The effects of <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis> on the leaching of cobalt and strontium adsorbed onto soil particles

Bioleaching from soil artificially contaminated with analogues of radionuclides, Co and Sr, was carried out using a Fe-oxidizing bacterium, Acidithiobacillus ferrooxidans. Due to bacterial metabolism, the pH and dissolved Fe³⁺ concentration in a biotic slurry decreased and increased respectively, over time, but the concentrations of Co and Sr extracted from the soil showed no significant enhancement compared with those under abiotic control. In both cases, Co and Sr were leached from the soil during the initial period of the experiment, due to the initially low solution pH of 2.0, and the dissolved concentrations remained almost constant for the duration of the experiment (300 h). Since oxidation of Fe²⁺ by A. ferrooxidans led to the production of Fe precipitates and colloidal suspensions, the Co and Sr extracted into solution were most likely re-adsorbed onto the Fe solids. Also, A. ferrooxidans, without an external supply of Fe²⁺, extracted almost equal or greater amounts of Co and Sr from the soil than when Fe²⁺ was supplied. Under the same leaching conditions, the extent of Sr removal was much lower than that of Co. On the contrary to the high efficiency of microbial metal leaching in biohydrometallurgy for low-graded sulfide ores, which has been widely documented, conventional bioleaching techniques with A. ferrooxidans supplied with enough Fe²⁺ showed low efficiency for the removal of radionuclides loosely bound onto soil particle surfaces.     

Effect of temperature on bacterial emissions in composting of swine manure

Swine manure was subjected to laboratory scale composting in order to quantify bioaerosols, i.e., airborne culturable bacteria and endotoxin, in the exhaust gas, which provided details on the effect of temperature on bacterial emissions. The concentration of airborne bacteria reached 31,250 colony-forming units (CFU)/m³ during the thermophilic stage of composting, and positively correlated with the temperature profile of the compost pile. Initially, the endotoxin concentration was 1820 endotoxin units (EU)/m³, but it decreased exponentially as the composting process proceeded. The temperature can be an excellent indicator of bacterial emissions during the composting process, indicating that the composting process requires a consistently high temperature to ensure sanitization of both compost and bacterial emissions. The cumulative emission data showed that emission factors was 11.2?13.5 CFU/g dry swine manure and that of endotoxin was 0.5?0.9 EU/g dry swine manure. The bacterial diversity in the bioaerosol was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis, revealing the presence of various gram-negative bacterial consortia.     

Absolute dominance of hydrogenotrophic methanogens in full-scale anaerobic sewage sludge digesters

Anaerobic digestion （AD） is gaining increasing attention due to the ability to covert organic pollutants into energy-rich biogas and, accordingly, growing interest is paid to the microbial ecology of AD systems. Despite extensive efforts, AD microbial ecology is still limitedly understood, especially due to the lack of quantitative information on the structures and dynamics of AD microbial communities. Such knowledge gap is particularly pronounced in sewage sludge AD processes although treating sewage sludge is among the major practical applications of AD. Therefore, we examined the microbial communities in three full-scale sewage sludge digesters using qualitative and quantitative molecular techniques in combination： denaturing gradient gel electrophoresis （DGGE） and real-time polymerase chain reaction （PCR）. Eight out of eleven bacterial sequences retrieved from the DGGE analysis were not affiliated to any known species while all eleven archaeal sequences were assigned to known methanogen species. Quantitative real-time PCR analysis revealed that, based on the 16S rRNA gene abundance, the hydrogenotrophic order Methanomicrobiales is the most dominant methanogen group （〉 94% of the total methanogen population） in all digesters. This corresponds well to the prevailing occurrence of the DGGE bands related to Methanolinea and Methanospirillum, both belonging to the order Methanomicrobiales, in all sludge samples. It is therefore suggested that hydrogenotrophic methanogens, especially Methanomicrobiales strains, are likely the major players responsible for biogas production in the digesters studied. Our observation is contrary to the conventional understanding that aceticlastic methanogens generally dominate methanogen communities in stable AD environments, suggesting the need for further studies on the dominance relationship in various AD systems.     

Enhanced cyclic performance initiated via an in situ transformation of Cu/CuO nanodisk to Cu/CuO/Cu2O nanosponge

Environmental Science and Pollution Research - A simple oxidation method for preparing CuO nanodisks on a flexible Cu sheet is presented. The crystal structure of as-prepared CuO nanodisks was...     

Digitalization and environment: how does ICT affect enterprise environmental performance?

Environmental Science and Pollution Research - Despite the increasing use of digital technology in industrial production, how industrial digitalization affects the environmental performance of...     

Reduction of Norovirus Surrogates Alone and in Association with Bacteria on Leaf Lettuce and Tomatoes During Application of Aqueous Ozone

Food and Environmental Virology - Retail foodservice establishments (FSE) frequently utilize washes with sanitizing agents during fresh produce preparation. This study evaluated the efficacy of...     

Application of an aerosol electrical mobility spectrum analyzer: Charged-particle polarity ratio measurement in the Antarctic and Arctic regions

An aerosol electrical mobility spectrum analyzer (AEMSA), developed at Hanyang University, was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions. The particle charge characteristics in these areas were compared with the charging state in Ansan, South Korea, located in the midlatitude, where artificial factors, such as human activity, urbanization, and traffic, might result in a higher total concentration. Furthermore, in Ansan, South Korea, the charged-particle polarity ratio was very stable and was close to 1. However, notably different particle charge characteristics were obtained in the Antarctic and Arctic regions. The imbalance between the numbers of positively and negatively charged particles was evident, resulting in more positive charges on the atmospheric particles. On average, the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher, respectively, compared with the negatively charged particles. The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms.     

Market‐based conservation: Aligning static theory with dynamic systems

This paper provides a broad evaluation of the implications of market‐based conservation (MBC) strategies from economic, social and ecological perspectives. After reviewing the economic theory that underlies MBC initiatives, we develop a list of approaches that have been labeled as “market‐based”, and categorize them according to the degree to which they are free‐standing markets or require the intervention of the state. A multidisciplinary critique reveals the potential problems and pitfalls of MBC are due to a lack of ability to deal with dynamic systems in the real world. The dynamics of these three systems can undermine the intended goals of MBC.