Mercury cleanup: The commercial application of a new mercury removal/recovery technology

Efficient, economical treatment of mercury-contaminated soils and industrial wastes requires a treatment process that reduces mercury content to near background levels (<1 ppm) and recovers the removed mercury in pure recyclable form without producing liquid, solid, or gaseous secondary wastes. This article reviews the results achieved using a medium-temperature thermal desorption process developed and commercialized by Mercury Recovery Services, Inc. (MRS) that has successfully achieved these goals.     

Case study: Using soil washing/leaching for the removal of heavy metal at the twin cities army ammunition plant

COGNIS TERRAMET® soil leaching and Bescorp soil washing systems have been successfully combined to remediate an ammunition test burn area at the Twin Cities Army Ammunition Plant (TCAAP), New Brighton, Minnesota. This cleanup is the first in the country to successfully combine these two technologies, and it offers a permanent solution to heavy metal remediation. Over 20,000 tons of soil were treated in the project. The cleaned soil remained on-site, and the heavy metal contaminants were removed, recovered, and recycled. Eight heavy metals were removed from the contaminated soil achieving the very stringent cleanup criteria of <175 ppm for residual lead and achieving background concentrations for seven other project metals (antimony, cadmium, chromium, copper, mercury, nickel, and silver). Initial contaminant levels were measured as high as 86,000 ppm lead and 100,000 ppm copper, with average concentrations over 1,600 ppm each. In addition, both live and spent ordnance were removed in the soil treatment plant to meet the cleanup criteria. By combining soil washing and leaching, COGNIS and Bescorp were able to assemble a process which effectively treats all the soil fractions so that all soil material can be returned on-site, no wastewater is generated, and the heavy metals are recovered and recycled. No hazardous waste requiring landfill disposal was generated during the entire remedial operation.     

A hierarchical approach to fisheries planning and modeling in the Columbia River Basin

The Columbia River Basin is the scene of a massive effort to restore populations of Pacific salmon (Oncorhynchus spp.) and steelhead (O. mykiss). Efficient restoration is confounded by a high level of complexity, competing sociopolitical goals and values, and uncertainty about key system properties. Simulation models and other tools of systems analysis are important to development of a comprehensive, regionally acceptable strategy. Hierarchy theory provides a useful paradigm for organized complexity within the Columbia Basin and the basis for a trilevel hierarchical structure for organizing and integrating models. Life-stage models compose the most basic simulation units at the lowest level in the proposed hierarchical modeling structure. Each life-stage model simulates a distinct period in the life cycle of anadromous salmonids. Population models at the intermediate level simulate the complete life cycles of salmon and steelhead populations. At the highest level in the hierarchy, interpopulation models simulate extensive, long-term processes that affect multiple species and stocks. A hierarchical system of models is preferable to a single model or to a group of models lacking formal structure. A principal advantage is that models have the correct spatial and temporal resolution for analyzing questions at different scales. A hierarchical structure also facilitates the flow of information among models, and aids in understanding the impacts of uncertainty. Constructing a hierarchy of models should involve both bottom-up and top-down perspectives that maintain logical consistency among models, while allowing unique model structures appropriate for each level in the hierarchy.     

Natural resource degradation in a small watershed in Nepal

Amid growing concern about the conservation of renewable natural resources, the process, extent and symptoms of their degradation are examined with specific reference to the Upper Pokhara Valley. Based on a household survey, field observations, informal deliberations and land use analysis, the results of this study reveal that forests and grazing land have been subject to increasing degradation caused by demographic, socioeconomic and institutional factors. The intensity of degradation varies by watershed. In particular, rainfed pakho land on steep slopes is under the severe threat of accelerating soil erosion, despite the construction of terraces. This calls for the formulation of a comprehensive natural resource conservation strategy which should be based on a framework comprising an integrated population control programme, planned land use changes and institutional reforms .     

Final treatment for cattle manure using immobilized microalgae. II. Influence of the recirculation

Some studies have been done dealing with cattle manure treatment, but literature scarcely reports the use of immobilized microalgae as final treatment of this waste. Recently, a complete technology for cattle manure treatment was established, including immobilized microalgae. The influence of the recirculation in the efficiency of the immobilized microalgae process was evaluated.     

An approach for analysing the potential for material efficiency improvement

Material efficiency improvement saves energy and reduces the consumption of primary resources and reduces the volume of waste. In this article an approach for analysing the potential for material efficiency improvement is proposed and discussed. In this approach the product functions performed by the materials and various improvement measures are taken into account. The potential for material saving and associated energy saving is assessed and evaluated economically. In this paper the approach is tested in an analysis of the potential for material efficiency improvement with respect to plastic packaging in the Netherlands. The technical reduction potential is found to be 34 ± 7% (157 ± 30 ktonne virgin plastics). Realization of this potential would improve the energy efficiency of the lifecycle of plastic packaging by 31% (10 PJ in 1988). From our study we conclude that our approach can indeed be used to investigate the potential for material efficiency improvement. However, a reliable technical and particularly an economical assessment of reduction measures cannot be made until more detailed data become available.     

CONTRIBUTION OF PRECIPITATION TO QUALITY OF URBAN STORM RUNOFF1

Precipitation and runoff samples were collected for 13 storms in a nonindustrial urban area in Central Pennsylvania between July 1980 and June 1981. Runoff was collected from tree surfaces, a residential roof and street, a shopping mall parking lot, a downtown business district alley, and a heavily traveled street. Analysis of the water samples showed 10 to 25 percent of the nitrogen, 25 percent of the sulfate, and less than 5 percent of the phosphorus, potassium, and calcium in water below a tree was deposited by the precipitation. The residential roof caused insignificant changes in water chemistry. The results for the four paved areas showed that all the nitrogen, and from 16 to 40 percent of the sulfate and 13, 4, and 2 percent of the phosphorus, potassium, and calcium, respectively, in runoff was deposited by the precipitation. Precipitation can also be an important source of sulfate and phosphorus in runoff. All of the surfaces raised the pH of the runoff, with the largest increases, from a pH of 4 to about 7, occurring in runoff from the paved areas. Precipitation and runoff chemistry was not related to antecedent conditions such as the length of the preceding dry period.     

Deep-Sea Mining: The Consequences of Failure to Agree at UNCLOS III

In July 1982 the US Government announced that it would not sign the new Convention on the Law of the Sea adopted at the eleventh session of the Third United Nations Conference on the Law of the Sea in April 1982. This article investigates the possible consequences of the failure to achieve a consensus between the Group of 77 and the western industrialised States on a regime to govern the deep-sea mining of manganese nodules. After considering the range of possible outcomes, the author identifies the benefits and costs involved in operating under the two alternative regimes, that provided by the new Convention and related Conference resolutions and the alternative Reciprocating States Regime based on unilateral legislation co-ordinated by a Mini-Treaty. En juillet 1982, le gouvernement des Etats-Unis a annoncé qu'il ne signerait pas la nouvelle Convention sur le droit de la mer qui a été adoptée à la llème session de la troisième Conférence des Nations Unies sur le droit de la mer en avril 1982. Cet article étudie les conséquences possibles de l'absence d'un consensus entre le Groupe des 77 et les nations industrielles occidentales sur un régime devant gouverner l'exploitation des nodules de manganèse que l'on trouve sur les fonds marins profonds. Après avoir consideéré tout un éventail de résultantes éventuelles, l'auteur dresse un état des avantages et désavantages que présentent les deux régimes possibles, c'est-à-dire le régime prévu par la nouvelle Convention et les résolutions concomitantes adoptées par la Conférence et le régime de réciprocité entre états basé sur une législation unilatérale et sanctionné par un mini-traité. En julio de 1982 el gobierno de los Estados Unidos anunció que no firmaría la nueva Convención sobre el Derecho del Maradoptada en la undécima sesión de la Tercera Conferencia de las Naciones Unidas sobre el Derecho del Mar en abril de 1982. Este artículo investiga las posibles consecuencias de la falta de consenso entre el Grupo de los 77 y los estados industriales occidentales sobre el régimen que gobierna la extracción de nódulos de manganeso en mares profundos. Después de considerar el posible rango de consecuencias el autor evalúa los costos y beneficios resultantes de operar bajo dos regímenes alternativos, aquel definido por la nueva convención y las resoluciones relacionadas y el Régimen de Reciprocidad entre Estados basado en legislación unilateral coordinados por el Mini-Tratado.