Microalgal Removal
Description
Management of release water in commercial prawn farming (and other forms of aquaculture) is particularly important in catchments where wastewater contains excess nutrients. Removal of nutrients, particularly total nitrogen (TN) and dissolved inorganic nitrogen (DIN), before release into environmentally sensitive waters (such as GBR catchment zones) is vital for compliance with governmental regulations and maintaining and enhancing social license credentials. Aquaculture wastewater is most commonly treated by microalgal removal. Naturally occurring microalgae can rapidly take up the excess dissolved nitrogen, but the conventional method of removal with gravity sedimentation takes up to 4 days for the microalgae to settle from the vast quantities of wastewater. One promising technique to speed up the removal of microalgae, and hence excess nitrogen, is electro-flocculation. A very low voltage electrical current is passed through the water which causes organic matter, including microalgae, to bind and float to the surface as a “flocculant” that can be easily removed. The resultant microalgal flocculant could also potentially be used as a value-added product.
This study will determine the optimal configuration for electro-flocculation to remove microalgae from prawn wastewater. We will also investigate N uptake in a range of microalgal species commonly observed in prawn ponds.
Partners
Working in collaboration with Department of Agriculture and Fisheries (DAF)
Impact
Wastewater treatment is currently a bottleneck for the aquaculture industry. There is a high priority and appetite for industry investment in new technology to achieve these aims. This research will help develop methods to speed up the rate of processing wastewater to facilitate farm expansion and increase production. It will also help prawn farmers to ensure wastewater discharges are compatible with the longer-term water quality objectives for the Great Barrier Reef and align with the Reef Long Term Sustainability Plan 2050.
Researchers
Dr Angela Capper (CMERC) and Dr Sanath Alahakoon
Acknowledgement of funding
This project has received funding support from Department of Agriculture and Fisheries (DAF) – Rural Economic Development grant
Sustainable Development Goals
SDG 6.3 - Wastewater Treatment
SDG 6.6 - Water-related ecosystems
SDG 12 - Responsible consumption and production
SDG14 - Life below water
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