Parameters optimization using an artificial neural networks and release characteristics of humic acids during lignite bioconversion.

The bioconversion of coal at ambient conditions is a promising technology for coal processing. However, there are few examples of the optimization of processes for industrial-scale use. In this work, the optimization of process parameters affecting lignite bioconversion by an isolated fungus WF8 using an artificial neural network (ANN) combined with a genetic algorithm (GA) was carried out for modeling of humic acids (HAs) yield and parameters. Kinetic models were used to understand the release characteristics of HAs from the bioconversion of lignite. The results of the present work indicate that the optimal process parameters (OPP) are 29 °C, initial pH of 7, 180 rpm, 0.6 mmol·L-1 of CuSO4, 0.4 mmol L-1 of MnSO4, and 6.4 µmol·L-1 of veratryl alcohol (VA). The predicted experimental data obtained by ANN is similar to the actual and the significant correlation coefficient value (R2) of 0.99 indicates that ANN has good predictability. The actual yield of HAs are 5.17 mg·mL-1. During bioconversion, the fungus WF8 could loosen and attack the structure of lignite. The release of HAs produced by bioconversion of lignite under the OPP via diffusion and swelling is fit to zero-order model independent on concentration. This provides support for the industrial bioconversion of lignite.

Effects of Different Energy Substrates and Nickel and Cadmium Ions on the Growth of Acidithiobacillus ferrooxidans and Its Application for Disposal of Ni-Cd Batteries.

In the present work, the effects of different energy substrates and nickel ions (Ni2+) and cadmium ions (Cd2+) on the growth of Acidithiobacillus ferrooxidans (A. ferrooxidans) were investigated. Ferrous sulphate (FeSO4) was the optimum energy substrate for A. ferrooxidans growth, among the selected substrates. When cultured together with FeSO4 and sulphur (S), A. ferrooxidans first oxidised the ferrous ions (Fe2+), and the S was utilised as the concentration of Fe2+ decreased. After adapting to culture with Ni2+ and Cd2+, A. ferrooxidans presented good tolerance to both ions, with the maximum concentration reaching 4.11 g/L Ni2+ and 1.69 g/L Cd2+. A preliminary simulation of industrial application was also performed on used Ni-Cd batteries. With bioleaching, the highest concentrations of Cd2+ and Ni2+ were 3003 mg/L at day 8 and 1863 mg/L at day 14, respectively.

Effects of Bacillus cereus strain Jdm1 on Meloidogyne incognita and the bacterial community in tomato rhizosphere soil.

Bacillus cereus strain Jdm1 was isolated and tested for activity as a biocontrol agent to suppress Meloidogyne incognita. Petri dish test results indicated that Jdm1 culture supernatant significantly inhibited the second-stage juvenile (J2) activity and egg hatching, and also decreased the number of galls on tomato roots in the pot test. Control efficiency reached 43%, with improved growth compared to control plants. In field tests, control efficacies were greater than 50% 30 day post-inoculation, before decreasing. Furthermore, when avermectins were included to manage M. incognita, the yield of tomatoes was increased significantly. The effect of Jdm1 on the bacterial community in the tomato rhizosphere soil was monitored using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) on field plants. DGGE band patterns and principal component analysis showed that application of Jdm1 did not permanently imperil the bacterial community, which recovered soon after inoculation, despite being impacted initially. The plant growth stage had a much greater influence on the bacterial community in tomato rhizosphere soil.