Using non-equilibrium biosorption column modelling for improved process efficiency

An unsteady-state biosorption column model in one space variable is considered in this paper. The theoretical study is motivated by the need for predicting the dependent variables of biosorption columns for removal of heavy metals from wastewater, which is potentially an important technology in cleaner production. Pollutant concentrations in the bulk phase, in the liquid filling the pores and in the solid biomass along the axial coordinate of the column were evaluated for a wide range of physical and chemical parameters of the global process. In particular, the assumption of instantaneous chemical reactions is replaced by a more realistic expression taking into account chemical kinetics and fluid advection time scales separately. The resulting system of partial differential equations was solved by means of a reliable numerical algorithm based on the method of lines. The data obtained using the model described in this paper are compared with published experimental data and an estimation of the increased efficiency is made.     

“In common nature”: an ethnography of climate adaptation in the Lesotho Highlands

In Lesotho, climate change adaptation funding is being managed and distributed by the same mechanisms which have traditionally operationalised humanitarian aid and international development assistance in the country. Lessons from the HIV/AIDS disaster, along with insights into the value of participatory approaches foregrounding the expertise of indigenous communities, must be heeded in order to ensure that those most affected by climate change have a say in how adaptation is carried out. This paper proposes that indigenous people have developed and actively maintained resilience strategies, encoded in social practices and farming techniques, designed out of long experience with climatic variability. Through case studies, indigenous resilience strategies are explored, with emphasis on the anarchistic, improvisational nature of traditional ecological knowledge. Future directions for policy-makers and practitioners dealing with climate change adaptation are suggested, namely the need to foreground indigenous knowledge and the experiences of frontlines experts in key policy arenas.     

It’s All in the Numbers: Acreage Tallies and Environmental Program Evaluation

Increasingly, performance measurement is being used to hold federal agencies accountable, represent environmental progress, and evaluate the effectiveness of environmental programs. The need to track measurable outputs has created a tendency to present programmatic progress solely by quantifiable data, despite the inherent complexity of natural resource management. Wetlands and fire management programs are two specific environmental arenas that have come to overemphasize the tracking of acreage numbers to validate existing policy direction. In both of these arenas, we find the definition and categorization of "countable" acres to be inconsistent and unreliable. We explore this systemic flaw for both wetlands and fire programs and describe its implications for environmental policy and natural resource management more broadly. We conclude with recommendations for improved performance measurement in these arenas.     

Effects of Water Availability and Habitat Quality on Bark-Stripping Behavior in Barbary Macaques

Abstract: The cedar oak forest of the Middle Atlas in Morocco is not only the last of the large forests in the southern Mediterranean, but it also contains all the surviving forest biodiversity. This forest has been severely affected by drought, overgrazing by mixed herds of goat and sheep, and excessive logging for timber, firewood, and livestock fodder. Recently, cedar bark stripping by Barbary Macaques (    Macaca sylvanus ) has begun to have an effect on the forest. We investigated this behavior by monitoring a 500-km² mosaic forest of cedar and oak in the Middle Atlas of Morocco between 1994 and 1996. We surveyed the forest 18 times in four different seasons along a 90-km transect. We recorded observations of bark stripping and a variety of quantitative ecological factors that could predict this behavior, such as livestock density, forest quality, undergrowth condition, water availability, and monkey density. The statistical analysis (including rank correlation, regression, and nonparametric variance analysis) strongly suggests that water scarcity and monkey exclusion from previously available permanent water sources are correlated with intense cedar bark-stripping behavior by macaques. The density of cedars and of monkeys appeared to be only secondary factors. As a conservation policy, making water more accessible to wild monkeys might reduce bark-stripping behavior.     

Microbial biomass yield and turnover in soil biodegradation tests: carbon substrate effects

Most of the standardized biodegradation tests used to assess the ultimate biodegradation of environmentally degradable polymers are based solely on the determination of net evolved carbon dioxide. However, under aerobic conditions, it has to be considered that heterotrophic microbial consortia metabolize carbon substrates both to carbon dioxide and in the production of new cell biomass. It is generally accepted that in the relatively short term, 50% of the carbon content of most organic substrates is converted to CO₂, with the remaining carbon being assimilated as biomass or incorporated into humus. The latter is particularly important when the metabolism of the organic matter occurs in a soil environment. A straightforward relationship between the free-energy content of a carbon substrate (expressed as the standard free-energy of combustion) and its propensity for conversion to new microbial biomass rather than mineralization to CO₂ has been established. This can potentially lead to underestimation of biodegradation levels of test compounds, especially when they consist of carbon in a fairly low formal oxidation state and relatively high free-energy content. In the present work, the metabolism of different kind of carbon substrates, especially in soil, is reviewed and compared with our own experimental results from respirometric tests. The results show that conversion of highly oxidized materials, such as the commonly used reference materials, cellulose or starch, to CO₂ may be significantly overestimated. The addition of glucosidic material to soil leads to greatly increased respiration and is accompanied by a very low conversion to biomass or humic substances. In contrast, relatively less oxidized substrates metabolize more slowly to give both CO₂ and biomass to an extent which may be significantly underestimated if glucosidic materials are used as the reference. The need for an overall carbon balance taking into account both the carbon immobilized as biomass and that volatized as CO₂ must be considered in standard respirometric procedures for assessing the biodegradability of slowly degrading macromolecules.