Issue 4, November 2003
A COAL COMBUSTION BYPRODUCT, FLY ASH, FOR FIRED BUILDING BRICK MAKING—A PRELIMINARY TECHNICAL FEASIBILITY STUDY
M.-I. M. Chou+, V. Patel, S.-F. J. Chou, and K.K. Ho*
Illinois State Geological Survey
615 E. Peabody Drive
*Illinois Clean Coal Institute
Carterville, IL 62918
Most of the three million tons (2.7 million metric tons) of class F fly ash produced from burning Illinois bituminous coals is ponded or disposed of in landfills, which represents a continuing solid waste disposal problem. The purpose of this study was to obtain a preliminary assessment of the technical feasibility of making fired bricks with Illinois class F fly ash generated by the Meredosia Power Plant in Illinois. The extrusion method was used to form bricks before firing. The fired test bricks were produced with increasing amounts (20% to 40% by weight) of fly ash as a replacement for conventional raw materials, and were examined for their chemical characteristics and engineering properties. The results indicated that the chemical properties of ash containing test bricks were comparable with those of standard test bricks containing no fly ash (that is, containing only the raw materials-clay and shale). The unburned carbon in fly ash was not a concern in producing fired bricks. Both the ash containing and the standard test bricks met commercial specifications for fired building bricks. However, some engineering properties of the ash-containing test bricks, such as color, physical consistency, and fired compressive strength are better than those of the standard test bricks.
Keywords: Fly ash; fired brick; coal; combustion; solid waste; environment
EVALUATION OF ACID EXTRACTION METHODS USED FOR THE METAL CONTENT ANALYSIS OF BOTTOM ASH AND SLAG FROM ELECTRIC ARC VITRIFICATION
Hirofumi Sakanakura#, Holger Ecke*, Anders Lagerkvist*
Toshihiko Matsuto** and Nobutoshi Tanaka**
# Division of Civil and Environmental Engineering, Akita National College of Technology
Iijima Bunkyo-cho, Akita 011-8511 JAPAN
* Division of Landfill Science and Technology, Lulea University of Technology
SE-971 87 Lulea SWEDEN
** Division of Environmental and Resource Engineering, Graduated School of Engineering
Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628 JAPAN
The objective of this investigation was to find the most reliable acid extraction method for the determination of the total metal content in a waste sample. Samples of bottom ash from a municipal solid waste incinerator and slag generated by electric arc vitrification of the bottom ash were investigated. Acid extraction methods were applied using the reagents nitric acid, aqua regia, hydrofluoric acid and a combination of aqua regia and hydrofluoric acid. Another experimental variation was whether the sample was milled prior to extraction or not. Extractants were analyzed by atomic absorption spectrometry (AAS). The data were evaluated statistically including both Welch’s equality test and partial least square analysis. The main conclusion was that bottom ash was most completely decomposed by milling followed by treatment with aqua regia and hydrofluoric acid. For slag, this method was only superior with respect to the extraction of Pb and Cd. Another observation was that electric arc vitrification causes the removal of Zn, Cd and Pb which was probably due to evaporation.
Keywords: Acid extraction; bottom ash; electric arc vitrification; heavy metals; partial least square modeling; slag
APPLICATION OF BIOVENTING TO WASTE LANDFILL FOR IMPROVING WASTE SETTLEMENT AND LEACHATE QUALITY—A LAB-SCALE MODEL STUDY
Tomonori Ishigaki, Wataru Sugano2, Akane Nakanishi3,
Masafumi Tateda3, Michihiko Ike3 and Masanori Fujita3
1National Institute for Environmental Studies
4-6-1, Shirokane-dai, Minato, Tokyo, 108-0071, JAPAN
2Yamatake Building Systems Co., Ltd.
2-15-1, Konan, Minato, Tokyo, 108-6030, JAPAN
3 Osaka University
Department of Environmental Engineering, Graduate School of Engineering
2-1, Yamada-oka, Suita Osaka, 565-0871, JAPAN
A pilot-scale aerobic landfill reactor in which a bioventing technique was applied is proposed and investigated in this study in order to obtain detailed information on the stabilization of aerobic landfill. The application of bioventing successfully transformed the condition of the waste landfill from anaerobic to aerobic, and it stimulated indigenous aerobic bacteria and enhanced the aerobic degradation of waste. The necessity of the control of the moisture content of the waste in the aerobic landfills to stimulate aerobic bacterial activity was also suggested. The aerobic waste degradation enhanced the waste settlement and effectively improved qualities of the leachate and the LFG. The enhancement of waste landfill stabilization could greatly shorten the period that is required for landfill management. Furthermore, toxicity assay of leachate revealed that aerobic landfill could greatly reduce the risks of waste landfilling. These results suggested that aerobic landfill operation could be an attractive countermeasure for overcoming major problems of existing landfills.
Keywords: Aerobic landfill, Bioventing, Waste settlement, Leachate, Landfill gas, Ecotoxicity
ANALYSIS OF URBAN SOLID WASTE IN NSUKKA, NIGERIA
Toochukwu Chibueze Ogwueleka
University of Agriculture
Department of Civil Engineering
Makurdi, Benue State
Solid waste management in Nsukka is evaluated. Nsukka was divided into four sanitation zones based on the population density for sampling. Plastic bags were distributed to shops, hostels, market and 20 households in each zone for collection of waste on daily basis. The survey lasted for 40 days. The wastes were weighted and sorted into components of food and putrescible, plastics, paper, textile, glass, metals and others. The waste showed high percentage of biodegradable materials. And when compared with waste from developing countries and developed countries, the analysis showed that the composition of waste in any country is dependent on the economic status of the country The waste generation rate and the average density of waste were estimated at 0.49 kg/capita/day and 268kg/m3 respectively. The unit waste management cost of $1.93 per ton was estimated from addition of annual collection cost and annual disposal cost and the sum divided by annual waste tonnage. The study reveals that collection cost has formed a large component of the solid waste management in developing economy.
Pollution prevention in the Portuguese natural stone industry
M.T. Chambino, A. Correia and J.M. Figueiredo
Departamento de Materiais e Tecnologias de Produ��o
Instituto Nacional de Engenharia e Tecnologia Industrial
Estrada do Pa�o do Lumiar, 1649-038 Lisboa Portugal
Email : email@example.com
Portugal is abundant in natural stone deposits and is well known for the quality of its marble. Accordingly the industry of natural stone has gained an increasing importance in the Portuguese economic activities. The most important stones for ornamental and industrial purposes are granite, marble, limestone and, in smaller quantities, also slate. This industry produces large quantities of wastes either in quarrying or processing activities, mainly rejected stone and sludge. These wastes are usually deposited in a disposal place, without adequate conditions and having a great visual impact on the landscape. The characterisation of the different types of wastes produced and the operations that originate them are of crucial importance to define a waste management strategy for this industrial sector. A solution for the accumulation of these wastes can be found in new waste reuse possibilities and prevention technologies to reduce the volume of wastes in stone quarrying and processing. Different possibilities of waste reuse as new products in several industries are presented, together with improvements in prevention technologies.
Keywords: Prevention, Portuguese natural stone, quarrying, stone processing, wastes, sludge
TURNING SOLID WASTE INCINERATION ASHES INTO A USABLE MATERIAL IN CONSTRUCTION
Jean G. Chatila, Ph.D., Assistant Professor
Sharbil Abishdid, Research Assistant
Lebanese American University
Department of Civil Engineering
P .O. Box 36 Byblos LEBANON
Email: firstname.lastname@example.org; Fax: +961 9 547 256
This paper describes a largely experimental investigation for turning solid waste incineration ashes into a usable material in concrete construction. The result is a method for incineration ashes to be disposed of in an environmentally safe method without creating a nuisance. In addition, there is a possibility to increase the compressive strength of concrete, reduce landfill volumes, and protect the public from environmental and health impacts of poor waste management. Based on the current applications and proportions, the flexural strength of concrete was affected. The variation of strength ranged between an increase of 12% and a decrease of 50% depending on the proportions, gradation, and source of ashes added. Furthermore, the dissolution of these ashes in water and acetic acid was checked and did not pose a problem within the applicable standards.
Keywords: Solid waste, incineration, ashes, dissolution, concrete mix, and strength
NUMERICAL MODELING OF LATERAL LANDFILL GAS MIGRATION
M. Nastev1, R. Lefebvre2, R. Therrien3 and P. G�linas3
1Natural Resources Canada, Geological Survey of Canada
880 Chemin Ste-Foy, Suite 840
Quebec (QC) G1S 2L2, Canada
Tel. (418) 654-2682; Fax. (418) 654-2615
2Institut National de la Recherche Scientifique — INRS �T�
880 Chemin Ste-Foy, P.O. Box 7500
Quebec (QC) G1S 2L2, Canada
D�partement de g�ologie et g�nie g�ologique
Quebec (QC) G1K 7P4, Canada
The decomposition of the organic content of disposed waste results in production of heat and landfill gas, composed mainly of methane and carbon dioxide. The developed pressure, concentration and temperature gradients lead to gas emissions to the atmosphere and to lateral migration through surrounding soils. Environmental and safety issues associated with landfill gas require control of the off-site gas migration. The numerical model TOUGH2-LGM was used to simulate the landfill gas migration through unsaturated sands adjacent to the St-�tienne-des-Gr�s landfill site in Quebec, Canada, and to assist the design of the off-site gas control system in compliance with regulatory requirements. The model simulates the migration of four fluid components (water, nitrogen, methane and carbon dioxide) and one energy component (heat) in partially saturated media. Two examples are simulated: free lateral gas migration, and lateral gas migration towards a horizontal extraction well. Results show that a vacuum of 0.5 kPa in the horizontal well installed 10 m from the landfill at 3 m depth is sufficient to limit further lateral migration of methane. The results also show the different flow patterns for methane and atmospheric air, and demonstrate the advantages of the multicomponent representation of the gas phase.
Keywords: Landfill; landfill gas; methane; production; migration; numerical modeling
Issue 3, August 2003
CHARACTERISTICS OF HEAVY METAL RELEASE FROM INCINERATED ASH AND MOLTEN SLAG USING DIFFERENT THERMAL TECHNIQUES
A. Idris1, Z. Abu-Kaddourah1, M.J. Megat Mohd Noor2 F.R. Ahmadun1, K. Saed1
1Department of Chemical and Environmental Engineering
2Department of Civil Engineering,
Faculty of Engineering
Universiti Putra Malaysia
43400 Serdang, Selangor MALAYSIA
Thermal treatment is one of the most acceptable treatment processes for stabilization of sewage sludge. This paper discusses the use of different thermal techniques for treating sewage sludge, by varying heating temperature, cooling rate and holding time. The heating temperature was in the range of 1250-1550�C; cooling rate, 2.5-10�C min-1; and holding time, 0-120 min. The indication of the stability was based on the US EPA leaching test on the produced molten slag. Results from leaching test showed that the molten slag produced at higher heating temperatures and slower cooling rate was more stable compared to those produced at lower heating temperature and faster cooling rate. Holding time was found to affect the leaching of heavy metals from the molten slag. Longer holding time gives a more stable molten slag in term of lower concentrations of heavy metals in leachate.
Keywords: Incinerated ash; thermal techniques; molten slag, heavy metals; leaching test; sewage sludge
DEGRADATION OF MUNICIPAL SOLID WASTE IN SIMULATED AEROBIC AND ANAEROBIC BIOREACTOR LANDFILLS
S. Rendra*, L. Fernandes*, and M.A. Warith**
* Department of Civil Engineering, University of Ottawa
161 Louis Pasteur Street, P.O. Box 450, Stn. A
Ottawa, Ontario K1N 6N5 CANADA
** Department of Civil Engineering, Ryerson University
350 Victoria Street
Toronto, Ontario M5B 2K3 CANADA
The biodegradation of municipal solid waste (MSW) was investigated in simulated bioreactor landfills under aerobic and anaerobic conditions. The bioreactors were operated to determine the quantity of moisture and sludge that would optimize waste degradation. The leachate generated was recycled over 47 and 63 weeks for aerobic and anaerobic bioreactors, respectively. Leachate samples were collected on a weekly basis and analyzed for pH and organic concentration measured in terms of BOD and COD. In addition, the generation of the biogas was monitored during the operation of the bioreactors. Leachate recirculation and sludge addition rate of 650 and 65 mL/kg of waste/d in the aerobic bioreactor proved to be sufficient to enhance the MSW degradation within 31 weeks where COD concentration was below 1000 mg/L. While in the anaerobic bioreactors, at the same rates of leachate recirculation and sludge addition, the MSW was stabilized within 51 weeks. This showed that aerobic degradation, with the addition of air at the rate of 84 L/kg of waste/d, provided greatly enhanced decomposition compare to the degradation under anaerobic operation. Reduction of leachate recirculation and sludge addition to 325 and 100 mL/kg of waste/d increased the stabilization period from 33 to 47 weeks in the aerobic bioreactors. While in the anaerobic bioreactors, after 63 weeks, MSW stabilization was still in progress. These results revealed that addition of supplemental material and air have a positive effect on the rate of biodegradation of MSW.
Keywords: Municipal Solid Waste; Bioreactors Landfills; Aerobic and Anaerobic Degradation; Leachate Recirculation; Sludge Addition
LEAST COST MANAGEMENT OF SOLID WASTE COLLECTION
J.C. Agunwamba, N. Egbuniwe, and T.C. Ogwueleka
Most developing countries have to grapple with the problem of efficient solid waste management in the face of increasing waste generation rate, high collection cost and dwindling financial resources. In some cities wastes are dumped indiscriminately and littered on the streets. This is the case with Onitsha, a heavy commercial city in Eastern Nigeria. This study is aimed at least cost solid waste collection in Onitsha through mixed integer programming. Actual transportation cost was estimated based on 1999 salaries and fuel prices. Optimum cost of collection via transfer stations to two disposal sites were compared with the existing situation of having no transfer station and only one disposal site. Post-optimality analysis was performed for several scenarios, investigating the sensitivities of the optimal cost to varying capacities of the transfer stations, investments and operating cost of the transfer stations, generation rates, unit collection costs via transfer stations were each operated at a capacity of 300 tons per day. The introduction of transfer stations resulted in $463.75 (38.9%) savings per day in the collection cost per day. Implementation of the programmed will facilitate regular collection of solid wastes by reducing the operation cost.
Keywords: Solid waste collection, integer programming least-cost, optimisation, Onitsha, Nigeria
METHODOLOGY AND FINDINGS OF A SOLID WASTE QUANTIFICATION AND CHARACTERISATION STUDY IN DAR ES SALAAM CITY, TANZANIA
Stephen E. Mbuligwe, Mengiseny E. Kaseva, and Gabriel R. Kassenga
Department of Environmental Engineering
Faculty of Lands and Environmental Engineering (FLEE)
University College of Lands and Architectural Studies (UCLAS)
P.O. Box 35176, Dar es Salaam TANZANIA
Quantification and characterisation of waste are a pre-requisite for any planning and design for solid waste management. This paper reports on lessons from a research and pilot scale demonstration project on community level solid waste management in Dar es Salaam City, Tanzania. As part of the project, a study area was selected, and waste collection routes and service schedules were designed using the Heuristic-Deterministic approach. Households in the study area were given storage bags of different colours to facilitate on-site sorting and storage of the waste. The collected waste was transported and re-sorted so as to quantify it and determine its composition. The per capita waste generation rate (WG) was found to be between 300 and 450g per day and organic waste made up more than 78% of the total amount of waste. The moisture content of the waste was found to be 65% – 75% while the bulk density was 310 kgm-3. The study demonstrated among other things, that composting of solid waste could greatly alleviate solid waste management problems in Dar es Salaam City. It also showed that it was possible to manage waste at community level on cost- recovery basis. A further observation was that, the project improved greatly the environmental sanitation of the study area.
Keywords: Solid waste management; Quantification; Characterisation; Generation rate; Solid waste collection; Environmental sanitation
RECOVERY OF COAL FROM WASTE FINE COAL BY COLUMN FLOTATION
Zonguldak Karaelmas University, Chemistry Department
67100 Zonguldak TURKEY
Tlf: 90-372-257 40 10/1409; Fax: 90-372-257 41 81
Zonguldak Karaelmas University, Mining Engineering Department
67100 Zonguldak TURKEY
Turkish Hardcoal Enterprises
67000 Zonguldak TURKEY
This study involved enriching by means of a laboratory-scale column flotation apparatus waste coal dust obtained from the Zonguldak coals. The effect of the factors such as the amount of the frothing agent, the amount of collecting agent, the feeding height, the thickness of the froth, the column height and the air rate on the coal yield was investigated and attempts were made to determine the efficiency level that would give the highest yield. Furthermore, in order to get the desired yield from column flotation, the most appropriate value was established for each variable under study in terms of ash content and yield, and a column flotation experiment was carried out under optimal conditions. It was established that through the column flotation of waste fire coal having an ash content of 53.35%, a volatile matter content of 19.20%, a fixed carbon content of 27.45%, a total sulfur content of 0.74% and a calorific value of 14.42MJ/kg, clean coal could be recovered whose concentrate weight yield would be 32.06%, combustibility yield 61.16% and ash content 11.15%.
Keywords: Waste fine coal, flotation, column, collector, frother, feeding height, column height, air rate, foam thickness
USING SURVEYS TO UNDERSTAND CURBSIDE RECYCLING PROGRAMS
Jess W. Everett
P.E. and Professor, Civil and Environmental Engineering
Glassboro, NJ 08028
Tel. 856-256-5326, Email: Everett@rowan.edu
Patrick C. Riley
Waste Management of Oklahoma, Inc.
5600 N.W. 4th, Oklahoma City, OK 73127
Curbside collection of recyclable material can be expensive because the inherent costs of curbside collection are high, but also because amounts collected per residence are small compared to the total waste stream, and extra activity may be required, such as sorting. A better understanding of how residents participate in curbside recycling programs may help operators reduce costs. In this paper, surveys and direct observations of set-out behavior are used to increase our understanding of recycling programs. Specifically, the paper addresses: (1) survey validity, i.e., the representativeness and accuracy of survey responses; (2) the measurement of respondent awareness of a recycling program and related activities by survey; and (3) relationships among set-out amount, set-out frequency, and household size.
Keywords: Recycling, Curbside, Collection
Issue 2, May 2003
CRITICAL FLUID EXTRACTION OF OIL FROM SORBENT MATERIALS
John F. Katers, Ph.D.
Assistant Professor of Natural and Applied Sciences
University of Wisconsin-Green Bay
2420 Nicolet Drive, ES317
Green Bay, WI 54311-7001
Medtox Laboratories Inc.
402 West County Road D
St. Paul, MN 55112
Spills of oils and lubricants occur frequently in industrial settings. These spills are often managed and cleaned up using materials ranging from mineral sorbents to cellulose and polypropylene sorbents in the form of mats, pads, and socks. It has been estimated that 1.09 billion pounds of environmental clay sorbents, 250 million pounds of environment cellulosic sorbents and 64 million pounds of environmental polypropylene sorbents are used annually in the United States. Disposal options for used oil sorbents have typically included burning for energy recovery, landfilling, incineration, and laundering. Each of these options clearly has environmental impacts, including potential long-term liability for the generator. Federal regulations specifically require that materials contaminated with or containing used oil be void of free-flowing liquids, and that all of the used oil be removed to the best ability of the generator. State regulations on sorbent materials vary considerably, with several states listing these types of material as a hazardous waste or requiring additional laboratory testing, while the majority of states follow federal regulations. Environmental concerns associated with used oil sorbent materials prompted the development of a patented technology that uses liquefied gas as a solvent to extract the oil, thereby allowing both the oil and the sorbent to be recycled. Cleaned sorbents, which exhibit properties similar to virgin materials even after being reused multiple times, are returned to the generator for reuse while the oil can be recovered for use in lube stock or for energy recovery.
Key Words: Sorbents, Used oil, Critical fluid extraction, Closed-loop, Recycling, Oil filters
DEVELOPMENT OF A NEW POROUS CARRIER FOR AMMONIUM REMOVAL AS INNOVATIVE USES FOR WASTE MATERIALS
Yasunori Kozuki 
Department of Ecosystem Engineering, Graduate School of Engineering
The University of Tokushima, 2-1 Minamijosanjima Tokushima, 770-8506 JAPAN
Department of Civil Engineering
Anan College of Technology, 265 Aoki Minobayashi Anan, 774-0017 Tokushima JAPAN
A promising new approach to improve the utilization of some industrial solid wastes, blast furnace slag (BFS) and zeolite synthesized from fly ash (ZFA), by their solidification to cylindrical Porous Carrier using Hydrothermal Hot-Pressing (HHP) method was presented in this paper. Porous Carriers made from the mixture of ZFA and BFS for easy way for subsequent practical application on the aquatic environment were developed. This study points towards viable carriers that could be effective as well as economically attractive for ammonium removal from eutrophic sea area. Ammonium adsorption efficiency was influenced by the presence of cations in the seawater. Ammonium adsorption also depended on the pH. It was found that a decrease in pH increased the ammonium adsorption. Freundlich isotherm coefficients showed that adsorption was the process involved in the removal of ammonium from seawater. The increase of porosity of carriers increased the adsorption of ammonium. The results indicated that ammonium adsorption was enhanced by HHP treatment adsorption. It could be explained by the fact that HHP treatment could convert a part of residual fly ash present in ZFA to zeolite.
Keywords: Synthesized zeolite from fly ash; blast furnace slag; ammonium adsorption; Hydrothermal Hot-Pressing; Porous Carrier; seawater
EVALUATING WASTE MANAGEMENT ALTERNATIVES BY WORTH—BENEFIT—UTILITY (WBU) ANALYSIS
Chemical Engineer, Ph.D.
Greek Ministry of the Environment
Regional Planning and Public Works
Pattission 147, 112 51 Athens GREECE
phone: +30 1 8654950
fax: +30 1 8663693
The selection of the optimal method for municipal solid waste (MSW) disposal is a complicated process. A method is proposed that extends the cost – benefit analysis to include analysis of worth, benefit and utility. The worth – benefit – utility (WBU) analysis method, allows consideration of environmental and social parameters in addition to economic and technological parameters, using a combination of statistical analysis methods, trends extrapolation and Delphi techniques. The goal structure is built by groups of stakeholders representing a variety of interests and priorities. The goal matrix is then checked for completeness and compatibility and the goals are ranked according to a grading system. Then the alternative MSW disposal methods are evaluated using WBU analysis. The method is applied for the selection of the optimal MSW disposal method in the Greater Athens Area (GAA). The analysis reveals sanitary landfill disposal to be slightly preferable to mechanical sorting – recovery – composting, and both methods to be superior to incineration. The results support the existing municipal waste disposal system in the GAA that combines landfilling and mechanical sorting, recovery and composting.
Keywords: Municipal solid waste management, worth – benefit – utility analysis, landfilling, mechanical sorting and composting, thermal treatment
FLYASH BASED ZEOLITE TECHNOLOGY— AN ILLUSTRATION OF WASTE TO WEALTH
S. Rayalu, S.U. Meshram, M.Z. Hasan and S.N. Kaul
National Environmental Engineering Research Institute
Nagpur – 440 020
Fax: 91 (712) 230673
Devastating effects of flyash on environment have been realized and therefore, regulations for disposal of such waste on land have accordingly been made stringent. It is, therefore, imperative to develop alternate methods of disposal with recourse to resource recovery, and in this context, the utilization of flyash for production of high value added products viz. zeolites is receiving increasing attention. Also, Flyash based zeolite (FAZ) production technology has advantages of value addition, attractive profit margins; with concomitant conservation of raw materials thus offering an edge over other flyash utilization technologies.
The focus of the synthesis program has been to synthesize a wider array of zeolites ranging from highly sorptive material viz. Zeolite-A & X to thermally stable and siliceous zeolites viz. Zeolite-Y, ZSM-5 and Mordenite. The process developed is simple, non-tedious and environmentally benign. The three major steps involved in the synthesis are fusion of flyash and caustic soda, aging and hydrothermal crystallization.
The FAZs have been thoroughly characterized with respect to crystallinity, exchange capacity, surface area, particle and pore size etc. The crystallinity for various zeolites is as follows : Zeolite-A : 100%; Zeolite-X : 99.8%, Zeolite-Y : 97% mordenite : 68% and ZSM-5 : 64%. The exchange capacity is significant parameter for assessing use of zeolites as a sorptive material and is as follows : Zeolite-A : 540 meq/100, Zeolite-X : 480 meq/100g, Zeolite-Y : 420 meq/100g, mordenite : 200 meq/100g and ZSM-5 : 100 meq/100g. The surface area for Zeolite-A, X, Y, ZSM-5 and mordenite is 580, 560, 480, 320, 200 m2/g respectively. The cost of production for most of the zeolites is 25-40% less than commercial zeolites.
Keywords: Flyash based zeolite, synthesis, characterization, cost-effectiveness
FRICTION AND WEAR BEHAVIOUR OF ALUMINIUM FLY-ASH COMPOSITE
Dr. S.K. Acharya*, P.K. Mahanta**, P.K. Pattanaik***
Department of Mechanical Engineering
National Institute of Technology
(Formerly Regional Engineering College)
Rourkela – 769 008
Composites are attractive materials for a number of applications. Their use is limited by their cost and this work looks at the use of fly- ash as a low cost option. The present work deals with an experimental investigation of wear behaviour of Aluminium fly-ash composite with different volume fraction (10,15,and 20 percent by weight) in dry sliding Condition with different working conditions using a pin-on-disk machine. The composite shows encouraging results in comparison to pure Aluminium for hardness, abrasion resistance, wear rate etc
Keywords: Composite, Fly-ash, Powerplant, Volume fraction, Wear rate, Aluminum
PERFORMANCE OF ANAEROBIC REACTORS IN THE BIOSTABILIZATION OF ORGANIC SOLID WASTES
1Wilton Silva Lopes, 1Valderi Duarte Leite and 2Shiva Prasad
1 Department of Chemistry, Center for Sciences and Technology
State University of Para�ba
58100-000 Campina Grande, PB, BRAZIL
2 Department of Chemical Engineering, Center for Sciences and Technology
Federal University of Paraiba, Post Box 10108
CEP 58109-970 Campina Grande, PB, BRAZIL
The objective of the present work was to study the process of biostabilization of the putrescible organic fraction of urban solid waste through utilization of bovine rumen as inoculum. The work was carried out in Environmental Sanitation Laboratory, CCT, UEPB, Campina Grande, Northeast of Brazil at 550 m above sea level, in four anaerobic batch reactors with a capacity of 50 L each, during a monitoring period of 365 days. The proportion between urban solid waste and inoculum in the substratum fed to the reactors A, B, C and D was 100/0, 95/5, 90/10 and 85/15, respectively. The anaerobic biostabilization constants of the substratum obtained were as follows: reactor A= 1.758 x 10-3 day-1, B= 1.857 x 10-3 day-1, C = 2.221 x 10-3 day-1 and D = 3.168 x 10-3 day-1. It was also verified that the mass decrease (%) of applied substratum was: reactor A = 13, B = 18, C = 26 and D = 36. Based on the data obtained, the viability of utilization of bovine rumen as inoculum in anaerobic biostabilization process of urban solid waste could be verified. This is due to the value of the biostabilization constant, which presented strong correlation with the percentage of inoculum used.
Keywords: Anaerobic treatment, solid waste, inoculum, batch reactor, biostabilization constant, kinetics
SITE SELECTION PROCESS FOR BROWNFIELDS RE-DEVELOPMENT
Department of Civil and Environmental Engineering
Bethlehem, PA 18015, USA
Department of Civil and Environmental Engineering
College of Engineering and Petroleum, P.O. Box 5969
Safat 13060, KUWAIT
Throughout the United States, abandoned industrial properties exist in both small and large cities and are difficult to revitalize due to the contamination. These abandoned urban facilities are commonly referred to as “Brownfields.” The problem in many communities, especially older industrial cities, is so severe that the U.S. Conference of mayors identified the issue of Brownfields as their top environmental issue for 1995. Cities, states, and the federal government collectively geared up to try to solve this problem.
In 1997, the Lehigh Valley Planning Commission developed a task force to assess Brownfields sites for potential redevelopment in the Northampton and Lehigh Counties in Pennsylvania. The task force developed a site selection criteria based on the following items: location, zoning, site size, public sewer service, community water service, highway access, rail service, bus service, natural gas service, benefit to municipality, and previous studies on reuse. Each of these items received a maximum rating from 2 to 4, and the maximum potential score that a site could receive was thirty-two. A computer program was developed to evaluate sites for redevelopment using the criteria specified by the Brownfields Task Force.
This study evaluated 71 potential sites for redevelopment. Two sites were viewed to be ideal for redevelopment. Most of the sites were located in rural settings that lacked the infrastructure for industrial development. This paper will also discuss the Bethlehem Steel site, which is considered a “National Model for Brownfields Development.” The geo-environmental considerations and concerns in the re-development of Bethlehem Steel are emphasized.
Keywords: Brownfields, site selection, cleanup, re-development, contamination, hazardous waste, Superfund
Issue 1, February 2003
A STUDY ON RESIDENTIAL SOLID WASTE COMPOSITION AND MANAGEMENT IN A SELECTED DEVELOPING COUNTRY—GUYANA
Anita Z�vodsk�, Ph.D.
Sonora Environmental Research Institute, Inc.
3202 East Grant Road
Tucson, AZ 85716
Solid waste is a global issue. As developing countries strive to improve their economic situations and standings in the world community, they face extreme under-funding in vital areas of local infrastructure, especially solid waste management. As populations continue to grow, solid waste and its management will become a very serious matter. This study addressed the problems of insufficient available data and inadequate funding in an urban center in a small developing country with respect to future solid waste management. Residential municipal solid waste was analyzed in Georgetown, the capital of Guyana. As has been found in other developing nations, the largest component of the waste was organic (food waste), and contained very little hazardous component. From the results obtained, suggestions for improved solid waste management in Georgetown are presented.
Keywords: Solid waste management; developing countries; Georgetown, Guyana; waste characterization; future planning; municipal solid waste
THE URBAN SOLID WASTE MANAGEMENT PROBLEM IN INDIA— AN ECONOMIC APPROACH AND FRAMEWORK FOR POLICY
Foundation to Aid Industrial Recovery
No.11, Prime Street, Richmond Town
Bangalore 560 025, INDIA
Tel: 91.80.2240311/2210828; Fax: 91.80.2211417
Urban solid waste presents a growing problem to policy-makers in many developing countries. In India, composting of organic waste and recovery/recycling of dry waste has been strongly recommended as the solution to the problem. However, social welfare is maximized only when composting is undertaken with organic waste segregated at-source. Many efforts have been made through awareness-building programs to induce households to segregate organic waste at-source. These have achieved limited success. Through a microeconomic analysis of organic waste management, we are able to understand why an incentive-based approach for source-segregation, which has been functioning efficiently for dry waste like paper, has not evolved sufficiently for organic waste. Market failure calls for government intervention through a tax and incentive approach, which imposes no net cost on stakeholders in the urban solid waste management system. However, many practical issues in its implementation remain unanswered and must be well thought-out.
Keywords: Urban solid waste, municipal solid waste, organic waste, composting, source separation.
COLLECTION, PROCESSING AND CHARACTERIZATION OF FOOD RESIDUES FROM RESIDENTIAL WASTE FOR USE IN BROILER CHICKEN FEED
Ednilson Viana; Harry Edmar Schulz
Engineering School of S�o Carlos
Department of Hydraulic and Sanitary Engineering
University of S�o Paulo
S�o Carlos, BRAZIL
Adriana Backx Noronha
Economic, Administration and Accounting Faculty
University of S�o Paulo
Ribeir�o Preto, BRAZIL
Food residues from residential waste were obtained through curbside collection in S�o Carlos/SP, Brazil and were processed and characterized chemically and microbiologically. The results showed absence of mycotoxins, heavy metals, organochlorine pesticides and pathogenic microorganisms. The nutritional composition, granulometry, smell and taste of the resulting component termed as “Feed of Ingredient from Food Residues” (FIFR), show its potential as an ingredient in broiler chicken feed, in association with other ingredients, such as corn bran and soybean bran.
Keywords: Recycling, Food Residues, Residential Waste, Organic Matter, Broiler Chicken Feed
A LIGHTWEIGHT FLOWABLE FILL USING GRANULATED RUBBER TIRES
Charles E. Pierce
Assistant Professor, Department of Civil and Environmental Engineering
University of South Carolina
300 Main Street, Columbia, SC 29208
voice: (803) 777-3855; fax: (803) 777-0670
M. Catherine Blackwell
Bridge Engineer, Federal Highway Administration
South Carolina Division, Columbia, SC 29201
voice: (803) 765-5331; fax: (803) 253-3989
Controlled low-strength materials, also known as flowable fills, are becoming widely utilized as earthwork materials in transportation construction. However, a typical flowable fill produced with sand carries a unit weight similar to compacted soil, often around 1.9 to 2 g/cm3 (120 to 125 pcf). As a result, both fill materials cause similar stress increases in, and subsequent settlement of, the bearing layer beneath the fill. Reducing the unit weight of flowable fill will reduce the potential for settlement of the bearing layer. Developing a lightweight flowable fill using crumb rubber granulated from discarded tires is the focus of this paper. While the cost of crumb rubber can be greater than natural sand, it compares well with other manufactured lightweight aggregates. To assess the feasibility of using crumb rubber, an experimental laboratory study was performed to measure the fluid- and hardened-state properties of nine mix designs. Mix designs were varied to include water-to-cement ratios of 1.5 to 4 and crumb rubber contents of 16 to 38% by weight. Flowability, bleeding and time-of-set were measured immediately after mixing; unit weight and unconfined compressive strength were measured after 7, 14 and 28 days of controlled curing. The laboratory results indicate that crumb rubber can be successfully used to produce a lightweight flowable fill (1.2 to 1.6 g/cm3 [73 to 98 pcf]) with excavatable 28-day strengths ranging from 269 to 1194 kPa (39 to 173 psi). Based on these results, a crumb rubber-based flowable fill may be used for any number of lightweight fill applications such as embankment fill construction for bridge approaches.
Keywords: Scrap tires, crumb rubber, controlled low strength materials (CLSM), flowable fill, lightweight aggregate
THE POTENTIAL FOR REDUCTION OF LANDFILL WASTE BY RECYCLING AND MINING OF CONSTRUCTION AND DEMOLITION WASTE AT THE WHITE STREET LANDFILL, GREENSBORO, NORTH CAROLINA
Shoou-Yuh Chang and Rebecca Cramer
Department of Civil and Environmental Engineering
North Carolina A&T University
1601 East Market Street
Greensboro, North Carolina 27411
Throughout the United States, many communities are faced with landfills that are reaching capacity. Due to stricter regulations and public awareness, simply opening new landfills is not always an option. Extending the life of a present landfill with a number of waste diversion initiatives including recycling as the key has become paramount. One type of waste that is currently of interest for potential recycling is Construction and Demolition (C&D) waste. In 1998, at the White Street Landfill, Greensboro, North Carolina, a section known as Phase II was dedicated to the disposal of C&D waste. This study explores the ability to extend the life of Phase II by a combination of mining the existing C&D waste, and recycling new C&D waste entering the landfill.
The City of Greensboro Construction/Demolition Permit Application originally indicated a total available volume of 612,195 cubic yards (yd3) for C&D waste material in Phase II. Using this volume, it was originally predicted that Phase II would reach capacity in approximately 9.5 years. The increase in C&D waste in 1999 due to the closing of other C&D waste landfills in the area has significantly changed the life of Phase II. A recalculation of the Phase II life with the increased volume and potential growth based on the expected increase in population establishes the Phase II closing date at the beginning of 2002. With the assumption that 59.5% of the incoming C&D waste volume is recyclable, the closing of Phase II could be extended to the end of 2005 or the beginning of 2006. This will add approximately 4 years to the life of Phase II, and will generate an additional $1.5 million in revenue. This revenue should be sufficient to fund the cost of establishing an on-site C&D waste-recycling center.
Keywords: Recycling, landfill, reclamation, construction and demolition
ADVANCED ANAEROBIC DIGESTION OF SLUDGE THROUGH HIGH PRESSURE HOMOGENISATION
T. I. Onyeche, Ph.D.
O. Schlaefer, Dipl.-Biol.
M. Sievers, Ph.D.
Leibnizstr. 21+23, D-38678
Clausthal Zellerfeld, GERMANY
The increased production of sewage sludge and its subsequent environmental pollution has been a pressing problem in industrial countries. Search for possible utilisation of sludge or reduction of its disposal quantities has been going on since recent years. This work shows the exploitation of valuable energy from stabilised sludge with subsequent mass reduction. The optimal combination of mechanical disruption of stabilised sludge at relatively low pressures using a special high pressure homogeniser followed by anaerobic digestion in a novel laboratory digester, is shown. Results showed that more energy (i.e. methane gas) could be obtained from concentrated and disrupted sludge than from untreated samples. The energy produced was higher than that invested during disruption and digestion processes. Appreciable sludge reductions were obtained. If this new process is integrated in any existing plant, the extra energy produced can be used for local electric supply, for heating the digestion tower while the sludge reduction provides new source of revenue for the plant operators.
Keywords: Concentration; digestion; disruption; high pressure homogeniser; pollutants; sludge