Long-term operation of electroactive biofilms for enhanced ciprofloxacin removal capacity and anti-shock capabilities.

Few studies have focused on the feasibility of microbial fuel cells (MFCs) for removing quinolones antibiotics and their anti-shock capabilities. After 1.5 years of operation, the removal efficiency of 10 mg/L ciprofloxacin in MFCs increased to 99.00% in 88 h. These results are in accordance with the enhanced activity of biofilms and voltage output of MFCs. Additionally, the anti-shock capacities of the biofilms in MFCs were evaluated by treating ofloxacin and enrofloxacin and operating at different temperature and salinity. These MFCs can remove 87.31% and 40.81% of ofloxacin and enrofloxacin in 72 h, respectively. Even exposed to a low temperature of 10 °C or a salinity of 3%, the MFCs can achieve greater than 50% and nearly 80% of ciprofloxacin removal efficiency, respectively. The enrichment of Alcaligenes and Chryseobacterium contributed mostly to the removal of quinolones antibiotics. This study provides scientific evidences for treating wastewater containing quinolones antibiotics using MFCs.

Chemical characteristics of PM1/PM2.5 and influence on visual range at the summit of Mount Tai, North China.

Daytime and night-time PM1 and PM2.5 samples were simultaneously collected at the summit of Mount Tai during summer and autumn 2014. The mass concentrations and chemical compositions were analysed to determine the temporal variations of PM1 and PM2.5 and their contributions to visibility impairment. In summer, the average mass concentrations of PM1 and PM2.5 were 38.16µg/m3 and 53.33µg/m3, respectively. In autumn, the values were 42.75µg/m3 and 59.16µg/m3. Water-soluble inorganic ions were the most abundant species in both PM1 and PM2.5, followed by organic mass (OM). Among the major water-soluble ions, SO42- and NH4+ had higher concentrations in summer than in autumn, whereas the concentration of NO3- showed the opposite seasonal trend. Lower concentrations of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) were obtained in summer than in autumn. The water-soluble components (SO42-, NO3-, NH4+ and WSOC) showed a clear diurnal variation due to the specific meteorological conditions of Mount Tai. The water content in PM1 and PM2.5 was enhanced by the water-soluble components, especially NH4NO3. The decreased visibility resulted from the combined influence of particulate matter and relative humidity (RH). The threshold PM2.5 concentration corresponding to a visibility of <10km was 56.60µg/m3, which decreased with an increase in RH. A revised IMPROVE equation was applied to estimate the light-extinction coefficient bext, which was found to be lower for these chemicals in autumn (364Mm-1) than in summer (482Mm-1). (NH4)2SO4 made the largest contribution to bext in both summer and autumn, with an average rate of 56.97%. OM (17.32%) and NH4NO3 (15.13%) were also important contributors, with similar contribution rates. The contribution of NH4NO3 to bext was higher during summer, and OM contributions were higher during autumn.