Issue 3/4, November 2001
Approaching Sustainable Landfilling
Alexander Zach, Marion Humer, Tanja Gomiscek, Carolin Heiss-Ziegler,
Doris Grassinger and Peter Lechner
Department of Waste Management, IWGA,
Universitaet fuer Bodenkultur, Wien (University of Agricultural Sciences, Vienna)
Nussdorfer Laende 29-31, A-1190 Vienna, Austria
Uncontrolled emitted landfill gas contributes to the greenhouse effect due to its high content of methane. Nitrogen and carbon are major constituents in leachates of landfilled waste and can pollute soil and water. Therefore both, gaseous emissions and leachate, require expensive treatment facilities. Taking this into consideration a landfill-model was developed where mechanical-biological pretreatment measures of municipal solid waste (MSW) should reach the goal of a stabilized waste deposition. Remaining methane emissions are minimized to a negligible level by microbial oxidation of methane in suitable cover layers. At last, self-adjusting biological processes together with controlled revegetation measures are responsible for aftercare. As this technology is simply applicable and economically acceptable it may especially be an option for developing countries.
Key Words: Aftercare, landfill, mechanical-biological pretreatment, methane oxidation, recultivation
Biological Activities Of Methane Oxidation In Tropical Landfill Cover Soils
W. Chiemchaisri , C. Visvanathan
Asian Institute of Technology
Box 4, Klong Luang, 12120 Pathumthani, Thailand
Jy S. Wu
Department of Civil Engineering,
University of North Carolina at Charlotte
Charlotte, NC 28223, U.S.A.
Microbial oxidation of methane in the aerobic portion of a landfill cap was found to play an important role of reducing methane emission to the atmosphere. Methanotrophic bacteria present in the landfill cover soils could utilize methane for cell reproduction and as energy source, while utilizing oxygen as electron acceptor. The atmospheric oxygen can only penetrate to a certain depth of the cover soils and, thus, oxygen is often the limiting factor for methane oxidation. Available nutrients also influence soil microbial activities. In this study, soil lysimeters were employed to examine the specific methanotrophs present in simulated landfill cover soils under tropical climatic conditions. The effects of extracellular polysaccharide, N-nutrients utilization and amendments, and pertinent biological processes were investigated, in batch experiments, using soil samples taken from the experimental lysimeter. The study provides an understanding of microbial activities and pertinent controlling mechanisms to help manage landfill soil covers for reducing methane emission.
Key Words: Methane oxidation, municipal solid waste, landfill gas, extracellular polysaccharide
Compactoin And Ompaction And Shear Strength Of Fly And Bottom Ash Mixtures
J. H. Lee
Assistant Professor, School of Civil and Envir. Engng.
A. Karim, R. Salgado, C. W. Lovell
School of Civil Engng.
West Lafayette, IN 47907
Bottom ash and Class F fly ash are by-products of energy generation in coal power plants. A large fraction of the coal ash generated is disposed as a waste material in the form of mixtures. Bottom ash and Class F fly ash could be more productively used as construction material for embankments and structural fills. For this reason, their engineering behavior needs to be investigated, particularly their compaction properties and shear strength. Representative, large ash samples were collected from a power plant in Indiana. The bottom ash was sampled from a pond, and the Class F fly ash was sampled from a silo. Samples of mixtures with different proportions of fly to bottom ash were composed and tested in compaction following the Standard Proctor Test procedure. To investigate stress-strain behavior, consolidated drained triaxial compression tests were performed on samples of mixtures compacted at two levels of relative compaction. The investigation focused on the effects of the fly ash content and the compaction level on the mechanical behavior of the mixtures. The application of the results to compaction control and construction of embankments is also discussed.
Key Words: Coal ash, Class F fly ash, bottom ash, waste, disposal, utilization, ash mixtures, compaction, compaction control, triaxial tests, shear strength
Durability Evaluation Of Asphalt Mixtures Modified With Recycled Tire Rubber
Dimitrios G. Goulias
Associate Professor, Department of Civil and Environmental Engineering
University of Maryland
0147A Glenn L. Martin Hall
College Park, MD 20742
Research Assistant, Civil and Environmental Engineering Department
Six Metrotech Center
Brooklyn, NY 11201
The use of natural and synthetic rubber for improving the properties of conventional asphalt materials is being investigated since the 1960s. However, due to the additional complexity in designing and producing asphalt rubber binders and mixtures, the high production cost, and in some cases, conflicting reports regarding their performance, the development and use of these mixtures was limited over the years. Recently, and due to the provisions of the 1991 Intermodal Surface Transportation Efficiency Act (ISTEA) on the use of tire rubber in federally funded projects, several extensive and intensive laboratory and field studies were undertaken.
This paper presents the results from the durability evaluation of asphalt rubber mixtures used in paving projects. While the presence of moisture affects the adhesion between the binder and the aggregate producing stripping effects, the characteristics of the asphalt rubber binder is expected to improve mixture durability and performance. The most frequent approach in evaluating the durability of asphalt mixtures considers the changes in the mechanical properties due to moisture exposure. The results are typically provided in terms of equivalent retained strength, durability curves, and/or durability indexes indicating the sensitivity level of the mixtures to moisture. In this laboratory evaluation the moisture damage effects on asphalt rubber mixtures was examined by exposing them at long-term hot immersion conditions, (i.e., 60oC), and average pavement in-service temperature (i.e., 25oC). The durability of the asphalt rubber mixtures was then compared to that of conventional paving mixtures. For such analysis modified and conventional mixtures were evaluated at their optimum binder content. In addition to the retained strength characteristics at different immersion times, stiffness analysis were conducted. The methodology and results of this study can be used for assessing the durability of modified and conventional materials elsewhere.
Key Words: Asphalt, tire rubber, recycling, durability, moisture susceptibility
Factors Influencing Solid Waste Generation And Management
Research Fellow, Research Department
Statistics Norway, P.O.B. 8131 Dep.
0033 Oslo, Norway
Tel: +47 2109 4948, Fax: +47 2109 4963
Insight into factors influencing waste generation and management options forms an important background for waste policy planning. This paper analyzes the effect of income, waste management fees and population density on the overall amount of waste generated, and of income, fees and recycling services on the choice of waste management methods.
The results show that economic incentives are effective in influencing the selection between different waste management methods. Landfill fees reduce the waste amounts landfilled and increase recycling and incineration. However, the effect of the landfill fees on total waste generation is negative, but not significant. An increased weight in recycling in the states with the highest landfill fees might undermine the effect of fees on waste generation. Thus, the total effect is substituting recycling for landfilling instead of source reduction.
The environmental Kuznets curve theory suggests that waste generation first increases, and then decreases with rising income. In this study, the overall quantities of municipal solid are not influenced by income.
Key Words: Incineration rates, environmental Kuznets curves, landfill rates, recycling rates, waste taxation, waste generation
Microbial Methane Oxidation For The Reduction Of Landfill Gas Emissions
Marion Humer, Peter Lechner
Department of Waste Management, IWGA,
Universität für Bodenkultur, Wien (University of Agricultural Sciences, Vienna)
Nußdorfer Lände 29-31, A-1190 Vienna, Austria
With about 40 to 60 Mt of methane emitted each year worldwide, landfills are an important global source of this greenhouse gas. These emissions are especially caused by inadequate gas extraction facilities, missing gas collection systems at old dump sites and landfills or unauthorized open dumping. A low cost alternative method or an additional measure to the conventional degasification systems is the application of the natural potential of microbial methane oxidation in landfills in suitable cover layers. By creating optimal ambient conditions for methanotrophic bacteria in cover layers, it is possible to foster the microbial activity and to attain very high oxidation rates. The results derived from laboratory experiments as well as first experiences from a large-scale field investigation show that waste composts are suitable carrier substrates for methanotrophic bacteria. Methane oxidation rates in compost were clearly higher than in natural soils. Even at a methane supply of about 200 – 350 l CH4 m-²d-1 in the laboratory experiments all methane could be oxidized in the compost material.
Key Words: Landfill gas, degasification, microbial methane oxidation, landfill cover, waste compost, greenhouse gas
Organic Waste Management Using Vermiculture Ecotechnology–A Case Study
R. W. Gaikwad, S. E. Vats
Department of Chemical Engineering
Pravara Rural Engineering College, Loni-413736
District: Ahmednagar, Maharashtra State, India
Deep burrowing earthworm Vermiculture Ecotechnology can be used for environmental protection. The present communication deals with the use of Vermiculture in the treatment of organic waste and colony sewage treatment, through a case study. It was found that using Vermiculture technology SS, BOD and COD values of organic wastewater reduces tremendously.
Key Words: Vermiculture, organic waste, sewage, Suspended Solids, BOD, and COD
Oxides Of Nitrogen Emissions From Burning Wood
Kenneth L. Tuttle
United States Naval Academy
Annapolis, Maryland, United States
Oxides of nitrogen, NOX emissions, are one of the most carefully monitored contributors to air pollution in metropolitan areas. NOX is known to contribute to smog and ground level ozone as well as having the potential to make rain more acidic. Fuels burned in air all produce NOX, however, some sources are much worse than others. NOX emissions data from a wood-burning boiler are presented in this paper to show the level of emissions from burning wood and to publish the data as well as to show the effects of combustion parameters on NOX production. This paper presents variables such as excess air, air temperature and distribution and fuel moisture, size and combustion rate and the effect of each on the production of nitric oxide during the combustion of wood fuel. The results apply to many other biomass fuels including agricultural wastes, industrial solid wastes, shipboard solid wastes and municipal solid wastes fired under similar conditions.
Key Words: Combustion, Emissions, Biomass, Incineration, Oxides of Nitrogen, NOX, Smog, Wood, Solid Wastes, Ozone, Acid Rain
Removal Of Cadmium And Chromium From Contaminated Water Using Alkali Activated Fly Ash Permeable Reactive Barrier (AFA-PRB)
Hossein Rostami, William Brendley
Mozhgan Bahadory, Shahriar Jahanian
In the past 15 years, one half million sites with potential contamination have been reported to federal or state authorities. Of these, about 217,000 sites still need remediation (1) and new contaminated sites continue to appear each year. The most common type of contaminants are metals, solvents and petroleum products. Heavy metals are present in two thirds of Department of Defense (DOD) and superfund sites and about 50% of Department of Energy (DOE) and Resource Conservation and Recovery Act (RCRA) sites.
Alkali Activated Fly Ash Permeable Reactive Barrier (AFA-PRB) is a new material that possesses the ability to remove heavy metal from contaminated water. AFA-PRB consists of fly ash activating chemicals and fillers. AFA-PRB barrier material was used to remove Cd and Cr from contaminated water. Class F fly ash from three different sources were used to produce reactive barriers of different permeability. AFA-PRB materials with permeability 10-2 to 10-1 cm/sec were manufactured. Only the samples with the highest permeability proved to be viable for reactive barrier material. AFA-PRB barrier from three ash sources with permeability of 10-1 cm/sec were produced and crushed into pelletized form. To determine the effectiveness of the various barrier types, batch and column tests were performed.
Contamination barriers with controlled permeability were tested to determine their ability to remove Cd and Cr from contaminated water. AFA-PRB barrier materials were used in batch and column tests to remove Cd and Cr ions from 1000 ppm and 10 ppm solution. The results indicate that AFA-PRB barriers are very effective in removing Cd and Cr from highly contaminated water (approximately 99% efficiency).
Key Words: Contaminated water, Cadmium, Chromium, AFA-PRB, Fly Ash, Permeability, Reactive Barrier
Study On The Gelation And Modification Of Caustic Sludge
Wang Lijiu, Ai Hongmei, Li Yu
School of Civil Engineering and Architecture
Dalian University of Technology
In order to solve the discharging and stacking of caustic sludge in Dalian Chemical Industry Company, the authors undertook the way of acidification and high temperature heating to transform caustic sludge into cementitious material, namely caustic sludge-gypsum. This paper studied mainly the material physico-mechanical properties, which was compounded by gypsum, hydraulic cementitious material, activator and waterproof agent. The study would give security for the wide application of caustic sludge.
Key Words: Caustic sludge; cementitious material; gypsum
Issue 2, May 2001
Bioconversion Of Wastepaper To Sugars By Cellulase From Aspergillus Niger, Trichoderma Viride And Penicillium Funiculosum
J.P.H. van Wyk, A.M. Mogale, T.A. Seseng
Medical University of Southern Africa
SOUTH AFRICA, 0204
Wastepaper materials are a major component of organic waste and its cellulose section can be bioconverted to sugars by cellulase, a complex enzyme system, present in microorganisms. Cellulase from Trichoderma viride, Aspergillus niger and Penicillium funiculosum were incubated with used newspaper, office paper, filter paper and foolscap paper and the resulting total reducing sugars, determined. Every paper material showed different susceptibilities for each cellulase with T. viride cellulase exhibited the highest activity on all these waste cellulose materials. Milling of the cellulose materials into a fine structure prior to enzymatic treatment increased the extent of saccharification of all paper materials by every cellulase. Mixtures of these cellulases caused a further increase in degradation although not all mixtures could exceed the hydrolytic action of sole T. viride cellulase.
Key Words: bioconversion; cellulase mixtures; paper materials; reducing sugars; pretreatment; waste
Fly Ash Utilization For Thermal Insulation Bricks Manufacturing
Chemical Engineering Department
University of Jordan, Amman
Cost-effective thermal insulating bricks were produced from treated fly ash pastes. The pastes were prepared by mixing dried fly ash ground to particles smaller than 63 µm (derived from a pressurized fluidized-bed combustor, PFBC) with water at different water to solid weight ratios in a 170-rpm agitated vessel for 5 min. The paste was cast into a rectangular mold before being placed in a humidity-controlled chamber for curing. The curing conditions were kept at 80°C, and 80% relative humidity for 3 days. The effect of the addition of 10, 20 and 30 wt% of car-window glass fragments to the paste was also investigated. Measurements of the density, thermal conductivity and mechanical properties of the resulting brick were used for the evaluation of its suitability as a thermal insulator. The insulators prepared from water to solid weight ratio (W/S) of 0.5 showed good specifications in terms of low density and thermal conductivity, and high mechanical strengths. The addition of 10-wt% glass to the ash during slurrying enhanced the mechanical properties of the insulating material produced but had no significant effect on its density and thermal conductivity.
Key Words: Thermal Insulators, Pozzolan, PFBC, Fly Ash, Ettringite, Glass
Gold In Municipal Sewage Sludges: A Review On Concentratons, Sources And Potential Extraction
School of Earth Sciences
James Cook University
P.O. Box 6811
Cairns, QLD 4870
Sewage sludges from municipal wastewater treatment plants in Australia, Germany, Austria, England, Canada and the United States contain on average 1 mg/kg gold with concentrations ranging from 0.1 to 56 mg/kg (dry matter). The gold contents are significant as some of them are similar to those of geological ore deposits currently being mined for gold. Sources of gold and platinum-group elements in sewage include industrial effluents, human excreta, domestic additions (abrasion of jewellery and dental works, hair loss, food residues, drugs), and background levels in drinking water and road runoff waters. The extraction of precious metals from sewage is possible using established hydrometallurgical treatment techniques. However, while a number of companies in North America and Australia have announced their intention to extract gold and silver from sewage sludge or incinerated sludge, none of these commercial enterprises have been successful and further research is needed to identify economic metal extraction techniques.
Key Words – Sewage sludge, gold, platinum-group elements, precious metals, wastewater, extraction
Reinforced Recycled Polymer Based Composites For Highway Poles
Prof. Dimitrios G. Goulias
Department of Civil & Environmental Engineering
University of Maryland
0147A Glenn L. Martin Hall
College Park, MD 20742
Al -Hosain Ali
Six Metrotech Center
Brooklyn, NY 11201
The rapidly emerging industry of recycled-based composites has made substantial R&D investment to develop high-performance construction materials, which provide the performance quality of treated wood without its inherent costly maintenance, and with highly durable strengths under outdoor construction conditions. Recycled plastic resins resist attacks by living organisms and marine borers, do not rust or decompose, present strength characteristics and have impact resistance higher than wood, and are environmentally sound in soil and ground water media. In addition, durability of plastic resins due to sunlight exposure is typically addressed by the industry with the use of additives in the resin mix.
This paper presents the results from a technical feasibility assessment of reinforced recycled plastic resins for highway utility poles. In order to produce a composite construction material that will meet the expected performance requirements and design specifications, technological and economic feasibility assessment, product development, and engineering performance evaluation, is needed. This paper describes the economic and technical feasibility evaluation undertaken in this study. First, the adaptability of these reinforced composite materials to current specifications was examined. Then, typical in-service loading conditions were identified for evaluating preliminary pole designs with these resins. Next, standard pole design criteria were used for developing alternative reinforced recycled composite pole designs that are comparable to wood poles. Finally, the economic advantages of reinforced composite-based poles were identified. The methodology and results of this study could be used for evaluating the potential of using recycled polymeric based resins in similar infrastructure applications.
Key Words: Composites, Recycled Plastics, Polymers, Resins, Fiberglass Fibers, Utility Poles
Water Transport In A Bottom Ash Landfill From A Municipal Solid Waste (“MSW”) Incinerator
Frank Hartmann , Hans-Peter Bader, Ruth Scheidegger
1Department of Resource and Waste Management
EAWAG (Swiss Federal Institute for Environmental Science and Technology)
Department of Civil and Environmental Engineering
Swiss Federal Institute of Technology
In this paper the water transport in a bottom ash landfill from a Municipial Solid Waste (“MSW”) incinerator is discussed.
Bottom ash contains micro- and also a large number of macropores (»2/3 of the total porosity of 43% [Lichtensteiger, 1996]). Therefore two different models with different physical/mathematical approaches are applied. The model “Microflux” describing micropores only is implemented in the computer-program “HYDRUS-1D” [Simunek et al, 1998] and the model “Combined Micro-Macroflux” describing micro- and macropores in the computer-program “MACRO” [Jarvis, N. et al, 1998], respectively.
As test site a landfill (profile depth: 6m) near Winterthur in Switzerland has been used. Precipitation, leachate and meteorological parameters have been measured every 15 minutes during more than one year. These time series were used to calibrate the models. With the model Microflux leachate fluxes cannot be simulated successfully (compared with the measured fluxes) even if unrealistic values for some hydraulic parameters are assumed.
On the other hand, by using the Combined Micro-Macroflux model and choosing a macroporosity of 29% (»2/3 of the total porosity) there is a very good correspondence between measured and simulated leachate fluxes.
Key Words: bottom ash landfill, leachate, macroporosity, modeling
Mathematical Model Of Leachate Transportation At Fly Ash Dumping Site
M.R. Hajarnavis, A.D. Bhide and R.S. Hajarnavis
National Environmental Engineering Research Institute
Despite three decades of research, there is still a lack of understanding on the phenomenon of contaminant migration which leads to ground water pollution at fly ash dumping sites. Many complex physical, chemical and biological phenomena influence the migration of contaminants. It is difficult to measure all the variables during field investigations.
To save time and expenses in investigation of ground water pollution resulting from migration of pollutants from fly ash dumping sites, a relationship has been proposed for contaminant migration. The paper presents results of laboratory investigation using non-dimensional approach on two lysimeters. The plots between non-dimensional parameters are presented to help predict the likely pollution caused by disposal of waste from thermal power plant on open land or in low lying areas and extent of transportation of pollutants.
Key Words: Leachate, transportation, fly ash, heavy metal, mathematical modelling
Source Seperation And Recycling In Tehran / Iran
Dr. Ali A. Tofigh
Chancellor of the University of Applied Technology
and Advisor to the Minister of Culture and Higher Education
Ministry of Culture and Higher Education
P.O. Box 14155-1644
Recovery should be practiced by taking the cost analysis and environmental factors into consideration. An effective and an efficient recovery starts through waste recovery separation techniques at the port of origin. Given the huge amount of garbage wastes in the city of Tehran that amounts to 68 to 73% of total waste in Iran, utilization of compost process and techniques, is deemed necessary. Participation and assistance of citizens can help to separate and to collect the dried, toxic and hygienic foodstuff wastes, therefore making the stages for processing foodstuff into compost less costlier and more hygienic.
Key Words: Waste management, compost, decaying, residues, separation from origin, participation of city dwellers, recovery
Issue 1, February 2001
Low Pressure Reverse Osmosis Treatment of Landfill Leachate
S.Hird, K.J. Kennedy ,R.L. Droset , A.Kumar
Dept. of Civil Engg
University of Ottawa
162 Louis Pasteur Street P.O. Box 450 Stn A
Ottawa Ontario K1N 6N5 Canada
Three low pressure reverse osmosis (RO) membranes were characterized and tested for the treatment of municipal landfill leachate.A low pressure polyamide membrabe designated H was selected as the msot appropriate membrane for the treametn of landfill leachate. A feed of 5000 mg/l NaCl was made up with Ro water gave removal efficiencies greater than 97% at permeate fluxes ranging from 27.0 to 53.0 l/m2/hr at operting pressures in the range of 100 to 200 psi .Using various concetrations of synthetic leachate the H membrane achieved consistently high removal rates for totla organic carbon(TOC) (>84%) NH3 (>83%) and Cl-(>81%).A cnetral composite experimental design showed that the product flux was dependant on the operating pressure and on the TOC concetration.For oeprating pressures greater than 150psi the permeeate fluxes were in the range of 7.7 to 31.7 l/m2/hr .
Using leachate from the Regional Municipality of Ottawa Carleton Trail Road municipal landfill the H membrane achieved TOC and CL- removal efficiencies greater than 96% and NH3 removal efficiences greater than 88%.For operating pressurs greater than 150 psi the permeate fluxes was in the range of 26.0 to 54.0.Using a spiral wound H membrane configuration produced low removal rates and low permeate fluxes for highly concetratd leachate.Removal rates for TOC and Cl- were 73 and 27%.The spiral wound H module was tested for lower operating pressures resulting in low permeate fluxes.
Key Words: Reverse Osmosis, membranes,landfill leachate treatment,low-pressure ,chloride,ammonia
Waste Tire Pile Quantification Through Surveying Techniques Statistical Analysis and Calculus
Ramirez Barreto Ma Elizabeth ,Gonzalez Navarro, F.Fernando,Ojeda Benite Sara
Instituto de Ingenieria
Universidad Autonoma de Baja
California PO BOX 3439
Calexico Ca USA 92232
Waste tire importation form the USA to MExico is a common practice in Mexicali, B.C.The frequent replacement of tires by Mexican drivers translates into higher waste tire disposal rates.These tires are either illicitly discarded or aken to a permitted waste tire site.Presently waste tires are viewed as having no value.In this research scrap tires sites in Mexicali wll be characterized.Additionally a methodology will be proposed to determine the number of waste tires in piles.Scrap tires have the potential to be reused as new material in manufacturing new products,or used as coke, or other processes which will oermit to clen up sites and will reduce contamination problmes.The work was made in 2 stages
1. sites on whcih waste tires are disposed in Mexicali are analyzed and described
2. one waste site was selected t characterize an dcalulate the number of tires contained within the piles.
These samples were used to statisticaly calculate the number of tires within the piles.
Key Words: Waste tires, usd tires,disposal site,sampling tires
Divided Collection Model for Household Waste Achieves 80% Landfill Diversion
M. Fehr, M.R,. Calcado
P.O Box 811
38400 974 Uberlandia Brazil
Technical an dadministrative shortcomings of present models for household waste management are identified.In order to correct them the philosophy of divided colllection is developed and the corressponding management moel i sdetailed.The model is applied to a test community.Experiments are conducted with behaviour management o fpeople and with collectin sorting of waste.The model is deemed to be functional.It opens the perspective to divert 81.8% of waste from landfill.This result suggests the beginning of a new era in household waste management.
Key Words: Solid waste,household waste management,source seperation,divided collection,twin bin management model, landfill diversion targets.
A Spray Based Crumb Rubber Technology in Highway Noise Reduction Application
Civil and Envrn. Engg Dept
Srizona State Unviersity
Tempe AZ 85287-5306
Director of Governmetn Relations
Rubber Pavements Association
Tempe AZ 85287
Crumb rubber is a commodity made by re-processing disposed automobile tires.This article presents a new tech on the application of crumb rubber in high way noise reduction systems.Advantages and disadvantages of 2 commonly used manufacturing processes of crumb rubber panels are analyzed.It is shown that for the intended appliation a spraying process is much preferable.Four types of spray devices are further examined.The bonding agent slection and the mix design are investigated.A number of crumb rubber panels are made by the sparying process and the test of acoustic absorption i sperformed on one type of the panels.the acoustic testing rseult shows that crumb rubber panels exhibit an excellent noise reduction capability.The theme of this article is to present th eprogres made in advancing this technology product developmetn as well as the feasibility and promise of what it can do for solving 2 environmentla problems scrap tires and traffic noise.
Key Words: Crumb rubber,traffic noise,highway sound wall,acoustic absorption,spray technology,polymer bonding agent.
Greenhouse Gas Emissions at a Semi-Arid Landfill Site
Douglas a Opseth
Jacques Whitford Environment Ltd
2510 12th Ave
Canada S4P 3X1
Kim D Barlishen
faculty of Engg
Univeristy of Regina
Canada S4S 0A2
Two semi arid landfills were investigated for landfill gas emissions.Several methods were used to characteize the gas emissins: a flame ionization detector,a flux chamber,shallow gas wells, and the US EPA landfill gas model.The results of the landifll gas investigation showed high spatial variations over the surface of the landfill with emissions being concentrated at the slopes.Overall the emissions proved to be in low to meduim range of literature values for totla gas generation.Waste samples retrieved from the landfill suggest below optimal conditions for decomposition.
Key Woords: Landfill gas, greenhouse gas,methane emissions,semi-arid-site.
Solid Waste Reduction and Environmental Impact in Concrete Block wall Construciton
Shoou Yuh Chang, Bryan Morton
Dept. of Civil and Envrn. Engg
North carolina A&T State Univ
Greensboro Norht Carolina USA
Concrete block wall systems are key components in residential an dcommercial constructions.the manufacture of concrete wall blocks consume large amount of energy and emits CO2 to th eatmosphere.Thus the true environmentla costs have to be relfected in the selectin of the wall systems for any building construction.Proper use of Life Cycle Assessment(LCA) models involves quantification of all environmental costs,in additin to th etraditionally used cost of construction,in the system selection porcess.LCA is an objective methodology that seks to evaluate the products overall cost including environmental loading from raw material acquisitin to final disposition.Environmentla costs considered include:the mining or farming of the raw material,processing those materials to produce the cmponents of the wall system,use of the structure an ddemolition of the structure.LCA methodology was used to compare the life cycle of the traditional two-core hollow concrete masonary unit(CMU) wall system with that of five innivative competitive systems.The results indicate that whil ethe material cost is the lowest for the 2-core hollow CMU the environmental costs are much higher compared to other innovative wall block system.Assessing realistic costs to the materials comprising the competing systems may be difficult,but it is essential to place the best value available on these materials to properly analyse their impact on the environmetn at the timeof building system demolition.Inclusion of these costs inthis model assures that proper considertionto solid waste minimization is given at the tim eo f the buildings design.
Key Words: Life cycle assessment,solid waste reduciton,concrete wall construction,pollution prevention.