Environmental and economic benefit of recycling model of packaging waste:a case study on aluminum

In order to achieve sustainable utilization of natural resources, save energy and protect environment and ecosystem, it is important for a region or a nation to develop and implement a viable waste recycling model from both theoretical and practical point of view. Some packaging recycling models operated in developed countries are introduced in this article. Aluminium can recovery and recycling is emphasized. Cost effective, economic and environmental benefit of different models are compared and analyzed. The result shows that all recycling models have their characteristics due to the initial purpose of recovery and the situation of the implementing country. However, all the models contribute to the reduction of municipal solid waste disposal and resources conservation.

Quantifying the Spatial Characteristics of the Moisture Transport Affecting Precipitation Seasonality and Recycling Variability in Central Asia

Moisture contribution and transport pathways for Central Asia(CA)are quantitatively examined using the Lagrangian water cycle model based on reanalysis and observational data to explain the precipitation seasonality and the moisture transport variation during 1979-2015.Westerly-related(northwesterly and westerly)transport explains 42%of CA precipitation and dominates in southwest CA,where precipitation is greatest in the cold season.Southeast CA,including part of Northwest China,experiences its maximum precipitation in the warm season and is solely dominated by southerly transport,which explains about 48%of CA precipitation.The remaining 10%of CA precipitation is explained by northerly transport,which steadily impacts north CA and causes a maximum in precipitation in the warm season.Most CA areas are exposed to seasonally varying moisture transport,except for southeast and north CA,which are impacted by southerly and northerly transport year-round.In general,the midlatitude westerlies-driven transport and the Indian monsoon-driven southerly-related transport explain most of the spatial differences in precipitation seasonality over CA.Moreover,the contribution ratio of local evaporation in CA to precipitation exhibits significant interdecadal variability and a meridionally oriented tripole of moisture transport anomalies.Since the early 2000s,CA has experienced a decade of anomalously low local moisture contribution,which seems jointly determined by the weakened moisture contribution from midlatitudes(the Atlantic,Europe,and CA itself)and the enhanced contribution from high latitudes(West Siberia and the Arctic)and tropical areas(South Asia and the Indian Ocean).

Physical Model of Drying Shrinkage of Recycled Aggregate Concrete

We prepared concretes（RC0, RC30, and RC100） with three different mixes. The poresize distribution parameters of RAC were examined by high-precision mercury intrusion method（MIM） and nuclear magnetic resonance（NMR） imaging. A capillary-bundle physical model with random-distribution pores（improved model, IM） was established according to the parameters, and dry-shrinkage strain values were calculated and verified. Results show that in all pore types, capillary pores, and gel pores have the greatest impacts on concrete shrinkage, especially for pores 2.5-50 and 50-100 nm in size. The median radii are 34.2, 31, and 34 nm for RC0, RC30, and RC100, respectively. Moreover, the internal micropore size distribution of RC0 differs from that of RC30 and RC100, and the pore descriptions of MIM and NMR are consistent both in theory and in practice. Compared with the traditional capillary-bundle model, the calculated results of IM have higher accuracy as demonstrated by experimental verifi cation.

Managing economic and social profit of cooperative models in three-echelon reverse supply chain for waste electrical and electronic equipment

In addition to maximizing economic benefits, reverse supply chains should further seek to maximize social benefits by increasing the quantity of waste electrical and electronic equipment （WEEE）. The paper investigates cooperative models with different parties in a three-echelon reverse supply chain for WEEE consisting of a single collector, a single remanufacturer, and two retailers based on complete information. In acldition, the optimal decisions of four cooperative models and the effect of the market demand of remanufactured WEEE products and the market share of two retailers on the optimal decisions are discussed. The results indicate that optimal total channel profit and recycle quantity in a reverse supply chain are maximized in a centralized model. The optimal total channel profit and recycle quantity increase with an increase in the market demand of remanufactured WEEE products. The three-echelon reverse supply chain consisting of duopolistic retailers maximizes total channel profit and recycle quantity in a reverse supply chain fbr WEEE.

Beat the plastic:an approach to polyethylene terephthalate(PET)bottle waste management in Nigeria

Rapid economic growth and production patterns have increased plastic consumption,plastic waste generation,and environmental pollution burden on both land and water habitats across the globe.The use of PET(polyethylene terephthalate)bottles in packaging has increased tremendously and accounts for a significant proportion of the plastic waste generated in Nigeria,along with its environment and economic cost.Achieving sustainable development goals of sustainable cities and communities,responsible consumption and production,ensure access to safe water and sanitation has necessitated the need for an efficient PET bottle waste management system.This study analyzed the PET bottle system in Nigeria and proposes an integrated PET bottle model/system for sustainable waste management,resource conservation,improved environmental sanitation,and economic development in Nigeria.Also,the need for the adoption of a holistic and indigenous approach in the formulation of the national policy on plastic waste management is emphasized,as it will encourage the citizens’participation and financial investments in waste management.

NUMERICAL SIMULATIONS OF EFFECTS OF LAND SURFACE PROCESSES ON CLIMATE——IMPLEMENTING OF SSiB IN IAP/LASG AGCM AND ITS PERFORMANCE

This is an investigation of exchanges of energy and water between the atmosphere and the vegetated continents,and the impact of and mechanisms for land surface-atmosphere interactions on hydrological cycle and general circulation by implementing the Simplified Simple Biosphere (SSiB)model in a modified version of IAP/LASG global spectral general model(L9R15 AGCM). This study reveals that the SSiB model produces a better partitioning of the land surface heat and moisture fluxes and its diurnal variations,and also gives the transport of energy and water among atmosphere,vegetation and soil explicitly and realistically.Thus the coupled SSiB-AGCM runs lead to the more conspicuous improvement in the simulated circulation,precipitation,mean water vapor content and its transport.particularly in the Asian monsoon region in the real world than CTL-AGCM runs.It is also pointed out that both the implementation of land surface parameterizations and the variations in land surface into the GOALS model have greatly improved hydrological balance over continents and have a significant impact on the simulated climate. particularly over the massive continents. Improved precipitation recycling model was employed to verify the mechanisms for land surface hydrology parameterizations on hydrological cycle and precipitation climatology in AGCM. It can be argued that the recycling precipitation rate is significantly reduced,particularly in the arid and semi-arid region of the boreal summer hemisphere,coincident with remarkable reduction in evapotranspiration over the continental area.Therefore the coupled SSiB-AGCM runs reduce the bias of too much precipitation over land surface in most AGCMs,thereby bringing the simulated precipitation closer to observations in many continental regions of the world than CTL-AGCM runs.

Experimental study on behavior of mortar-aggregate interface after elevated temperatures

A push-out test program was designed and conducted to study the meso-scale behavior of mortaraggregate interface for concrete after elevated temperatures ranging from 20℃ to 600℃ with the concept of modeled concrete （MC） and modeled recycled aggregate concrete （MRAC）. The MCs and MRACs were designed with different strength grade of mortar and were exposed to different elevated temperatures. Following that the specimens were cooled to room temperature and push-out tests were conducted. Failure process and mechanical behaviors were analyzed based on failure modes, residual load-displacement curves, residual peak loads and peak displacements. It is found that failure modes significantly depended on specimen type, the elevated temperature and the strength grade of mortar. For MC, major cracks started to propagate along the initial cracks caused by elevated temperatures at about 80% of residual peak load. For MRAC, the cracks appeared at a lower level of load with the increasing elevated temperatures. The cracks connected with each other, formed a failure face and the specimens were split into several parts suddenly when reaching the residual peak load. Residual load-displacement curves of different specimens had similarities in shape. Besides, effect of temperatures and strength grade of mortar on residual peak load and peak displacement were analyzed. For MC and MRAC with higher strength of new hardened mortar, the residual peak load kept constant when the temperature is lower than 400℃ and dropped by 43.5% on average at 600℃. For MRAC with lower strength of new hardened mortar, the residual peak load began to reduce when the temperatures exceeded 200℃ and reduced by 27.4% and 60.8% respectively at 400℃ and 600℃. The properties of recycled aggregate concrete （RAC） may be more sensitive to elevated temperatures than those of natural aggregate concrete （NAC） due to the fact that the interracial properties of RAC are lower than those of NAC, and are deteriorated at lower temperatures.