Treatment of Aquaculture Wastewater by Utilizing Single and Symbiotic Systems of Microalgae‐Based Technology and Strigolactone Induction

This study investigated the efficacy of two microalgae treatment systems (Chlorella vulgaris monoculture and a Chlorella vulgaris-S395-2-Clonostachys rosea symbiotic system) in treating aquaculture wastewater, under varying concentrations of synthetic strigolactone analog (GR24). By exposing the systems to four GR24 doses (0, 10^-11, 10^-9, and 10^-7 M), we examined the impact on biomass growth, photosynthesis, and wastewater treatment. Elevated GR24 concentrations bolstered metabolism and photosynthesis in the systems, fostering rapid symbiont growth and enhanced treatment efficiency. Notably, the coculture system outperformed the monoculture in terms of photosynthetic rate, daily biomass accumulation, and nutrient reduction in aquaculture wastewater (p < 0.05). Optimally, at 10^-9 M GR24, the symbiotic system achieved remarkable average removal rates of COD (78.54 ± 6.11%), TN (81.69 ± 7.02%), and TP (82.67 ± 7.58%) from aquaculture wastewater. Additionally, a comparative analysis revealed the system's exceptional capacity to reduce oxytetracycline hydrochloride (OTC) levels, achieving a notable 98.72% removal rate. The outcomes significantly advance bioenhancement approaches and inform the design of efficient algal-bacterial-fungal symbiotic processes for treating antibiotic-contaminated wastewater.