Revisiting the elemental composition and the calorific value of the organic fraction of municipal solid wastes

In this work, the elemental content (C, N, H, S, O), the organic matter content and the calorific value of various organic components that are commonly found in the municipal solid waste stream were measured. The objective of this work was to develop an empirical equation to describe the calorific value of the organic fraction of municipal solid waste as a function of its elemental composition. The MSW components were grouped into paper wastes, food wastes, yard wastes and plastics. Sample sizes ranged from 0.2 to 0.5 kg. In addition to the above individual components, commingled municipal solid wastes were sampled from a bio-drying facility located in Crete (sample sizes ranged from 8 to 15 kg) and were analyzed for the same parameters. Based on the results of this work, an improved empirical model was developed that revealed that carbon, hydrogen and oxygen were the only statistically significant predictors of calorific value. Total organic carbon was statistically similar to total carbon for most materials in this work. The carbon to organic matter ratio of 26 municipal solid waste substrates and of 18 organic composts varied from 0.40 to 0.99. An approximate chemical empirical formula calculated for the organic fraction of commingled municipal solid wastes was C₃₂NH₅₅O₁₆.     

Monitoring and optimizing the co-composting of dewatered sludge: a mixture experimental design approach

The management of dewatered wastewater sludge is a major issue worldwide. Sludge disposal to landfills is not sustainable and thus alternative treatment techniques are being sought. The objective of this work was to determine optimal mixing ratios of dewatered sludge with other organic amendments in order to maximize the degradability of the mixtures during composting. This objective was achieved using mixture experimental design principles. An additional objective was to study the impact of the initial C/N ratio and moisture contents on the co-composting process of dewatered sludge. The composting process was monitored through measurements of O(2) uptake rates, CO(2) evolution, temperature profile and solids reduction. Eight (8) runs were performed in 100 L insulated air-tight bioreactors under a dynamic air flow regime. The initial mixtures were prepared using dewatered wastewater sludge, mixed paper wastes, food wastes, tree branches and sawdust at various initial C/N ratios and moisture contents. According to empirical modeling, mixtures of sludge and food waste mixtures at 1:1 ratio (ww, wet weight) maximize degradability. Structural amendments should be maintained below 30% to reach thermophilic temperatures. The initial C/N ratio and initial moisture content of the mixture were not found to influence the decomposition process. The bio C/bio N ratio started from around 10, for all runs, decreased during the middle of the process and increased to up to 20 at the end of the process. The solid carbon reduction of the mixtures without the branches ranged from 28% to 62%, whilst solid N reductions ranged from 30% to 63%. Respiratory quotients had a decreasing trend throughout the composting process.     

Economies of integration and sources of change in productivity in the Chilean water and sewerage industry: a translog cost function approach

Environmental Science and Pollution Research - This paper researches the existence of economies of scale and scope in the Chilean water and sewerage industry using a translog cost function approach...     

Life Cycle Assessment of the MBT plant in Ano Liossia, Athens, Greece

The aim of this paper is the application of Life Cycle Assessment to the operation of the MBT facility of Ano Liossia in the region of Attica in Greece. The region of Attica is home to almost half the population of Greece and the management of its waste is a major issue. In order to explicitly analyze the operation of the MBT plant, five scenarios were generated. Actual operation data of the MBT plant for the year 2008 were provided by the region of Attica and the LCA modeling was performed via the SimaPro 5.1 software while impact assessment was performed utilizing the Eco-indicator’99 method.The results of our analysis indicate that even the current operation of the MBT plant is preferable to landfilling. Among the scenarios of MBT operation, the one with complete utilization of the MBT outputs, i.e. compost, RDF, ferrous and non-ferrous metals, is the one that generates the most environmental gains. Our analysis indicates that the exploitation of RDF via incineration is the key factor towards improving the environmental performance of the MBT plant. Our findings provide a quantitative understanding of the MBT plant. Interpretation of results showed that proper operation of the modern waste management systems can lead to substantial reduction of environmental impacts and savings of resources.     

Land use and cover change in Japan and Tokyo’s appetite for meat

Urban consumption of ecosystems services such as food generates environmental impacts at different geographical scales. In the last few decades Tokyoites have shown an increasing appetite for meat. This study examines the environmental implications of Tokyo’s increasing meat consumption by analyzing how this trend has affected land use and cover change in areas near and far away. Historical databases (1970–2005) are employed in order to explore meat consumption patterns in Tokyo and to relate it with beef and pork production in areas within the country and abroad. It also integrates the historical analysis of production and consumption patterns with a discussion of the drivers (e.g., wealth, price, policies and seafood availability) behind these trends. We identified that meat production in Japan followed three distinct phases between 1877 and 2005. In the first period it took 50 years for production to increase by 50%, while during the next phase production showed the same growth in just half the time. Major changes in land use/cover change because of domestic meat production occurred mainly during the second phase and, thereafter, when domestic production declined and was substituted to a great extent by imports. Despite the increasing consumption of imported meat, Tokyo relies greatly on domestic meat produced in its neighboring prefectures. The paper concludes that regional planning can be used as an effective instrument to protect the environment and secure protein for the population of mega-urban areas such as Tokyo.     

A study of fatal pedestrian crashes at rural low-volume road intersections in southwest China

Objective: Although intersections correspond to a small proportion of the entire roadway system, they account for a disproportionally high number of fatal pedestrian crashes, especially on rural roads situated in low- and middle-income countries. This article examines pedestrian safety at rural intersections and suggests applicable accident prevention treatments by providing an in-depth analysis of 28 fatal pedestrian crashes from 8 low-volume roads in southwest China.

Methods: The driving reliability and error analysis method (DREAM) is a method to support a systematic classification of accident causation information and to facilitate aggregation of that information into patterns of contributing factors. This is the first time that DREAM was used to analyze pedestrian–vehicle crashes and provide suggestions for road improvements in China.

Results: The key issues adversely affecting pedestrian safety can be organized in 4 distinctive thematic categories, namely, deficient intersection safety infrastructure, lack of pedestrian safety education, inadequate driver training, and insufficient traffic law enforcement. Given that resources for traffic safety investments in rural areas are limited, it is determined that the potential countermeasures should focus on low-cost, easily implementable, and long-lasting measures increasing the visibility and predictability of pedestrian movement and reducing speeding and irresponsible driving among drivers and risk-taking behaviors among pedestrians.

Conclusions: Accident prevention treatments are suggested based on their suitability for rural areas in southwest China. These countermeasures include introducing better access management and traffic calming treatments, providing more opportunities for pedestrian education, and enhancing the quality of driver training and traffic law enforcement.     

Annoyance due to aircraft noise has increased over the years—Results of the HYENA study

In the HYENA study (HYpertension and Exposure to Noise near Airports) noise annoyances due to aircraft and road traffic noise were assessed in subjects that lived in the vicinity of 6 major European airports using the 11-point ICBEN scale (International Commission on Biological Effects of Noise). A distinction was made between the annoyance during the day and during the night. L_den and L_night were considered as indicators of noise exposure. Pooled data analyses showed clear exposure–response relationships between the noise level and the noise annoyance for both exposures. The exposure–response curves for road noise were congruent with the EU standard curves used for predicting the number of highly noise annoyed subjects in European communities. Annoyance ratings due to aircraft noise, however, were higher than predicted by the EU standard curves. The data supports other findings suggesting that the people's attitude towards aircraft noise has changed over the years, and that the EU standard curve for aircraft noise should be modified.