Plasma-assisted ammonia synthesis in a packed-bed dielectric barrier discharge reactor: roles of dielectric constant and thermal conductivity of packing materials

In this article, plasma-assisted NH3 syntheses directly from N2 and H2 over packing materials with different dielectric constants (BaTiO3, TiO2 and SiO2) and thermal conductivities (BeO, AlN and Al2O3) at room temperature and atmospheric pressure are reported. The higher dielectric constant and thermal conductivity of packing material are found to be the key parameters in enhancing the NH3 synthesis performance. The NH3 concentration of 1344 ppm is achieved in the presence of BaTiO3, which is 106% higher than that of SiO2, at the specific input energy (SIE) of 5.4 kJ·l−1. The presence of materials with higher dielectric constant, i.e. BaTiO3 and TiO2 in this work, would contribute to the increase of electron energy and energy injected to plasma, which is conductive to the generation of chemically active species by electron-impact reactions. Therefore, the employment of packing materials with higher dielectric constant has proved to be beneficial for NH3 synthesis. Compared to that of Al2O3, the presence of BeO and AlN yields the 31.0% and 16.9% improvement in NH3 concentration, respectively, at the SIE of 5.4 kJ·l−1. The results of IR imaging show the addition of BeO decreases the surface temperature of the packed region by 20.5% to 70.3°C and results in an extension of entropy increment compared to that of Al2O3, at the SIE of 5.4 kJ·l−1. The results indicate that the presence of materials with higher thermal conductivity is beneficial for NH3 synthesis, which has been confirmed by the lower surface temperature and higher entropy increment of the packed region. In addition, when the SIE is higher than the optimal value, further increasing SIE would lead to the decrease of energy efficiency, which would be related to the exacerbation in reverse reaction of NH3 formation reactions.

Biofiltration of Methane Fugitive Emissions from Landfills Using Scum from Municipal Wastewater Treatment Plants (Wwtp) as Alternative Substrate

Biofilters have been recognized as key technology in the mitigation of greenhouse gases (GHG) emitted by landfills. This study aimed to evaluate the methane (an important GHG) oxidation efficiencies of two experimental biofilters at the municipal landfill of Guarapuava (Brazil) under normal conditions (control column), just using landfill cover soil with low organic matter content, and improved, exploiting dried scum from municipal wastewater treatment plant (SWWTP) mixed with the cover soil (enriched column, with a high organic matter content). The influence of parameters such as the methane inlet loading rates (22 and 44 gCH4.m− 2.d− 1), temperatures, methane concentration in the raw biogas, carbon/nitrogen ratio and moisture content of the packing materials on the oxidation of methane was also evaluated during 25 campaigns. The campaigns with the lowest methane loading rates applied to the biofilters showed the best methane oxidation efficiencies (98.4% and 89.5% in the enriched and control columns, respectively) as compared to campaigns with a higher load (92.6% and 82.6% in the enriched and control columns, respectively). In addition to the loading rates, the methane oxidation efficiencies were highly influenced by the organic matter content and C/N ratio of the packing materials evaluated.

Fungal Flora Isolated from Deteriorating Card Board and Corrugated Box Samples in Thane and Bhiwandi, India

Many cellulose based articles have found their way into human requirements and have become articles of necessity, paper being one such article. Card board and corrugated boxes are used as packing materials universally and alike paper, these are vulnerable to invasion by cellulose degrading fungi. The study in regions of Thane and Bhiwandi cities on the outskirts of Mumbai city in Western coastal part of Maharashtra, India focused on the invasion of cardboard and corrugated paper boxes by fungi. Twenty four species of fungi belonging to 11 genera were found on the deteriorating card board and corrugated paper samples during the study, prominent amongst them being the genus Aspergillus, Chaetomium, Curvularia, Trichoderma, Penicillium, Alternaria and five other cellulolytic fungal genera. Growth of fungi resulted in crumbling of the cardboard at places due to loss of strength. Many of the fungal forms isolated were potential health hazards which was cause for concern.

GERMINABILITY OF VARIETIES OF BEAN (Phaseoulos Vulgaris L.) AND OKRA (Abelmoschus Esculentus L. Moench) UNDER LOW TEMPERATURE STORAGE CONDITION

Bean and okra are common vegetables cultivated in the most regions of Sri Lanka. The seeds of these crops are mainly stored in cold storage as bulk before releasing retail lots to sales outlets. Commercial growers and gardeners buy seeds in bulk or in packages at retail stores. Although certified seeds are frequently tested by the seed testing laboratories, they do not guarantee the maximum field emergence. Certified seed lots of two pole bean varieties, ‘Keppetipola Nil’ (KN) and ‘Bandarawela Green’ (BG) and two okra varities,’MI-5’ and ‘Haritha’ were stored in poly sack and polypropylene bags under controlled temperature (17±1 °C) and relative humidity (RH) (52-55%) over a two-year period. Bulk seeds of bean and okra varieties packed in polypropylene and poly sack bags depicted a high germination percentage throughout the storage period for two years. Seed quality parameters, seed germination, seed moisture, field emergence and vigour index significantly varied with the storage duration and declined in varieties. Significant differences in moisture, field emergence and vigour index were recognized as affected by the packing materials in all varieties except MI-5. Both Poly sack and polypropylene packing materials were found suitable to maintain viability at the minimum seed certification standards for two years of storage period. Poly sack was more appropriate than polypropylene to keep viability for more than 2 years of storage under low temperature and RH condition. These findings would help seed handlers including seed producers and seed sellers to store crop seeds between growing seasons in the tropical environment.

Bacterial Cellulose: Multipurpose Biodegradable Robust Nanomaterial

One of actual global problem is clothes and packing materials biodegradability leading to tremendous water contamination. In order to develop ecologically friendly, game-changing in global industry fabric production, we propose a concept to implement kombucha. Kombucha is a symbiotic bacteria and yeast multispecies consortium producing the most abundant polymer on Earth - bacterial cellulose. There are many advantages of bacterial cellulose that are widely used in medicine, material science, food industry and waste management. Unfortunately: long time of bacterial cellulose polymerisation process, lack of its control, diversity in biological composition, finally, acidic smell and disturbances of kombucha growth - all this issues limit the interest of kombucha use to replace easy-accessible and widely applied synthetic materials. In this chapter will be described a revolutionary concept to develop practical and sustainable use of bacterial cellulose as natural alternative for synthetic materials, particularly for a synthetic fabrics and plastics replacement. The optimal cultivation conditions and examples of bacterial cellulose in applications for daily life will be explained.