Effect of propionate-cultured sludge augmentation on methane production from upflow anaerobic sludge blanket systems treating fresh landfill leachate.

This research investigates the effect of propionate-cultured sludge augmentation on methane (CH4) production from upflow anaerobic sludge blanket systems (UASB) treating fresh landfill leachate. In the study, both UASB reactors (UASB 1 and UASB 2) contained acclimatized seed sludge, and UASB 2 was augmented with propionate-cultured sludge. The organic loading rate (OLR) was varied between 120.6, 84.4, 48.2, and 12.0 gCOD/L·d. The experimental results indicated that the optimal OLR of UASB 1 (non-augmentation) was 48.2 gCOD/L·d, achieving the CH4 production of 4019 mL/d. Meanwhile, the optimal OLR of UASB 2 was 12.0 gCOD/L·d, achieving the CH4 yield of 6299 mL/d. The dominant bacterial community in the propionate-cultured sludge included the genera Methanothrix, Methanosaeta, Methanoculleus, Syntrophobacter, Smithella, Pelotomamulum, which are the VFA-degrading bacteria and methanogens responsible for unblocking the CH4 pathway bottleneck. Essentially, the novelty of this research lies in the use of propionate-cultured sludge to augment the UASB reactor in order to enhance CH4 production from fresh landfill leachate.

Near-infrared aza-BODIPY fluorescent probe for selective Cu2+ detection and its potential in living cell imaging.

A near-infrared (NIR) fluorescent sensor 1 composed of an aza-boron-dipyrromethene (aza-BODIPY) core covalently bound to two di-2-picolylamine moieties was conceived for Cu2+ detection in aqueous solutions. Spectroscopic properties and binding abilities with several metal ions were investigated in phosphate buffered saline (pH 7.4): acetonitrile (95 : 5 v/v) with Triton X-100 via fluorometric titrations. The fluorescence of sensor 1 was quenched selectively by cupric ions in the presence of alkali- and transition-metal-ions. A detection limit of 13 ppb was measured for this system, and this is significantly lower than permissible levels of Cu2+ in drinking water according to the guidelines described by the U.S. Environmental Protection Agency (EPA) and by the World Health Organization (WHO). Application of the sensor in detecting Cu2+ in HepG2 cells was demonstrated.