Antifungal effects of BiOBr nanosheets carrying surfactant cetyltrimethylammonium bromide.

BiOBr nanosheets are important photocatalytic nanomaterials. However, their biological effects remain to be explored. In this study, we investigated the antifungal effect of BiOBr nanosheets on Candida albicans. Strikingly, the nanosheets strongly inhibited the growth of C. albicans [IC50=(96±4.7) mg/L], hyphal development and biofilm formation. Compareed to the antifungal effect of the cationic surfactant cetyltrimethylammonium bromide, the inhibitory effect of the nanosheets on fungal pathogen was attributed to cetyltrimethylammonium bromide adsorbed by the nanosheets. Thermal gravity analysis and cetyltrimethylammonium bromide release experiment indicated that only 0.42% cetyltrimethylammonium bromide on BiOBr nanosheets was released. Taken together, this study uncovers the contribution of surfactant released from the nanosheets to their antifungal activity.

[Fast Start-up and Performance of the CANON Process Based on a SBAF Systemand Evolution Properties of Microorganisms].

The CANON process has the disadvantages of long start-up periods and unstable operation. In the SBAF system, under strictly controlled conditions of dissolved oxygen (DO) and temperature, a CANON process is started up in 51 days and is operated stably for 278 days using a new method of independent research and development. The results show that the maximum and average ARR are 98.9% and 95.1%, respectively. The maximum and average TNR are 85.9% and 75.1%, respectively. Furthermore, a small quantity of nitratenitrogen exists in this system. The microbial structure features of the sludge are analyzed by 16S rDNA macro high-throughput genome sequencing. It is verified that Proteobacteria is the main microorganism in the AOB, and Planctomycete Candidatus Brocadia is the main microorganism in the AnAOB. Both of them collaborate on total nitrogen removal in the CANON process.

[Fast Start-up of SBAF System Assisted CANON Process and the Microbial Analysis].

Long period start-up is one of the main restraining factors of the single-stage completely autotrophic nitrogen removal over nitrite (CANON) process.This study investigated the fast start-up of the CANON process initiated by a submerged biological aerated filter (SBAF) method.With conventional activated sludge from the secondary sedimentation tank of municipal waste water treatment plants as the seed sludge,the CANON process was successfully started up after the acclimation of sludge microorganisms for 48 days under the experimental conditions of (30±2)℃,organic carbon free and controlled dissolved oxygen (stage Ⅰ:0.3-0.5mg·L-1;stage Ⅱ-Ⅳ:0.1-0.2mg·L-1),with the maximum removal rates of ammonia nitrogen and total nitrogen achieved at 99.9% and 86.5%,respectively.The population structure characteristics of microorganisms in the system were studied using high-throughput sequencing of 16S rDNA amplicon.The results demonstrated that the two dominant microbial strains in the system were Proteobacteria and Planctomycetes,accounting for 26.6% and 17.8%,respectively.The major contributors of nitrogen removal were Nitrosomonas in ß-Proteobacteria and Candidatus brocadia in Brocadiae.Through the above experiments,it was revealed that the investigated SBAF based CANON possesses had the advantages of fast start-up,efficient biological nitrogen removal and stable operation process.

[Enhanced Treatment of Printing and Dyeing Wastewater Using H2O2-Biochemical Method].

The traditional biochemical treatment of printing and dyeing wastewater has limited efficiency. This study investigated whether H2O2 could strengthen the biological ability of the hydrolytic acidification/biological contact oxidation process (A/O), which effectively treats the printing and dyeing wastewater. After biofilm formation and the biochemical system startup and operation by H2O2, the system was successfully started and steadily operated when H2O2was added into reactor A with the H2O2 voluve fraction of 3 mL·L-1, doses of 100.0 mL, the flow velocity of 0.67 mL·min-1, and dosing frequency of once a day. The experimental results showed that the average removal efficiencies of COD, ammonia nitrogen, PVA, and color of printing and dyeing wastewater were 89.8%, 96.7%, 87.4%, and 92.1%, respectively. The microorganism community structures of reactor A and reactor O in this system were analyzed by high-throughput sequencing of 16S rDNA amplicon. The results demonstrated that the three dominant microbial strains in reactor A were Proteobacteria, Bacteroidetes, and Verrucomicrobia, and in reactor O were Planctomycetes, Proteobacteria, and Acidobacteria.