Efficient bioremediation of distillery and dairy wastewaters: A three-stage biorefinery for high-quality aquaculture feed and bioenergy generation

Abstract

The present study is motivated by the need to address the environmental issues related to dairy and ethanol plant wastewaters and to generate valuable products, including mycoprotein and bioenergy, through a novel three-phase fungi-based biorefinery. In the initial phase of the biorefining process, the cultivation conditions of Aspergillus oryzae were optimized. The objective was to maximize mycoprotein production using wastewater as a resource. The effluent generated during the first phase of the biorefinery underwent the second phase, where it was subjected to cultivation with Neurospora intermedia. In the third phase, the effluent obtained from the fungal growth underwent anaerobic digestion as a final treatment step, producing 306 NmL methane/g VS. This three-phase biorefinery contributed to a remarkable reduction in the chemical oxygen demand level of the wastewater by 56.8%, 11.6%, and 28.1% in each respective phase. Overall, the three-phase biorefinery process yielded promising results, generating 17.8 kg of mycoprotein and 5.0 Nm3 of biomethane per cubic meter of wastewater. The mycoprotein obtained through this process contains noteworthy quantities of essential amino acids, fatty acids, and minerals. These characteristics open up opportunities for substituting conventional feed in aquaculture with the produced mycoprotein.