Rapid and Sustainable Conversion of Phenol to Microalgae Biomass

Rapid and continuous degradation of toxic organic pollutants and conversion to microalgae biomass are attracting enormous interest for resource recovery and wastewater treatment. Aiming toward this goal, we develop and demonstrate a novel photocatalytic-biological system in which photocatalytic optical hollow fibers coated with the N-doped TiO2 photocatalyst and a Scenedesmus obliquus biofilm cooperatively convert phenol to microalgae biomass. The photocatalytic optical hollow fibers exhibit high UV–visible photocatalytic activity to rapidly degrade phenol and emit visible light for biofilm growth, lipid synthesis, and O2 production. O2 produced as an electron acceptor is transferred to the surface of the photocatalytic optical hollow fibers, limiting electron–hole recombination and generating reactive oxygen species such as •OH and •O2–. Upregulation of nicotinamide adenine dinucleotide + hydrogen and adenosine triphosphate and enrichment of Rhodococcus and Pseudomonas in the biofilm enhance the resistance to phenol toxicity, maintain rapid and stable biofilm growth, and increase lipid content. This photocatalytic-biological system rapidly and sustainably converts phenol to microalgae biomass.