• Energy Research

To assess the inherent effects of light-dark cycle on the aniline degradation and nitrogen removal in algal-bacterial symbiotic system, three groups with different photoperiods (0L:12D;6L:6D;12L:0D) were set up. The results revealed that the aniline degradation rate of the three systems all surpassed 99 %, the total nitrogen removal rate of Z2-6L:6D was approximately 36 % higher than Z1-0L:12D eventually, the Z1-0L:12D was restrained by NH4+-N assimilation and nitrification while anoxic denitrification in Z3-12L:0D. The disappearance of microalgae biomass was accompanied by the sharp decreased of polysaccharide in Z1 and longer illumination suppressed the secretion of extracellular polymeric substances, the Z3 yielded slightly superior biomass production despite the double illumination compared with Z2. Moreover, high throughput sequencing analysis illustrated that the microbial community structure in Z2 was more abundant and even than Z3, the TM7a, norank_f__norank_o__Saccharimonadales, Ellin6067 and Scenedesmus proliferated wildly and the photoinhibition to functional genus was effectively alleviated in Z2.

In this work, a KMnO4-modified-biochar-based composite material with manganese oxide produced at 600 °C was fabricated to investigate the sorption mechanism of Cd(II) and to comprehensively evaluate the effect of the modification on biochar properties. Cd(II) adsorption mechanisms were mainly controlled by interaction with minerals, complexation with oxygen-containing functional groups, and cation-π interaction. The sorption capacity was significantly reduced after a deash treatment of biochar, almost shrunk by 3 and 3.5 times for pristine biochar (PBC) and modified biochar (MBC). For deashed PBC, oxygen-containing functional groups were the main contributor toward Cd(II) adsorption while interaction with minerals was significantly compromised and became negligible. The sorption capacity was also apparently decreased after the deash treatment of MBC; however, for deashed MBC, interaction with minerals still was the main contributor to the sorption ability, which could be attributed to the mechanism of interaction of Cd(II) with loaded MnOx on biochar. Cation-π interaction in MBC was notably enhanced compared to PBC due to the oxidation of KMnO4 on biomass. Also, sorption performance by oxygen-containing functional groups was also enhanced. Hence, the modification by KMnO4 has a significant effect on the Cd(II) sorption performance of biochar.