Organic degrading bacteria and nitrifying bacteria stimulate the nutrient removal and biomass accumulation in microalgae-based system from piggery digestate

• Published in: The Science of the total environment 2020-03, Vol.707, p.134442-134442, Article 134442
• Main Authors: Wang, Min, Zhang, Shu-Chi, Tang, Qin, Shi, Ling-Dong, Tao, Xing-Ming, Tian, Guang-Ming
• Format: Article
• Language: English
• Subjects: Bacteria; Biomass; Biomass accumulation; Commercial bacterial agent; Microalgae; Microalgae-based system; Microbial community; Nitrogen; Nutrient removal; Phosphorus; Waste Water
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.134442

[Display omitted] •Raw piggery digestate was used for Desmodesmus sp. CHX1 cultivation.•Inoculation with nitrifying bacteria showed better performance.•Microalgae aggregating bacteria dominated in the optimized systems. The microalgae-based system has been applied in anaerobic digestate treatment for nutrient removal and biomass production. To optimize its performance in treating piggery digestate, here, commercial bacterial agents, including organic degrading bacteria (Cb) and nitrifying bacteria (Nb), were inoculated into the microalgae-based system dominated by Desmodesmus sp. CHX1 (D). Reactor DN (inoculated with D and Nb) and DCN (inoculated with D, and Cb to Nb at a ratio of 1:2) have better performance on NH4+-N removal, with a final efficiency at 40.26% and 39.87%, respectively, and no NO3−-N or NO2−-N accumulations. The final total chlorophyll concentration, an indicator of microalgal growth, reached 4.74 and 5.47 mg/L in DN and DCN, respectively, three times more than that in D. These results suggested that high NH4+-N removal was achieved by the assimilation into high microalgal biomass after the inoculation with functional bacteria. High-throughput sequencing showed that the richness of microbial community decreased but the evenness increased by inoculating functional microorganisms. Microalgae aggregating bacteria were Cellvibrio, Sphingobacterium, Flavobacterium, Comamonas, Microbacterium, Dyadobacter, and Paenibacillus. This study revealed that the inoculation with functional bacteria reconstructed the microbial community which benefited for the microalgal growth and nutrient removal, providing a promising strategy for treating highly-concentrated digestate.