Issue 3/4, November 1999
Developing Effective Waste Minimization Clubs: A Case Study from the Midlands of England
Paul S Philips, Karen Pike, Margaret P.Bates
School of Environmental Science
University College of Northampton,Park Campus
Northampton NN2 7Al,UK
Adam D Read
Dept. Of Geography
Penrhyn Road,Kingston -upon-Thames
Surrey Kt1 2EE,UK
The UK waste strategy is based upon the central concept of the hierarchy of preferable options for the treatment and disposal of waste.Minimisation is placed at the top of the hierarchy and the Government seeks to encourage its uptake.Approximately 60 regional minimization clubs have been set up,in the UK since the early 1990s.Not all clubs have been successful,a significant number have failed to run to completion or meet their planned objectives and rarely are sufficient data made available for a cost-benfit analysis.The East Midlands has a diverse economy with a relatively large proportion of Small to Medium Enterprise(MSE) .The Northamptonshire Resource Efficiency Project is an example of a club which was designed to be highly cost-effective and to develop a culture of waste minimization in the county.Its success has been based upon a management partnership that includes a local higher Education Institution which is in a unique position to offer wide ranging expertise.Such a partnership stands as a model for future cost-effective waste minimization developments worldwide.
Key Words: National Waste Strategy, Minimisation, Municipal Solid Waste, Project Clubs, East Midlands, Northamptonshire Resource Efficiency Project
Effect of Landfill Leachated on Native grass Species of Eastern Washington State USA
Philip L. Thompson, David J. Murphy Po-hsiang Chang, John Harmsen
Dept. of Civil and Environmental Engg.
900 Broadwasy-Room E524
Seattle Washington 98122
This project assessed the survivability of different grass species that were candidates for a vegetative landfill cover in Wenatchee Washington.Five species of native grasses were tested:Sheep Fescue,Nezpar Ricegrass,Secar Bluebunch,Joseph Idaho Fescue and Critana Thick spike Wheatgrass.landfill Leachate nutrient enhanced model water and anaerobic ally digested municipal wastewater sludge were evaluated for their effects on seedling germination and growth.Experiments revealed that leach ate did not significantly hinder the germination or growth of the species tested and can be used as a possible water source for cover vegetation.A .dasystachyum A.spicatum,F.idahensis,F.ovina adn O.hymenoides all performed well in unfertilized and nutrient enhanced soils.Sludge amendments significantly (p<0.05) hindered seedling germination of most and the initial growth of all species tested ,however the grasses grew one they had sprouted.
Key Words: landfill, vegetative cover, irrigation, leachate, toxicity, sludge.
Review of Applications of High Solids Anaerobic Digestion to Solid Waste Management
N.Hamzawi, K.J.Kennedy, D.D. McLean
Dept.Of Chemical Engg.
University of Ottawa
While composting is viewed as a major contributor to achieving solid waste reduction goals for residential and commercial waste,it is recognized that traditional aerobic composting presents challenges which must be overcome if large scale composting is to be accepted in large urban communities.These challenges include requirements for a large amount of land,long gestation periods for handling,digestion an during and solutions for numerous process control issues(eg leachate entering groundwatermnoise and dust odors and sensitivity to climatic conditions.
Anaerobic digesting in contrast to aerobic composting does not require air and still generates a product that has approximately the same solid amendment value per unit weight as that produced in aerobic process.While the anaerobic process may not generate the same quantity of heat this can be offset by the production of methane gas.The potential for energy recovery in anaerobic processes has been promoted as a solution to energy problems in many industries in addition to producing greater amounts of humic materials than those generated by aerobic composting processes.
In recent decades several developments have occurred which have greatly increased the energy efficiency and attractiveness of anaerobic waste treatment processes.Research groups throughout the world have developed anaerobic reactors to treat wastes in an efficient economical and environmentally acceptable way.Full scale implementations of these developments have met with success and competitive installations continue to take advantage of the new tech. This paper presents a review of the state of the art of high solid anaerobic digestion.
Key Words: Municipal Solid Waste, Sewage Sludge, Anaerobic Digestion.
Utilization of Biowaste Solids by Extracting Volatile fatty Acids with
Subsequent Conversion to Methane and Manure
E.V.Ramasamy , S.A. Abbasi
Center for Pollution & Energy Technology
Pondichery Central Univ.
Kalapet Pondicherry-605 014
The aquatic weed water hyacinth was aerobically fermented in ‘acid -phase’ reactors to generate volatile acids(VFA).The reactors were continuously stirred tanks seeded with partly digested cow dung slurry and operated under conditions conducive for acidogenic and acitogenic bacteria.The VFA were then converted to methane in upflow anaerobic filter(UAF) reactors seeded with a consortia of methanogenic bacteria.The slurry of the spent weed ensuing from the acid phase reactor’s was vermicomposted to generate manure.
The gist of the findings is :
1.Chopped hyacinth yielded more VFA on aerobic fermentation than whole plants.
2.the overall VFA yield from the aerobic digesters was higher if the VFA were taken out of the digester everyday than when they were not
3.the UAF reactor at steady state removed 55-60% of the feed COD and generated biogas at the rate of 0.38 m3 kg-1 VS d-1
Key Words: Anaerobic digestion,Volatile fatty acids, Biowaste, Water hyacinth, Vermicomposting
Pollution Prevention Incentives for Marine Maintenance and Repair Industries
Mujde Erten Unal , Joseph M. Marchello
Dept. of Civil and Envrn. Engg
Old Dominion Univ,Kaufman Hall
Rochelle K. Young
Lockheed Marine Engineering Management Program
University of Colorado at Boulder
Boulder CO -80309-0433
Norfolk Housing and Redevelopment Authority
201 Granby Street
This study illustrates the effectiveness of an innovative partnership formed between an institution of higher education and a municipal wastewater treatment district and reports the results of pollution prevention/waste minimization assessments performed on four marine maintenance and repair industries.
The partnership provided local marine maintenance business with on-site technical consolation on waste reduction.Industry profiles were prepared to identify the facility services and pollution prevention opportunites.At each facility material usage,waste generation and waste minimization recommendations were determined.Financial analysis of alternatives for reducing pollution and waste were used to show cost savings.The proposed waste minimization recommendations included loss prevention,good housekeeping paint and steel recycling,solvent recycling,waste segregation and the installation of an aerosol recovery system.
The pay back of an aerosol recovery system recommended for Company A was less than 2 months.Annual cost savings from raw materials purchases and waste disposal costs ranged from $9000 to $20,000.
Working together the partnership contributed to providing comprehensive pollution prevention services for specific marine maintenance facilities and helped developing information and resources that are now available to all area marine maintenance and repair operations.
Key Words: Pollution prevention,marine maintenance and repair industry, shipyards, source reduction and waste management.
Assessment of Environmental Impacts generated by Coal Solid Residues
A.Aguero , L.F. Alonso
CIEMAT Dept. de Impacto Ambiental de la Energia
Avda Complutense 22.28040
V Cortes, C.Fernandez
AICIA Dept de Ingenieria Quimicia y mbiental
Universidad de Sevilla
Camino de los Descubrimientios s/n 41092 Seville
QuantiSci Ltd, Chiltern House
45 Station Road,Henley-on-Thames
Oxfordshire RG9 1 AT,UK
Utilitzation of coal produces a variety of solid residues.The environmental impacts of coal-use residues have been fully recognized only in the last few decades.CIEMAT has developed and tested a methodology based on the SACO methodology previously developed by QuantiSci and CIEMAT that i considered to be appropriate for assessing an comparing reuse and disposal strategies of solid residues generated from the coal flue cycle.The first phase of the development consisted of a review of solid residues produced in the coal fuel cycle identifying contaminants that may influence management options for the residue from a physical and chemical point of view.management options as well as the environmental impacts associated with the reuse and disposal of the residues were then analyzed and a review of previously developed assessment methods were done.Second and third phases of the work involved the development and testing of a methodology framework to assess the environmental impacts of solid residues from real cases.
Key Words: Environmental Impacts, Fly Ashes, Reuse, Disposal, Assessment Methodology.
Anaerobic Capacity of Solid Pulp and Paper Mill Waste
Thomas G.Tornabene, Madhuri Ganta
School of Biology
Georgia Institute of Technology
Atlanta GA 30332-0230
Keshav C. Das
School of Biology & Agricultural Engineering
University of Georgia
Athens GA 30602-4435
Frank D Wohrely
Weyerhaeuser Po Box 238
Oglethorpe GA 31068
Aqueous suspensions of solid paper mill waste fortified with nitrogen supplements were effectively biodegraded into CO2 and CH4 under anaerobic conditions with the major portion of the gas production occurring within 25-30 days. The process was operated as a batch culture seeded with mesophilic methanogenic granular sludge.NH4Cl, NH4NO3 or Urea at initial C:N ratios 125:1, 125:1 or 150:1 respectively supported the best bioconversion rates.Other nitrogen sources at higher and lower concentration as well as mixtures of nitrogen salts and trace minerals supplements were less effective in promoting methanogenesis and substrate reduction.Digesters supplemented with NH4Cl urea or NH4NO3 produced and average 100 L, 95 L or 77 L of CH4kg of organic solid waste respectivelly.The potential commercial value of the methane gas produced was calculated to be an average of $315 per ton of organic content of the solid waste or $150 per ton of the total solid waste.
Key Words: methane, anaerobic, biodegradation, cellulosic material, paper mill waste, solid pulp
Polish Made Pyrolytic Convective Waste Utilizer of Wps Type Structure ,Principle of Operation and Evaluation Problems of Residue Management After Thermal Waste Utilization
Tadeusz Piecuch, Tomas Dabrowski, Tadeusz Hryniewicz, Waldemar Zuchowicki
PL 75-620 Kozalin Poland
This paper is concerned with solid waste utilizatin in the specially made for this purpose Pyrolytic Convective Waste Utilizer(PCWU) of WPS Type, a technology which may be in essential way helpful in getting rid of a very noxious wastes.A family of the PCWU WPS utilizer is presented dependent on the amount of wastes and operations capacities required.The discussed PCWU WPS type utilizer was tested in several areas of Poland by different users.The paper presents structural composition ,principal of operation of the PCWU WPS and then aims at analyzing flue gases and eluates coming form the epyrolytic rendering waste harmless.Th eprimary studies were carried out to determine the most important indicators of pollution in the eluate flowing out of the waste layer after pyrolytic decomposition on the samples taken from the WPS Type Utilizer operating near Gdansk and at Tczew.The comparative study of secondary wastes obtained after thermal decomposition without oxygen access i presented.The detailed study results of utilization an neturalizatin of secondary wastes coming from the WPS are also included.The studies covered 3 groups of secondary wastes coming from WPS:
- acrylic paint waste
- phtalic paint wastes
- plastic wastes
The studies were carried out in 3 stages:
- covering the studies of eluated outflowing from the layer of secondary wastes
- covering the studies of compression strength of cobble stones
- covering the studies of water extracts from cobble stones
In the paper the authors present comparative direct cost analyze of thermal waste liquidation using classical method in comparison with pyrolytic method.The paper delivers also the authors own evaluation of the PCWU of WPS type with indication of the possibility for its broader application.
Key Words: Solid waste utilizer, pyrolytic incineration, flue gas analysis, eulate, cementation,comparative evaluation.
Issue 2, May 1999
Chemical Fixation of Bivalent Copper by Granulation in Aqueous Solution
L.Di.Palma, F.Medici, C.Merli, E.Petrucci
Dipartimento di Ingegneria Chimica
dei Materiali,Materie Prime e Metallurgia
Universita di Roma “La Sapienza”
In the filed of industrial waste management ,granulation in aqueous solution constitutes an effective alternative to the traditional stabilization /solidification technologies.This paper presents results obtained on the chemical fixation of bivalent copper.
The tests were carries out utilizing three different concentration levels(2%,4% and 8% by weight) of bivalent copper,added as copper chloride.Two series of tests were carried out,the first by using only cement as binder ,the second silica fume to the cement.
The results obtained show that the immediate leaching of copper in the alkaline solidification bath i s very slow and that the addition of silica fume to the matrix causes a reduction in copper release leading immediately to a greater amount of this element being immobilized in the cement matrix.
Key Words: Chemical fixation, cement, silica fume, granulation, bivalent copper.
Potential Utilization Method of Scrap Ceramic Insulators
Robert Sekula, Maciej Wnek
ABB Corporate Research
University of Mining and Metallurgy
Solid waste management is an area which many utilities are examining.So far a landfill has been the most often used method for utilization of different waste residues.However the more ambitious programs emphasize waste prevention activities such as reconditioning and reuse of materials.
Electricity transmission and distribution companies are a significant source of different solid waste materials including utility poles,procelain bushings and insualtors,street lamp units,transformers,protective equipment etc.
Every year these companies generated a lot of scrap porcelain insulators and to date there is no effective method which can be accepted world-wide for utilization of scrap ceramics.An innovative utilization option for used porcelain insulators is presented in the paper.Utilization of this material in a cement process is suggested due to the fact that the chemical composition of porcelain insulators is close to that of cement raw materials.Special way of the introduction of scrap insulators to the cement rotary kiln is proposed.
Influence of this operation on NO reduction has been investigated in laboratory scale experiments ,results of which are presented in the paper.
Key Words: Solid Waste Management, scrap ceramics, NO, reduction, combustion, cement, air pollution.
Study of the Alum Sludge’s from Cali City Water Treatment Plants
Ruby de Gutierrez, Silvio Delasto
Engineering Materials Dept
Universidad del Valle,Ciudad Universitaria Melendez
Engineer Empresa de Acueducto y Alcantarillado
Emcali Cali Colombia
Three of the water treatment plants of the Colombian city of Santiago de Cali produce an average of 553 million liters per day of drinking water.Solid particles in the water being treated are high,the total content of solids suspended in the raw water typically fluctuates between 46 mg/l in summer and 119 mg/l in the rainy season.Alum sludges discarded from these water treatment plants are being disposed in watercourses.The municipal water treatment company of Cali is considering abandoning this method of disposal as a result of an enforcement of a local government agency to avoid the pollution of the surface water supplies.
In order to look for a utilization or disposition of these sludge’s it is necessary to reduce the water content.In a bench scale study several methods of dewatering were tried including centirfugation,plate pressure filtration,normal vacuum filtration and a special type of rotary vacuum filtration.The tests were carried out on non-thickened sludge and on thickened sludge with and without chemical pretreatment.The plate pressure filtration method achieved the best results.Its efficiency expressed as the amount of water expelled related to the total content of water in the sludge flurry was 89.8% and the water content was reduced from 93.3% (w/w) to 65.9% (w/w).Polymer pretreatment of sludge improves the filterability of the sludge.The study demonstrated the feasibility of partial alum sludge dewatering in the Cali City system of water treatment plants.The final steps in the selection of the mechanical dewatering equipment should be pilot scale tests.
In this paper is presented the diagnosis of the problem,the methodology,and the criteria followed to set up the potential utilization of these alum wastes.
Key Words: Water treatment Plant, Alum Sludge, Dewatered Sludge, Sludge Disposing, Alum Wastes, Mechanical Dewatering.
Bioremediation of Phenol-Contaminated Soil in Slurry-Phase
as Affected by Nutrients Content
M.R. Boni, G.Lombardi
University of Rome “La Sapienza”
Engineering faculty via Eudossiana 18,Roma
Dept. of Idraulic,transportation and Roads.
Over the past years the increasing number of aromatic hydrocarbons-contaminated sites has increased the need to develop and improve technologies allowing hazardous pollutants to be removed and therefore contaminated soils to be detoxified.
Among the different available technologies the most promising ones seem to be the bioremediation techniques that convert the contaminants into simpler and generally less toxic compounds by means of microbial activity.
For remedial actions to be successfully applied,conditions suitable for microbial growth must be provided :aeration,moisture content,pH ,temperatures and nutrients.
The aim of the present paper was to investigate the influence of nutrients on phenol and p-nitrophenol biodegradation using a slurry phase process.
Key Words:Contamianted soil, phenol, p-nitrophenol, nutrients, biodegradation, slurry-phase treatment
Oxidation of Powdex Resin in Supercritical Water
Y J Huang
Dept.Of Industrial Safety and Hygiene
Chung Hwa Institute of Technology
Chun Teh Li, H.Paul Wang, M.C Hsiao
Dept. Of Environmental Engg
National Cheng Kung University
Experiments were carried out to provide information concerning the feasibility of the SCWO(supercritical water oxidation) process for treatments of LLRA(low level radioactive) spent resins and determined if further development of this process would be warranted.Process development in the present work was directed to minimal nuclide emission in the flue gas and a maximal possible inclusion of radioactive species in ashes which would be solidified for final disposal.Experimentally the spent resin was completely degraded in supercritical water in a five minute residence time.The activation energy of this SCWO reaction was 5-10 Kcal/mol.Yield of PAHs formed in the SCWO process was very low.
Key Words: SCWO, wet oxidation, spent resin, low-level radioactive wastes.
Simulating Temperature Variations in Landfills
American University of Beirut
Dept.Of Civil and Envrn. Egg
P.O. Box 11-0236
Gas generation within solid waste landfills occurs as a result of biodegradation of organic matter in the landifll.Biodegradation processes in a landifll are exothermic and highly dependant on microbial growth in that environment.The heat generated during exothermic reaction’s increases landfill temperatures.Temperature is an important factor controlling their own internal temperature.Therefore predicting and controlling the temperature variation within a landfill are essential to ensure normal gas generation an drecovery and enhance stabilization processes.This paper presents a mathematical model to estimated the temperature distribution resulting from the heat release during organic waste decomposition in layered solid waste landfills.The heat source within the landfill is estimated based on the amount of heat generated during the biodegradation processes.Temperature profiles are obtained by solving the heat flow equation within the landfill.The resulting model is coupled with a gas generation and transport component ans. was used to simulated data from a field scale test.
Key Words: Solid Waste, landfill, gas and heat generation, temperature, mathematical modeling.
Potential and Constraints of Composting as a Market Solid Wastes Disposal
Option for Dar-Es-Salam Tanzania
Gabriel R. Kassenga
Dept.Of Environmental Engg.
University College of Lands and Architectural Studies
P.O Box 35176 Dar-Es Salaam
This paper is based on the results of a study on assessment of the potential and constraints of composting as a disposal method for market solid wastes in Dar Es Salam.The assessment was done on the basis of the acceptability and marketing of compost ,carbon/nitrogen ration (C/N ratio) and composition of market reuse.The paper starts by discussing the results of different studies on the determination of generation rates of solid waste in Dar Es Salam,emphasising market wastes.Results of the study on composition and carbon nitrogen content have shown that market wastes are rich in vegetable and putrescible matter(41.56 – 75.89 % by weight) however their C/N ration (18.41-26.1) may not be very favorable for good composting.The study also revealed that vegetable growers (the main potential users of compost) were generally not in favor of refuse derived compost.According to the study fears of undermining customers confidence because of using refuse derived compost in vegetable growing and the availability of alternative and less expensive soil conditioners and fertilizers aware found to be the main reasons for ejecting the compost,according to the interviewed vegetable growers.Finally some recommendations for the promotion of solid waste composting technology are outlined.
Key Words: composting, market wastes, Tanzania, vegetable growers, waste-disposal, Dar-Es Salaam
Issue 1, February 1999
Parametric Seismic Evaluation of Lanfill Liner and Final Cover Slopes
Dept.Of Civil and Materials Engg
University of Illinios at Chicago
842 West taylor Street
Senior Geotechnical Engineer
Rust Environmetn & Infrastructure,3121 Butterfiled Road
Oak Brook,IL 60523
Graduate Research Assistant
Dept.Of Civil and Materials Engg
University of Illinios at Chicago
This paper describes a study of the factors that affect the seismic stability of landfill liners and cover systems for the mid-western US seismic conditions.Soil and composite base liner adn final cover systems were analyzed for two conditions:
1. during landfill operation
2. after landfill closure
Pseudo-static and displacement analyses were performed for threee Midwestern earthquakes:
1. 1976 Arkansas earthquake
2. 1982 Arkansas main earthquake
3. 1982 Arkansas after shock
The results showed that the operational phase is critical for landfill liner systems because the stability factors of the combined refuse and the lining system are in general lowest at this stage.The shear strength of the compacted clay liner and the interface shear strength between synthetic components of a composite liner system are shown to significantly influence the calculated permanent dispalcements of base liner and final cover systems in the event of an earthquake induced instability.This study also showed that a seismic co-efficient of greater than 0.5a max/g and preferably not less than 0.67a max/g is appropriate for pseudo-static analyses to establish overall stability an densure small displacements of the landfill waste and the final cover.
Key Words: landfill,municipal solid wste,liner,final cover,sloep stability,seismic analysis,displacement,factor of safety.
Anaerobic Co-Digestion of Sewage Sludge And Municipal Solid Waste From Markets:
Dipartimento di Ingegneria Chimica
dei Materiali,Materie Prime e Metallurgia
Universita di Roma “La Sapienza”
This paper discusses the anerobic co-digestion of sewage sludge from a wastewater treatment plant and the organic fraction of municipal solid waste from markets(market waste).The organic fraction of market waste was collected by means of spearate collection systems.
The experimental results obtained through the use of suspended biomass anaerobic reactors make it possible to measure certain parameters characterizing the process of bioconversion.The rpospects for large-scale utilization of this particular disposal technique are considered with reference to the situation exisiting in the city of Rome.
Key Words: Municipal Solid Waste,market Waste,Sewage sludge,Anaerobic co-digestion,System developmetn,Energy balance.
Assembly Of Mineral Processing Unit Operations For benefication Of a Titania-Rich Pigment Sludge
L.Piga , N.Shehu
Mineral Processing Institute,CNR
Via Bolognola 7, 00138 Rome
A study has been conducted to assess a new wet beneficiation treatment for the recovery of the sulfuric acid soluble titanium dioxide contained in the waste from an Italian TiO2 pigmetn facility.The waste is produced during treatmetn of a Ti-enriched slag adn contains as main components TiO2 (54% of which 42% acid-soluble adn 12% insoluble) SiO2(27%) and Al2O3(6%).Eighty percent of the material is finer than 35um.The first step was to ascertain the possibilities offered by size classification,wet gravity separation,froth floatation and wet high-intensity magnetic separation to improve the grade and recovery of the acid soluble TiO2 and reduce SiO2 content.The next step was to optimize the oeprating conditions of the various separations and assemble them into a completed flow-sheet.Beneficiation ensures the recovery of about 46% of the acid soluble titanium that at the present is disposed of in a landfill.In addition the treatment of the sludge permits to double the life of the landfill.
Key Words: Titanium dioxide,pigment industry,recycling,waste ,beneficiation.
Refining Landfill Gas To Natural Gas Pipeline Quality
Chukwu Ony Ph.D
Department of Civil Engineering
Southern University and A&M College
Baton Rouge,Louisiana 708113
About 85 to 90% fo solid waste generated in the United States us disposed of in sanitary landfills.Even with the present stringent regualtions on sanitary landfills there are about 6,000 active waste disposal site.s in the country,out of which approximately 250 of them have landfill gas recovery systems either in operation,design or construction.It is a well. known fact that decompostion of organic wastes in conventional landfills produces landfill gas(LFG) which typically comprises about 50-55% methane,45-50% carbon-di-oxide and less than 1% non methane organic compounds.however by properdesign and operation including maintaenacne of some environmental controls in the present landfill system,the LFG composition can be improved to about 88% methane with CO2 and other trace organic vapors constituting abotu 12%.This gas can easily be refined to remove the CO2 moisture and other trace organics.Refinement can further enhacne the concentration of CH4 raising it to as high as 99%.
A lab bench-scale landfill simulator was constructed and optimized to obtain a landfill gas with concentration of better than 80% methane.The simulator was operated as a leachate recirculation system in tandem with a fixed bed anaerobic reactor.The sytem produced a very high pruity landfill gas.It is possible to refine this fas by removing CO2 moisture and other trace organic compounds,hence producing gas that meets the natural gas pipeline standard.Such a gas can then be carried in the same conduit that transports natural gas to consumers.
Key Words: landfill gas,methane,energy,recovery,refining landfill gas,natural gas pipeline quality.
A Standardized Data Reporting Methodology For Long Term Integrated Municipal Solid Waste
Management -A Case Study
Roman Kowalewski, W.Reid Lea
Vice President Int`l Operations
United Companies Financial Corp
4041 Essen Lane Baton Rouge
Marty E. Titlebaum
Professor Dept of Civil & Env.Engg
834 Engr Bldg
University of New Orleans
A practical methodology has been developed for standardized municipal solid wsate(MSW) data reporting.Common data requirements have been classifed and general data requirement guidelines bave been established efforts.The methodology has been untilized in a long term MSW management study of Terrebonne community a single parish county in Louisiana.
Design ,Operation and Performance of Compressed windrow Composting
Center for the Environment adn Water Resources Engineering
Dept.Of Civil and Envrn. Engg
University of Californai
Davis CA 95616
The present paper describes the design operation and performance characteristics of compressed windrow composting.A compressed windrow system consists of large rectangular piles typically with length of 61m widths of 49m and heights of 2.2-3.4m wiht no forced air.Adding one window to another with no space between them creates this shape.The composting process operates in a plug-flow manner where the material is introduced to the piles and then removed from teh active composting process with a60 day retention time.
The process utilizes a unique water recircualtion system which eliminates leachate production.The process effectively removes pathogens adn produces quality compost for agricultural use.The principal advantage of the compressed windrow,compared to the conventional windrow is the savings of land area required.It has been demonstrated that compressed windrows use only half of the land needed by conventional windrows to process the same amount of yard wast.
Key Words: Compresses windrow,yard waste,SCAT, leachate,compost characteristics
Properties of Asphalt Rubberized with Waste Tires Crumb
Civil Engg. Dept.
Schenectady New York USA 12308
The effect of adding crumb waste tires on the performance and the mechanical characteristics of asphalt mixtures was investigated.Addding a percentage of tire rubber to asphalt pavement has long been considered beneficial in addressing a solid waste disposal problem adn in reducing the negative environmental hazard of billions of stockpiled tires.In this study crumb rubber made from old tires has ben used in hot mixed asphalt(HMA).The asphalt mixture was designed using Marshall method and crumb rubber was added using the dry process.Specimens were designed and prepared with crumb rubber content of 0,4,7 and 10%C of total weight.Furthermore compression tests on confined specimens with different percentages of asphalt adn rubber contents were conducted to determine the effect of crumb rubber containing 4% rubber and 5% asphalt cement by weight of total mix nearly satissy the stability and flow limits of teh specifications.The controlling characteristics of teh rubberized asphalt mixture was found to be the air voids within the specimen.A rubber content of 2.6% by weight satifies the stability flow adn air void specifications.This amounts to 24 kg of rubber per ton of asphalt paving mix.
Key Words: Asphalt,MArshall method,Optimum asphalt content,Rubber,Solid waste,waste tires