Dan Willett (M.Sc) has over 14 years research experience in Aquaculture and Fisheries Management, including developing and implementing marine and freshwater effluent remediation trials, and developing breeding protocols for the artificial propagation of fish species for rec. fishing enhancement programs, industry and bioremediation purposes. Currently, senior technician on the DPI&F Sustainable Intensive Systems program developing treatment strategies for intensive livestock effluent.
Duckweed-based Wastewater Treatment (DWT) for Environmental and Productivity Gains in Aquaculture
Dealing with wastewater is a bane for most industries, and aquaculture is no different. Aquaculture, as an industry, has received criticism about how it’s discharged water impacts on the environment. Consequently, the larger industry associations now list on-farm wastewater remediation as a priority. From an industry perspective, addressing this issue is not only important for maintaining Australia’s reputation for ‘clean and green’ production, but strict EPA quotas on discharged nutrient levels are now limiting farm production in some areas. Even if meeting regulated discharge quotas is not currently an issue to your operation, the ability to restore wastewater for recirculation back through the farm can make good sense. Duckweed-based Wastewater Treatment (DWT) is a low-cost option that can help farmers meet environmental regulations or restore water for reuse – as well as providing a valuable additional crop.
A significant research program at the Bribie Island Aquaculture Research Centre (BIARC) is to develop production technologies for the aquaculture industry that limit the amounts of nutrients released into waterways. In the course of this research, we learned much about the response of nature to excess nutrients and how to harness and promote the various processes to capture nutrients before they leave the farm.
The main goal of our research is to convert and trap nutrients in a form that can be easily harvested. And whatsmore, harvested for profit. If treatment is profitable, wastewater becomes a productive resource rather than a liability. The technology is conceptually simple and relies on actively promoting nutrient processing by bacteria into forms suitable for uptake by aquatic plants or animals. These plants or animals in turn act as an easily harvested ‘sink’ for nutrients that would otherwise be discharged. Queensland in particular, is climatically well positioned to take advantage of lagoon treatment systems that use native duckweed as a productive and potentially profitable ‘sink’ for wastewater nutrients.
This session discusses the advantages of integrating Duckweed-based Wastewater Treatment (DWT) within aquaculture operations. It also highlights the value of harvested duckweed as a by-product of the treatment process; e.g. duckweed can be substituted for soy meal and fishmeal in a variety of products. Basic principles and system design aspects of DWT will also be presented.