Volume 17 - 2015

Attrition of limestone particles in bubbling fluidized bed has significant influence on cyclic CO₂ capture ability of sorbents. The limestone particle attrition and size distribution characteristics were investigated experimentally in a bench scale fluidized bed. The effects of initial particle sizes, fluidized velocity, attrition time and temperature on limestone attrition characteristics were studied. An empirical fitting correlation was proposed to describe the relationship of cumulative mass fraction of limestone fines (R) and attrition time (t). The results show that the fines generation rate decreases and particle size reduction rate increases with increasing initial size. Chipping of large particle takes predominant position when fluidized velocity exceeds the minimum fluidization velocity resulting in more prominent reduction of particle size. After 4 hours attrition, particle size reduction and fines generation rate become constant. It is suggested that cumulative mass fraction of limestone fines (R) increases with attrition time with a function of decaying exponential correlation.

In the present work the physically based distributed rainfall–runoff modeling system, MIKE SHE, is used to simulate the surface runoff at a semi-mountainous impermeable area of Tavronitis River basin in Crete-Greece.  The objective of this surface flow model is to develop an appropriate irrigation plan for olive trees. For the model calibration, a simulation time of one year (01/09/2000 - 31/08/2001) was considered, while for the model verification a two-year period (01/09/2001 - 31/08/2003). During these periods river flow measurements were obtained at two specified locations. These measurements were employed as targets for calibration and verification of the surface flow model. After the successful calibration and validation processes, the 2D maps of the overland flow were produced. Using these maps, the locations of significant surface water accumulation in the study region and for a specific time period were identified. Next, these locations were proposed for the construction of potential small hydraulic structures (dam or/and reservoir), for covering the irrigation needs of olive trees in the study area. 

This paper presents an assessment of the impact of uncontrolled and unscientific disposal of MSW on ground water in Dhanbad city, India. In this study, ground water quality around municipal solid waste disposal sites was investigated. Ground water quality analysis was carried out on samples collected at various distances from two disposal sites. The study has revealed that the ground water quality near dumping sites does not conform to the drinking water quality standards as per IS:10500. The impacts of indiscriminate dumping activity on ground water appeared most clearly as high concentrations of total dissolved solids, electrical conductivity, chlorides, chemical oxygen demand, and sulphates. High amount of metals like Na, K, Ca, Mg, Cd, Cu, Ni, Fe, Zn and Mn has also been detected in the groundwater samples near dumping area. Leachate characterization study also reveals high potential for groundwater contamination. Presence of feacal coliform contamination in groundwater samples indicates potential health risk for individuals exposed to this water. 

The contribution of integrated municipal solid waste (MSW) management systems to greenhouse gas emissions is not negligible, even though it is moderate compared with other anthropogenic activities. The main emission from landfills that accept biodegradable MSW is methane that escapes from the biogas collection system. Such emissions are partially compensated if the collected biogas is exploited for energy production. Further compensation measures would also increase the overall sustainability of the landfill site. This study analyses the possibility of exploiting closed landfills to produce energy based on the case study of the Valdina landfill (Messina, Italy). Two possible scenarios are presented: the installation of a photovoltaic system and the cultivation of giant reed (Arundo donax L.) to be used for energy production through combustion. The results of a preliminary experimental activity are presented for the second scenario. The findings demonstrate the possibility of using the leachate produced in the landfill for irrigation purposes. For each scenario, the costs, potential energy production rate, avoided emissions and issues related to the integration of energy production with the landfill aftercare are evaluated. The presented results suggest that the cultivation of giant reed is the best option, especially during the early post-closure period, in terms of investment (18,000 € against 8,300,000 €), high production yield in the Mediterranean climate, simplicity of cultivation and integration with ordinary post-closure landfill management, limited cost of the energy produced (0.1€ kWh^-1 against 0.27€ kWh^-1). On the other hand avoided emissions are higher for the photovoltaic plant (27804  against 778  on an horizon of 20 years).