Aerobic denitrification is a novel strategy for nitrogen removal in wastewater treatment. As an important functional component, extracellular polymeric substances (EPS) secreted by aerobic denitrifiers during the denitrification process are poorly understood. This paper presents the characteristics of EPS production by thermophilic bacterium Chelatococcus daeguensis TAD1 during aerobic denitrification in liquid cultures. Results indicated that strain TAD1 was capable of simultaneously accumulating EPS and reducing nitrate, with 245.1 mg g−1 EPS obtained after aerobic denitrification. Polysaccharide and protein were determined to be the major components of EPS. Further single factor experiments showed that the EPS production was significantly affected by the carbon source, C/N ratio and pH value, rather than the incubation temperature. Moreover, good positive correlation (R2 = 0.86) was observed between the EPS production and the nitrate removal efficiency, which implied that aerobic denitrification might prompt EPS production by strain TAD1.

Cr(VI) pollution is increasing continuously as a result of ongoing industrialization. In this study, we investigated the thermophilic denitrifying bacterium Chelatococcus daeguensis TAD1, isolated from the biofilm of a biotrickling filter used in nitrogen oxides (NOX) removal, with respect to its ability to remove Cr(VI) from an aqueous solution. TAD1 was capable of reducing Cr(VI) from an initial concentration of 10 mg/L to non-detectable levels over a pH range of 7–9 and at a temperature range of 30–50°C. TAD1 simultaneously removed both Cr(VI) and NO3−-N at 50°C, when the pH was 7 and the initial Cr(VI) concentration was 15 mg/L. The reduction of Cr(VI) to Cr(III) correlated with the growth metabolic activity of TAD1. The presence of other heavy metals (Cu, Zn, and Ni) inhibited the ability of TAD1 to remove Cr(VI). The metals each individually inhibited Cr(VI) removal, and the extent of inhibition increased in a cooperative manner in the presence of a combination of the metals. The addition of biodegradable cellulose acetate microspheres (an adsorption material) weakened the toxicity of the heavy metals; in their presence, the Cr(VI) removal efficiency returned to a high level. The feasibility and applicability of simultaneous nitrate removal and Cr(VI) reduction by strain TAD1 is promising, and may be an effective biological method for the clean-up of wastewater.

In3+-doped BiVO4 nanoparticles with enhanced visible light activity have been successfully synthesized by a hydrothermal method. The synthesized materials were characterized by X-ray diffraction, Raman, X-ray photoelectron spectroscopy, scanning electron microscopy, BET surface areas analysis, and ultraviolet–visible diffuse reflectance spectra. In comparison with pure BiVO4, the In3+-doped BiVO4 displayed greater photocatalytic activity in the degradation of methyl blue under visible light illumination. All samples possessed a single monoclinic structure. The introduction of In ions resulted in structural distortion and the decreased band gap energy, producing more electrons and holes for photocatalytic reaction. In the meantime, the doping In ions entails a red shift in the absorption edge and an increase in the intensity of light absorption. The best photocatalytic performance was obtained with the BiVO4 sample containing 5.0 mol% In ions.

SnO2/BiVO4 heterojunction composite photocatalysts with various mole ratios have been prepared via a simple hydrothermal method. The structure, composition and optical properties of the SnO2/BiVO4 composites were determined by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface analysis, X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). Photocatalytic activities of the composites were evaluated by studying the degradation of methylene blue (MB) solutions under simulated visible light irradiation (500 W halogen tungsten lamp). The 3:7 mol ratio SnO2/BiVO4 composite exhibited the highest photocatalytic performance, leading to 72% decompositon of MB within 120 min of irradiation.

Bio-based degradable plastic is superior to petroleum-based plastic in terms of environmental protection and preservation of resources. A novel cross-linking system using tributyl citrate (TBC) as a cross-linking agent was used to create a bio-based degradable plastic via acetylation modified starch acetate (SA) and cellulose acetate (CA). Fourier transform infrared spectroscopy of the new plastic films revealed that a cross-Claisen ester condensation reaction had indeed occurred among TBC, CA and SA in the cross-linking system. Thermogravimetric analysis, X-ray diffraction, Scanning electron microscopy and mechanical properties tests confirmed that the fabricated films had mechanical properties and thermal stability that were comparable to conventional plastic films. A degradation-in-soil test showed that the fabricated films have controllable biodegradation properties by adjusting the amount of SA added. The tensile stress of two films—one with mass ratio of SA to CA1:3 and the other with mass ratio of 2:3—reached 3.5 and 3.0 MPa, respectively, the corresponding tensile strains were 22.3 and 17.9 %. The highest thermal stability temperature for both films was 205 °C. After being buried in soil for 35 days, the first film was 36 % degraded, and the second film was 41 % degraded. This paper is expected to promote the study and fabricate of bio-based degradable plastic film.

The capacity and mechanism of Limnoperna fortunei to reduce the concentration of forchlorfenuron [or 1-(2-chloropyridin-4-yl)-3-phenylurea (CPPU)] in water has been studied under laboratory conditions. Firstly, the evasive response of mussels to CPPU (10, 20, 40 and 60 mg L−1) was evaluated, and a toxicity test was carried out at these concentrations. Secondly, the effect of two different sizes of mussels on CPPU concentrations was investigated in a 24-day experiment. Thirdly, the role of intact mussels and valvae only were respectively evaluated in another 24-day experiment. The CPPU concentration decreased by about 40 % in the presence of large mussels and about 20 % in the presence of valvae only. Finally, nucleic acid extracts from the gut and biofilm microbial communities of L. fortunei were analyzed, and the number of copies of the bacterial genes amoA, nirK and nirS were determined. Based on these results, we propose possible mechanisms for CPPU degradation involving bacteria-associated nitrification and denitrification reactions. In summary, we found that the CPPU half-life depended on the presence of mussels, their size and their associated microorganisms.

In spite of numerous advantages on operating fermentation at elevated temperatures, very few thermophilic bacteria with polyhydroxyalkanoates (PHAs)-accumulating ability have yet been found in contrast to the tremendous mesophiles with the same ability. In this study, a thermophilic poly(3-hydroxybutyrate) (PHB)-accumulating bacteria (Chelatococcus daeguensis TAD1), isolated from the biofilm of a biotrickling filter used for NOx removal, was extensively investigated and compared to other PHB-accumulating bacteria. The results demonstrate that C. daeguensis TAD1 is a growth-associated PHB-accumulating bacterium without obvious nutrient limitation, which was capable of accumulating PHB up to 83.6 % of cell dry weight (CDW, w/w) within just 24 h at 45 °C from glucose. Surprisingly, the PHB production of C. daeguensis TAD1 exhibited strong tolerance to high heat stress as well as nitrogen loads compared to that of other PHB-accumulating bacterium, while the optimal PHB amount (3.44 ± 0.3 g l−1) occurred at 50 °C and C/N = 30 (molar) with glucose as the sole carbon source. In addition, C. daeguensis TAD1 could effectively utilize various cheap substrates (starch or glycerol) for PHB production without pre-hydrolyzed, particularly the glycerol, exhibiting the highest product yield (YP/S, 0.26 g PHB per gram substrate used) as well as PHB content (80.4 % of CDW, w/w) compared to other carbon sources. Consequently, C. daeguensis TAD1 is a viable candidate for large-scale production of PHB via utilizing starch or glycerol as the raw materials.

A new fluorescent Zn2+ chemosensor (3) based on functionalized 8-hydroxylquinoline has been synthesized and characterized. Compound 3 shows weak fluorescence in CH3CN–HEPES buffer solution (50 mM, pH 7.2 v/v = 1:9), but the fluorescence is significantly enhanced upon binding to Zn2+ through a zinc(II)-catalyzed ester hydrolysis reaction to form a highly emissive zinc(II) complex. This suggests that 3 can be served as a typical “switch–on” chemosensor with high selectivity for Zn2+ over other metal ions.A new Zn2+ responsive chemosensor based on functionalized 8-hydroxylquinoline shows significantly fluorescent “switch–on” properties with high selectivity for Zn2+ over other metal ions.

A bio-trickling filter (BTF) packed with polyhedral spheres was used to remove nitrogen oxides (NOx) from the flue gas of a coal-fired power plant. The BTF system consistently removed 64–95% of the NOx after start-up and acclimation under dynamic conditions (e.g., 120–240 m3/h flue gas flow rate and inlet 300–900 mg NOx/m3). Scanning electron microscopy of the biofilms that were formed showed a shift in the predominating bacteria. Analyses by PCR-denaturing gradient gel electrophoresis showed that the naturally-selected mixed cultures in the biofilm under a flue gas environment were mainly Klebsiella sp. and Pseudomonas sp.