New concept in swine wastewater treatment: development of a self-sustaining synergetic microalgae-bacteria symbiosis (ABS) system to achieve environmental sustainability. Coelastrella sp.

Much attention has been paid to developing methods capable of synchronous removal of various complex pollutants from swine wastewater, due to the continually increasing number of negative environmental impacts associated with this wastewater type. However, most biological processes have been reported to perform badly in these systems. Due to the natural symbiotic interactions between microalgae and bacteria, the microalgae-bacteria symbiosis (ABS) system has been found to have potential for use treating swine wastewater. However, the corresponding biological mechanisms in the ABS system and the role of dynamic microbial community evolution in pollutant removal systems remain poorly understood impeding the practical applicability of the ABS system. Therefore, we here investigate the potential of an ABS system for pollutant removal applications and analyze the bacterial consortium symbiotically combined with two microalgal strains (Chlorella sp. MA1 and Coelastrella sp. KE4). The NH+ 4-N and PO3- 4-P removal efficiency were significantly increased to 99.52% and 96.06% in the ABS system due to biotic interactions between the microalgae and bacteria. During wastewater treatment, the abundance of bacterial taxa and genes related to oxidative stress, cell growth and nitrogen transfer were found to increase. Furthermore, pathogen inactivation was induced via microalgae, co-driven by microbial succession under high dissolved oxygen conditions. This study offers a promising microalgae-enhanced ABS system capable of highly-efficient swine wastewater treatment. The interactions between microalgae and bacteria are established for pathogen elimination and nitrogen cycling, verifying that the developed ABS system is an effective and environmentally sustainable swine wastewater treatment method.