Enhancement of black and odorous water treatment coupled with accelerated lipid production by microalgae exposed to 12C6+ heavy-ion beam irradiation

In this study, Auxenochlorella protothecoides (AP-CK) was selected due to its reported high growth potential in sterilized black and odorous water (SBOW). In order to improve the resource utilization level of microalgae for wastewater treatment, AP-CK was mutated using C-12(6+) heavy-ion beam irradiation, and a high lipid-containing mutant (AP-34#) was isolated and further evaluated to treat original black and odorous water (OBOW). Compared with the wild type, the maximum removal rates of COD, NH4+-N and TP of the mutant increased by 8.12 +/- 0.33%, 10.43 +/- 0.54% and 11.97 +/- 0.16%, respectively, while maximum dissolved oxygen content increased from 0 to 4.36 +/- 0.25 mg/L. Besides, the mutant lipid yield increased by 115.87 +/- 3.22% over the wild type in OBOW. The fatty acid profile of AP-34# grown in SBOW and OBOW showed higher proportion of saturated fatty acids (C16:0 and C18:0) and valuable polyunsaturated fatty acids (mainly C20:5n3 and C22:6n3) which are more suitable for biodiesel production and value-added products, respectively. This work provides a new perspective on improving the characteristics of microalgae and an innovative approach for resource-based microalgae wastewater treatment through bioremediation of black and odorous water.

Automated summary

In this study, a high lipid-containing mutant (AP-34#) of Auxenochlorella protothecoides (AP-CK) was successfully isolated and evaluated for treating original black and odorous water (OBOW). The mutant exhibited higher removal rates of COD, NH4+-N, and TP compared to the wild type, along with an increase in maximum dissolved oxygen content. Furthermore, the mutant showed a significantly increased lipid yield in OBOW, containing a higher proportion of fatty acids suitable for biodiesel production and value-added products.