Establishment of unit generation rates of building debris in Kathmandu Valley,Nepal, after the Gorkha earthquake

Journal of Material Cycles and Waste Management - Significant quantities of building waste were generated from collapsed residential and dilapidated buildings as a result of the disastrous Gorkha...     

Comparison of end-of-life vehicle material flows for reuse,material recycling,and energy recovery between Japan and the European Union

Journal of Material Cycles and Waste Management - Japan and the European Union (EU) both have well-established End-of-Life Vehicle (ELV) policies and management systems. However, due to the...     

Municipal solid waste composition and food loss reduction in Kyoto City

For 35 years, Kyoto City has conducted detailed household waste composition surveys under the guidance of Kyoto University by dividing household waste into approximately 400 categories. In addition, the city has conducted detailed composition surveys of commercial waste generated by businesses. These surveys show that food loss accounts for approximately 40% of total waste, of which leftovers and untouched food account for about 40% in both households and business facilities. Consequently, the annual generation of household and commercial food loss is estimated at about 30,000 tons. Various efforts have been made to reduce waste, including food loss, but further reduction in environmental burden is needed. Thus, Kyoto City revised the ordinance for waste reduction, and in March 2015, formulated a new municipal waste management plan. The plan not only includes the 2Rs (reduce, reuse), but also, for the first time in Japan, sets quantitative targets for reducing food loss. Kyoto City must ensure that the necessary waste reduction measures are clearly explained to the residents and business operators. To ensure that this plan is successful, it is important to clarify concrete actions that residents and business operators should implement, along with their effects.     

Influence of arsenic stress on synthesis and localization of low-molecular-weight thiols in Pteris vittata

The roles of low-molecular-weight thiols (LMWTs), such as glutathione and phytochelatins, in arsenic (As) tolerance and hyperaccumulation in Pteris vittata an As-hyperaccumulator fern remain to be better understood. This study aimed to thoroughly characterize LMWT synthesis in P. vittata to understand the roles played by LMWTs in As tolerance and hyperaccumulation. LMWT synthesis in P. vittata was induced directly by As, and not by As-mediated oxidative stress. Expression of PvECS2, one of the putative genes of γ-glutamylcysteine synthetase (γECS), increases in P. vittata shoots at 48 h after the onset of As exposure, almost corresponding to the increase in the concentrations of γ-glutamylcysteine and glutathione. Furthermore, localization of As showed similar trends to those of LMWTs in fronds at both whole-frond and cellular levels. This study thus indicates the specific contribution of LMWTs to As tolerance in P. vittata. γECS may be responsible for the As-induced enhancement of LMWT synthesis.     

Greenhouse gas emissions from biogenic waste treatment: options and uncertainty

A simplified life cycle assessment was conducted to estimate greenhouse gas (GHG) emissions and energy production from each component of biogenic waste treated in an open dumping site, and by composting, anaerobic digestion, and incineration employed with additional options. The impact of uncertainties and sensitivities of the parameters in the treatment methods were investigated. We conducted a sensitivity analysis to identify the most sensitive parameters, and we discussed the relationship between uncertainty and sensitivity. Our results revealed that the moisture content of food waste and the biomass-derived carbon and methane concentration of the landfill gas of biogenic waste subjected to open dumping are the most sensitive parameters across all the treatment methods. The net GHG emissions from food waste treated in an open dumping site ranged over ten times (0.30 ? 3.67 Gg CO₂ eq/Gg). In addition, by employing additional options for the open dumping site, including soil cover, a landfill gas collection system, shifting to a semi-aerobic condition, and energy conservation by using a gas engine, we found that the net GHG emissions could be reduced by 10, 27.9, 37.4 %, and up to 56.7 %, respectively. Shifting to a semi-aerobic system is the most effective method for reducing GHG emissions, followed by landfill gas collection.     

Effect of density-driven flow on the through-diffusion experiment

Diffusion is one of the main mechanisms of solute transport in pore water of geologic media. The effective diffusion coefficient of a solute in a rock is usually measured by the through-diffusion experiment. However, in this experiment, the effect of advection, induced by density difference between dense aqueous solution and pure water, has not been considered. To evaluate the effect of density-driven flow, a through-diffusion experiment using Fontainebleau sandstone was conducted for KCl and KI aqueous solutions with various densities. The measured effective diffusion coefficients were positively correlated with the density difference; the effective diffusion coefficient of a 1 M KI solution (density difference, 0.119 g/cm³) was one order of magnitude larger than that of a 0.1 M KCl solution (density difference, 0.005 g/cm³). The result is explained by a theoretical model using a diffusion–advection equation including Darcy's law. Based on the theory, a diagram to evaluate the condition at which the measured effective diffusion coefficient does not include the effect of advection is presented.     

Relative importance and interactive effects of photosynthesis and food in two solar-powered sea slugs

Sacoglossans use chloroplasts taken from algal food for photosynthesis (kleptoplasty), but the adaptive significance of this phenomenon remains unclear. Two con-generic sacoglossans (Elysia trisinuata and E. atroviridis) were collected in 2009–2011 from Shirahama (33.69°N, 135.34°E) and Mukaishima (34.37°N, 133.22°E), Japan, respectively. They were individually maintained for 16 days under four experimental conditions (combination of light/dark and with/without food), and their survival rate and relative (=final/initial) weights were measured. Both light and food had positive effects on the survival in E. trisinuata, whereas no positive effects of light or food on survival were detected in E. atroviridis. Both light and food had positive effects on relative weights in both species, but light had smaller effects than food. A significant interaction term between light and food was detected in E. trisinuata (but not in E. atroviridis) in that only the presence of both resulted in weight gains. This result suggests that E. trisinuata can obtain sufficient additional energy from photosynthesis for sustaining growth when fresh chloroplasts are continuously supplied from algal food. In addition, fluorescence yield measurements showed that unfed individuals of both E. trisinuata and E. atroviridis lost photosynthetic activity soon (<4 and 4–8 days, respectively). In conclusion, photosynthesis may function to obtain supplementary nutrition for sustaining growth when food is available in sacoglossans with short-term functional kleptoplasty.     

Japan’s waste management policies for dioxins and polychlorinated biphenyls

We summarize the measures taken by the Japanese government to prevent the emission of dioxins and polychlorinated biphenyls (PCBs) into the environment. Because incineration is the main method of waste management in Japan, reducing the amount of dioxins emitted from waste incinerators is an essential aspect of proper waste treatment. Intensive measures to prevent the formation of dioxins at the source have been implemented, with a focus on waste treatment methods and improving comprehensive management. The efforts have been very successful, with a 95% reduction in the amount of dioxins emitted between 1997 and 2003. The toxicity of PCBs has been monitored with keen interest since the Yusho incident. Unfortunately, treatment facilities for PCB wastes were not built until long after PCBs had been removed from use, and PCB wastes remained in storage in an untreated state. The Japanese government has promoted the construction of facilities for treating PCB wastes, and five such facilities have commenced operations. To more completely eradicate dioxins, a future challenge will be to reduce the amount of PCB-derived dioxins, which are persistent in the environment and have a long exposure pathway from the environment media to the organism and the human body.     

Effect of unburned carbon on lead, zinc, and copper recovery from molten fly ash by chloride-induced volatilization

The present work focuses on investigation of the effective recovery of heavy metals from molten fly ash by applying chloride-induced volatilization. In particular, the effect of unburned carbon on the chloride-induced volatilization of lead, zinc, and copper from model and real molten fly ashes was investigated in the temperature range 873–1173 K under a N₂ atmosphere. As a result, almost 100% of lead and a significant proportion of zinc were volatilized from the real molten fly ash samples at 1173 K. In contrast, for the model fly ash, volatilization ratios of lead and zinc at 1173 K were only 85% and 25%, respectively. Further, the results of X-ray diffraction analysis suggested that PbO in molten fly ash was converted either to Pb₂OCl₂ or Pb by respective chlorination and reduction reactions. Meanwhile ZnO and CuO in the molten fly ash were reduced to Zn and Cu by reaction with unburned carbon. Subsequently, Pb, Zn, and Pb₂OCl₂ were volatilized, but Cu remained in the solid residue. Finally, the volatilization ratio of zinc increased with the addition of carbon, and more than 98% of zinc was volatilized at 1173 K from a fly ash with a carbon content of 20%.