Chromium steel from chromite ore processing residue ?? A valuable construction material from a waste

As species we humans generate excessive amounts of waste and hence for sustainability we should explore innovative ways to recover them. The primary objective of this study is to demonstrate an efficient and optimum way to recover chromium and iron from chromite ore processing residues (COPR) for the production of chrome steel and stainless steel. In Hudson County, New Jersey, there are more than two million tons of leftover COPR. Part of COPR was used as fill materials for construction sites, which spread the problem to a larger area. With high solubility along with their toxicity leached chromate from COPR is threatening the environment as well as human health. In this research, COPR was thermally treated to recover iron with chromium by applying techniques used in steel manufacturing. An extensive experimental program was performed using a Thermo-Gravimetric Analyzer (TGA) and bench scale tests to thermally treat the processed chromium contaminated soils with carbon and sand at varying temperatures and under reducing environment. The optimum chemical composition of COPR and additives to be used in the melts were evaluated based upon the thermodynamic properties of the mixture to ensure good phase separation, least amounts of iron and chromium oxides in the slag and minimum variability of final product (steel or iron with chromium). The impact of other oxides on the steel making process was evaluated to minimize the adverse impact on the process. The research demonstrated the feasibility of recovering a valuable construction material (chrome steel) from a waste (COPR).     

Investigation of Waste Oil Disposal by Direct Incineration

Most of the reliability analyses performed today assume that the system being considered is either in the operating state or in the failed state. However, there are systems in use which are considered to be operational even when they are in certain degraded states. An example is art electrostatic precipitator. This paper will take advantage of the special physical structure of a precipitator to obtain a mathematical model for its reliability. With appropriate modifications, this methodology can be extended to other systems.     

种下一粒绿色种子--乌杜邦峡谷牧场保护区(ARC)的公众环境教育

导语:在美国,志愿者是社会生活中的一部分,在环境教育领域也是一样。在美国旧金山市,一个很小的民间自然保护区——乌杜邦峡谷牧场中就活跃着一批环境教育志愿者。这些志愿者的热情参与是这个小小民间环境组织运作成功的重要因素之一,也许大家在阅读中会得到一些启发。     

Depletion of forest resources in south eastern Nigeria: who loses?

Forest management in south eastern Nigeria has changed hands from the forest communities to foreign technology. As a result the sustainable, conservative and cyclical use that characterised the communities that lived in balance with their forest resources are no longer practised. Consequently, a great deal of the region's valuable timber trees has been lost and the environmental influences of the forest grossly reduced. The local communities have not only been deprived of a multitude of non-timber forest resources upon which they depend for their survival and well-being but have also lost their knowledge of traditional forest management. Although these consequences are far-reaching, the neglected majority in the rural areas bear the brunt. To save what is left of the once vast forest areas, communities in and around the biome need to be empowered to manage their forest resources. Empowerment will challenge their responsibility and their ability to function for the common good—themselves, the State and the world at large.     

A reassessment of the mating system characteristics of the army ant Eciton burchellii

In a recent study, Denny et al. (2004a) showed that queens of the army ant, Eciton burchellii, mate with multiple males and presented estimates suggesting that they mate with more males than queens of any other ant species so far investigated. They also inferred that data were consistent with queens being inseminated repeatedly throughout their life, which would be exceptional among the social Hymenoptera and contradictory to predictions from kin selection theory. In the present study, we reanalyze these data using new software and supplement them with similar microsatellite data from other colonies of the same species. Mating frequencies in E. burchellii are indeed very high (mean observed and effective queen-mating frequencies of 12.9 each) but considerably lower than the previous estimates. We show that the number of patrilines represented in the first worker offspring of a young queen is lower than in older queens but suggest that this may be due to initial sperm clumping in the queen’s sperm storage organ, rather than to repeated inseminations. Moreover, we found no evidence for repeated mating by genotyping sequential worker generations produced by a single old queen, showing that she did not obtain new inseminations despite ample opportunities for mating.     

Nitrogen saturation in stream ecosystems

The concept of nitrogen (N) saturation has organized the assessment of N loading in terrestrial ecosystems. Here we extend the concept to lotic ecosystems by coupling Michaelis-Menten kinetics and nutrient spiraling. We propose a series of saturation response types, which may be used to characterize the proximity of streams to N saturation. We conducted a series of short-term N releases using a tracer (15NO3-N) to measure uptake. Experiments were conducted in streams spanning a gradient of background N concentration. Uptake increased in four of six streams as NO3-N was incrementally elevated, indicating that these streams were not saturated. Uptake generally corresponded to Michaelis-Menten kinetics but deviated from the model in two streams where some other growth-critical factor may have been limiting. Proximity to saturation was correlated to background N concentration but was better predicted by the ratio of dissolved inorganic N (DIN) to soluble reactive phosphorus (SRP), suggesting phosphorus limitation in several high-N streams. Uptake velocity, a reflection of uptake efficiency, declined nonlinearly with increasing N amendment in all streams. At the same time, uptake velocity was highest in the low-N streams. Our conceptual model of N transport, uptake, and uptake efficiency suggests that, while streams may be active sites of N uptake on the landscape, N saturation contributes to nonlinear changes in stream N dynamics that correspond to decreased uptake efficiency.