Cylinder cyclone (LARCODEMS) density media separation of plastic wastes

Cylindrical cyclone media separators using a suspended calcite separation media simulating industrial scale operations are demonstrated to effectively separate a wide variety of forms and a greater range of particle sizes of plastics by density than presently recycled. Purities of plastic products and recoveries obtained from mixed plastic wastes are comparable to those reported for established separations. Products of ≈100% purity with recoveries of >99% were obtained for high density fractions and >98% purities and recoveries for the low density fractions. Cyclonic centrifugal forces and/or the fine particle size of the separation media appear to minimize hydroscopic and particle shape effects.A mathematical model is proposed for defining plastic waste feed rates and treatable particle size ranges for the LARCODEMS media separator.Waste plastic separations yielded Ecart probable (Ep) values ?0.024 for a water only separation media. The Ep for 1.1 g cm^?3 separation medias was <0.032 with minimal to no variation in values for 1–8 mm particle sizes. Variation in the quality of separations is shown to be minimal with <72 μm, <45 μm and <2 μm media particle sizes. Media density offset created varied according to particle size.     

Removal of ammonium from aqueous solution by ion exchange on natural and modified chabazite

The ammonium exchange capacity of a natural chabazite was studied in this work. The XRD analysis of the zeolite sample revealed that the main zeolitic phase was chabazite. The textural properties were determined by the N₂-BET method and the surface morphology and charge were examined using a scanning electron microscope and a zetameter, respectively. The ion exchange equilibrium data were obtained in a batch adsorber and the Langmuir isotherm fitted plausibly well the equilibrium data. The effects of the temperature and pH on the ammonium exchange capacity of chabazite were investigated and the capacity increased augmenting the temperature from 15 to 35 °C and pH from 3 to 6. The natural chabazite was modified by a hydrothermal treatment using NaCl and KCl solutions and it was found that the modification influenced the ammonium exchange capacity of the chabazite. The ammonium capacity of natural chabazite was compared with that of a natural clinoptilolite and it was concluded that the chabazite capacity was 1.43 times higher than that of clinoptilolite.     

The application of reliability models in traffic accident frequency analysis

Analysis of traffic accident frequency represents an important subject of research of many authors. From the aspect of temporal analysis of traffic accident occurrence, two approaches have been singled out in previous practice: the collective (analyzes traffic accidents over a longer period of time) and individual (analyzes traffic accidents in real time). The paper shows that the system reliability theory, with certain adjustments, can be largely used to analyze traffic accident frequency based on the individual approach. A certain similarity has been observed between the system reliability theory and the traffic safety theory, and conceptual adjustment of equivalent terms and states has been performed based on this. A model has been successfully tested on the basis of which, for the road and sections, we have determined the traffic accident frequency, the probability of the occurrence of a certain number of traffic accidents and the mean time between two consecutive traffic accidents.     

A Framework to Evaluate Ecological and Social Outcomes of Collaborative Management: Lessons from Implementation with a Northern Arizona Collaborative Group

As collaborative groups gain popularity as an alternative means for addressing conflict over management of public lands, the need for methods to evaluate their effectiveness in achieving ecological and social goals increases. However, frameworks that examine both effectiveness of the collaborative process and its outcomes are poorly developed or altogether lacking. This paper presents and evaluates the utility of the holistic ecosystem health indicator (HEHI), a framework that integrates multiple ecological and socioeconomic criteria to evaluate management effectiveness of collaborative processes. Through the development and application of the HEHI to a collaborative in northern Arizona, the Diablo Trust, we present the opportunities and challenges in using this framework to evaluate the ecological and social outcomes of collaborative adaptive management. Baseline results from the first application of the HEHI are presented as an illustration of its potential as a co-adaptive management tool. We discuss lessons learned from the process of selecting indicators and potential issues to their long-term implementation. Finally, we provide recommendations for applying this framework to monitoring and adaptive management in the context of collaborative management.     

Surface-enhanced Raman scattering of the adsorption of pesticide endosulfan on gold nanoparticles

The absorption of pesticide endosulfan on the surface of gold nanoparticles results from the formation of micrometric structures (1–10 μm) with irregular shape because of the aggregation of individual particles. Such aggregation of gold nanoparticles after absorption of pesticide shows a surface-enhanced Raman scattering (SERS) spectrum, whose intensity depends on the concentration of endosulfan. In addition, the discoloration of the colloidal solution and a diminishing of the intensity of the surface plasmon resonance absorption from individual particles were observed by UV-visible spectroscopy. At the same time, a second band between 638 and 700 nm confirms the formation of aggregates of gold nanoparticles as the concentration of endosulfan increases. Finally, we used the SERS intensity of the S?O stretching vibration at 1239 cm^?1 from the SO₃ group as a measure of concentration of pesticide endosulfan. This method could be used to estimate the level of pollution in water by endosulfan in a simple and practical form.     

To cope or to sustain? Eroding long-term sustainability in an Indonesian coral reef fishery

Small-scale fisheries in coral reef areas support the livelihoods of millions of people worldwide. Anthropogenic impacts such as overfishing and climate change increasingly threaten both the reef ecosystem and the livelihood security of the people that depend on the reefs. Adaptive management strategies are needed to adequately deal with these threats, but they require an understanding of the underlying drivers, which often originate and act on multiple levels. Using a social-ecological system approach, the coral reef fishery of the Spermonde Archipelago in South Sulawesi/Indonesia is assessed to identify key drivers and strategic leverage points for management. Under the influence of international markets and technological changes, several export-oriented fisheries have developed in the area that led to distinct subsequent peaks in fishing activity in a pattern of sequential marine resource exploitation. In response to stressors such as seasonality and overfishing of individual locations or species, a number of coping strategies have developed locally. These include extensive borrowing from fishing patrons, diversification of fishing methods, fishing migrations, and the crafting of local institutions to regulate fishing activity. However, the coping strategies hinder, and even decrease, the capacity of the system to adapt to future stressors and undermine the sustainability of the fishery. Potential strategies that target different levels of the fishery system in order to strengthen adaptive management are identified.     

Effect of a mixture of flufenacet and isoxaflutole on population numbers of soil-dwelling microorganisms,enzymatic activity of soil,and maize yield

Abstract

This study was aimed to evaluate the effect of a mixture of flufenacet?+?isoxaflutole on counts of microorganisms, ecophysiological diversity index (EP), colony development index (CD) and on the enzymatic activity of soil and maize growth. The experiment was conducted with sandy clay, to which the tested herbicide was administered in doses of: 0.25, 5.0, 10, 20, 40, 80 and 160?mg/kg. Soil without the addition of the mixture served as the control. Results demonstrated that the tested mixture contributed to a decrease in numbers of Azotobacter, organotrophic bacteria, actinobacteria and fungi. The negative effect of the herbicide could also be noticed in the case of the enzymatic activity of soil. Soil contamination contributed to suppressed activities of dehydrogenases, catalase, urease, alkaline phosphatase and arylsulfatase. In turn, the initial increase in the activity of β-glucosidase was followed by its decline observed with time. The flufenacet?+?isoxaflutole mixture affected also maize plant growth, reducing maize dry matter yield when used at doses from 5.0 to 160?mg/kg. In summary, it may be concluded that mixture evokes a negative effect on the microbiological and biochemical activity of soil and that their excess in the soil leads to plant decay as at the seeding stage.     

Optimal planning for the sustainable utilization of municipal solid waste

The increasing generation of municipal solid waste (MSW) is a major problem particularly for large urban areas with insufficient landfill capacities and inefficient waste management systems. Several options associated to the supply chain for implementing a MSW management system are available, however to determine the optimal solution several technical, economic, environmental and social aspects must be considered. Therefore, this paper proposes a mathematical programming model for the optimal planning of the supply chain associated to the MSW management system to maximize the economic benefit while accounting for technical and environmental issues. The optimization model simultaneously selects the processing technologies and their location, the distribution of wastes from cities as well as the distribution of products to markets. The problem was formulated as a multi-objective mixed-integer linear programing problem to maximize the profit of the supply chain and the amount of recycled wastes, where the results are showed through Pareto curves that tradeoff economic and environmental aspects. The proposed approach is applied to a case study for the west-central part of Mexico to consider the integration of MSW from several cities to yield useful products. The results show that an integrated utilization of MSW can provide economic, environmental and social benefits.