Nutrient recovery from ethanol co-products by a novel mycoalgae biofilm: attached cultures of symbiotic fungi and algae

BACKGROUND: Fungal and algae treatment of food-industry waste opens a new avenue for valorizing waste to valuable products through the production of desirable cell biomass. A novel mycoalgae biofilm (symbiotic growth of algae and fungi) was developed in ethanol co-products, the profuse remains from the ethanol distillation process. RESULTS: The mycoalgae biofilm flasks produced more biomass compared with pure fungal cultures under all the conditions tested. The total microbial biomass concentration in mycoalgae biofilm increased from 5.998 g L⁻¹ at 4 d (98.81% fungal biomass and 1.19% algae biomass) to 9.358 g L⁻¹ at 12 d (97.2% fungal biomass and 2.8% algae biomass) with a drop in attached residual solids from 6.304 g L⁻¹ at 4 d to 3.349 g L⁻¹ at 12 d in 10× condensed distillers solubles medium. The high nutrient concentration of P (818 mg L⁻¹) and N (924 mg L⁻¹) in the samples was recovered in the attached mycoalgae biomass at 55.7% and 74%, respectively, with a reduction in COD of up to 65.6%. CONCLUSION: The results show that ethanol co-products support excellent mycoalgae biofilm growth. The nutrients in ethanol co-products can be efficiently recovered and recycled for agricultural applications and better nutrient management.