Investigating the effect of compression on solute transport through degrading municipal solid waste

The effect of applied compression on the nature of liquid flow and hence the movement of contaminants within municipal solid waste was examined by means of thirteen tracer tests conducted on five separate waste samples. The conservative nature of bromide, lithium and deuterium tracers was evaluated and linked to the presence of degradation in the sample. Lithium and deuterium tracers were non-conservative in the presence of degradation, whereas the bromide remained effectively conservative under all conditions. Solute diffusion times into and out of less mobile blocks of waste were compared for each test under the assumption of dominantly dual-porosity flow. Despite the fact that hydraulic conductivity changed strongly with applied stress, the block diffusion times were found to be much less sensitive to compression. A simple conceptual model, whereby flow is dominated by sub-parallel low permeability obstructions which define predominantly horizontally aligned less mobile zones, is able to explain this result. Compression tends to narrow the gap between the obstructions, but not significantly alter the horizontal length scale. Irrespective of knowledge of the true flow pattern, these results show that simple models of solute flushing from landfill which do not include depth dependent changes in solute transport parameters are justified.     

Enhanced degradation of the antibiotic tetracycline by heterogeneous electro-Fenton with pyrite catalysis

There is actually increasing concern about the accumulation of antibiotics, such as tetracycline, in soil and water bodies. There is therefore a need for efficient methods to degrade antibiotics and thus clean waters. Here we tested the degradation of tetracycline using the heterogeneous electro-Fenton-pyrite method and compared the results with the conventional electro-Fenton method. The reaction was performed with a boron-doped diamond or Pt anode and carbon-felt cathode allowing electrogeneration of H₂O₂ from O₂ reduction. Results show an increasing tetracycline mineralization using the following methods: anodic oxidation with electrogenerated H₂O₂, electro-Fenton and then electro-Fenton-pyrite using boron-doped diamond. Ion-exclusion HPLC revealed the complete removal of malic malonic, succinic, acetic, oxalic and oxamic acids. Nitrogen present in tetracycline was mainly mineralized in NH₄ ⁺. The higher efficiency of electro-Fenton-pyrite is explained by self-regulation of soluble Fe²⁺ and pH to 3.0 from pyrite catalyst favoring larger ^·OH generation from Fenton’s reaction.     

Assessing the Influence of Social Responsibility on Reputation: An Empirical Case-Study in Agricultural Cooperatives in Spain

The attention to ethics has gradually become a concurrent topic of modern companies’ management. In the last years Social Responsibility has become a key issue in the strategic agenda of competitive agriculture cooperatives. However, reputation management has not been a visible strength in the cooperative enterprises. First of all, this work theoretically analyzes the relationship between Social Responsibility and reputation in cooperatives. Later, from a practical point of view, we carry on an empirical analysis focused on the olive oil cooperatives in the south of Spain, in the province of Jaén. With respect to the previous studies on the topic, this work reveals a main reason of interest reinforcing the role of research in addressing real problems of cooperatives. The article points out the characteristics of this kind of agribusiness and shows the importance of the adoption of a responsible orientation in fostering reputation for creating sustainable competitive advantages.     

Robust optimization evaluation of reliance on locally produced foods

While local food production may be beneficial in terms of developing the local economy and reducing greenhouse gases from transportation, sustainability strategies focused on local food production may generate their own risks due to yield variability. We have developed a robust optimization (RO) model to determine the minimum amount of land (cropland and pasture) required to grow food items that would satisfy a local population’s (accounting for gender and age) calorie and nutrient needs. This model has been applied to Boone County, Missouri, which has a population of approximately 170,000. Boone County is 1790 km², with 16% of the land defined as cropland and 30% defined as pasture. The model includes 27 nutrients from 17 potential foods that could be produced: six fruits and vegetables, five grains and six animal-sourced foods. Yield estimates are based on the predominate methods of agriculture in the USA. We first run our model assuming no variability, using the midpoint yield estimates. Then, to quantify uncertainty in yield for different food types, we use historical yield data over 10 years to estimate this variability and run our RO model under these variability estimates. We compare the two model results to illustrate the impact of data uncertainty on meeting sustainable local food for communities. Solutions suggest that nutrition needs can be met for the Boone County population within the land area defined.     

Effects of fly ash addition on physical properties of porous clay-fly ash composites via polymeric replica technique

The porous composites of clay and fly ash have the potential to be used in many fields, such as catalyst support and gas adsorbents. In this study, various ratios of fly ash (1–2) with different percentage of suspension (50–70 wt%) were applied to produce porous clay-fly ash composites via polymeric replica technique. Fabrication process starts by mixing clay and fly ash in distilled water to form slurry. The process is followed by fully immersing polymer sponge in slurry. The excess slurry is then removed through squeezing. Finally, the sponge coated with slurry is sintered at 500 and 1250 °C for 1 h. It is found that the compressive strength of porous composites improves significantly (0.178–1.28 MPa) when the amount of clay-fly ash suspension mixture (50–70 wt%) increases. The compressive strength of porous composites is mainly attributed to the mullite, quartz and amorphous phase formations. These results are supported by X-ray diffraction analysis. On the other hand, increase in the amount of suspension reduces the apparent density (from 2.44 to 2.32 g/cm³) and porosity (from 97 to 85 %). The reduction in apparent density is believed to be caused by the presence of high fly ash content in porous composites. The melted fly ash cenospheres have closed the internal pores and increased density of samples. Higher suspension level not only reduces porosity, but also increases close pores of the porous composites. The results are justified through the observation from the structures of porous clay-fly ash composites.     

Erosional Consequence of Saltcedar Control

Removal of nonnative riparian trees is accelerating to conserve water and improve habitat for native species. Widespread control of dominant species, however, can lead to unintended erosion. Helicopter herbicide application in 2003 along a 12-km reach of the Rio Puerco, New Mexico, eliminated the target invasive species saltcedar (Tamarix spp.), which dominated the floodplain, as well as the native species sandbar willow (Salix exigua Nuttall), which occurred as a fringe along the channel. Herbicide application initiated a natural experiment testing the importance of riparian vegetation for bank stability along this data-rich river. A flood three years later eroded about 680,000 m³ of sediment, increasing mean channel width of the sprayed reach by 84%. Erosion upstream and downstream from the sprayed reach during this flood was inconsequential. Sand eroded from channel banks was transported an average of 5 km downstream and deposited on the floodplain and channel bed. Although vegetation was killed across the floodplain in the sprayed reach, erosion was almost entirely confined to the channel banks. The absence of dense, flexible woody stems on the banks reduced drag on the flow, leading to high shear stress at the toe of the banks, fluvial erosion, bank undercutting, and mass failure. The potential for increased erosion must be included in consideration of phreatophyte control projects.     

Preliminary assessment of CO2 geological storage opportunities in Greece

This paper provides a preliminary assessment of the suitability of Tertiary sedimentary basins in Northern, Western and Eastern Greece in order to identify geological structures close to major CO₂ emission sources with the potential for long-term storage of CO₂. The term “emissions” refers to point source emissions as defined by the International Energy Agency, including power generation, the cement sector and other industrial processes. The Prinos oil field and saline aquifer, along with the saline formations of the Thessaloniki Basin and the Mesohellenic Trough have been identified as prospective CO₂ geological storage sites. In addition, a carbonate deep saline aquifer occurring at appropriate depths beneath the Neogene-Quaternary sediments of Ptolemais-Kozani graben (NW Greece) is considered. The proximity of this geological formation to Greece's largest lignite-fired power plants suggests that it would be worthwhile undertaking further site-specific studies to quantify its storage capacity and assess its structural integrity.     

Geographic information systems (GIS) based model of dairy manure transportation and application with environmental quality consideration

Survey information was used to develop a minimum cost spatial dairy manure transportation model where environmental quality and crop nutrient requirements were treated as constraints. The GIS model incorporated land use types, exact locations of dairy farms and farmlands, road networks, and distances from each dairy farm to receiving farmlands to identify dairy manure transportation routes that minimized costs relative to environmental and other constraints. Our analyses indicated that the characteristics of dairy manure, its bulk and relatively low primary N, P₂O₅ and K₂O nutrient levels limit the distribution areas or distances between the farms and the land over which the manure can be economically spread. Physical properties of the land limit the quantities of nutrients that can be applied because of excess nutrient buildup in soil and potential to harm nearby waterbodies and downstream people and places. Longer distances between dairy and farmland favor the use of commercial fertilizers due to the high cost of manure transportation. At $0.08 per ton per km transportation cost, the optimal cut-off distances for dairy manure application is 30 km for N and 15 km each for P₂O₅ and K₂O consistent rules. An analysis of dairy manure application to different crop types suggest that, on average, 1 ha of land requires 61 tons of dairy manure to meet the recommended N, P₂O₅ and K₂O needs.