Traditional aquaculture provides food for humans, but produces a large amount of wastewater, threatening global sustainability. The antibiotics abuse and the water replacement or treatment causes safety problems and increases the aquaculture cost. To overcome environmental and economic problems in the aquaculture industry, a lot of efforts have been devoted into the application of microalgae for wastewater remediation, biomass production, and water quality control. In this review, the systematic description of the technologies required for microalgae-assisted aquaculture and the recent progress were discussed. It deeply reviews the problems caused by the discharge of aquaculture wastewater and introduces the principles of microalgae-assisted aquaculture. Some interesting aspects, including nutrients assimilation mechanisms, algae cultivation systems (raceway pond and revolving algal biofilm), wastewater pretreatment, algal-bacterial cooperation, harvesting technologies (fungi-assisted harvesting and flotation), selection of algal species, and exploitation of value-added microalgae as aquaculture feed, were reviewed in this work. In view of the limitations of recent studies, to further reduce the negative effects of aquaculture wastewater on global sustainability, the future directions of microalgae-assisted aquaculture for industrial applications were suggested.

Anaerobic digestion piggery effluent (ADPE), dark brown with high turbidity and ammonium, inhibits algal growth and requires pretreatment for cultivation. This study compared various physical/biological pretreatment methods for microalgae cultivation. The results showed that the strategy of 10%ADPE fungal cultivation (10%AF) pretreatment and subsequent microalgae cultivation achieved maximum specific growth rate (0.094 d⁻¹) with productivity (0.014 g L⁻¹ d⁻¹) and significant nutrient removal: 100% ammonium nitrogen, 99% total nitrogen, 63% total phosphorus, 91% chemical oxygen demand. However, the pathogenic fungus used poses safety risks, requiring future screening of eco-friendly alternatives. This study demonstrated that the strategy could be a promising approach to algal biomass production and nutrient removal from ADPE.