COST ANALYSIS OF WATER AND WASTE WATER TREATMENT PROCESSES IN DEVELOPING COUNTRIES1

ABSTRACT: Mathematical modeling techniques are used to develop predictive equations for cost of water and waste water treatment processes in developing countries utilizing socioeconomic, environmental, and technological indicators. Predictive equations are developed for each of the three regions (Africa, Asia, and Latin America) for construction, operation, and maintenance costs of slow sand filter, rapid sand filter, stabilization lagoon, aerated lagoon, activated sludge, and trickling filter. Data analysis indicated that cost of water treatment processes is a function of technological indicator (percentage of imported materials), population, and the design capacity. The variables which gave the best correlation for waste water treatment cost were population, design flow, and the percentage of imported waste water disposal materials.     

PROCEDURE FOR SELECTING A MINIMAL ENVIRONMENTAL IMPACT ROUTING FOR A WATER CONVEYANCE CANAL1

ABSTRACT: Several techniques for selecting a least environmental impact corridor have been proposed. Two approaches have been found workable; the computer graphics and the map overlay. This report combines features of both to determine an appropriate routing for a water conveyance canal. The study was conducted by an interdisciplinary planning team. Environmental factors were mapped and weighted on overlay maps. Alternative routes were identified and carefully studied. Several critical environmental implications were noted. Aesthetic factors, out door recreation interpretation, visitor safety and disruption of human and animal travel routes were considered and dealt with.     

Analysis of the Threshold and Expected Coverage Approaches to the Probabilistic Reserve Site Selection Problem

Two approaches to formulating the reserve site selection problem when species occurrence data is probabilistic were solved for terrestrial vertebrates in a small set of potential reserve sites in Oregon. The expected coverage approach, which maximizes the sum of the occurrence probabilities, yielded solutions that covered more species on average in Monte Carlo simulations than the threshold approach, which maximizes the number of species for which the occurrence probability exceeds some threshold.     

Monitoring of Biodiversity Indicators in Boreal Forests: a Need for Improved Focus

The general principles of scale and coarse and fine filters have been widely accepted, but management agencies and industry are still grappling with the question of what to monitor to detect changes in forest biodiversity following forest management. Part of this problem can be attributed to the lack of focused questions for monitoring including absence of null models and predicted effects, a certain level of disconnect between research and management, and recognition that monitoring can be designed as a research question. Considerable research from the past decade has not been adequately synthesized to answer important questions, such as which species or forest attributes might be the best indicators of change. A disproportionate research emphasis has been placed on community ecology, and mostly on a few groups of organisms including arthropods, amphibians, migratory songbirds, and small mammals, while other species, including soil organisms, lichens, bats, raptors, some carnivores, and larger mammals remain less well-known. In most studies of community ecology, the question of what is the importance, if any, of the regularly observed subtle changes in community structures, and causes of observed changes is usually not answered. Hence, our ability to deal with questions of persistence is limited, and demographic research on regionally--defined key species (such as species linked to processes, species whose persistence may be affected, species with large home ranges, species already selected as indicators, and rare and threatened species) is urgently needed. Monitoring programs need to be designed to enable managers to respond to unexpected changes caused by forest management. To do this, management agencies need to articulate null models for monitoring that predict effects, focus fine--scale monitoring on key species (defined by local and regional research) in key habitats (rare, declining, important) across landscapes, and have a protocol in place to adapt management strategies to changes observed. Finally, agencies must have some way to determine and define when a significant change has occurred and to predict the persistence of species; this too should flow from a well--designed null model.     

痕量分析中容器的选择与洗涤

在痕量分析中,为获得准确的分析结果,容量材质以及洗涤方法的选择至关重要。试验分析表明:聚乙烯是较好的容器材料,它玷污最小、易洗涤、价廉、容器清洗。经实验证明:蒸汽法效果好,但需要相应装置;浸泡法简单易行,但消耗较大。其他方法则各有利弊,因此可根据不同的分析元素及特征,选择合适的洗涤方法。     

污泥脱水机械的选择讨论

CaSO4沉淀污泥的脱水因化学性质的特殊性，在脱水机械的选用上应考虑一些影响其脱水的因素，对部分影响因素作一些探讨。     

连续流培养好氧颗粒污泥研究进展

好氧颗粒污泥(AGS)因其沉降性能好,生物量高,抗冲击能力强等优点而受到青睐.相比于传统的序批式反应器(SBR),连续流AGS技术具有易于操作控制以及匹配实际污水厂的大水量,连续流的优势,因而更具有研究价值和应用潜力.通过文献分析和整理,归纳了连续流AGS技术面临的挑战,总结了连续流培养AGS的研究现状和经验教训,并对...     

Selecting small reserves in a human-dominated landscape: a case study of Hong Kong, China

In this case study of a degraded tropical landscape, we examine how the protected area system in Hong Kong, China, should be modified to improve its efficiency in protecting the surprisingly rich biota. The challenge lies in the fine scale of site selection, and the absence of a core area with high species richness and rarity. Site selection was first conducted in 1 km grid units by selecting hotspots and irreplaceable sites using field records for eight groups of species (amphibians, reptiles, mammals, breeding birds, ants, butterflies, dragonflies and rare vascular plants). The habitats of conservation value within the selected grid units were then delineated on the basis of expert knowledge. Recommendations for increasing the total existing protected area by 6% (i.e. an additional 2% of Hong Kong's total land area) were submitted to the Government in August 2000. To test the robustness of the results, site selection was repeated in 2001 using updated data and different selection methods. The numbers of squares selected by complementarity-based algorithms were similar to those by the hotspots and irreplaceable site method. Sites selected for rare species were very sensitive to data completeness, implying that the application of complementarity-based algorithms at fine scales might be limited.     

Distorting Gene Pools by Conservation: Assessing the Case of Doomed Turtle Eggs

Sea turtles have a high reproductive output and high mortality at early stages of the life cycle. In particular, many nests are laid below or close to high tide lines, and subsequently large numbers of eggs may be inundated and destroyed. A common conservation procedure is to relocate such doomed eggs to higher ground. This article examines this practice in the light of recent data revealing that some individual turtles tend to nest relatively near the water and others relatively higher up the beach. Discussion is focused on the question of why apparently poor placement of nests has not been selected against. Comparison between the ecology of leatherback and hawksbill turtle nesting beaches suggests that predictability of environmental conditions on the nesting beaches has an important influence on patterns of nest-site selection. Options are outlined for the management of nesting beaches where a high proportion of turtle eggs is subject to destruction by flooding. An erratum to this article is available at.     

地震灾害应急物流配送系统模型优化方法研究

为合理选择应急物流配送中心地址,提高应急管理能力,基于地震灾害风险评价数据,通过ArcGIS平台形成Voronoi图,可视化表达地震应急准备分区方案并进行应急物流中心预选址;在考虑需求权重情况下,构建应急物流配送中心优化选址模型,通过LINGO软件编程求解得出基于震灾应急准备分区的应急物流配送中心选址方案,并以A市为例,通过与传统行政区划建设方案进行对比,验证本文选址方案的有效性。研究结果表明：本文选址优化模型综合考虑各方面因素,使服务里程总量减少31.39%,单位服务量提高30.61%,验证选址方案的配送效率与公平性。