Issue 4

Municipal solid waste (MSW) landfills are one of the major and most preferred waste management options in the United States and many other countries across the globe. The waste in conventional MSW landfills undergoes very slow decomposition due to limited amount of moisture. In this regard, the bioreactor landfills have emerged as an effective waste management option, wherein leachate recirculation/injection is carried out to enhance the moisture levels within the waste thereby facilitating rapid waste decomposition and leading to early waste stabilization. However, in practice the performance of bioreactor landfills has remained inconclusive due to the lack of sound basis for effective design and operation of such landfills. This further stems from the fact that there is a limited understanding of the physical, chemical and biological processes and their coupled interactions on the MSW behavior in landfills. Hence, it becomes imperative to understand the influence of the coupled processes on the waste behavior to predict the overall performance of bioreactor landfills. Several researchers have developed numerical models to simulate waste behavior but only a few models have considered the simultaneous interactions of hydraulic, mechanical, and biological processes within the waste in their numerical model. In this study, newly developed numerical framework incorporating coupled thermo-hydro-bio-mechanical processes is presented. The numerical model can predict the spatial and temporal variation of waste temperatures, moisture distribution, gas generation, pore pressures, waste settlement, waste slope stability, and interface shear response in the landfill liner system. The numerical model has been validated with lab-scale and field-scale experiments and could be used to design and operate stable and effective bioreactor landfills.

Reference evapotranspiration (ETo) is an important component in water resources, agricultural and environmental modeling, thus its assessment is critical in understanding the impacts of climate change on the sector of agriculture. In this study, the effect of climate change on reference evapotranspiration in Northern Greece, was assessed. For this purpose, the climate change scenarios RCP2.6, RCP4.5 and RCP8.5 based on four Earth System Models (ESMs) CanESM2, GFDL-ESM2M, HadGEM2-ES and IPSL-CM5A-LR were used for the time periods 2041-2060 and 2081-2100 and for the baseline period (1981-2000). Reference evapotranspiration was estimated with the use of the FAO Penman-Monteith equation. Results showed that mean annual ETo is projected to increase in response to climate change during 2041-2060 and 2081-2100 according to the four ESMs with the greater increase predicted by the end of the 21st century. The increase in ETo is driven mainly by the temperature rise and secondly by the solar radiation increase in the future. The results indicate that the development of adaptation strategies is necessary for the improvement of agricultural water management and the reduction of climate change impacts on agriculture.

Waste management is one of the most crucial part of the sustainability concept. In Turkey, waste management of the small household appliances under waste of electrical and electronic equipment (WEEE) category still remains as an issue to handle although its production is very large and long-established. The main reason is that many of the household appliances’ wastes are not properly treated in waste management process despite the fact that Turkey is a country which has recovery and collection targets. This outboard of wastes non-treated in an environmentally friendly way, such as recycling or reuse, gives rise to environmental damage. The aim of this paper is to integrate a system dynamics and fuzzy cognitive mapping model in order to evaluate and develop recovery options of small household appliances’ wastes which are not treated according to the regulations in Turkey. The first part of the proposed model is to build a system dynamics model by developing recovery options for small household appliances’ waste management while the second part is to evaluate the relations between supporting factors of recovery options by using Fuzzy Cognitive Mapping.