Toluene vapor capture by activated carbon particles in a dual gas-solid cyclone system

Capturing of odorous compounds such as toluene vapor by a particulate-activated carbon adsorbent was investigated in a gas-solid cyclone, which is one type of mobile beds. The test cyclone was early modified with the post cyclone (PoC) and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially when dealing with a low concentration of odorous elements and a large volume ofdust flow. In this device, the toluene capturing efficiency at a 400 ppm concentration rose up to 77.4% when using activated carbon (AC) particles with a median size of 27.03 microm. A maximum 96% of AC particles could be collected for reuse depending on the size and flow rate. The AC regenerated via thermal treatment showed an adsorption potential up to 66.7% throughout repeated tests.     

Bioelectrochemical technology for recovery of silver from contaminated aqueous solution: a review

Environmental Science and Pollution Research - A large amount of silver-rich wastewater is generated from different industrial processes. This wastewater is not considered a waste, but a valuable...     

Microbial abundance and community in subsurface flow constructed wetland microcosms: role of plant presence

In this research, the role of plants in improving microorganism growth conditions in subsurface flow constructed wetland (CW) microcosms was determined. In particular, microbial abundance and community were investigated during summer and winter in Phragmites australis-planted CW microcosms (PA) and unplanted CW microcosms (control, CT). Results revealed that the removal efficiencies of pollutants and microbial community structure varied in winter with variable microbial abundance. During summer, PA comprised more dominant phyla (e.g., Proteobacteria, Actinobacteria, and Bacteroidetes), whereas CT contained more Cyanobacteria and photosynthetic bacteria. During winter, the abundance of Proteobacteria was >40 % in PA but dramatically decreased in CT. Moreover, Cyanobacteria and photosynthetic bacterial dominance in CT decreased. In both seasons, bacteria were more abundant in root surfaces than in sand. Plant presence positively affected microbial abundance and community. The potential removal ability of CT, in which Cyanobacteria and photosynthetic bacteria were abundant during summer, was more significantly affected by temperature reduction than that of PA with plant presence.     

Waste prevention for sustainable resource and waste management

Although the 2Rs (reduce and reuse) are considered high-priority approaches, there has not been enough quantitative research on effective 2R management. The purpose of this paper is to provide information obtained through the International Workshop in Kyoto, Japan, on 11–13 November 2015, which included invited experts and researchers in several countries who were in charge of 3R policies, and an additional review of 245 previous studies. It was found that, regarding policy development, the decoupling between environmental pressures and economy growth was recognized as an essential step towards a sustainable society. 3R and resource management policies, including waste prevention, will play a crucial role. Approaches using material/substance flow analyses have become sophisticated enough to describe the fate of resources and/or hazardous substances based on human activity and the environment, including the final sink. Life-cycle assessment has also been developed to evaluate waste prevention activities. Regarding target products for waste prevention, food loss is one of the waste fractions with the highest priority because its countermeasures have significant upstream and downstream effects. Persistent organic pollutants and hazardous compounds should also be taken into account in the situation where recycling activities are globally widespread for the promotion of a material-cycling society.     

Green environmental technologies and waste utilization

Environmental Science and Pollution Research -     

Landsat-8 and Sentinel-2 data for mapping plastic-covered greenhouse farming areas: a study from Dalat City (Lam Dong Province), Vietnam

Plastic-covered greenhouse (PCG) farming has been practiced worldwide, particularly in highland areas, for planting fruits and garden plants. Highland areas in south-central Vietnam have been witnessing an expansion of PCG farming in recent decades. For sustainable management of plastic-covered greenhouse farming areas, a proper and continuous monitoring of their spatial patterns is necessary. In this study, we used spaceborne multispectral imagery (Landsat-8 OLI and Sentinel-2 MSI) for automatic detection and mapping of plastic covered greenhouse farming areas in and surrounding areas of Dalat City in Lam Dong province, south-central Vietnam. Unsupervised (K-Means algorithm) and automatic delineation using spectral indices were applied to the Sentinel-2 and Landsat-8 data for mapping plastic-covered greenhouses in Dalat City and surrounding areas. The results were evaluated using field data; automatic spectral index-based mapping of PCGs using Sentinel-2 and Landsat-8 data was found as robust in terms of the overall accuracy. The overall accuracies of PCG maps derived from Sentinel-2 and Landsat-8 data by applying spectral indices were 90.8% and 88.7%, respectively, and those of unsupervised K-Means classification were estimated as 73.2% and 71.7%, respectively. This study estimated that about 2425 ha of plastic-covered greenhouses existed within in Dalat City in 2020.

     

Analysis of polychlorinated dibenzo-p-dioxins and furans in various aqueous samples in Taiwan

Twenty-one fresh water samples were taken from reservoirs, wells and drinking water treatment plants in Taiwan for measurement of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) concentrations. Due to low concentration of PCDD/Fs, water samples (400-1000 L) were collected by using the on-site large volume pre-concentration system and analyzed by high resolution gas chromatography (HRGC)/high resolution mass spectrometer (HRMS). Different characteristics of dioxin profiles in surface water and groundwater are observed. The PCDD/F concentrations in fresh water samples varied from 0.001 to 0.265 pg WHO₉₈-TEQ/L which are lower than the standard (12 pg WHO₉₈-TEQ/L) set by the Taiwan Environmental Protection Administration (TEPA) for drinking water. Only a small fraction (<5%) of the total PCDD/F concentration in fresh water samples was water-soluble. As a result of their hydrophobicity, PCDD/Fs are effectively removed along with suspended solid via the water treatment process (average 98% removal efficiency).     

Air pollution modeling at road sides using the operational street pollution model--a case study in Hanoi, Vietnam

In many metropolitan areas, traffic is the main source of air pollution. The high concentrations of pollutants in streets have the potential to affect human health. Therefore, estimation of air pollution at the street level is required for health impact assessment. This task has been carried out in many developed countries by a combination of air quality measurements and modeling. This study focuses on how to apply a dispersion model to cities in the developing world, where model input data and data from air quality monitoring stations are limited or of varying quality. This research uses the operational street pollution model (OSPM) developed by the National Environmental Research Institute in Denmark for a case study in Hanoi, the capital of Vietnam. OSPM predictions from five streets were evaluated against air pollution measurements of nitrogen oxides (NO(x)), sulfur dioxide (SO2), carbon monoxide (CO), and benzene (BNZ) that were available from previous studies. Hourly measurements and passive sample measurements collected over 3-week periods were compared with model outputs, applying emission factors from previous studies. In addition, so-called "backward calculations" were performed to adapt the emission factors for Hanoi conditions. The average fleet emission factors estimated can be used for emission calculations at other streets in Hanoi and in other locations in Southeast Asia with similar vehicle types. This study also emphasizes the need to further eliminate uncertainties in input data for the street-scale air pollution modeling in Vietnam, namely by providing reliable emission factors and hourly air pollution measurements of high quality.     

A mixed Bentham–Rawls criterion for intergenerational equity: Theory and implications

This paper proposes a welfare criterion that balances the need for development and the concern for the least advantaged generations, and explores its implications. This criterion, called the mixed Bentham–Rawls criterion, moderates the effect of discounting, yet permits some degree of intertemporal trade-off. It is a weighted average of two terms: (a) the sum of discounted utilities and (b) the utility level of the least advantaged generation. We derive necessary conditions to characterize growth paths that satisfy our criterion, and show that in some models with familiar dynamic specifications, an optimal path exists and displays appealing characteristics.     

Water-induced erosion potentiality and vulnerability assessment in Kangsabati river basin,eastern India

Environment, Development and Sustainability - The large-scale water-induced erosion is one of the most determining elements on land degradation in subtropical monsoon-dominated region. From this...