Using algae bacteria consortia to effectively treat coking wastewater: Performance, microbial community, and mechanism

Coking wastewater is widely generated and poses a significant threat to the environment. Adopting algae bacteria consortia is promising and viable for coking wastewater treatment. In this study, the performance of activated sludge, non-aerated and aerated algae-bacteria consortia (ABC) for treating coking wastewater was investigated and compared. Aerated ABC showed maximum 87.16 ± 1.12% COD removal rates while non-aerated ABC could remove 78.62 ± 0.56% COD. TIN removal rates of aerated ABC and non-aerated ABC were 72.50 ± 0.78% and 80.99 ± 1.26%, respectively. Algae addition could increase the removal performance due to the material exchange between algae and bacteria. Aerated ABC had a larger particle size (119–225 μm) and good settling performance. Genus Comamonas, nitrogen removal bacteria, was predominant in two ABC reactors (average 62% and 60%, respectively) treating low coking wastewater. By comparison, genus Planococcus, denitrifying bacteria, became predominant in aerated algae-bacteria with a higher concentration of coking wastewater. Both genus Comamonas and Planococcus were detected with the benzene ring cleavage reaction function genes. The nitrogen removal pathway showed that nitrogen was removed by ammonia detoxification and nitrate dissimilation. The findings of this study would contribute to the application of ABC in coking wastewater treatment with reduce aeration energy input.