Transitioning Toward a Circular Economy in Super-Intensive Shrimp Aquaculture: A Comprehensive Review of Resource Recovery From Wastewater and Waste Sludge

Abstract

Super-intensive shrimp farming activities in the Mekong Delta of Vietnam generate substantial waste loads that threaten coastal environments. This review paper systemizes eco-circular technologies aiming toward zero-discharge and resource recovery from aquaculture wastewater and sludge, drawing from reputable domestic and international scientific publications. For wastewater treatment and recirculation, consolidated data indicate that integrating biological settling ponds optimized for hydraulic retention time ~13.4 days, Biofloc technology, ultrafiltration membrane systems, and constructed wetlands efficiently removes 76–94% of organic and nutrient pollutants, cutting effluent discharge from 1,000 m3/day down to 33 m3/day. For waste sludge recovery, compiled empirical studies demonstrate that anaerobic co-digestion of shrimp sludge with sugarcane bagasse boosts methane yields by up to 53% at an optimal mixing frequency of 1 time/day. Additionally, aerobic co-composting of shrimp sludge with coconut coir pith (at a 7 : 3 ratio) inoculated with an EM consortium over 65 days produces a mature organic fertilizer with an ideal C/N ratio (~19.7), which strongly supports Lactuca sativa growth, though the residual electrical conductivity (EC ~12 mS/cm) requires careful monitoring. Systematized LCA and LCC analyses confirm the outstanding ecological sustainability and economic efficiency of this closed-loop configuration, yielding a net residual value of 32.22 VND/m3 of recirculated water and 786.67 VND/kg of compost. Ultimately, linking smallholders through agricultural cooperative models is the key strategic recommendation to overcome capital expenditure and land availability barriers.