bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Peat Extract in the Ensiling of Fisheries Wastes
Authors: Martin Antonio M. , Bemister Paul L.
Published: July 2007

Fish processing wastes, namely minced cod (Gadus morhua) offal and minced male capelin ( Mallotus villosus), were used in two kinds of ensiling (silage making) processes. In one process they were ensiled by the direct addition of acids, and in the other they were ensiled using various carbohydrate sources and bacterial cultures to produce organic acids in situ. Ensiled material was analysed for various components at times throughout its storage period, and monitored for onset of spoilage. It was found that neither prior freezing nor initial heat treatment of capelin had an effect on the preservation effectiveness of the ensiling process. It was concluded that both the addition of formic acid to cod offal and the fermentation of lactic acid bacteria are effective methods of ensiling this material. Peat extracts with a relatively high carbohydrate content were found to be a satisfactory source of carbohydrates for the fermentation of lactic acid bacteria in cod offal silage. However, peat extracts with a relatively low pH were found to be unsatisfactory as a direct source of acid for ensiling.
A Comparative Overview of Recycling in London and Hamburg
Authors: Gandy Matthew
Published: July 2007

The level of recycling for household waste is significantly higher in Hamburg than in London, yet the extent of materials recovery in both cities is well below technically achievable levels. This paper shows that the higher level of recycling in Hamburg can be accounted for by three main factors: a higher density of recycling facilities combined with the use of more sophisticated collection systems such as a dual-bin service for putrescible wastes; a unified administrative structure for waste management under direct control of an elected regional government; and finally, a system of proportional representation in local government allowing environmentalist political demands to be directly translated into public policy. Despite these differences however, both cities face difficulties with the expansion of recycling derived from the weakness of the secondary materials market, the lack of legislative control over the size and composition of the waste stream, the fiscal constraints on local government and the expense of comprehensive recycling programmes in comparison with alternative forms of waste disposal. This paper concludes that the high cost of recycling presents a fundamental political dilemma for sustainable waste management policy in developed economies.
Cadmium in the European Community: a Policy-Oriented Analysis
Authors: van der Voet Ester , van Egmond Lipkjen , Kleijn René , Huppes Gjalt
Published: July 2007

The economic production and use of cadmium leads to environmental problems within the European Community (EC). The use of cadmium is still increasing significantly, mainly in batteries. This article presents an analysis of cadmium flows in the economy and the environment of the EC, using the 'Substance Flow Analysis' method, a variant of the materials balance approach. Several cadmium abatement packages are evaluated for their effectiveness in terms of sustainability. Proposed EC policy on cadmium, embodying (1) end-of-the-pipe measures, (2) a phase-out of certain applications, and (3) recycling of batteries and certain other products, does not appear to offer a sustainable solution to the cadmium problem, primarily because of the inelastic nature of cadmium supply: mainly as a by-product of zinc production. On the inflow side, measures should focus not on cadmium but on the main products, zinc and phosphate. Otherwise, recycling will only lead to increased availability of cadmium and thus to larger future losses to the environment. On the outflow side, collection of cadmium-containing waste and products and subsequent safe storage in a concentrated form seems to offer the best solution. The ineffectiveness of cadmium recycling is the result of its complicated economic behaviour: inelastic inflow in the world economy, a wide variety of intentional applications, and occurrence as a contaminant in zinc and phosphate products. All ore by-products show this behaviour and are equally difficult to manage in an environmental policy. In general, a policy on an individual pollutant derives its goals from the environmental characteristics of the substance. In order to be effective, the measures it encompasses should be based on the economic characteristics of the substance: characteristics related to supply and demand.
Interactions Between Gas Extraction Wells
Authors: Young Alan , Gay Nigel J.
Published: July 2007

Most modern landfills are fitted with a number of gas extraction wells. The concept of "radius of influence" of a well has become established as a single parameter related to the size of the region that a particular well can control. When several wells are present, their individual suctions interact to alter the radius influence of each. This paper uses mathematical modelling to develop a simple quantitative measure which relates the effect on gas yield at one well due to the pressure of its neighbours. This measure (termed the "yield reduction coefficient") is independent of the underlying rate of gas generation. Some generic guide-lines are given to show how the physical parameters of a site affect these yield reduction coefficients.
A Calorimetric Study of the Effect of Organic Compounds On the Initial Behaviour of Cement-Based Solidified Wastes
Authors: Hills C.D. , Sollars C.J. , Koe L.C. , Perry R.
Published: July 2007

Seven organic compounds commonly found in toxic wastes were added to ordinary Portland cement (OPC) at varying concentrations. The influence of these organics, which display a variety of chemical characteristics, on the heat of hydration, setting, strength development and microstructure were observed. Most organics influenced early hydration by retardation or acceleration but mature samples displayed a similar phase composition to the OPC control. Microstructural observation of organic-containing OPC indicated that subtle spatial variations in the distribution of hydration phases and topographic features existed despite the absence of significant interference with normal hydration reactions.
Biodegradability of the Organic Fraction of Municipal Solid Waste in a High-Solids Anaerobic Digester
Authors: Kayhanian Masoud
Published: July 2007

Three methods were used to estimate the ultimate biodegradability of the organic fraction of municipal solid waste. These methods included: long-term batch digestion studies, measurement of lignin content, and chemostat studies. The ultimate biodegradability values obtained from these methods were compared to a field operation using a pilot scale, high-solids, complete-mix, thermophilic, anaerobic digestion process. The biodegradability obtained from the pilot study, at a mass retention time of 30 days, was approximately 83 and 81% of the estimated values obtained from the lignin content and the batch study, respectively. In addition, it has been shown that the contents of the biodegradable volatile solids affects the prediction of biogas production rate, the computation of the organic loading rate, and feedstock C/N ratio.
Lysimeter Washing of Msw Incinerator Bottom Ash
Authors: Stegemann J.A. , Schneider J. , Baetz B.W. , Murphy K.L.
Published: July 2007

Stockpiled municipal waste incinerator bottom ash is frequently considered for utilization as a construction material. Two 360 kg lysimeter experiments were conducted to study percolation washing of contaminants from stockpiled MSW bottom ash. One lysimeter was leached with a concentrated sodium hydroxide solution, as a possible pre-treatment for improvement of the bottom ash characteristics prior to utilization, while the other was leached using distilled water. The lysimeter leachate was analysed, and at the end of the 2-year leaching period, the bottom ash from each lysimeter was subjected to several laboratory tests to assess the effect of the treatments. The laboratory tests showed that distilled water leachability of both treated ashes was an order of magnitude lower than that of fresh ash, but long-term contaminant leachability under acidic conditions had not changed. Although alkaline washing clearly resulted in greater contaminant removal than did distilled water washing, the chemical properties of the alkaline-leached bottom ash were not significantly different from those of the water-leached ash.
Utility of Risk-Time Curves in Selecting Remediation Alternatives
Authors: McBean Edward A. , Rovers Frank A.
Published: July 2007

The basis for risk-time curves associated with remediation of hazardous waste sites is developed. The utility of the risk-time curves as a part of a methodology for selecting between alternative remediation schemes is demonstrated when the time-frames for remediation are different for different alternatives. The potential for inclusion of uncertainty aspects in risk-time curves is considered.
The Choice of a Solid Waste Management System Using the Electre Ii Decision-Aid Method
Authors: Hokkanen J. , Salminen P. , Rossi E. , Ettala M.
Published: July 2007

A multicriteria decision-aid method, Electre II, was applied to the real choice process of a solid waste management system in the Uusimaa region, Finland. The criteria used were chosen by a supervision group. The weights of the criteria were defined by the managers of environmental and technical affairs of each municipality in Uusimaa, Finland. The use of the Electre II method leads us to recommend centralized incineration as the best municipal solid waste management system for the planning region. However, the second best alternative, intermediate RDF combustion with intermediate landfilling was finally chosen by the municipalities.
Physiological Responses of Red Maple Saplings To Sub-Irrigation With an Untreated Municipal Landfill Leachate
Authors: Shrive S.C. , McBride R.A.
Published: July 2007

An experiment was undertaken to examine the response of hydroponically-grown red maple ( Acer rubrum L.) saplings to a series of four flooding (sub-irrigation) treatments distributed over a 25-day period with an untreated (saline) municipal solid waste landfill leachate or deionized water. Net photosynthesis rates measured for water-treated saplings rapidly declined to 62% of the levels measured in untreated (control) saplings, but returned to pre-treatment levels with subsequent flooding treatments. Net photosynthesis rates measured for leachate-treated saplings decreased to about 50% of the levels measured for control saplings over the 25-day treatment period, and remained suppressed. Loss of turgor in leaves and a iron-oxyhydroxide plaque on root surfaces were also observed. Reasons proposed for this acute and apparently irreversible response to leachate exposure include: (i) extreme root anaerobiosis conditions caused by root system flooding and exacerbated by a high chemical oxygen demand leachate; (ii) increased root-soil interface resistance to transpiration water flow (osmotic potential gradient, iron oxyhydroxide plaque); (iii) metabolic intolerance to high solute concentrations in plant tissue; and (iv) exposure to potentially toxic volatile organic compounds. Water sub-irrigation had virtually no effect on nutrient and non-nutrient element concentrations in foliage or on the spectral reflectance characteristics of the leaves. Leachate treatment decreased the foliar content of many plant macro- and micro-nutrients significantly, and shifts in spectral reflectance patterns indicated declining plant vigour. Certain chemical constituents present in high concentrations in the leachate irrigant and which can be phytotoxic, such as Cl, accumulated to a significant degree in leachate-treated plant tissue.
Comparative Studies of Waste Incineration Bottom Ashes From Various Grate and Firing Systems, Conducted With Respect To Mineralogical and Geochemical Methods of Examination
Authors: Pfrang-Stotz G. , Schneider J.
Published: July 2007

Mineralogical and geochemical techniques can be used successfully to characterize and evaluate bottom ashes produced in waste incineration. At the present time, it is not quite clear to what extent the mineral phase compositions and the content of main elements and heavy metal concentrations of bottom ashes are influenced by the conditions of combustion. Once the location of heavy metals in or with specific minerals is known, it may be considered, in the light of technical possibilities, whether a change in temperature or in the residence time of waste in the combustion chamber could be sufficient to remove these components from their mineral phases.
The Ümraniye-Hekimbaşi Open Dump Accident
Authors: Kocasoy Günay , Curi Kriton
Published: July 2007

The open dump of Ümraniye-Hekimbaşi was the main solid disposal site of the Asiatic side of Istanbul. At this site, which was in operation since 1976, 1500-2000 tonnes of solid wastes were disposed of daily. No waste compaction was undertaken during placement. The slope formed by the solid wastes was very steep (3 vertical to 1 horizontal), and recently demolition wastes were disposed of on top of these wastes. On 28 April 1993, an "explosion" took place, followed by the displacement of a large mass of solid wastes which engulfed 11 houses causing the death of 39 people. This paper investigates the possible reasons for this accident and concludes that it was caused by the initial sliding of the solid wastes, which were not deposited in a stable way, followed by an explosion of the methane generated and retained in the landfill. © 1995 ISWA
Processing Scheme Based On Selective Dissolution To Recycle Food Packaging and Other Polymeric Wastes and Its Economic Analysis
Authors: Zagouras N.G. , Koutinas A.A.
Published: July 2007

This investigation proposes the development of the selective dissolution process for recycling food packaging and other polymeric wastes. This process takes into account that the specific solvent of a particular polymer which is to be separated, must be a non-solvent for the remaining polymers. Likewise, taking into account the solubility of each polymer into various solvents as well as its production costs, the order of the polymers produced can be polyvinylchloride (PVC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polybutadiene (PB), polyacrylnitrile (PAN), polyesters (PES), nylon and polyurethanes (PU). However, cost analysis of the process revealed that the recycling of food packaging polymers in the order of PE, PVC, PP, and PS is more cost-effective. © 1995 ISWA
A Comparison of Two Waste Stream Quantification and Characterization Methodologies
Authors: Yu Chang-Ching , Maclaren Virginia
Published: July 2007

This paper compares a traditional engineering approach (direct waste analysis) for collecting waste quantity and waste composition data to a social science approach (questionnaire surveys) for dealing with the same problem. The advantages and disadvantages of these two methodologies are discussed, and a comparison made of the results obtained from applying these methodologies to a case study of the industrial-commercial-institutional waste stream in Metropolitan Toronto. The study shows that while the two approaches produce fairly similar waste quantity estimates, their waste composition estimates are not as close and vary considerably by material.
Simulation of the Wicking Effect in a Two-Layer Soil Liner System
Authors: Yeh T-C. Jim , Guzman Amado , Srivastava Rajesh , Gagnard Philip E. , Kramer John H.
Published: July 2007

A series of simulation runs were made using the computer model VSAFT2 (Yeh & Srivastava 1990) to estimate the "wicking" potential of five low-permeability liner materials including excel, celite slurry, kiln dust, rock creek clay and celite waste. The unsaturated hydraulic properties for these materials were assumed to be represented by the van Genuchten model (1978). The hypothetical liner system simulated consisted of 0.305 m (1 foot) of low permeability material underlain by a medium sand. The purpose of this modelling effort was to quantify the effects of liner thickness and leakage rate on the lateral spreading of the wetting front, and to determine the effectiveness of the diffusivity function in predicting the migration of the wetting front. Results indicate, as expected, that the liner material with the lowest permeability retards vertical movement the most; however, the horizontal wicking effect is also limited. Additional multi-layer liner systems will be simulated in the next phase of the project to improve liner wicking performance.
Statistical Modelling for the Prediction and Control of PCDDs and PCDFs Emissions From Municipal Solid Waste Incinerators
Authors: Chang Ni-Bin , Huang Shyh-Horng
Published: July 2007

The emissions of a full range of polychlorinated dibenzo- p-dioxins and furans (PCDDs/PCDFs) have become one of the most controversial issues in siting and building new municipal incinerators. The lack of comprehensive evaluation of the PCDDs/PCDFs formation and emission control technologies in earlier times resulted in ambiguity in the decision-making of incineration projects. Until the last decade, several emission tests of municipal solid waste incineration regarding to new combustion criteria, public regulations, and risk assessments were conducted and reported in the literature. However, only a few analyses of statistical prediction and control have been established. This paper presents a series of multiple linear regression models for PCDDs/PCDFs emission prediction and control corresponding to different types of incinerators. The data used in the regression analysis were integrated from several testing programmes held in North America. By applying these regression results, evaluation of various combustion criteria, public regulations, and environmental and health risk assessment can then be achieved. Such evaluation is valuable for some developing countries which do not have sufficient finance or engineering experience to pursue large scale emission tests, but need rapid promulgation of emissions control for municipal solid waste incinerators.
Radioactivity and Elemental Composition of Phosphogypsum Produced From Three Phosphate Rock Sources
Authors: Rutherford P.M. , Dudas M.J. , Arocena J.M.
Published: July 2007

Phosphogypsum, a by-product of phosphate fertilizer production, is produced in large quantities worldwide. Most phosphogypsum is stockpiled while lesser quantities are recycled or dumped into water. Phosphogypsum is primarily CaSO4·2H2O, but also contains impurities of environmental concern such as residual acids, fluoride, heavy metals and naturally-occurring radionuclides. Impurity composition within phosphogypsum can vary greatly depending on the source of phosphate rock used in phosphoric acid production. This study was undertaken to obtain detailed information on the composition of phosphogypsum produced from the processing of rock from Florida, Togo and Idaho, to define more clearly the chemical issues of importance to management and use of the by-product. All freshly produced phosphogypsum had sufficiently high fluoride levels that leaching and decomposition of silicate minerals beneath repositories might occur. Phosphogypsum from Idaho rock had elevated Ag, Cd and Se concentrations, and the greatest Ra-226 activity concentrations (up to 1780 Bq kg— 1). Radon-222 emanation coefficients ranged between 12-51%.
Determining Controls On Element Concentrations in Fly Ash Leachate
Authors: Reardon E.J. , Czank C.A. , Warren C.J. , Dayal R. , Johnston H.M.
Published: July 2007

It is possible, by conducting fly ash leaching tests at two different water:ash ratios, to determine whether or not the concentration of an element in the leachate is controlled by mineral solubility. If a mineral solubility control exists, the element's concentration can be readily predicted with chemical equilibria models. On the other hand, if the concentration of an element is controlled by the rate of release from ash particles, more sophisticated hydrochemical transport models are required. The conduct of leach tests on waste materials at two different water:solid ratios is recommended as a general procedure in waste management.

In this study, the concentration of Na, K, Cl, B, and Cr(VI) in Lakeview fly ash leachate were found not to be controlled by mineral solubility. Therefore, the solution concentrations of these elements will be influenced by the relative amounts of water to ash in a mix, and the flux of these elements from hydrating primary ash particles with time. Evidence of solubility control was found for Ca, Sr, SO4 , Al, Si, As(V), and Se in leachate solutions. Calcium and SO 4 concentrations were controlled by gypsum solubility; Sr, probably by a (Ba,Sr)SO4 solid solution; Al and Si, by a hydrous aluminosilicate, probably allophane; Mg, by a hydrous magnesium silicate like sepiolite; and As, by either a ferric metal arsenate or strongly associated with a ferric oxide phase. The probable control on Se concentrations is through coprecipitation in secondary sulphate mineral precipitates.
Porewater Velocity Influence On Zinc Sorption By a Clay-Bearing Sand
Authors: Cornelis Heijn Ethan , Peirce J. Jeffrey , Sperry James M.
Published: July 2007

Natural clay materials can limit the subsurface mobility of dissolved heavy metals by providing sites for cation sorption and exchange. The objective of this research is to determine the influence of porewater velocity on these attenuation mechanisms. Zinc was selected to evaluate the reactive properties of a clay-bearing sand (4% bentonite clay, 96% silica sand) under different flow conditions. Columns containing the clay-bearing sand were used to generate solute breakthrough curves (BTCs) for zinc solutions at porewater velocities of 1.4 x 10 -5, 6.1 × 10-4, 8.3 x 10-4, and 4.8 x 10 -3 cm s-1. Zinc influent concentrations of 2.1 × 10 -4 M and 2.1 x 10 5 M were employed in column and batch experiments. Chloride is used as a conservative solute to determine the mechanical flow properties of the clay-bearing sand. Zinc BTCs indicate a non-equilibrium process based upon rate-limited diffusive mass transfer between bulk solution and non-advective pore space, where numerous sorption-exchange sites may exist. Models for similar systems which incorporate the "local equilibrium assumption" and neglect diffusive mass transfer limitations may underestimate contaminant mobility at higher flow rates and over-estimate the contaminant removal efficacy of pump-and-treat remediation in field applications.
Relationship of Microbial Mass and Activity in Biodegradation of Solid Waste
Authors: Murphy R.J. , Jones D.E. , Stessel R.I.
Published: July 2007

Limited landfill space and resistance to siting such facilities has spurred consideration of new approaches to increase the longevity of landfills. Such efforts have included exploring methods to enhance degradation rates of municipal solid waste (MSW) and subsequently, mining landfills to recover materials and landfill space.

Microbial mass and activity of MSW incubated in lysimeters, with moisture content sustained with recycled leachate, were compared under anaerobic and aerobic conditions in this study. Bacterial biomass and number were quantified by adenosine triphosphate analysis and acridine orange direct counts. Viability, adenylate energy charge and cellulase activity were also assessed.

Bacterial number and energy status were lower in the anaerobic system. Cellulase activity in the anaerobic lysimeter decreased to undetectable levels while activity in the aerobic system continued to increase throughout the 92-day experiment. The results indicated that aeration, even at a relatively low volume, with leachate recirculation, significantly accelerated degradation of MSW. Furthermore, the results demonstrated the potential of using cellulase activity as a surrogate parameter of relative microbial activity of MSW degradation.
Bioremediation of Olive-Mill Wastewaters By Composting
Authors: Tomati U. , Galli E. , Pasetti L. , Volterra E.
Published: July 2007

Olive-mill wastewaters (O.M.W.) containing about 7% solids were composted with wheat straw in a forced aeration static pile. Two percent urea was added to ensure a C/N ratio of about 35. To avoid overdosing with water, a fraction of the O.M.W. equal to the weight of the straw was added initially. When composting had reached the thermophilic phase, additional doses of O.M.W. were added every 3 days as water evaporated. The ratio of O.M.W. solids:straw approached 1:1 and the thermophilic phase was extended to 35 days. Temperature, oxygen consumption, pH, C/N, total organic carbon, total extractable carbon, humic and fulvic acids and lignin degradation were followed during the process. The humification was assayed following the degree of humification, the humification rate and the humification index which respectively reached the values of 78%, 37.8% and 0.28 after 2 months. Humic acids were characterized by their elemental composition and molecular weight. A lignin degradation of about 70% was assayed at the end of the thermophilic phase. No phytotoxicity was recorded on the end product, the chemical and physical properties of which suggest its possible use as fertilizer. © 1995 ISWA
The Recycling of Linz-Donawitz (Ld) Converter Slag By Use as a Liming Agent On Pasture Land
Authors: Lopez F.A. , Balcazar N. , Formoso A. , Pinto M. , Rodríguez M.
Published: July 2007

Slag is a major by-product of the basic oxygen steelmaking converter process (BOS). Methods are being developed to make use of this by-product and large quantities are now employed in agriculture and in the production of aggregates in several European Community (EC) countries. However, a great deal of slag is still either simply discarded or discharged in landfills. This paper reports the effects over a 3-year period on both soil and crops, of the application of Linz-Donawitz (LD) converter slag on pasture land. Comparative studies were performed using different quantities of low phosphorus LD converter slag and fertilizer on land sown with Dactylis glomerata, Trifolium repens and Lolium perenne. The results showed an increase in soil pH and in the availability of Ca and Mg in the soil exchange complex. Aluminium content was reduced. When LD converter slag and fertilizer were applied together, plants were seen to contain the greatest concentrations of nutrients and greater yields were obtained. © 1995 ISWA
A Re-Evaluation of Objections To Tree Planting On Containment Landfills
Authors: Dobson M.C. , Moffat A.J.
Published: July 2007

Legislation from developed countries indicates that planting trees on containment landfills is generally forbidden. Concerns centre on the supposition that tree roots can penetrate into and through capping materials, and will thus compromise control of water ingress into waste, and allow the escape of landfill gas. An associated anxiety is that if roots penetrate a clay cap they could cause desiccation and cracking of the clay through excessive moisture abstraction. It is also considered that trees growing on the relatively shallow soil above a landfill cap could be especially prone to uprooting. However, a review of the world literature indicates that maximum depths achieved by tree roots are usually between 1-2 m. Almost 90% of a tree's roots may be found in the upper 0.6 m of soil. Tree roots are highly sensitive to environmental conditions and their downward penetration can be restricted by a number of soil factors including compaction, poor aeration and infertility. A detailed study of these factors indicates that the materials used for capping landfill sites, such as HDPE (high density polyethylene) and compacted clays, can provide an effective barrier to downward root growth. The available information also suggests that tree roots are extremely unlikely to be a primary cause of desiccation cracking in a clay cap owing to their inability to extract more than about one-quarter of the total moisture held in a clay of the density required to ensure a permeability of 1 ×10-9 m s-1. Trees growing on landfill sites with a rootable soil depth of at least 1.5 m should be at no greater risk of windthrow than most forest trees on undisturbed sites. Methods are available to assess the likelihood of windthrow. In any event, windthrow should not cause disruption of a cap, due to the inability of tree roots to penetrate HDPE, or mineral materials compacted to a bulk density of 1.8 g cm-3. © 1995 ISWA
Physico-Chemical Characterization and Leaching of Desulphurization Coal Fly Ash
Authors: Lecuyer I. , Bicocchi S. , Ausset P. , Lefevre R.
Published: July 2007

Fly ash produced by coal combustion using two types of desulphurization process were studied: a conventional pulverized coal boiler equipped with lime injection (PCL ash), and a circulating fluidized bed combustion boiler with limestone injection (CFBC ash). The ashes were characterized completely: granulometry, morphology, mineralogy, chemical composition and behaviour to water contact.

Both PCL ash and CFBC ash present similar features: fine granulometry, presence of anhydrite phase and sulphate content. However, PCL ash also shows lots of spherical particles, unlike CFBC ash, and a much higher lime content, due to the lower desulphurization rate in PC boilers. Unlike CFBC ash, most of the trace elements in PCL ash show an inverse concentration-particle size dependence.

Leachates obtained from both samples are rich in soluble salts [CaSO4 and Ca(OH) 2] and arsenic and selenium are prevented from solubilizing by high lime content.

In wetted PCL ash, the formation of ettringite crystals stabilizes calcium and sulphate ions. Simultaneously, arsenate, selenate and chromate anions are trapped in the crystal. CFBC ash does not really harden because the lime content is too low. However, the leached selenium concentration is cut down in wetted CFBC ash samples. © 1996 ISWA
Regulatory Leaching Tests for Fly Ash: a Case Study
Authors: Egemen Ege , Yurteri Coskun
Published: July 2007

In many countries throughout the world, fly and bottom ashes originating from coal-fired thermal power plants are declared as wastes requiring special care during reuse and disposal. In this regard, a number of toxicity tests have been developed to assess the metal leaching potential of ash residues. In this study, fly ash samples obtained from the Çatalağzl thermal power plant, located on the northwestern coast of Turkey, were subjected to toxicity tests such as the extraction (EP) and toxicity characteristic leaching (TCLP) procedures of the U.S. Environmental Protection Agency (U.S. EPA), and the so-called Method A extraction procedure of the American Society of Testing and Materials (ASTM). The results observed for the extracts were compared with each other and the selected tests were evaluated in terms of their use in representing leaching under natural field conditions.
A Model of Leaching Behaviour From Msw Incinerator Residue Landfills
Authors: Lu Chungsying
Published: July 2007

A mathematical model is presented to predict quantity and quality of leachate from incinerator residue landfills. The model is based on the unsaturated flow equation, the solute transport equation, the equation of chemical and microbial processes, and the water balance equation of the leachate collection system. Good agreement was obtained by comparing model simulation with data of laboratory column-leaching tests in the literature. The important parameters were evaluated in a sensitivity analysis to determine their respective effects. Five parameters were identified to strongly influence the model performance: saturated volumetric moisture content (0s), ultimate mass of leachable contaminant ( M 0), maximum contaminant concentration ( Cmax) , saturated hydraulic conductivity of the drainage layer ( Kd), and slope angle of the liner ( ϕ). © 1996 ISWA
Development of a Decision Support System for Municipal Solid Waste Management Systems Planning
Authors: Barlishen K.D. , Baetz B.W.
Published: July 2007

A review of the municipal solid waste (MSW) management and planning literature reveals the growing number and complexity of the available mathematical models. A technical survey of practising waste management professionals indicated a general interest in, but lack of practical applications of, mathematical modelling techniques. The creation of knowledge-based systems to interface with individual MSW management and planning models, or assist with model selection and integration is proposed. As a means of demonstrating the validity of the suggested decision support approach, a prototype decision support system was developed to assist with the preliminary planning of MSW management systems. This planning tool combines knowledge-based system components with spreadsheet, optimization and stimulation models to assist with: waste forecasting; technology evaluation; recycling and composting programme design; facility sizing; location and investment timing; waste allocation; and MSW management system analysis using stimulation. A case study application of the planning tool is described. © 1996 ISWA
A Model for the Optimal Allocation of Trucks for Solid Waste Management
Authors: Bhat Vasanthakumar N.
Published: July 2007

Solid waste collection and disposal costs constitute 75-80% of a city's solid waste management budget. Therefore, even a small improvement in the waste collection and transfer operations can lead to significant savings in costs. Trucks collect refuse from different parts of cities and transport to incinerators, landfills and transfer stations. These trucks spend a considerable amount of time travelling and waiting at disposal sites which could otherwise have been used for refuse collection. In this paper, a simulation-optimization model is described that helps to allocate trucks to disposal sites so as to reduce travelling and waiting time costs. This model can help city administrators to make long-term decisions relating to the number, capacities, and locations of waste disposal sites, routing of trucks, crew sizes etc. This model can also be of significant use to make short-term operational decisions, including those relating to diversion of trucks if their normal disposal site is not operational.
Multi-Axial Testing of Geomembranes
Authors: Goldsmith P.M. , Stessel R.I.
Published: July 2007

There are many accepted methods to ascertain the integrity of a geomembrane (GM) by subjecting it to a battery of physical, mechanical and chemical tests. However, there is no single comprehensive performance testing programme that simulates the stresses to which a GM might be subjected in a service environment. This paper first discusses the development and testing of a new test system based on multi-axial deformation; observations concerning system design criteria and relevance to field conditions are made. The paper also presents the results of a physical testing programme, wherein standard materials tests were implemented using the new system; stress/strain, strain rate, creep and relaxation data are presented. Where comparisons were possible, these results reinforced fluid-based multi-axial testing data in the literature. New data and conclusions are discussed. Finally, a new test, cyclic testing, is suggested, demonstrated and discussed. © 1996 ISWA
Municipal Solid Waste Policy and Public Participation in Household Source Reduction
Authors: Lober Douglas J.
Published: July 2007

This study examines the nature of public participation in implementing household source reduction of municipal solid waste in order to inform the development of waste policy. The objectives are to determine the degree of public participation in household source reduction, the importance given to this waste strategy relative to other waste management approaches with an emphasis on recycling, but also including landfilling and incineration, the motivations behind its practice and the demographic and attitudinal correlates of its practitioners. The method used was a telephone survey of residents in a community in Connecticut, U.S.A. The results were analysed using descriptive and correlational statistics.

The results indicate that the activity of source reduction, using a variety of measures, is being widely practiced. Over 50% of respondents participated in at least one source reduction activity. However, the intensity of participation was low, with many individuals participating only infrequently in the activity. Furthermore, the amount of material potentially reduced through source reduction in the home is small. There was an equal degree of public support for recycling efforts with a large percentage of respondents considering recycling to be more important than source reduction. Demographic variables in this community did not prove to be significantly correlated with source reduction attitudes and behaviour.

One policy implication is that the home may not be the most effective place for source reduction, as contrasted with recycling, given the limited number of source reduction activities available in the home. A second policy implication is that mechanisms to facilitate source reduction need to be developed. Finally, policy makers need to concentrate educational efforts towards public recognition of both what constitutes source reduction and the importance of this activity.
Full-Scale Mesophilic Anaerobic Co-Digestion of Municipal Solid Waste and Sewage Sludge: Methane Production Characteristics
Authors: Rintala Jukka A. , Järvinen Kimmo T.
Published: July 2007

The methane production characteristics of a full scale anaerobic biogas digester processing the putrescible fraction of municipal solid waste (PFMSW) and sewage sludge (SS) were studied by using the operation data of the digester and laboratory experiments. The batch assays indicated methane yields of 3001 kg volatile solids (VS) -1 for PFMSW and 2201 kg VS-1 for SS. The full scale digester showed methane production yields up to 90% of the methane yield potential of the added feed. The rates of methane production and the specific methanogenic activities varied during the cycle of feeding. Apparently, the methanization in the digestion process was substrate-limited, especially during weekends when no feed was added. The batch studies indicated that the propionate and butyrate conversions were no more limiting than acetate methanization. The sludge from the digester was more active than the sludges from digesters processing sewage sludge alone. © 1996 ISWA
The Solid Waste Management Scene in Greater Beirut
Authors: Nuwayhid R.Y. , Ayoub G.M. , Saba E.F. , Abi-Said S.
Published: July 2007

The magnitude of the solid waste problem in Beirut (Lebanon) is apparent to any onlooker. Waste collection has improved recently but is frequently incomplete and sometimes sporadic. Considerable labour problems exist and are made worse by the disruption from the aftermath of civil war. The most suitable future disposal methods have not been fully studied, and existing disposal sites and plants are near to saturation or collapse. In order to start a new waste management study correctly, the first step was to analyse the waste composition, characteristics and generation rates. The authors attempt to show that some form of incineration with energy recovery may be the preferred disposal option given the current local prevailing social conditions. Composting is argued to be the next choice. Direct landfill of untreated waste is the choice for the present time, but its continuance is open to question if new landfills are not identified and permitted to be used. © 1996 ISWA
Effect of Drying Temperature On the Fuel Value of Wastewater Sludge
Authors: Vesilind P. Aarne , Ramsey Thomas B.
Published: July 2007

Two operational problems that plague the multiple hearth furnace (MHF) are the frequent need for supplementary fuel to maintain the incineration process, and emission of volatile compounds from the incinerator. Sludge is exposed to elevated drying temperatures prior to active combustion in the MHF and many of the volatile emissions are a result of thermal degradation of organic matter within the sludge. This loss of volatile matter from the sludge prior to its combustion represents a direct loss of fuel from the MHF. The objective of this research is to determine the effect of drying temperature on the final heating value of sludge. This objective is accomplished through the determination of higher heating values (HHV) by oxygen bomb calorimetry of sludge samples heated to temperatures between ambient and 400°C prior to the calorimetric measurements.

Results from laboratory work performed for this research indicate that for temperatures in excess of 105°C, the HHV of dried sludge is dependent upon the temperature to which it is exposed prior to the measurement of the heat value. Sludges exposed to temperatures above 105°C lose enough volatile matter to have measurably lower HHVs than those sludges exposed to temperatures below 105°C. Since sludge biomass is thermally unstable at temperatures as low as 105°C, application of this research to the MHF reveals that the countercurrent flow of sludge and exhaust gases within the MHF is a fundamental handicap to the efficient combustion of sludge in this type of incinerator.
Field System for Continuous Measurement of Landfill Gas Pressures and Temperatures
Authors: Spokas K.A. , Bogner J.E.
Published: July 2007

The driving forces for gas movement in the subsurface include both concentration gradients (diffusion) and pressure gradients (convection). Near the top of the landfill, small soil gas pressure differences with respect to atmospheric pressure have been typically disregarded but may be important to considerations of gas flux into and out of landfill cover materials. The authors have developed a portable, inexpensive system using off-the-shelf components to sensitively monitor pressures, temperatures and meteorological variables on a continuous basis. Previous experience has indicated that continuous monitoring of pressure changes is necessary to understand the dynamics of convection in the shallow subsurface.

This application relies on a distributed network of commercially available Z-180 microprocessor-based integrated controllers to condition signals from electronic pressure transducers, meteorological sensors, and various temperature-sensing devices : thermocouples, thermistors and resistance temperature detectors (RTDs). Output is recorded continuously over an Appletalk™ network. The sensitivity of the authors' current system exceeds 4 Pa for pressure and 0.01°C for temperature (thermistor sensors).

This paper will describe the basic system components. The various choices for both temperature and pressure sensors will be discussed with respect to their sensitivity, adaptability and resolution. In addition, sample data output will be presented to illustrate the dynamics of shallow subsurface pressure and temperature changes. © 1996 ISWA
Changes in Major and Trace Components of Landfill Gas During Subsurface Migration
Authors: Ward R.S. , Williams G.M. , Hills C.C.
Published: July 2007

A gas plume emanating from the Foxhall Landfill in Suffolk (U.K.) has been defined within unsaturated ferruginous sands on the basis of elevated concentrations of methane, carbon dioxide and volatile organic compounds (VOCs). The plume is relatively narrow, extends more than 100 m from the landfill boundary, and lies mainly between 2 m bgl (below ground level) and the water table at 9.5 m bgl. With increasing distance along the axis of the plume, the ratio of methane to carbon dioxide gradually decreases, while nitrogen increases. Oxygen appears beyond 80 m from the landfill boundary. Stable carbon and hydrogen isotope ratios in methane become heavier with distance, while carbon dioxide becomes isotopically lighter with respect to stable carbon. This provides strong evidence for microbially mediated methane oxidation. Zones of black reduced sediment near the landfill suggest that ferric iron [Fe(III)] may be acting as an electron acceptor for oxidation. No thermal anomaly was observed, thus suggesting that the rate of oxidation/flux of methane is low.

Volatile organic compounds in the plume were trapped using a combination of sorbants (Tenax GR, Haysep Q and Carbosieve S-III), and desorbed thermally into a GC/MS for semi-quantitative analysis. The 79 VOCs identified were similar to those found in other landfills, and their concentrations, both in the landfill and in the soil gas, were broadly related to their volatility. Only two compounds (vinyl chloride and dichlorofluoromethane) approached or exceeded the long-term exposure limit (LTEL, as defined by the U.K. Health and Safety Executive, 1992) outside the landfill. Halogenated compounds (dichlorodifluoromethane, dichlorofluoromethane and trichlorofluoromethane) were found to be most mobile but their concentration profiles suggest that they may have been flushed out of the landfill during its early stages. It is suggested that the association of volatile halogenated compounds with methane is good evidence that they are derived from a landfill.
The Potential for Re-Use of Preservative-Treated Utility Poles Removed From Service
Authors: Cooper Paul , Ung Tony , Aucoin Jean-Paul , Timusk Chris
Published: July 2007

This study investigates the feasibility of re-using or recycling utility poles or parts of poles for solid wood products. Four hundred and fifty-six poles or pole sections, removed from service in Ontario and Quebec, Canada, were characterized by age, wood species, preservative type, residual preservative, dimensions and condition. Based on this characterization, the potential for re-use as round poles or posts, sawn posts, timber, lumber and cedar roof shingles was evaluated. About 8% of the poles can be re-used without reprocessing, 15% of the pole volume can be used for cedar shingles, and about 35% of the pole volume can be converted to sawn products based on the selected hierarchy of preferred uses.

Most of the poles removed from service had been treated with pentachlorophenol. The average levels of treatment decreased with age of the poles and approached the toxic threshold retentions in 25-year-old (or older) poles. For older poles (>35 years), creosote was the predominant treatment. Creosote levels were about 50% of the assumed levels when fresh treated. Creosote extracted from these poles contained fewer polynuclear aromatic hydrocarbon components than "new" creosote. The poles treated with chromated copper arsenate (CCA) retained high levels of preservative, even after many years in service.

Used poles can be sawn into lumber of a good grade (#2 and better) using a small portable bandsaw. Special sawdust handling and disposal provisions must be made if this use is to be adopted. Treated poles with depleted reserves of creosote or pentachlorophenol could be re-treated with CCA or creosote preservatives to acceptable retentions. The quality of re-treatment was as good or better than that observed with new wood, and the re-treatment should ensure several decades of protection for guide-rail posts and other high decay hazard applications.
Preparation of Ceramic Membrane Filters, From Waste Fly Ash, Suitable for Hot Gas Cleaning
Authors: Jo Y.M. , Huchison R. , Raper J.A.
Published: July 2007

The preparation and performance of ceramic membrane filters made from fly ash from coal-fired power stations were investigated. The porous and crack-free ceramic composite membrane was prepared by dip-coating a stainless steel mesh in a slurry of fly ash. Membrane properties investigated included pore structure, permeability and mechanical strength. The ash membrane filter shows great potential for the filtration and microfiltration of high-temperature gas-particulate streams, and reuses waste fly ash composed of multiple oxides with a wide size distribution. The median pore size of the tested membrane was 2.3 μm and the differential pressure gradient was 0.9 kPa 1-1 min-1, which is comparable to fabric filters currently in use in some New South Wales power stations. The high mechanical strength of the membrane was caused by fusion of the glassy material in the fly ash. Since the membrane consists of metal and ceramic composities, it also shows good flexibility.