AQUACULTURE ENVIRONMENT INTERACTIONS Aquacult Environ Interact Vol. 4: 285–300, 2013 doi: 10.3354/aei00088 Published online December 19 INTRODUCTION Land-based aquaculture is an integral part of global aquaculture production for fishes (28.8 million t), molluscs (13.1 million t) and crustaceans (5.0 million t; FAO 2010, Hall et al. 2011). The majority of land- based systems which support the intensive culture of fresh, brackish and marine water organisms do so through the addition of high-protein feeds to sus- tain the rapid growth of intensively farmed animals © The authors 2013. Open Access under Creative Commons by Attribution Licence. Use, distribution and reproduction are un- restricted. Authors and original publication must be credited. Publisher: Inter-Research · www.int-res.com *Email: s.castine@cgiar.org REVIEW Wastewater treatment for land-based aquaculture: improvements and value-adding alternatives in model systems from Australia Sarah A. Castine 1,4, * , A. David McKinnon 2 , Nicholas A. Paul 3 , Lindsay A. Trott 2 , Rocky de Nys 3 1 AIMS@JCU, Australian Institute of Marine Science and School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia 2 Australian Institute of Marine Science, Townsville MC, Queensland 4810, Australia 3 School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia 4 Present address: WorldFish, Jalan Batu Maung, 11960 Bayan Lepas, Penang, Malaysia ABSTRACT: Settlement ponds are used to remove particulate and dissolved nutrients in Aus- tralian land-based aquaculture wastewater. At best, marine and brackish water settlement ponds reduce total suspended solids by 60%, but their efficiency is inconsistent. Functional improve- ments to nutrient removal systems are essential to provide uniform and predictable treatment of flow-through aquaculture wastewater. Furthermore, environmental regulation of discharge from intensive systems in Australia is increasing, providing the impetus to upgrade rudimentary single- step settlement pond systems. We characterise technologies used for land-based aquaculture wastewater treatment prior to discharge from shrimp systems in Australia. We identify opportuni- ties to integrate technologies developed for the treatment of municipal wastewaters and intensive recirculating aquaculture systems, and use these to develop a model system for intensive shrimp farm wastewater. The first stage is the reduction of solids through the use of deep anaerobic ponds, which are tailored to dilute saline wastewater. Non-settled colloidal and supracolloidal solids can subsequently be removed through trapping in a sand bed filter and biological transfor- mation to dissolved inorganic nitrogen or N 2 . The resulting dissolved nutrients can be treated in a 3-stage algal treatment system by assimilation into harvestable biomass, and finally constructed wetlands polish wastewater through further trapping of particulates, and transformation of dis- solved nitrogen. Given that upgrading wastewater treatment facilities is costly, we highlight options that have the potential to offset nutrient treatment costs, such as the use of algal biomass for food or energy products, and the recycling of nitrogen and phosphorus via pyrolysis creating products such as biochar and biofuel. KEY WORDS: Settlement ponds · Crustaceans · Nutrients · Nitrogen · Bioremediation OPEN PEN ACCESS CCESS