bluuebunny/crossref_metadata_2025 huggingface dataset:
Waste Minimization and Recycling Strategies and Their Chances of Success
Authors: Gilnreiner Gerhard
Published: July 2007

This paper addresses a new perspective to waste minimization and recycling scenarios by combining ecological and economic aspects with facts and trends of human ethology. The work is based on the avoidable and recyclable shares of household waste fractions, which are called "potentials". The people's approval of measures exploiting these "potentials"—such as less consumption or separate collection-described as "acceptance". This "acceptance" was assessed by opinion polls that were conducted over several years, and the results were superimposed on the corresponding "potentials". This has made it possible to assess how much of the "potentials" can actually be exploited. This resulting share of exploitable minimization and recycling potentials for household waste is termed "effectiveness". The first part of this article approaches the chances of success of minimization and recycling strategies from the theoretical angle. In the second part, "effectiveness" is evaluated on the basis of data for the City of Vienna and used as a model for future trends. The results show that, on average, the household waste fractions can be reduced by 10% due to waste minimization, and by 40 to 50% due to recycling.
Characterization of Compost From a Pilot Plant-Scale Composter Utilizing Simulated Solid Waste
Authors: Schwab Burney S. , Ritchie Carla J. , Kain D. James , Dobrin G. Chris , King Lawrence W. , Palmisano Anna C.
Published: July 2007

A pilot plant-scale composter using simulated solid waste was developed to test the fate of consumer products such as disposable diapers. The simulated waste consisted of a mixture of rabbit chow (which included alfalfa), shredded newspaper, sand, and composted cow manure. The compost mass self-heated from an ambient temperature of 27°C to about 55°C in the first 24 h. Dissolved ammonia levels, high in the early stages of the process, began to decrease after about 4 weeks as nitrate concentration began to increase. Both volatile solids and carbon:nitrogen ratios exhibited gradual decreases with time. Microbial biomass, esterase activity, cellulose mineralization, direct microscopic counts (AODC), and relative APIZYM enzyme activity increased significantly in the first several days, and maintained higher levels than initial measurements throughout the 22-week testing period. We concluded that the simulated solid waste underwent physical, chemical, and microbiological changes that would be expected to occur in municipal solid waste in a full-scale composting system. The pilot plant-scale composter should prove to be a valuable tool in assessing the fate of products and materials under simulated compost conditions.
Kinetic Study of the Composting of Evergreen Oak Forestry Waste
Authors: Martinez-Iñigo M.-J. , Almendros G.
Published: July 2007

The successive stages in the composting process of forestry waste from evergreen oak ( Quercus ilx sbsp. ballota) were studied under controlled conditions (initial) carbon to nitrogen ratio = 30, T= 27°C). The original material was composted for 6 months and sampled every 15 days. The variables measured on the oak biomass in the course of the experiment showed different kinetics: the weight loss and germination index underwent a monotonic increase whereas the reducing sugars, phenols and E465/ E665 extinction ratio of the water-soluble fraction stabilized at their lowest values after the first 2 weeks. Other variables, such as alkali solubility, water repellency, pH and particle size, showed maximum or minimum values at intermediate stages of the experiment. In contrast to the adverse agrobiological effects of the direct application to soil of the original waste, germination biotests and greenhouse experiments showed that plant response improved from the 2 first weeks of composting. The kinetics observed for the parameters studied suggested that the less favourable effect on plant yield may come from phytotoxic substances in compost but also from the microbial use of soil N required for the transformation of the most biodegradable compost fractions in special hemicelluloses.
Transport of Benzene and Trichloroethylene Through a Landfill Soil Liner Mixed With Coal Slurry
Authors: Malone Rob , Warner Richard C. , Evangelou V.P. , Wong John L.
Published: July 2007

The effect of mixing three Kentucky, U.S.A. coal slurries with soil on the transport of benzene and trichloroethylene (TCE) through a compacted landfill soil liner was investigated. Using typical values for variables, assuming no competition between contaminants, and a two to one soil-coal slurry ratio all three coal slurries were predicted to maintain the concentration of benzene emanating from a landfill liner below the maximum concentration limit (MCL) of 0.005 mg/l for at least 40 years. The concentration of TCE emanating from a landfill liner was predicted to remain below 0.001 mg/l for at least 100 years. The saturated hydraulic conductivity of a compacted silty loam soil (typical landfill soil liner material) was not found to be affected by the addition of coal slurry at a ratio of two parts soil to one part coal slurry. The results presented indicate that coal slurry amended soil will slow the movement of non-ionic organic contaminants through a landfill liner while the liner retains a low hydraulic conductivity.
A Model for Environmental Costs for Corporations (Mec)
Authors: Diependaal M.J. , de Walle F.B.
Published: July 2007

Managing environmental issues and setting priorities requires an environmental costing procedure. The present study developed a "Model for Environmental Costs" (MEC) using five cost categories. The testing of the model in a furniture manufacturing plant showed that 35.2% of the total environmental costs were in effect mitigating correction costs, while 20.5% were prevention costs. Total environmental costs were 2.13% of the added value. The total amount of waste material amounted to 28% of the total material input. The MEC can be used as an internal management tool for priority setting and resource allocation, or for comparative analysis of industrial categories.
Biochemical Parameters in Soils Regenerated By the Addition of Organic Wastes
Authors: García C. , Hernández T. , Costa F. , Ceccanti B.
Published: July 2007

The effect of the addition of the organic fraction from a fresh municipal solid waste on the regeneration of a degraded soil from the Mediterranean area of Spain was studied. Sufficient waste to increase the organic matter of the soils by 0.5%, 1%, 1.5% and 21% was applied to a field in plots with a 10% incline. Forty months after treatment, increases were observed in organic matter, available nitrogen, water soluble carbohydrates and compounds determined by the Folin method (polyphenols and proteins) in all the treated plots as compared to the control. Changes were the greatest in the plot whose organic matter had been increased to 1.5%). An increase in enzymatic activity was also noticed (urease, BAA hydrolysed by protease, casein hydrolysed by protease, phosphatase, β-glucosidase and dehydrogenase) in the treated soils, particularly those which received higher rates of waste. The extracellular enzymatic activity of the plots treated with higher doses also increased, indicating a regeneration of the soils from a biochemical viewpoint. A positive correlation was observed between the parameters referring to microbial biomass and the enzymatic activities determined in the soils.
An Optimization Approach for Locating a Hazardous Waste Disposal Facility in Istanbul Province
Authors: Or Ihan , Akgül Mustafa
Published: July 2007

In the present paper, the problem of locating a hazardous waste disposal facility in Istanbul province is taken up as an "undesirable" facility location problem. An optimization model is set up, in which the objective is to maximize the minimum distance of the location to be selected, to a set of predetermined, environmentally sensitive entities. Topographical conditions and restricted areas are defined using a series of linear and circular inequality constraints. The solution procedure implemented to the resulting constrained nonlinear optimization problem is briefly discussed and various solutions obtained under different parameter settings are presented.
The Handling and Disposal of Residuals From the Treatment of Urban Stormwater Runoff From Separate Storm Drainage Systems
Authors: Field Richard , O'Shea Marie L.
Published: July 2007

Given the magnitude of stormwater runoff (from separate storm drainage systems) and its pollutional contribution, the treatment of stormwater would generate residuals in amounts equal to or in excess of the volume of sludge now generated by municipal wastewater treatment. The characteristics of stormwater runoff differ substantially from that of wastewater or combined sewer overflow (CSO) in several important parameters, most notably suspended solids (SS) and organic content. The increased SS content of stormwater runoff results in higher volumes of residuals and increased handling and disposal costs. Similarly, the lower organic and nutrient content of stormwater runoff limits both the effectiveness of conventional biological treatment processes and land application disposal options. Several treatment and handling approaches are discussed and evaluated, including both centralized and satellite options. In addition, the primary and secondary economic (e.g. cost, land requirements) and environmental (e.g. air and water pollution, public health, etc.) impacts of stormwater runoff residuals treatment, handling, and disposal are reviewed.
Wet Oxidation of Refractory Organic Compounds in Industrial Aqueous Wastes Via the Oxyjet Technology
Authors: Gassó S. , González M. , Baldasano J.M. , Lemonnier J.P. , Abatzoglou N. , Chornet E.
Published: July 2007

The work presented in this paper is concerned with the application of a jet-mixer device to the wet oxidation process. This device allows the formation of a mist two-phase flow that leads to oxidation of the organic matter in a kinetically controlled regime. Thus a compact technology, denoted as OXYJET, based on jet-mixers and tubular reactors has been developed. The oxidation of standard solutions used as prototype of toxic effluents and organic industrial aqueous wastes is considered. In the experimental work, total organic carbon (TOC) feed concentration ranged between 3400 to 80000 mgl-1.
Modeling Spatial Variation in the Demand for Waste Collection Service
Authors: Petersen Terry D. , Su Ruby T. , Massie Keith J. , Reinke David
Published: July 2007

Three models were developed for spatially projecting the demand for waste collection service by manufacturing, retail, and service businesses, and were compared with a model commonly used for this purpose. Model I is similar to most earlier work in which unit demand rates (kg employee-1 wk-1) are estimated for a variety of businesses. These rates are then multiplied by the number of employees in the area being modeled. Model II differs from Model I in that unit demand rates are estimated for businesses of different sizes (number of employees), rather than activities. In Model III businesses are cross-classified by both activity and size, and then unit demand rates are estimated within each class. Data for model estimation were obtained by weighing waste deposited for collection by 435 businesses over a 25-wk period in the Portland, Oregon metropolitan region. Business size accounted for significantly more of the variation in unit demand rate than did business activity. This suggests that demand models used in planning solid waste collection and disposal systems can be improved by including indicators of business size.
Measurement of Microbial Biomass and Activity in Landfill Soils
Authors: Bogner J.E. , Miller R.M. , Spokas K.
Published: July 2007

Two complementary techniques, which have been widely used to provide a general measure of microbial biomass or microbial activity in natural soils, were evaluated for their applicability to soils from the Mallard North and Mallard Lake Landfills, DuPage County, Illinois, U.S.A. Included were: (1) a potassium sulphate extraction technique with quantification of organic carbon for measurement of microbial biomass; and (2) an arginine ammonification technique for microbial activity. Four profiles consisting of replaced soils were sampled for this study; units included topsoil (mixed mollisol A and B horizons), compacted clay cover (local calcareous Wisconsinan age glacial till), and mixed soil/refuse samples. Internally consistent results across the four profiles and good correlations with other independent indicators of microbial activity (moisture, organic matter content, nitrogen, and phosphorus) suggest that, even though these techniques were developed mainly for natural mineral soils, they are also applicable to disturbed landfill soils.
The Influence of Fly Ash Load and Particle Size On the Formation of Pcdd, Pcdf, PCBz and Pcb in a Pilot Incinerator
Authors: Fangmark Ingrid , Strömberg Birgitta , Berge Nils , Rappe Christoffer
Published: July 2007

A laboratory-scale, fluidized bed reactor fuelled by a synthetic fuel was used to study the influence of fly ash load, particle size, temperature and residence time on the low-temperature formation of chlorinated aromatic compounds. Large fly ash particles were removed from the flue gases by means of a cyclone at the entrance to the cooling section of the reactor. The experimental variables were varied according to an experimental plan of full factorial design. Polychlorinated dibenzo- p-dioxins, dibenzo-furans, polychlorinated benzenes and biphenyls were analysed in the collected flue gas samples. Despite the fact that most of the fly ash load was removed by the cyclone, formation of chlorinated aromatics occurred to the same extent as in earlier experiments, without the cyclone. These results demonstrate the importance of small fly ash particles in the post-combustion formation of chlorinated aromatics.
Occurrence of Enteric Pathogens in Composted Domestic Solid Waste Containing Disposable Diapers
Authors: Gerba Charles P. , Huber Mary S. , Naranjo Jaime , Rose Joan B. , Bradford Susan
Published: July 2007

Information has not been previously available on the occurrence of enteric pathogenic viruses and protozoan parasites in composted municipal domestic solid waste. A potential source of these pathogens in domestic solid waste is disposal diapers. The occurrence of enteroviruses, Giardia cysts, Cryptosporidium oocysts and Salmonella were determined in municipal composted domestic solid waste, and solid waste to which extra diapers had been added to increase their concentration 2-4 fold (6.6-7.7% by weight) above that found normally in municipal solid waste before composting. The compost was tested at various periods of time during aging (101-203 days). No enteroviruses or protozoan cysts or oocysts were detected in any of the samples collected during this period. One sample out of 19 collected (after 175 days aging) was positive for Salmonella. These results suggest that enteric pathogens were destroyed during the composting process, or were present in numbers below the detection method (i.e. one organism per 40-50 g of compost) used in this study.
Evaluation of the Homogeneity of Stabilised/ Solidified Wastes By a Video Imaging Technique
Authors: Gao Yi-Min , Mei Liu  , Grow James M. , Knox Dana E.
Published: July 2007

A video imaging technique is described for the homogeneity assessment of wastes that have been treated by stabilisation/solidification (S/S). The method incorporates a fluorescent tracer into the S/S reagent. A test "waste" consisting of an artificial soil was stabilised/solidified with varying degrees of mixing using Portland cement as the S/S reagent. The tracer distribution was monitored with a video camera, and the cement distribution was determined by chemical analysis for calcium. Measurement of the homogeneity of the products by the video imaging technique gave results comparable to those obtained by the chemical analysis. The results warrant use of the video imaging technique in field applications since it is easier, cheaper and faster than traditional chemical methods. © 1995 ISWA
Polypropylene Strap Reinforcement in Compacted Coal Mining Wastes
Authors: Bouazza A. , Wei M.J. , Finlay T.W.
Published: July 2007

This paper reports the results of a test programme to determine the friction characteristics of polypropylene straps embedded in compacted colliery spoil. These straps are being considered as an alternative to traditional high adherence galvanized steel straps because of possible corrosion problems associated with steel straps. Laboratory tests have been performed to assess the suitability of colliery discards as backfill material and the soil-strap interaction. The test results showed that the more angular fill gave higher pull-out resistance and friction values. The results provide information on the friction characteristics which can be used in the design of reinforced earth retaining walls using compacted coal wastes as the fill material. Finally, comparison is made of the cost benefits of using these materials in a more conventional structure.
Landfill Gas Migration—Field Investigations At Skellingsted Landfill, Denmark
Authors: Kjeldsen Peter , Fischer Erling V.
Published: July 2007

The background for a landfill gas explosion accident which happened at Skellingsted Landfill in Denmark was investigated. To understand the behaviour of the lateral migrating landfill gas in the area where the accident occurred, an intensive investigation was carried out after the explosion accident measuring time-series of gas composition in 30 wells over a 35-day period. The changes in gas composition in selected wells following a decrease in barometric pressure were measured over a 33-h period. The maximal distance for measured methane concentrations above 5% (vol.) in the pore gas was 90 m. The investigations showed that changes in barometric pressure have a great impact on the pore gas composition. Indications of methane oxidation were observed down to 2 m below ground in distances of more than 60 m from the landfill.
Solid Waste Management in Tehran
Authors: Abduli M.A.
Published: July 2007

The main objective of this paper is to analyse the present status of solid waste management in Tehran, and subsequently, to draw up a policy regarding their generation, collection, on-site handling, storage, processing, recycling, transportation and safe disposal.

Through a detailed survey, all functional elements of the present solid waste management system in Tehran were studied. Factors affecting the important management issues in the operation of Tehran's solid waste management system are discussed. Key design data and other useful information selected from a variety of reliable sources are presented. The practical aspects associated with solid waste management systems, such as organizational structure, financing, operations, equipment management, personnel, reporting, cost accounting and budgeting, ordinances and guidelines, and public communications are described. © 1995 ISWA
Landfill Settlement and the Impact On Site Capacity and Refuse Hydraulic Conductivity
Authors: Bleiker David E. , Farquhar Grahame , McBean Edward
Published: July 2007

A settlement model was developed for predicting the compression of each layer of refuse in response to the weight of overlying refuse in deep landfills. The compression of each layer was used to estimate its hydraulic conductivity which was used to simulate leachate movement through the refuse mound. The results indicated that low refuse hydraulic conductivity at the bottom of the landfill interferes with movement of the leachate down to the leachate collection system (LCS), and that a leachate mound can form in the refuse above an operating LCS. This leachate mound has the potential to cause leachate side seeps and could interfere with the landfill gas collection system. If these are concerns at a specific site, alternative LCS designs to high permeability layers on low permeability liners should be considered. However, the results also indicate that a leachate mound within the refuse is not necessarily indicative of the head on the liner. © 1995 ISWA
Stabilization of Residue Containing Heavy Metals By Means of Matrices Generating Calcium Trisulphoaluminate and Silicate Hydrates
Authors: Albino V. , Cioffi R. , Santoro L. , Valenti G.L.
Published: July 2007

Two binding matrices based on blast furnace slag or fly ash/lime mixtures were studied in relation to the stabilization/solidification of a residue from a municipal solid waste incinerator. Their use is of interest because of the formation of calcium trisulphoaluminate and silicate hydrates.

Mixtures of the above matrices with up to 80% of the incinerator residue were paste-hydrated and cured for 28 days at 25°C and 100% relative humidity. The effect of added waste on the hydration phenomena was studied by means of differential thermal analysis and X-ray diffraction analysis. The effectiveness of these systems as stabilization/solidification matrices was checked by means of mechanical and leaching tests. Cured samples with up to 20-40% of added waste gave compressive strengths sufficiently high for reuse as building materials.

The U.S. Environmental Protection Agency leaching test has shown that disposal in a landfill in which no facilities for collecting and treating percolating waters are provided, is possible with 40-60% of waste content.

Finally, the American Nuclear Society dynamic leaching test has shown that the entrapment is mainly dependent on the physical binding potential of the matrices. © 1996 ISWA
Recommendations for the Management of Wastes From Healthcare Facilities in Helsinki
Authors: Pönkä Antti , Kaski Alli , Lähdevirta Juhani
Published: July 2007

In Helsinki, Finland, new guidelines have been adopted for the management of wastes from healthcare facilities. The purpose has been to rationalize waste management, reducing the amount of waste needing special treatment and lowering costs, while at the same time maintaining occupational safety and preventing environmental hazards. The changes are mainly due to the new definition of infectious waste, based on practical assessment of the possibility of spread of infection via the wastes. As a result, it has been possible to omit one chain of waste handling which has led to simpler practices and economic benefits. Sanitary landfill has been accepted for disposal of clinical waste, except for the biological waste to be incinerated for ethical reasons and infectious waste contaminated by class 4 viruses, Yersinia pestis or Bacillus anthracis. Diseases caused by these micro-organisms are not a practical problem in Finland. © 1996 ISWA
Enumeration of Anaerobic Refuse-Decomposing Micro-Organisms On Refuse Constituents
Authors: Xingdong Qian  , Barlaz Morton A.
Published: July 2007

Hydrolytic, acetogenic and methanogenic bacteria are required for the conversion of refuse to methane in landfills. In order to identify sources of these trophic groups in refuse, the total anaerobic population and the sub-populations of cellulolytic, hemicellulolytic, butyrate catabolizing acetogenic, and acetate- and H2-CO2 -utilizing methanogenic bacteria as present on grass, leaves, branches, food waste, whole refuse and two landfill cover soils were enumerated by the most probable number (MPN) technique. Total anaerobes ranged from 10 3 cells per dry gram in cover soil to 109 in grass, food waste and fresh refuse. Hemicellulolytics ranged from 160 cells per dry gram in cover soil to 109 in grass. The highest cellulolytic population was measured on branches (316 cells per dry gram), while the maximum acetogenic population was measured on leaves (2.5 x 104). The highest methanogen populations were measured on leaves (6.3 x 103) and one of two fresh refuse samples (105). Yard waste was the major carrier of the trophic groups required for refuse decomposition, while the cover soils tested did not represent major inputs of the requisite bacteria to landfills. © 1996 ISWA
Laboratory Sorption and Hydraulic Conductivity Tests: Evaluation of Modified-Clay Materials
Authors: Lo Irene M-C. , Liljestrand Howard M.
Published: July 2007

This study examines a new design philosophy for liner systems; that of controlling the hydraulic conductivity of leachate as a whole as well as retarding the advective and diffusive fluxes of pollutants by increasing the sorption of pollutants onto the liner systems. Claymax® (pure clay) and Organo-Clay (commercially available clays coated with organic amines) were evaluated as hydraulic barriers and as resistances to pollutant transport. Batch adsorption tests show that the removal capacity of lead by Claymax is 12-fold greater than that of Organo-Clay. However, the partition coefficients of a series of chlorobenzenes for Organo-Clay are 420-600 times greater than those for Claymax. The hydraulic conductivity of Claymax to tap water is at least two orders of magnitude lower than the value of 1 x 10-7 cms-1 for a clay liner required by the United States Environmental Protection Agency (EPA). Moreover, the hydraulic conductivity of Claymax with Organo-Clays is virtually unaffected when it is permeated with synthetic leachate. © 1996 ISWA
The "Recycling" of Densified Refuse-Derived Fuel
Authors: Alter H.
Published: July 2007

People are beginning to look again at densified refuse-derived fuel (d-RDF) for use in stoker boilers. The several advantages of this form of fuel will not be realized unless and until improvements are made in its preparation and properties. The history of d-RDF is reviewed as a way of teaching how to do this. © 1996 ISWA
Stick or Carrot?: the Use of Policy Measures To Move Waste Management Up the Hierarchy
Authors: Wilson David C.
Published: July 2007

A systematic shift in waste management away from disposal and towards waste prevention and recycling requires the use of an integrated set of policy measures to change the behaviour of waste generators; industry, commerce and consumers. This paper uses comprehensive data on policy measures in some 25 countries to examine the available options. The conclusion is that a balanced strategy needs to combine information dissemination mechanisms, legislative "sticks", producer responsibility, other economic "sticks" and economic "carrots". © 1996 ISWA
Optimization of Infectious Hospital Waste Management in Italy: Part II. Waste Characterization By Origin
Authors: Liberti L. , Tursi A. , Costantino N. , Ferrara L. , Nuzzo G.
Published: July 2007

This second paper in a two-part series offers more detailed data on the physicochemical characteristics of normal (NHW) and infectious (IHW) hospital waste determined experimentally in a large sanitary district that includes four hospitals, public and private, with 164 sanitary departments, 40 analytical laboratories and 2500 rehabilitation beds, near the town of Bari (Southern Italy). The wide variation of experimental results may be better understood if reference is made to the origin of such waste, i.e. to the types of medical departments and sanitary services wherein waste production appears to be related strictly to the therapeutic or diagnostic procedures adopted. In all cases, IHW was shown to be classified as "non-toxic" deserving 950°C rather than 1200°C incineration temperature according to Italian legislation. © 1996 ISWA
Solid Waste Management System Analysis With Air Pollution and Leachate Impact Limitations
Authors: Chang Ni-Bin , Shoemaker Christine A. , Schuler Richard E.
Published: July 2007

Conventional location/allocation models for solid waste management usually focus on the economic optimization. However, the siting of important facilities, such as landfills, incinerators and transfer stations, in the solid waste management system still encounters several other limitations which must be considered through the use of optimization techniques. This paper presents sustainable waste management strategies in which the decision makers may put forward their views on material recycling and the assimilative capacity of the environment for two major factors; air pollution control and leachate impact. A mixed integer programming model with the framework of dynamic optimization is applied to achieve such a goal.
Numerical Modelling of Generation and Transport of Gas and Heat in Landfills I. Model Formulation
Authors: El-Fadel M. , Findikakis A.N. , Leckie J.O.
Published: July 2007

A mathematical model for the generation and transport of gas and heat in a sanitary landfill was developed based on earlier work on the Mountain View Controlled Landfill Project (MVCLP) in California, U.S.A. The present model incorporates biokinetic model equations describing the dynamics of the microbial landfill ecosystem into multi-layer, time-dependent transport and generation of gas and heat models. It is based on the fundamental principles governing the physical, chemical and microbiological processes in a porous media context such as a sanitary landfill. The model includes biochemical and temperature feedback loops to simulate the effects of their corresponding parameters on microbiological processes. The resulting integrated biokinetic, gas and heat generation and transport model was used to simulate field data from the MVCLP and to assess the sensitivity of model results to biological parameters. The model can be used to predict the rate and total production of methane in a landfill. The present work is presented in a series of three papers: (I) model formulation; (II) model application; and (III) sensitivity analysis*.
Numerical Modelling of Generation and Transport of Gas and Heat in Sanitary Landfills Ii. Model Application
Authors: El-Fadel M. , Findikakis A.N. , Leckie J.O.
Published: July 2007

A mathematical model for the generation and transport of gas and heat in a sanitary landfill was developed based on earlier work on the Mountain View Controlled Landfill Project (MVCLP) in California, U.S.A. The present model incorporates biokinetic model equations describing the dynamics of the microbial landfill ecosystem into multi-layer, time-dependent transport and generation of gas and heat models. It is based on the fundamental principles governing the physical, chemical and microbiological processes in a porous media context such as a sanitary landfill. The model includes biochemical and temperature feedback loops to simulate the effects of their corresponding parameters on microbiological processes. The resulting integrated biokinetic, gas and heat generation and transport model was used to simulate field data from the MVCLP and to assess the sensitivity of model results to biological parameters. The model can be used to predict the rate and total production of methane in a landfill. The present work is pressented in a series of three papers: (I) model formulation; (II) model application; and (III) sensitivity analysis*.
Determination of Organic Parameters in Waste and Leachates From the Hazardous Waste Landfill of Raindorf; Germany
Authors: Gade B. , Layh M. , Westermann H. , Amsoneit N.
Published: July 2007

Extensive investigations of leachates and solid waste samples for organic sum parameters and environmentally relevant organic compounds were carried out at the hazardous waste landfill of Raindorf, which is operated in accordance with German Technical Instructions on Waste (TI Waste). The measurements showed that the majority of the waste samples contained only minor amounts of phenols, highly volatile chlorinated organic compounds (VCHC), benzene, toluene, ethylbenzene and xylene (BTEX), polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH). The concentrations ranged from less than 100 μg/kg-1 up to 1000 μg/kg-1 of dry substance. Only hydrocarbons were detected in higher concentrations (mg to g kg-1 of dry substance). In most leachate and gas samples taken at the landfill, the concentrations of the abovementioned parameters were close to or even below the detection limit. The measurement of organic single compounds underlined the usefulness of the sum parameters, adsorbable organic halogen compounds and phenol index, for the estimation of the total amount of these substances. A comparison of organic sum parameter concentrations measured in leachates from landfills of differing ages indicates that the application of TI Waste leads to a reduction of the organic load in the leachate. © 1996 ISWA
Local Management of Hazardous Wastes From Small-Scale and Cottage Industries
Authors: Bartone Carl R. , Benavides Livia
Published: July 2007

This paper reviews, documents and discusses the hazardous waste problems associated with small-scale and cottage industries (SSIs) in developing countries. It aims at achieving a better understanding of the characteristics of SSIs, helps to identify those industries that contribute significantly to environmental pollution and occupational exposure, and focuses attention on local management options. Four case studies confirm that the troublesome SSIs are highly concentrated in urban areas and give rise to local impacts primarily. Priorities for action will almost certainly include some combination of information and educational campaigns for SSI owners and workers, accompanied by policies and incentives to promote good housekeeping and the adaption of low-waste, efficient production technologies, and by some form of collective waste handling—possibly through industrial relocation, but more likely by local waste collection and treatment systems whether municipal or private. To succeed, coordinated actions are needed by national and local officials, local training and technology transfer centers, non-governmental organisations (NGOs) and industrial associations. International technical and financial assistance can help promote and support such local actions. © 1997 ISWA
Seasonal and Diurnal Methane Emissions From a Landfill and Their Regulation By Methane Oxidation
Authors: Börjesson Gunnar , Svensson Bo H.
Published: July 2007

Rates of methane emission from a Swedish landfill, measured by chamber technique and permanent frames, ranged between 0.034 and 20 mmol CH4 m-2.h-1 on average. The emissions followed a seasonal pattern, with the highest fluxes occurring between September and May. Methane concentrations in soil also followed a seasonal pattern, with a marked decrease during summers. Using the means of methane emission rates from frost-free periods, a stepwise regression model was made, that could explain 95% of the variation. Soil temperature turned out to be the dominating factor, explaining 85% when transformed to a second-degree function. Methane emissions were negatively correlated with soil temperature, which strongly suggests that biological methane oxidation is an important regulating factor. The activity of methane-oxidizing microorganisms was greatest around 0.5-0.6 m depth in the soil profile, and moisture at this level enhanced emissions. The tendency for methane emissions to be higher at night was probably due to the inhibitory influence of low soil temperatures on methane-oxidizing microorganisms. © 1997 ISWA
Time and Time Again: The Phylogeny of Melatonin as a Transducer of Biological Time
Authors: Cassone Vincent M. , Natesan Arjun K.
Published: July 2007

The circadian secretion of melatonin is a critical component in circadian and seasonal rhythms in many vertebrate species. This hormone is produced by photoreceptors and cell types derived from photoreceptors in vertebrate retinas and pineal complexes via circadian regulation of the biosynthetic enzymes arylalkylamine N-acetyltransferase and hydroxyindole- O-methyltransferase at both transcriptional and posttranscriptional levels. The question of whether other multicellular animals and organisms from other taxa produce melatonin in a homologously regulated pathway is at this point unclear, but preliminary evidence suggests that vertebrate and insect melatonin are produced by convergent or parallel phylogenies. The existence and function of algal and plant melatonin is worthy of further study but is unresolved at this point. In vertebrates, the role of melatonin in behavioral and systems physiology follows two phylogenetic patterns. First, the circadian regulation of visual system structures, including the hypothalamic suprachiasmatic area, the inner retina, and retinorecipient and integrative visual structures, is a primitive characteristic among vertebrate species. Second, the relative loss of visual regulation and the presence of melatonin binding in the pars tuberalis of the adenohypophysis among mammals is a derived characteristic because these characteristics are present in this group only
Melatonin Receptors: Molecular Biology of a New Family of G Protein-Coupled Receptors
Authors: Reppert Steven M.
Published: July 2007

A family of high-affinity, G protein-coupled receptors for the pineal hormone melatonin has been cloned from vertebrates. These recombinant receptors exhibit similar affinity and pharmacological characteristics to each other and to endogenous receptors, as defined with the melatonin agonist 2-[ 125I]iodomelatonin (125I-Mel). Two mammalian melatonin receptor subtypes have been identified by molecular cloning studies. The mammalian Mel1a melatonin receptor is expressed in most sites containing 125I-Mel binding. This includes the hypothalamic suprachiasmatic nucleus and hypophyseal pars tuberalis, presumed sites of the circadian and some of the reproductive actions of melatonin, respectively. The mammalian Mel 1b melatonin receptor is expressed in retina and brain and may mediate the reported effects of melatonin on retinal physiology in some mammals. A third receptor subtype, the Mel1c melatonin receptor, has been cloned from zebra fish, Xenopus, and chickens but not from mammals. Molecular cloning of a melatonin receptor family now makes possible gene targeting to precisely determine the physiological role(s) of each receptor subtype.
Photic Regulation of Melatonin in Humans: Ocular and Neural Signal Transduction
Authors: Brainard George C. , Rollag Mark D. , Hanifin John P.
Published: July 2007

Light is a potent stimulus for regulating the pineal gland's production of melatonin and the broader circadian system in humans. It initially was thought that only very bright photic stimuli (≥ 2500 lux) could suppress nocturnal melatonin secretion and induce other circadian responses. It is now known that markedly lower illuminances (≤ 200 lux) can acutely suppress melatonin or entrain and phase shift melatonin rhythms when exposure conditions are optimized. The elements for physical/biological stimulus processing that regulate photic influences on melatonin secretion include the physics of the light source, gaze behavior relative to the light source, and the transduction of light energy through the pupil and ocular media. Elements for sensory/neural signal processing become involved as photons are absorbed by retinal photopigments and neural signals are generated in the retinohypothalamic tract. Aspects of this physiology include the ability of the circadian system to integrate photic stimuli spatially and temporally as well as the wavelength sensitivity of the operative photoreceptors. Acute, light-induced suppression of melatonin is proving to be a powerful tool for clarifying how these elements of ocular and neural physiology influence the interaction between light and the secretion of melatonin from the human pineal gland.
Melatonin as a Chronobiotic: Treatment of Circadian Desynchrony in Night Workers and the Blind
Authors: Sack Robert L. , Lewy Alfred J.
Published: July 2007

Although the causes are different, totally blind people (without light perception) and night shift workers have in common recurrent bouts of insomnia and wake-time sleepiness that occur when their preferred (or mandated) sleep and wake times are out of synchrony with their endogenous circadian rhythms. In this article, the patterns of circadian desynchrony in these two populations are briefly reviewed with special emphasis on longitudinal studies in individual subjects that used the timing of melatonin secretion as a circadian marker. In totally blind people, the most commonly observed pattern is a free-running rhythm with a stable non-24-h circadian period (24.2-24.5 h), although some subjectively blind people are normally entrained, perhaps by residually intact retinoypothalamic photic pathways. Experiments at the cellular and behavioral levels have shown that melatonin can produce time dependent circadian phase shifts. With this in mind, melatonin has been administered to blind people in an attempt to entrain abnormal circadian rhythms, and substantial phase shifts have been accomplished; however, it remains to be demonstrated unequivocally that normal long-term entrainment can be produced. In untreated night shift workers, the degree and direction of phase shifting in response to an inverted sleepwake schedule appears to be quite variable. When given at the optimal circadian time, melatonin treatment appears to facilitate phase shifting in the desired direction. Melatonin given prior to a night worker's daytime sleep also may attenuate interference from the circadian alerting process. Because melatonin has both phase-shifting and sleep-promoting actions, night shift workers, who number in the millions, may be the most likely group to benefit from treatment.
The Acute Soporific Action of Daytime Melatonin Administration: Effects on the EEG during Wakefulness and Subjective Alertness
Authors: Cajochen Christian , Kräuchi Kurt , Wirz-Justice Anna
Published: July 2007

Melatonin has been reported to have soporific effects; following daytime administration, it induces sleepiness and reduces sleep onset latency. However, subjective sleepiness is masked by a variety of stimuli and behaviors; thus, it is important to be able to delineate objective psychophysiological sequelae of melatonin administration. Alertness decrements during wakefulness are correlated with augmented theta/alpha power in the waking electroencephalogram (EEG). This has been validated in a constant routine protocol. In a variety of experiments with melatonin administration (5 mg), the authors have shown that the EEG changes can be measured immediately, before any subjective soporific effects are recognized. These increases in theta/alpha power occur when melatonin is administered during the day (1300 or 1800 h) but are less visible when near the endogenous melatonin rise in the evening (2040 h). Importantly, both subjective and objective measures of sleepiness are suppressed when subjects change posture from supine to standing.
Efficacy of Melatonin as a Sleep-Promoting Agent
Authors: Zhdanova Irina V , Wurtman Richard J.
Published: July 2007

Numerous studies have demonstrated sleep-promoting effects of melatonin treatment in humans, as evidenced by subjects' self-reports, polysomnographic recordings, and continuous actigraphic registration of motor activity. The sleep-promoting effects of either physiological or pharmacological doses of melatonin typically are observed within 1 h following treatment regardless of the time of melatonin administration. This fact indicates the acute nature of this effect of melatonin on sleep, independent of any effect of the melatonin treatment on circadian organization. This article considers a dose dependency of melatonin effects on sleep, interindividual variability, and age-related differences in circulating melatonin levels produced in response to a given dose of the hormone. Possible side effects of melatonin treatment, and the use of an animal model to serve as a guide in the development of therapeutic applications, also are considered.
Efficacy of Melatonin as a Hypnotic Agent
Authors: Mendelson Wallace B.
Published: July 2007

The seemingly contradictory literature on the use of melatonin in insomnia is best understood by considering issues of time of administration (day or night), dose range (physiological or pharmacological), subject selection (normals or insomniacs), choice of dependent variable (self-report or electroencephalogram), and comprehensiveness of the reported variables (sleep onset or sleep maintenance). Available data on nighttime administration to normals and insomniacs are reviewed. It is concluded that there is not yet a convincing body of evidence, using generally accepted measures, that melatonin administration improves sleep in insomniacs with noncircadian sleep disturbance.
Taiwanese International Students: Acculturation Level and Vocational Identity
Authors: Shih Shu-Fen , Brown Chris
Published: July 2007

This study explored the relationship between acculturation level and vocational identity among 112 graduate and undergraduate Taiwanese international students attending two midwestern universities. The results revealed that Taiwanese international students who were older and who had a shorter length of U.S. residency were more likely to identify themselves as Asian. The results also indicated that Taiwanese international students who were older and who had a lower acculturation level had higher vocational identity.
Career Counseling for Longevity: Self-Care and Burnout Prevention Strategies for Counselor Resilience
Authors: Skovholt Thomas M. , Grier Tabitha L. , Hanson Matthew R.
Published: July 2007

Balancing self-care and other-care is often a struggle for career counselors and others in the helping professions. The process of caring is made up of a constant series of empathic attachments, active involvements, and felt separations. The ability to continually engage in "the caring cycle" is important for success. However, the constant need to re-create the cycle of caring can lead to counselor depletion and burnout. This article provides a developmental framework for assisting career counselors to avoid depleted caring while prolonging their professional longevity. The model of self-care includes recognizing the hazards of "high touch" work, such as limited resources and constant one-way caring. Also addressed are specific means of professional and personal sustenance, such as maximizing experiences of professional success and balancing personal wellness throughout one's career.
How the Decision-Making Literature Might Inform Career Center Practice
Authors: Krieshok Thomas S.
Published: July 2007

Krieshok (1998) reviewed the empirical literature and concluded with ten things the field knows for sure about career decision-making, as well as ten things we assume we know but which the literature suggests need reconsideration. This article summarizes those findings in light of their implications for career center practice, including less emphasis on becoming decided, more emphasis on acting as one's own agent, and the importance of addressing clients' resistance to engaging in anything more than simple short-term interventions.
The Computerization of Career Services: Critical Issues to Consider
Authors: Davidson M. Meghan
Published: July 2007

Increasingly, career centers on university and college campuses are making use of the World Wide Web to help their users with a myriad of career related needs. This technological service delivery mode has many advantages that will be briefly reviewed in this article. As well, a computer emphasis has the potential for drastically changing career centers as we know them: their traffic patterns, staffing needs, resource procurement, and perhaps most importantly, their outcomes in the lives of the students who make use of them. This article discusses these changes and through a review of seven critical issues, challenges the reader to closely examine the implications for technology within their own career centers.
Horizons: 2000
Authors: Bartholomew Cheryl G.
Published: July 2007

This article presents evidence that girls are not receiving an equal education and describes a program model which offers solutions for counselors and teachers to adopt.