Bin Guo

Comparison of the removal of ethanethiol in twin-biotrickling filters inoculated with strain RG-1 and B350 mixed microorganisms

This study aims to compare the biological degradation performance of ethanethiol using strain RG-1 and B350 commercial mixed microorganisms, which were inoculated and immobilized on ceramic particles in twin-biotrickling filter columns. The parameters affecting the removal efficiency, such as empty bed residence time (EBRT) and inlet concentration, were investigated in detail. When EBRT ranged from 332 to 66 s at a fixed inlet concentration of 1.05 mg L(-1), the total removal efficiencies for RG-1 and B350 both decreased from 100% to 70.90% and 47.20%, respectively. The maximum elimination capacities for RG-1 and B350 were 38.36 (removal efficiency=89.20%) and 25.82 g m(-3) h(-1) (removal efficiency=57.10%), respectively, at an EBRT of 83 s. The variation of the inlet concentration at a fixed EBRT of 110 s did not change the removal efficiencies which remained at 100% for RG-1 and B350 at concentrations of less than 1.05 and 0.64 mg L(-1), respectively. The maximum elimination capacities were 39.93 (removal efficiency=60.30%) and 30.34 g m(-3) h(-1) (removal efficiency=46.20%) for RG-1 and B350, respectively, at an inlet concentration of 2.03 mg L(-1). Sulfate was the main metabolic product of sulfur in ethanethiol. Based the results, strain RG-1 would be a better choice than strain B350 for the biodegradation of ethanethiol.

Efficient capture of SO2 by a binary mixture of caprolactam tetrabutyl ammonium bromide ionic liquid and water.

The solubility of SO(2) in a binary mixture of water and caprolactam tetrabutyl ammonium bromide ionic liquid (CPL-TBAB IL) was investigated. Though the ionic liquid and water were fully miscible, a phase separation occurred when SO(2) was introduced into the mixture. The SO(2) concentrated in the lower layer, and it could be released by heating the solution under reduced pressure (382.2K, 10.1 kPa). After desorption, the mixture could be reused to absorb SO(2). It was found that SO(2) acts as a switch to cause the water and CPL-TBAB IL to phase separate, and the mechanics of this phase separation process was studied by gas chromatography-mass spectrometry, fourier transform-infrared spectroscopy and Karl-Fisher titration. The absorption and desorption of SO(2) in the CPL-TBAB/water mixtures were reversible.

Co-treatment of single, binary and ternary mixture gas of ethanethiol, dimethyl disulfide and thioanisole in a biotrickling filter seeded with Lysinibacillus sphaericus RG-1.

The work reports the aerobic co-treatment characteristics of single, binary and ternary mixture gas of ethanethiol, dimethyl disulfide (DMDS) and thioanisole in a biotrickling filter seeded with Lysinibacillus sphaericus RG-1. 100% removal efficiency (RE) was achieved for sole ethanethiol, DMDS and thioanisole at inlet concentration below 1.05, 0.81 and 0.33 mg/L, respectively, at empty bed resident time 110 s. In addition, 100% RE was also obtained with binary ethanethiol and DMDS (1:1) and ternary ethanethiol, DMDS and thioanisole (3:2:1). Michaelis-Menten equation was modified to incorporate the plug flow behavior of the bioreactor. The maximum removal rate (V(max)) was calculated as 56.18, 57.14 and 22.78 g/m(3)/h for sole ethanethiol, DMDS and thioanisole, respectively, while the V(max) was 41.84 and 14.56 g/m(3)/h for DMDS and thioanisole in binary and ternary systems, respectively. Overall, these suggest that not only sole but also binary and ternary mixture can be efficiently removed in this system.

Characteristics of penicillin bacterial residue.

Implications: During the production of penicillin, a mass of waste bacterial residue is generated. In the past, the bacterial residues have been used for food additives. Unfortunately, doubts of their suitability as a feedstock have been raised because of the small amount of antibiotics and the degradation products remaining in the bacterial residues. So, penicillin bacterial residue is one of the hazardous wastes. Therefore, penicillin bacterial residue should be managed in accordance with the hazardous waste. To get a right method, the penicillin bacterial residue was characterized.

Absorption of NO and NO2 in Caprolactam Tetrabutyl Ammonium Halide Ionic Liquids

ABSTRACT To explore environmentally benign solvents for the absorption of NO and NO2, a series of caprolactam tetrabutyl ammonium halide ionic liquids were synthesized. The solubility of NO and NO2 was measured at temperatures ranging from 298.2 to 363.2 K and atmospheric pressure, and the following trend in the solubility of NO and NO2 in ionic liquids with various halide anions was observed, respectively: F > Br > Cl and Br > Cl > F. Moreover, as the temperature increased from 308.15 to 363.15 K and the mole ratio of caprolactam increased from 2:1 to 6:1, the solubility of NO increased. Alternatively, the solubility of NO2 decreased as the temperature increased from 298.15 to 363.15 K, and the mole ratio of caprolactam increased from 2:1 to 6:1. The absorption and desorption of NO and NO2 was practically reversible in the ionic liquids, which was characterized by nuclear magnetic resonance. The method, which is at least partially reversible, offers interesting possibilities for the removal of NO and NO2. IMPLICATIONS Basic ionic liquids with amino groups were synthesized and used to capture CO2, SO2, and H2S, and to promote hydrogenation of CO2. In this paper, the authors used caprolactam tetrabutyl ammonium halide ionic liquid (IL) as absorbing medium in which NOx could be absorbed. NOx desorbed from the absorbent could be efficiently reduced by right catalysts at high temperature. The absorbed NO and NO2 gas could be desorbed at higher temperature, allowing the ionic liquids to be reused several times without loss of capability. It was believed that caprolactam tetrabutyl ammonium bromide (CPL-TBAB) ILs may be useful for NOx removal reagent for pollution control.

Preparation, characterization, and phenol adsorption of activated carbons from oxytetracycline bacterial residue

The oxytetracycline bacterial residue–activated carbon (OBR-AC) prepared from oxytetracycline bacterial residue with K2CO3 under chemical activation was studied. The effects of activation temperature, activation time, and activation ratio on the specific surface area (SSA) and methylene blue adsorption (MBA) were studied. Characterization of the optimum OBR-AC was performed by using scanning electron microscopy (SEM), pore structure (PS,) and Fourier-transform infrared spectroscopy (FT-IR). The optimum parameters were as follows: 800°C activation temperature, 3 hr activation time, and 1:3 activation ratio. The SSA and MBA under optimum conditions were 1593.09 m2/g and 117.0 mg/g, respectively. Adsorption equilibrium and kinetics data were determined for the adsorption of phenol from the synthetically prepared phenol solution. The results showed that the Langmuir model gave the best fit for equilibrium isotherm, whereas the kinetics data were well fitted by the pseudo-second order model. Implications In the past, the bacterial residues have been used for feed additives in China. Unfortunately, doubts of its suitability as a feedstock have been raised because of the small amount of antibiotics, a large number of the fermentation by-products and metabolic products and by-products remaining in the bacterial residues. So Oxytetracycline Bacterial Residue (OBR) is one of hazardous wastes in China. In order to solve the problem of OBR, the preparation of OBR-AC is studied, and OBR-AC under optimum operation parameters is characterized by Scanning Eldctron Microscopy (SEM), Pore Structure (PS) and Fourier Transfer-Infra Red (FT-IR). Moreover, the phenol adsorption isotherms and kinetics models for OBR-AC under optimum operation parameters are studied.

Adsorption and oxidation of SO2 in a fixed-bed reactor using activated carbon produced from oxytetracycline bacterial residue and impregnated with copper

The SO2 removal ability (including adsorption and oxidation ability) of activated carbon produced from oxytetracycline bacterial residue and impregnated with copper was investigated. The activated carbon produced from oxytetracycline bacterial residue and modified with copper was characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The effects of the catalysts, SO2 concentration, weight hourly space velocity, and temperature on the SO2 adsorption and oxidation activity were evaluated. Activated carbon produced from oxytetracycline bacterial residue and used as catalyst supports for copper oxide catalysts provided high catalytic activity for the adsorbing and oxidizing of SO2 from flue gases. Implications: To improve the SO2 removal efficiency and reduce costs, the pretreatment of activated carbon or activated carbon-based materials has been widely studied. Oxytetracycline bacterial residue is currently a hazardous waste, which has been investigated in terms of an adduct to active carbon (OBR-AC). Unfortunately, the application of OBR-AC was limited due to the absence of several metals in it, such as Fe and K. The OBR-AC was loaded with copper by immersion method to prepared Cu/OBR-AC, which was used to absorb and oxidize SO2. Cu/OBR-AC exhibited significantly greater catalytic activity than OBR-AC.

Viscosity of Methylbenzene in [Bmim][BF4] and [Bmim][PF6] Ionic Liquids

To well know the properties of ionic liquid mixtures, the viscosity of the binary mixtures containing the methylbenzene and imidazole ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4] or 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF6]) were measured. Within the temperature range from 298.15 K to 308.15 K, the viscosity of the four binary systems decreased sharply as the increase of temperature. The viscosity decreased slowly in the temperature range from 308.15 K to 338.15 K. The viscosity also decreased with decreasing of the mole fraction of ionic liquid. The viscosity of methylbenzene in the imidazole ionic liquids was in sequence: [Bmim][BF4] < [Bmim][PF6]. The experimental viscosity values had been correlated using the binary parameters of Vogel-Fulcher-Tamman equation.

Styrene Removal from Polluted Air in Biotrickling Filter with Pyrocarbon-Sawdust and Ceramic-Raschig-Rings-Sawdust Packings

In this paper, a mixed microbial population biotrickling filter (BTF) was investigated for styrene removal with two different packings at different empty bed residence times and gas-liquid ratio(GLR). The two biotrickling filters inoculated with a Pyrocarbon-sawdust and ceramic-raschig-rings-sawdust mixed packings were filled respectively in two identical laboratory-scale biotrickling filters which were operated in parallel. The results showed that the BTF filling with pyrocarbon-sawdust packings had higher rate of bio-film formation and removal efficiency of styrene than that of ceramic-raschig-rings-sawdust packings. When an inlet gas concentration of 50 to 450 mg/m³, an Empty Bed Residence Time (EBRT) of 21.6 to 43.2 s, and a gas-liquid ratio (GLR) of 110.7 to 55.3, a maximum styrene removal load is up to 153.1 g/(m³·h). During shock-load experiments with shutdown, the styrene removal efficiency of the BTF could gradually reach 92 % to 100 % by 14 h.

Pollution Level and Assessment of Chromium in Agricultural Soil around Chromate Plant

Based on the environmental standard and environmental quality risk assessment criteria for soil of China, the pollution level and assessment of chromium in agricultural soil samples around chromate plant were analyzed. The 176 agricultural soil samples were collected according to radial distribution method near chromium slag disposal site and a radius of 150m in 11 areas at 10cm interval from the surface layer to the underground 150cm vertically on each monitoring point. The results showed that the concentration of Cr (VI) and total chromium decreased with the increase of the chromium slag disposal site distance. The content of Cr (VI) in the soil near pile of chromium slag was significantly higher than the background value and the surface soil Cr (VI) content is up to 30.54 mg/kg that the pollution index was 5.7. The content of Cr (VI) decrease with increase of the soil depth. The total chromium pollution index in surface soil near Chromium slag heap is highest for 4.61. The Cr (VI) content in soil is less than the standard value proposed by Environmental quality risk assessment criteria for soil at manufacturing facilities.