No abstract

Pseudoxanthomonas sp. RN402 was capable of degrading diesel, crude oil, n-tetradecane and n-hexadecane. The RN402 cells were immobilized on the surface of high-density polyethylene plastic pellets at a maximum cell density of 10(8) most probable number (MPN) g(-1) of plastic pellets. The immobilized cells not only showed a higher efficacy of diesel oil removal than free cells but could also degrade higher concentrations of diesel oil. The rate of diesel oil removal by immobilized RN402 cells in liquid culture was 1,050 mg l(-1) day(-1). Moreover, the immobilized cells could maintain high efficacy and viability throughout 70 cycles of bioremedial treatment of diesel-contaminated water. The stability of diesel oil degradation in the immobilized cells resulted from the ability of living RN402 cells to attach to material surfaces by biofilm formation, as was shown by CLSM imaging. These characteristics of the immobilized RN402 cells, including high degradative efficacy, stability and flotation, make them suitable for the purpose of continuous wastewater bioremediation.

Aim:  To develop a liquid formulation of Pseudoxanthomonas sp. RN402 for prolonged storage and maintaining high survival rates and pyrene biodegradability. Methods and Results:  Liquid formulations of RN402, designated as L‐RN402, were prepared by suspending bacterial cells (109 CFU ml−1) in various buffers. Analysis found that phosphate buffer containing glycerol maintained high survival rate (94%) as well as pyrene biodegradability of bacteria after a 30‐day storage. This L‐RN402 could be stored at 30°C for at least 6 months. Bioaugmentation treatment with stored L‐RN402 resulted in the complete degradation of pyrene (300 mg kg−1) in soil microcosms within 4 weeks. RN402 could be detected by denaturing gradient gel electrophoresis throughout the period; moreover, real‐time PCR indicated the presence of high number of nidA‐containing bacteria. Conclusions:  A liquid formulation of RN402, an effective pyrene degrader, was developed by suspending RN402 in phosphate buffer containing 1% glycerol. This formulation could be stored at 30°C for at least 6 months and maintain high efficacy in the treatment of pyrene‐contaminated soil. Significance and Impact of the Study:  This work is the first description of a liquid formulation of pyrene‐degrading bacteria for prolonged storage that retains biological activity for the treatment of environmental pollutants.

This work focused on the application of a microchannel contactor for CO2 capture using water as absorbent, especially for the application of CO2-rich gas. The influence of operating conditions (temperature, volumetric flow rate of gas and liquid, and CO2 concentration) on the absorption efficiency and the overall liquid-side volumetric mass transfer coefficient was presented in terms of the main effects and interactions based on the factorial design of experiments. It was found that 70.9% of CO2 capture was achieved under the operating conditions as follows; temperature of 50 °C, CO2 inlet fraction of 53.7%, total gas volumetric flow rate of 150 mL min−1, and adsorbent volumetric flow rate of 1 mL min−1. Outstanding performance of CO2 capture was demonstrated with the overall liquid-side volumetric mass transfer coefficient of 0.26 s−1. Further enhancing the system by using 2.2 M of monoethanolamine in water (1:1 molar ratio of MEA-to-CO2) boosted the absorption efficiency up to 88%.