Ultraviolet-B radiation of Haematococcus pluvialis for enhanced biological contact oxidation pretreatment of black odorous water in the symbiotic system of algae and bacteria

Abstract

Black odorous water contains abundant organics and nutrients, such as nitrogen and phosphorus, which would lead to eutrophication of the water body and affect the water environment. In this study, the eutrophic water body in the campus landscape was taken as the research object, and the biological contact oxidation (BCO) method and co-cultivated indigenous microorganisms were adopted to pretreat black odorous water. Inoculating mutant strain M1 through ultraviolet-B radiation formed algae-bacteria symbiosis system in optimal effluent. The results showed that under the conditions of dissolved oxygen (DO) concentration of 5 mg/L, light intensity of 3000 Lx and inoculum size of 125,000 cells/mL, the optimal organic migration effect was achieved by the combined process. In addition, the ability of H. pluvialis to transform from green vegetative cells to red cyst cells under stressful conditions (strong light, nitrogen starvation, etc.) made it as an indicator for monitoring the degradation status of pollutants in black odorous water.