CFWs to enhance wastewater treatment, TasWater commenced a two-year, full-scale pilot project in December 2024 utilising CFWs at three separate lagoon-based sewage treatment plants (STPs) to investigate the nutrient removal and assess the application of CFWs in wastewater treatment in Tasmania. The target is to reduce the environmental nutrient discharges, specifically nitrogen and phosphorus, by 50 per cent, using a natural, low-energy NBS solution.
The growth of the CFW plants at all three sites has been exceptional since the practical completion of installation (late 2024) and plant harvesting has already commenced as of March 2025. The initial results of the pilot study are currently being assessed, inclusive of water quality monitoring, and will be presented at the conference.