Abstract: A process utilizing enhanced photosynthesis and photocatalysis to purify water and/or utilize CO2 on a large scale by growing biomass in reduced time and space in a closed, continuous-flow system. Added CO2 and balanced nutrients combine with light to increase the growth rate of autotrophic microalgae which require CO2 for growth and produce oxygen. Organic and inorganic compounds and chemical toxins are mineralized in photocatalysis using such produced oxygen, which are then absorbed (metabolized) in the microalgal biomass that is harvested.