Work

Two-stage continuous cultivation of microalgae overexpressing cytochrome P450 improves nitrogen and antibiotics removal from livestock and poultry wastewater

Year: 2024

Type: article

Abstract: • Implemented a continuous LPWW treatment process using a two-stage CSTR system. • Continuous feedback process reduced HRT to 4 days and NH 4 -N to ∼30 mg/L. • Application of synthetic biology improved NH 4 -N removal rate to 470 mg/L/d. • Clarified mechanisms for nitrogen and antibiotics removal from LPWW by microalgae. • C. vulgaris P450 A23292 plays essential role in nitrogen and antibiotics removal. Improper treatment of livestock and poultry wastewater (LPWW) rich in ammonium nitrogen (NH 4 -N) and antibiotics leads to eutrophication, and contributes to the risk of creating drug-resistant pathogens. The design-build-test-learn strategy was used to engineer a continuous process using Chlorella vulgaris to remove NH 4 -N and antibiotics. The optimized system removed NH 4 -N at a rate of 306 mg/L/d, degraded 99 % of lincomycin, and reduced the hydraulic retention time to 4 days. The physiological, metabolic, and genetic mechanisms used by microalgae to tolerate LPWW, remove NH 4 -N, and degrade antibiotics were elucidated. A new cytochrome P450 enzyme important for NH 4 -N and antibiotic removal was identified. Finally, application of synthetic biology improved the NH 4 -N removal rate to 470 mg/L/d, which is the highest removal rate using microalgae reported to date. This research contributes to the mechanistic understanding of wastewater detoxification by microalgae, and the goal of achieving a circular bioeconomy for nutrient and water recycling.

Source: Bioresource Technology

DOI: 10.1016/j.biortech.2024.131994

Authors: Rui Xiao, Chang Tian, Haijun Wang, Hui Zhang, Huan Chen, Howard H. Chou