Volume 23, 1997


Issue 4, November 1997



H.I. Park and S.R. Lee
Department of Civil Engineering
Korea Advanced Institute of Science and Technology
Taejon, 305-701


Long-term settlement of landfills is one of the important items in the design of protection systems such as caps and leachate collection systems as well as in the technical consideration o feasible redevelopment of a landfill site for building foundations and pavement. Long-term settlement mechanisms cannot be merely dealt with by classical Soil Mechanics concepts, since they are considerably dependent upon the biological decomposition of refuse which distinguishes it from typical soil behavior. Nevertheless, a detailed mechanism by which the decomposition causes settlements has not been found. This paper presents a mathematical model that considers the decomposition process of biodegradable refuse from a geotechnical point of view and suggests the overall compressibility behavior of refuse, including the decomposition effect.

Key Words: Decomposition, refuse landfill, long-term settlement, secondary compression, prediction model, compressibility

Return to the top of page  



Waldemar A. Zuchowicki
Department of Civil Engineering

Tadeusz Hryniewicz
Division of Electrotechology and Electrochemistry

Wanda M. Twardowska and Wojciech Kuczynski
Department of Civil Engineering
Politechnika Koszalinska


This paper presents a new technological solution for waste management in the region of Central Pomerania, Poland. An innovative method of obtaining biogas has been introduced based on the municipal waste landfill for Koszalin and Sianow. With the stockyard gas-cap driving and biogas processing (the production of biogas being self-contained during solid waste treatment, rendering wastes harmless) some disadvantageous interaction with the environment is eliminated, and a renewable energy source is gained. Besides the biogas production and its management, the reduction in pollution and rendering waste harmless is achieved, resulting in effects/advantages in environmental protection. Although the waste storage has been known for years, the implementation of the biogas recovery and transforming it into energy is a novelty in Polish conditions.

Another interesting solution of waste management is presented by the example of Kolobrzeg waste utilization plant working on the basis of the compost yard at Grzybowo. In this case, besides gaining secondary raw materials one obtains compost, which is an excellent fertilizing material used for gardening purposes and for terrain recultivation.

The presented ways of waste disposal, preceded by initial segregation in the towns, are intended to diminish the stockyard areas and cost of garbage disposal, gaining biogas and/or compost, and secondary materials for further processing. For the inhabitants of the region, the environmental protection is of special importance specifically due to the prevailing conditions–lack of big industrial centers, sea-shore strip with the land of clean lakes and forests–making an excellent basis for touristic development.

It is also essential at present that, having started the adaptational process for full participation in the European Union, Poland puts a special stress on waste management problems by making efforts aimed at the protection of natural environment.

Key Words: Waste segregation, garbage disposal, waste stockyard, compost, biogas

Return to the top of page  



Adam D. Read
Department of Geography
Kingston University
Penryhn Road, Kingston-upon-Thames
Surrey KT1 2EE

Paul S. Phillips and Alice Murphy
Nene College of Higher Education
Park Campus, Boughton Green Road
Northampton, NN2 7AL


An analysis of the adoption of environmental bodies in two English counties is based empirically upon a survey of waste disposal contractors in the case study locations. The Government is actively attempting to shift the emphasis of municipal solid waste management further up its hierarchy of waste options. In the wake of recycling targets, recycling credits, minimisation trials and general waste related policy and legislation, the Government has enforced the landfill tax, to artificially raise the cost of landfill, thus making other waste treatment methods more economically viable and feasible for local authorities to implement and operate. This is primarily a descriptive piece of research focusing upon a new fiscal tool initiated by the UK Government to encourage the adoption of waste management strategies at higher levels of the hierarchy. This research focuses upon the impact of this new tool and its associated policies at the local level on waste management practices.

However, of perhaps greater significance than the tax, are the associate environmental bodies which can be set-up to reclaim up to 20% of the disposal company’s landfill tax payments if used for the initiation of local environmental improvement schemes. The environmental bodies which can be set up to implement these schemes must focus their attentions on land reclamation, building restoration or education and research. Awareness of the potential of these bodies in providing positive local environmental improvement is assessed by focusing upon their adoption by, and involvement of, private sector landfill operators in the counties of Northamptonshire and Surrey. Environmental Bodies are currently being viewed warily by the industry, with little firm commitment to initiate bodies or provide funding for existing bodies; only 20% of the sampled companies positively expressed an interest in funding environmental bodies. However, the results do suggest that the bodies which are currently being set up independently of the landfill operators, should eventually be successful in attraction funding from these companies, providing an important source of funding for local environmental initiatives. All companies who expressed an interest in the initiation of environmental bodies expected funding to be available within the coming financial year, providing a timely boost to a scheme which is currently only developing slowly with little firm commitment of funds. Perhaps the areas most likely to receive funds are education and research, where the benefits could prove to be industry wide, with 36% of companies supporting these uses of their funds. As environmental bodies develop, there will be opportunities for companies to improve their environmental performance and image, and more importantly for academic institutions to become actively involved in the organisation and operation of these bodies, and benefit from this new source of research money.

Key Words: England; Environmental Bodies; Landfill Operators; Landfill Tax; Northamptonshire; Surrey; Telephone Survey

Return to the top of page  



Qiang Shi
John Z. Wang
Institute of Wood Research
Michigan Technological University
Houghton, Michigan


Automobile fluff, also referred to as automobile shredder residue (ASR) is an industrial solid waste. Ear year, in USA alone, about 1.4 million tons of automobile fluff is disposed in municipal landfills. Among the landfilled automobile fluff, about 50% of the materials is polymeric. The objective of this research is to investigate the feasibility of utilizing the polymer automobile fluff to manufacture wood fiber/fluff composites. To this end, dry-form method was used to manufacture the wood fiber/fluff composite boards at a fiber to polymer fluff particles weight ratio of 70:30 and particle size of 35 meshes. Polymeric diphenylmethane diisocyanate (PMDI) and phenol formaldehyde (PF) resins were used as binders in separate experiments. Experimental results indicated that thickness swelling, moisture absorption, and decay resistance of the wood fiber/fluff composites were substantially improved when compared to the neat wood fiberboard. However, the mechanical properties, viz. the modulus of rupture (MOR) and modulus of elasticity (MOE) were moderately reduced. It is believed that the improvement in the physical properties and decay resistance is significant due to the non-structural nature of most fiberboard applications, especially when such applications involve high humidity environments.

Key Words: Wood fiber/fluff composites; Automobile fluff; Automobile shredder residue; Wood fiberboard; Dry-form; Composites

Return to the top of page  



Michael J. Hare
University of Toronto


Beverage-packaging regulations have been introduced in many jurisdictions in Canada and in the United States since the early 1970’s. A principal aim of these government command-and-control programs in Canada has been to significantly reduce the quantity of soft drink packaging waste sent for disposal through increased recycling diversion. The waste management externalities associated with soft drink packaging would thereby be reduced. A wide-array of provincial fiscal and regulatory recycling programs have been used including bans on the sale of recyclables, packaging taxes, deposit-refund systems and mandatory household source separation systems.

Although theoretically desirable, source reduction diversion appears to be rare and largely unmeasured. Packaging waste reduction programs most often do not include consideration of source reduction diversion. Source reduction diversion arises through private sector activities when consumer goods industries invest in technologically improved packaging. Source reduction diversion allows for reductions in municipal waste management costs both now and for the future and works to conserve both resources and landfill and to reduce environmental effluents. In short, source reduction diversion works to improve resource sustainability, to reduce packaging waste generation and to enhance the environment. Recycling diversion appears to have caught the government’s eye: source reduction diversion has not. Source reduction diversion appears to be the missing “R”.

In this paper, soft drink packaging waste diversion rates are presented for the four principal Canadian provinces [Ontario, Quebec, Alberta and British Columbia] which account for about 80% of containerized soft drink sales in Canada. The diversion rates were based upon the weight of packaging waste sent for disposal per litre of soft drink sales for 1995 over the weight for 1972 as a result of new source reduction and new recycling activities in the province which were introduced during the 1972 to 1995 assessment period. The research results reveal that Canadian soft drink packaging waste diversion rates have been exceptional. The diversion rates for Ontario, Alberta and British Columbia exceeded 90% and for Quebec were 85%.

The analytical model allocated the 1995 soft drink diversion gains for the four principal Canadian provinces between source reduction and recycling. The research results reveal that source reduction diversion accounted for about 75% of the total diversion gains: on average, for every four tonnes of diverted waste, three tonnes were through source reduction and the remaining tonne from recycling. The importance of source reduction diversion has been unmasked. Competitive market forces have worked to successfully divert large quantities of packaging waste, at least in the Canadian soft drink industry.

The principal findings are both surprising and exceptional. The study results reveal the strategic importance of the missing “R” in the Canadian soft drink industry and provide new insights into the “packaging waste problem” for all consumer product packaging in Canada, in the United States and in other nations.

Key Words: Source Reduction, Packaging Waste, Packaging Diversion, Soft Drinks

Return to the top of page  


Issue 3, August 1997



John Sykes
John Sykes Rural Consulting
Albury, New South Wales, Australia

Robert Harrod
Elders Ltd.
Albury, New South Wales, Australia

Percival Thomas
La Trobe University
Wodonga, Victoria, Australia 


An investigation was carried out in southern Australia to test the response of differing application rates of paper mill biosolids, and mixes of it with conventional fertilizer on wheat crops. The results show that the application of biosolids raised the grain yield of wheat when conventional fertilizer was applied at sowing. Best yielding crops were those that had medium rates of biosolids application (6.5 – 12.8 tonnes/ha) together with conventional fertilizer at a rate of over 5kg/ha of phosphate applied. At low yield levels up to 2.5 tonnes/ha, the paper mill biosolids act as a source of both phosphate and nitrogen, but at high yield levels the phosphate is contributed from the fertilizer and the nitrogen from the biosolids. No soil problems have been encountered and the paper mill is able to supply its solid waste for agricultural use resulting in environmental, economical and social benefits.

Key Words: Biosolids, paper mill waste, land spreading, wheat production, wheat crops, paper mill sludg

Return to the top of page  



Dimitrios G. Goulias, Ph.D.
Department of Civil Engineering
Polytechnic University
Brooklyn, NY


Al-Housain M. Ali
Department of Civil Engineering
Polytechnic University
Brooklyn, NY 


With the mandatory use of tire rubber in hot mix asphalt for federally funded projects by the 1991 Intermodal Surface Transportation Efficiency Act (ISTEA), the highway community intensified laboratory and field investigations on rubber modified asphalt mixtures nationwide. The use of natural and synthetic polymers for improving binder and mixture properties was initiated several years ago in the US and Europe. However, up to the 1991 ISTEA mandate, rubber modified binder and mixtures received little attention due to the additional complexity in understanding, designing and producing rubber modified mixtures and the lack of construction guidelines. These issues coupled with questionable performance and cost effectiveness further delayed the development of rubber modified mixtures. Conflicting performance for these materials, as reported by several pilot studies, might be attributed to the use of mixture preparation guidelines developed with different conventional materials and for different conditions thereby producing significant variation in binder preparation and mixture design requirements, as well as construction guidelines. Asphalt rubber mixtures further complicate asphalt mixture design because additional factors affecting binder and mixture performance are introduced in the process. In addition, current standards methods of mixture design do not always produce mixtures with the best field performance.

It is the objective of this paper to identify and examine factors affecting binder and mixture characteristics and provide comparative mixture design data between conventional and rubber modified mixtures. First, the factors affecting asphalt rubber binder properties and characteristics are presented, such as asphalt and rubber type, binder composition, asphalt rubber interaction period and percent rubber, along with suggested recommendations and specifications. Then, mixture design results are presented for conventional and rubberized mixtures, prepared with typical state specifications for dense graded surface materials, for comparative purposes.

Key Words: Asphalt Mixtures, Rubber, Design, Asphalt Rubber Binder, Stiffness, Stability

Return to the top of page  



Chillara Subbarao
Professor of Civil Engineering
Indian Institute of Technology, Kharagpur, India


Ambarish Ghosh
Lecturer of Dept. of Civil Engineering
Bengal Engineering College
(Deemed University), Howrah, India 


At present an enormous amount of fly ash is being produced by thermal power plants throughout the world. Stabilization of the fly ash is one of the promising methods to manage environmental problems of fly ash disposal. The strength of the stabilized fly ash is also more than that of the unstabilized fly ash. In this investigation an attempt has been made to study the effect of stabilization on leachate characteristics of a stabilized low lime fly ash. Hydraulic conductivity of the stabilized material is very low and hence it can be used in a rigid waste containment liner. Fly ash was stabilized with lime (4%, 6%, and 10%) and compacted to Proctor density. Specimens were cured for 7 days and 28 days. Water was allowed to pass through the cured specimens continuously for 7 days. The concentrations of Cd, Cr, Cu, Fe, Mg, Ni and Pb in the effluent were analyzed by Flame Atomic Absorption Spectrophotometer. Results presented herein for first and sixth day of flow for both the curing periods, show that the concentrations of Cd, Cr and Pb for some of the mixes are more than the allowable limits for drinking water quality. Hydraulic conductivity of the stabilized material being low, the total amount of metals emanating from stabilized material is low compared to that of unstabilized material, though sometimes with stabilization the concentrations of metals in the leachate have increased. Hence this stabilized fly ash can be accepted as a nonhazardous material for field applications. The use of stabilized pond ash for high strength and the use of stabilized fly ash for low hydraulic conductivity of liners or impermeable barriers are advocated.

Key Words: Fly ash disposal, Hydraulic conductivity, Leachate analysis, Lime stabilization, Lining material, Strength

Return to the top of page  



Timothy G. Townsend and W. Lamar Miller
Department of Environmental Engineering Sciences
University of Florida
Gainesville, FL


An issue of concern in the implementation and success of a landfill gas (LFG) recovery system is the ability to collect gas prior to landfill closure. A large percentage of the LFG generated may be produced during the time when waste is actively deposited. Proposed federal regulations will soon require many landfills to install LFG recovery systems, sometimes necessitating gas collection while the landfill is operational. Traditional LFG collection systems (vertical wells) are generally constructed and operated after the final layer of waste has been placed. This paper examines a LFG extraction system which utilizes a lined landfill’s leachate collection system to recover gas from an operating landfill prior to closure.

A landfill gas collection system was constructed at a lined, operating solid waste landfill to remove gas by means of the landfill’s underdrain system. The system utilized the landfill’s existing leachate collection system along with a blower-flare station which was originally constructed to extract gas from an adjacent capped landfill. Gas flow and composition were measured as a function of applied vacuum at the extraction point, and the resulting distribution of pressure throughout the leachate collection system was monitored. A maximum of 10.4 scmm of total LFG (5.6 scmm methane) was collected from a single extraction point with an applied vacuum of 7.6 cm water column and a methane concentration of 54%. The system successfully provided the means to collect and combust a large volume of gas from an operating landfill which was not scheduled to have a gas collection system installed and operated for at least four years.

Key Words: Landfill, Solid Waste, Landfill Gas, Methane, Gas Collection, Leachate Collection System

Return to the top of page  



M. R. Boni, A. Delle Site, G. Lombardi, E. Rolle
University of Rome “La Sapienza”
Faculty of Engineering
Via Eudossiana 18, 0018, Rome 


Municipal solid waste (MSW) aerobic landfilling has been recently demonstrated, in laboratory and pilot-plant scale studies, to be able to obtain a number of advantages: improvement of leachate characteristics; reduced time for site end uses; lower production of landfill gas. Moreover, the measurements of the settling of landfilled waste showed that both aerobic conditions and leachate recirculation increase subsidence.The present paper deals with the behavior of the wastes disposed according to the following innovative technique: in the first phase, the waste was maintained under aerobic conditions, while in the second phase, under anaerobic conditions. Such conditions were simulated in a laboratory sanitary landfill in order to evaluate the efficiencies of the two phases in relation to: quality and quantity of leachate produced; carbon mass balances; quantity and quality of landfill gas produced (in the second phase only) The waste composition was: organic fraction of municipal solid waste to be composted (40% w/w), dry refuse derived fuel (30% w/w); inert materials (25 % w/w) and metals (5 % w/w).

Key Words: Municipal solid waste, Aerobic pretreatment, MSW organic fraction stabilization, Innovative landfill, Improvement of landfill operation

Return to the top of page  



Edward D. Rawski
Pennsylvania State University
Harrisburg, PA

Charles A. Cole, Ph.D.
Pennsylvania State University
Harrisburg, PA USA 


Old newspaper (ONP) comprises close to seven percent of the United States’ solid waste. Conventional products of ONP recycling include cellulose insulation, animal bedding, ceiling tile, boxboard, compost, and more newspaper. Since newspaper contains a large amount of cellulose it was hypothesized in this project that the viscose process could use ONP exclusively as a cellulose source for production of

cellophane film or sponge. A bench-top experiment of the viscose process was performed using ONP as the cellulose source. Old newspaper was converted, via the viscose process, to crude forms of both cellophane film and cellulose sponge. Other paper types were then successfully used as cellulose sources for the viscose process. It was concluded from the project that ONP, as well as other types of paper, may be converted to useful products via the viscose process. It is recommended that further research be conducted on this topic, particularly for product improvement and process enhancement.

Key Words: Viscose; Recycled Paper; Cellulose; Post-Consumer Paper

Return to the top of page  



Martin Medina
El Colegio de la Frontera Norte
P.O. Box L
Chula Vista, CA 91912


The relationship between municipal solid waste generation rates and income is assumed to be a direct and positive one. The present paper analyzes this relationship for 123 countries, based on data compiled by the United Nations. It was found that instead of a straight line, solid waste generation shows a curvilinear shape as income increases. The proposed model indicates a transitional pattern: as a country develops, its waste generation rate increases; then for middle and upper-income countries a transition takes place, in which waste generation and income show a very weak association, and for the wealthiest countries, their waste generation rates actually decrease.

Key Words: Solid waste generation rates, income, municipal solid waste management, waste reduction, resource use, economic development

Return to the top of page  


Issue 2, May 1997


Andrs Salas, Ruby de Gutirrez, and Silvio Delvasto
Departamento de Materiales de Ingeniera
Universidad del Valle
Apartado aereo 25360, Cali, Colombia


High performance concretes were studied using 15 % silica fume ( a solid waste ), 2 – 5 % of a melamine superplasticizer, four types of siliceous gravel, a calcareous aggregate, a siliceous sand, and type I Portland cement. Two maximum sizes of aggregates were tried: 12.7 mm and 19.1 mm. The water/cement ratio ranged between 0.28 and 0.31. The highest compressive strength obtained at 56 days of normal curing was 83 MPa. The maximum flexural strength was 10.3 MPa. The average chloride permeability reported 350 coulombs. This result complies the ASTM Standards. The chloride diffusion coefficient was 3.3 x 10-13 m2/s which is low compared with the typical values of normal concretes. From the research results could be concluded the positive effect of the silica fume incorporation in order to obtain high performance concretes.

Key words: High Performance Concrete; Silica Fume; Chloride Permeability; Diffusion Coefficient; Rice Husk Ash; Solid Wastes

Return to the top of page  


Adam D. Read
Postgraduate Research Student
Department of Geography, Kingston University
Penrhyn Road, Kingston-upon-Thames
Surrey, KT1 2EE, England


The opinions and views of professionals from both the private and public sectors of the municipal waste industry were obtained using a postal questionnaire. This research provides an insight into the broader issues of current interest to the waste industry, focusing upon the future role of landfill, the growth of recycling, waste to energy and composting, and Government control over the industry’s future development and direction.

Landfill remains the dominant waste management method employed in the UK, whilst recycling and waste to energy schemes have struggled due to the historically cheap nature of landfill. By 2010 almost all of England will be suffering from a landfill shortage, and it is in response to this scenario that the Government has begun to promote the development and use of alternative strategies, through the initiation of the Recycling Credit Scheme, and the imposition of the Landfill Tax, in the hope of preserving landfill void for the future disposal of untreatable residues.

Both the private and public sectors are responding to the Government’s lead, although at differing rates, by adopting the use of Recycling, Minimisation and Waste to Energy ideals, in contrast to their previous landfill dominated practices. The industry is evolving rapidly with the new Environment Agency, the landfill tax, tighter regulations and greater awareness of the need for environmentally acceptable disposal strategies, and this may prove to be the impetus required for greater Central Government legislation and policy.

“The new tax on landfill waste disposal demonstrates the Government’s commitment to extending the use of economic instruments to achieve environmental objectivesàà the landfill levy is an important development for the proposed national waste strategyàà the new levy will help to achieve, in the most cost effective and least regulatory manner, our objectives of waste minimisation and of boosting the recovery of value from waste, including recycling, whilst reducing our reliance on landfill.” — Rt. Hon. J. Gummer MP, Secretary of State for the Environment (1995)

Key words: England; Landfill Availability; Municipal Waste; Policy; Postal Survey

Return to the top of page  


O. Porcel, F.J. Aguilar, J.J. de Leon, J. Revilla, J. Diz
Empresa Municipal Saneamientos de Cordoba
Dpto. de Estudios
Tte. Braulio Laportilla no. 7,2-14008 CORDOBA (SPAIN)
Universidad de Almera
Dpto. Ingeniera Rural-04120 ALMERIA (SPAIN)


This paper presents a study of the spacial and seasonal variability in Municipal Solid Waste (MSW) production in C<rdoba. The objective is to improve the design and operation of the collection and treatment system by understanding the variations in percentages of each fraction which will finally reach the treatment plant. All of this is necessary for the design of the plant and commercialization of the products recovered.

The methodology used includes a previous selection of MSW collection circuits which represent three socioeconomic sectors : popular sector, residential sector and commercial sector. The circuits were studied every two months during a whole year. A total of 117 different characterizations were carried out. An important variability was noted regarding seasonal production among the socioeconomic sectors. In general terms, the average composition of MSW in C<rdoba shows higher levels of organic matter than the average in Spain. The levels of glass are lower and similar levels for paper and plastic were noted. The chemical analysis produced interesting results, such as an important difference among sectors regarding total organic matter, humidity, porosity, C/N relation and content of nutrients.

The high content of organic matter in C<rdoba’s MSW, together with the adequate characteristics which the organic fraction shows for its composting, and the great agricultural activity which takes place around the city, makes recycling – composting treatment the most adequate for this city.

Key words: Municipal Solid Waste, Physical Characterisation, Chemical Characterisation, Seasonal Variability, Spacial Variability, Recycling Programs

Return to the top of page  


Heather L. Robinson
Environmental Engineer
URS Greiner
5606B Virginia Beach Blvd.
Virginia Beach, VA

Mujde Erten-Unal, Ph.D.
Assistant Professor
Department of Civil and Environmental Engineering
Old Dominion University
Norfolk, VA


This paper represents the results of six pollution prevention/waste minimization assessments performed on commercial printing industries in the Hampton Roads area of the Commonwealth of Virginia. The pollution prevention project is the result of a working partnership (the Partnership) formed between Old Dominion University’s Department of Civil and Environmental Engineering (ODU) and Hampton Roads Sanitation District’s Industrial Waste Division (HRSD) for the Pollution Prevention Incentives for States (PPIS) grant awarded by the United States Environmental Protection Agency (EPA).

Local businesses were provided with direct on-site technical consultation on waste reduction, and possible alternatives for the reduction or elimination of solid and hazardous waste, wastewater discharges, and air emissions, were evaluated. Financial analyses of identified technology and procedural options were developed in order to prepare comprehensive reports for each business on findings and recommendations.

Industry profiles are provided in order to establish the type of services rendered by the facilities participating within the program. Material usage, waste generation, and waste minimization recommendations are examined for six commercial printing businesses. Proposed waste minimization recommendations include loss prevention and good housekeeping, hazardous solvent source reduction, recycling of available markets, and proper flow measurement of all materials and waste streams. Economic incentives have been addressed for several of the suggested recommendations to encourage facility implementation.

Successful implementation of the proposed measures is dependent upon each facility. Performance measures will be taken on a routine basis by HRSD’s personnel during regular inspections and should also be taken by plant personnel for optimum effectiveness.

Key words: Pollution Prevention; Commercial Printing Industry; Source Reduction; Recycling; Waste Management

Return to the top of page  


Malcolm T. Hepworth
Professor Department of Civil Engineering, University of Minnesota
500 Pillsbury Drive, S.E., Minneapolis, MN 55455-0220

Rachid Slimane
Scientist, Institute of Gas Technology
1700 S. Mount Prospect Rd.; Des Plaines, IL 60018


An acid leaching process is developed and achieves nearly 100% extraction of vanadium and nickel which could readily be purified and also a carbon residue which may be suitable for use in electrodes during aluminum refining. Total recovery of these significant resources was achieved by atmospheric leaching followed by solvent extraction to yield 99.6% pure V2O5 product. [The lower valence state V2O3 leaches better in acid than the higher valence state V2O5.] During this study on sulfuric acid leaching of vanadium coke the effects of releaching the burned acid-leach residue with either H2SO4 or NaOH are examined. It is shown that vanadium recoveries can be increased to 98% by caustic releaching in 2 normal sodium hydroxide. The use of ultasonics during acid leaching improves vanadium extraction from a control of 73% recovery to 85% recovery, with increasing recovery a function of the ultrasound energy applied. Solvent extraction tests show that tertiary amine extractants will extract vanadium from the sulfuric acid leach solutions, but additional test work is needed to improve this process. The V2O5 product precipitated from the sulfuric acid leach liquor was 99.1% vanadium as V2O5 with phosphorous and iron being the major impurities.

Key words: Acid leaching; Solvent extraction; Flexicoke residues; Vanadium; Nickel; Carbon

Return to the top of page  



Professor of Civil Engineering
Govt. Engineering College
Ujjain (MP) – 456 010, INDIA

Principal, Technical Teachers Training Institute
Madras, INDIA

Research Scholar, Govt. Engineering College
Ujjain, INDIA


Vermicomposting technique for agricultural solid waste treatment uses earthworm species which need soil as habitat. However little work has been done for its application in community solid waste management. In the present studies an exotic species of earthworm – Eudrilus Eugeniae (African Night Crawler) – was used in treatment of organic part of community solid waste (produced from populous city of Madras, India). The species does not need soil substratum, thereby reducing reactor volumes to around 60%. Bench scale reactor studies were performed on the organic solid waste, under controlled optimum environmental conditions (temperature: 20C – 30C, moisture content: 48 – 52%), with variable vermi-loading (4.5 – 10.5 kg/m3). Characteristics of solid waste and process progress were monitored through conventional and additional parameters (BOD, COD). Studies yield kinetic rate constants of vermicomposting process (with respect to BOD/COD), useful for rational approach to vermicomposting reactor design.

Key words: Solid waste; Vermiculture; Vermicomposting; BOD; COD, C:N Ratio

Return to the top of page  



Serji Amirkhanian
Associate Professor, Civil Engineering Department
110 Lowry Hall
Clemson University
Clemson, SC 29634-0911


Each year, over 4.1 billion metric tons of solid wastes are generated in the United States, equaling about 16 metric tons per person annually. A growing amount of this waste is being landfilled, and as landfilling costs increase, new disposal options are needed. One possibility is the use of waste materials in highway construction. In this research project, state highway and health departments were surveyed to determine: the extent of use of waste materials in highway construction; problems that highway agencies had encountered in their use of waste materials in pavements; and health concerns related to the use of waste materials in pavements. Seventeen solid waste materials were investigated for this research project. The advantages and disadvantages of use of the waste material in highway construction are discussed. Several laboratory and field testing results are also investigated.

Key words: Solid Waste; Recycling; Flexible and Rigid Pavements; Landfills; Highway Construction

Return to the top of page  


Issue 1, February 1997



Crispin Wingfield-Hayes
Water and Environmental Management Unit, University of Strathclyde, Scotland
Professor George Fleming
Water and Environmental Management Unit, University of Strathclyde, Scotland
Claire Keenan
Centre for Environmental Management Studies, Scotland


In the majority of developed countries landfill is by far the most common waste disposal route for controlled waste. Transportation costs to major sites from rural and remote communities are usually prohibitive, necessitating small scale shallow landfill sites. These are not widely accepted as feasible options, with the inherent problems of low technology and low quantities of waste.

The Mid Auchencarroch Landfill Research facility has shown through its first phase, that methanogenesis can be established and sustained in shallow landfill, and further that the waste can be manipulated in several ways to optimise the methanogenic processes at work. The second phase is currently attempting to establish optimisation techniques with a view to promoting gas utilisation from small scale landfill, and achieving stabilisation at an accelerated rate.

This work aims to show the benefits of maintaining rural and remote landfill as an asset to the community, given that the appropriate levels of technology and cost are achieved.

Key Words: Shallow landfill; appropriate technology; methane; bioreactor; rural; agricultural diversification

Return to the top of page  



Binner S. Galeotti L,Lombardi F, Mogensen E, Sirini P.
Technical Director  and R&D Manager, Vlund Ecology Systems A/S, Brndby, Denmark
University of Rome ìLa Sapienzaî – Faculty of Engineering – Rome, Italy


Incineration plants are recognized as a valid and efficient technology to treat Municipal Solid Wastes (MSW), particularly when they are part of integrated treatment plants. Waste incineration reduces the waste volume and weight, thus saving space on the landfill; also the end products are hygienized by transforming organic matter into water and carbon dioxide (CO2); it is also possible to recover steam and/or energy. The main environmental impact in an incineration plant is due to the residues of the process (solid, liquid and gaseous emissions). Consequently waste incineration can gain public acceptance only if the concentration of low volatile organic compounds and the elution stability of heavy metals can be guaranteed. The characteristics of the residue depend on many factors such as composition of municipal solid wastes, properties of the individual metals, incineration technology and operating conditions of the incinerator.

In the present work, the mass balance and the transfer of some heavy metals in a Danish full scale incineration plant (combined grate and rotary kiln furnace, boiler, filter bag) were tested. The elemental analysis and leaching test data of solid residues were also evaluated. The obtained results confirm the high efficiency of the examined incineration plant. That is confirmed by the heavy metals distribution, in relation to their lithophilic or volatile behavior. The results of the leaching test show the reduced associated environmental risk associated to the slags (about 87% by weight of the solid residues), while they confirm the necessity to dispose of fly ashes in a landfill with a high level of environmental protection.

Keywords: Incineration, mass balance, heavy metals, slags, fly ashes, leaching test

Return to the top of page  



Shoou-Yuh Chang and Zhi Li
Department of Civil Engineering
North Carolina A&T State University
Greensboro, NC, U.S.A.


A model utilizing a modeling-to-generate-alternatives (MGA) approach for generating solid waste management (SWM) alternatives is presented in this study. The goal of this study is to create a computer program for the preliminary design of SWM systems. The program can be used to determine the least cost treatment and disposal system for a given SWM problem, and generate a set of alternatives that are widely ‘different’ with respect to treatment processes. Therefore, a wide range of technical alternatives and possible effects can be analyzed. A Bounded Implicit Enumeration (BIE) technique is first applied to produce a set of SWM systems within a specified cost constraint. The Pairwise Difference (PWD) approach is then used to rank the alternatives and screen out designs which employ similar treatment processes. The information and cost data collected on SWM processes, disposal methods, and costs for City of Greensboro, NC are compiled and used to demonstrate how the model can be used in practice. The results of this study show that the model developed is capable of generating SWM systems that are different from each other and cost no more than a specified percent above the lowest cost design.

Key Words: Solid waste management, Mathematical model, Optimization, Systems approach, Generating alternatives

Return to the top of page  



Abdullah KEYVANI S.
Doctoral Candidate
Dept. of Civil Eng.
Hokkaido University
Sapporo, 060, JAPAN
Noboru SAEKI
Dr. of Eng., Professor
Dept. of Civil Eng.
Hokkaido University
Sapporo, 060, JAPAN 


Steel shavings or chips are long, narrow steel strips, 0.1-1.0 mm in thickness, 1-3 mm in width and have a rough surface, toothed edges and twisted section. They are produced by milling or drilling machines in assembly plants and steel forming workshops. These chips or steel shavings have very high tensile and shear strengths, and are much harder than original steel. Steel shavings have different shapes according to the machining process. However, the important point is the quantity of these materials which can be found in the heavy industrial sites. Also, these materials are waste materials, and therefore can usually be obtained without any charge. By cutting these chips into the desirable length, steel fibers can be obtained. Steel fiber reinforced concrete as a composite material has many applications and using steel shavings as steel fibers for concrete reinforcement is a new practical method of recycling waste solid materials in the concrete industry. The results of experiments showed that steel fiber reinforced concrete using recycled steel shavings results in a 94% increase in ultimate flexural strength, 113% increase in ultimate tensile strength, 62% increase in ultimate splitting strength, 80% increase in ultimate shear strength and a flexural toughness index of more than 800% compared to these in unreinforced concrete.

Key Words: Waste steel shavings, chips, steel fiber, aspect ratio, roughness, hardness, bonding, pulling-out, rupture, toughness, fracture behavior, flexural toughness index.

Return to the top of page  



Slavomira Macakova
Fulbright Scholar
Malcolm T. Hepworth
Professor, University of Minnesota
Natalia Pliesovska, Jozef Hatala, and Frantisek Siska
Professor, Technocal University of Kosice, Slovak Republic


In the autumn of 1993, a research program was initiated in Slovakia to employ a by-product from a magnesium processing plant, Sorel cement, to stabilize fly ash originating from municipal waste incinerators. Sorel cement is a combination of magnesium oxide and chloride, currently a by-product of magnesium operations. The resulting product is mechanically strong and also passes environmental testing by the Slovak Waste Extraction Test and also EPA extraction testing. The potential therefore exists to combine two industrial wastes into one to make a stable, strong, and environmentally acceptable material which, if not suitable for construction, can readily be managed without risk.

Key Words: Incinerator ash; fixation; immobilization; heavy metals; sorel cement

Return to the top of page  



T.Viraraghavan, V. Mahendraker and D. J. Mihial
Faculty of Engineering
University of Regina
Regina, Saskatchewan, Canada S4S OA2


When the approved or licensed design capacity of a landfill is exhausted, it must be closed in an environmentally acceptable manner. A landfill closure plan should be developed at the design stage of the landfill or during the site development phase to comply with environmental controls during closure and post-closure periods as per the local, provincial and federal regulations. This paper examines the closure options for landfills especially the characteristics of landfill covers. The specific functions of the individual layers in the cover, as well as their design, and constructional aspects are discussed. The closure plan for the City of Regina landfill is reviewed in detail in respect of its cover design.

Keywords: Landfill; Closure; Post-closure care; Landfill gas; Leachate

Return to the top of page