A zero-waste approach to Sarcodia suiae valorization: Recycling aquaculture wastes and carbon dioxide for biostimulant, biofertilizer, and bioenergy production.

Aquaculture waste and carbon dioxide (CO2) are a global concern. Sarcodia suiae cultivated in outdoor photobioreactors (PBRs) using shrimp aquaculture wastewater and CO2 from biogas demonstrates significant benefits. It boosted biomass by 18.72 % with nearly 100 % removal of COD, inorganic nitrogen (N), phosphorus (P), and 41-89 % organic N and P removal from AWW. Sarcodia aqueous extracts were biostimulants for promoting mung bean and rice seedling growth, and Sarcodia remnants/shrimp pond bottom sludge generated a biogas yield of 457.07 L/kg-VS methane (CH4)/day. Biogas provides renewable energy for the system's needs. The solid residues after biogas fermentation serve as biofertilizers for enhancing rice yield by a 15 % increase up to 5.53 tons/ha/year. A Zero-Waste approach is successfully established using S. suiae as a model for recirculating aquaculture wastes to sequester 239.04 tons CO2/ha/year, capture N and sulfur (S), and produce renewable energy. and create biostimulants and biofertilizers.