Inhibitory Effect of Gamma-Irradiated Chitosan on the Growth of Denitrifiers

In order to find an environmentally benign substitute to hazardous inhibitory agents, the inhibitory effect of γ-irradiated chitosans against a mixed culture of denitrifying bacteria was experimentally evaluated. Unlike other studies using pure aerobic cultures, the observed effect was not a complete inhibition but a transient inhibition reflected by prolonged lag phases and reduced growth rates. Raw chitosan under acid conditions (pH 6.3) exerted the strongest inhibition followed by the 100 kGy and 500 kGy irradiated chitosans, respectively. Therefore, because the molecular weight of chitosan decreases with the degree of γ-irradiation, the inhibitory properties of chitosan due to its high molecular weight were more relevant than the inhibitory properties gained due to the modification of the surface charge and/or chemical structure by γ-irradiation. High dosage of γ-irradiated appeared to increase the growth of mixed denitrifying bacteria in acid pH media. However, in neutral pH media, high dosage of γ-irradiation appeared to enhance the inhibitory effect of chitosan

Integrated CCS Aspect into CO2 EOR Project Under Wide Range of Reservoir Properties and Operating Conditions

AbstractCarbon Capture and Storage (CCS) aspects can be combined with enhanced oil recovery (EOR) aspects for environmental responsibility and project economics. Oil Field in Pattani Basin, Gulf of Thailand is one candidate for this process integration. However, because of unique field characteristics like the number of reservo irs, and lack of data on fluid composition, and rock properties, full detailed reservoir simulations are hard to accomplish. Hence, this study proposes the use of numerical s imulations with generalized field parameters to briefly quantify the potential for integrating CCS and EOR in Pattani Bas in oil reservo irs. GEM composition reservo ir simulator was used for comparison of six operating conditions: 1) Natural Production, 2) Waterflooding, 3) Gasflooding, 4) S ingle Cycling Water Alternated Gas (WAG), 5) Double Cycling WAG, and 6) Simultaneous Water Alternated Gas (SWAG).Two levels fractional factorial experimental design techniques were applied to reduce the number of required simulation runs. Central composite design was utilized additionally if assumptions in the fractional factorial design were vio lated. By using statistical analysis, important input parameters called factors were determined. Regression analyses of important factors to responses of interests (incremental recovery factor, required gas injection volume and gas storability) were used to establish a metamodel.Our results suggest that for general Pattani Basin oil reservo irs the most preferab le technique is SWAG method with CO2 injection because it provides highest recovery factor and gas storage volume. Using a higher CO2 portion in SWAG injection stream can further increase recovery factors. When using natural gas as the injection gas, the most preferab le method in terms of recovery factor is the double cycling WAG method followed by the s ingle cycling WAG method

Dynamic behavior of a floating water droplet with hydrocarbon-degrading bacteria

This study investigated the influence of hydrocarbon-degrading bacteria on the floating water droplet, which aims to explore a safer removal method for oil spills. An aqueous solution was prepared by mixing a bacterial mixture, SDS and NaCl, and then deposited on the surface of paraffin oil. The floatable volume of bacteria-containing droplet was smaller than the previously reported droplet, which was stabilized by surfactant only. Nevertheless, the water droplet remained floating effectively for the bio-processes. The bacterial activities have distinguished influence on the floating behavior. First, the bio-film was formed on the air/water interface, and noticeably reduced the evaporation rate. Second, the water was removed in ∼30 min. The results provide important new insights for removing oil spills by an economical and environmentally friendly method. The method can be combined with the current practices to reduce the ecological impact of the oil spills