Efficacy and Mechanism of Carbon Source Chlorella sorokiniana Enhanced Constructed Wetland for Treating Piggery Biogas Slurry.

In response to the problems of insufficient denitrification and poor denitrification effect of traditional constructed wetlands for the treatment of livestock biogas slurry, in this study Chlorella sorokiniana was used as an additional carbon source for the construction of C. sorokiniana - constructed wetland systems to treat piggery biogas slurry. The effect of the system on the removal of water quality of piggery biogas slurry and the change rule of the dissolved organic matters (DOMs) through the addition of C. sorokiniana under different concentrations (0, 0.25, 0.5 and 1.0 g/L) were investigated, and the mechanism of en- hanced nitrogen removal was explored from the perspective of microorganisms. The results showed that compared with the constructed wetland without the addition of C. sorokiniana, the removal of total nitrogen was obviously increased up to 70.24%, and the removal of nitrate nitrogen reached up to 93.45%. Based on the three-dimensional fluorescence parallel factor analysis, the three components in DOMs were fulvic acid/humic acid-like substances, polymer aromatic substances and humic acid-like substances, while the addition of C. sorokiniana enhanced the removal of DOMs from piggery biogas slurry and reduced the content of humic acid-like substances. The addition of C. sorokiniana evidently increased the Alpha diversity of microorganisms in the constructed wetland. Particularly, at the phylum level the relative abundance of dominant bacteria related to denitrification (Proteobacteria) increased obviously, while at the genus level the genera Nitrosomonas and Limnobacter played important roles in the ammonia oxidation and denitrification processes of the system. This study provides theoretical support for the use of C. sorokiniana as an additional carbon source to enhance nitrogen and phosphorus removal in constructed wetlands. [ABSTRACT FROM AUTHOR]