Issue 4, November 2004
STRATEGIC WASTE MANAGEMENT PLANNING IN A SWEDISH REGION
Maria Ljunggren S�derman#
Energy Systems Technology Division, Chalmers University
SE-412 96 G�teborg SWEDEN
#Email: email@example.com Phone: +46-31-722 52 47
This paper describes a study of waste management planning in a Swedish region. The purpose of the study was to increase the knowledge and understanding of using systems engineering models in real waste management planning. Such knowledge is central for ensuring that models developed can be efficiently applied in real-world situations. In this study, significant development of a systems engineering model based on MIMES/Waste (an existing framework for modelling waste management) was carried out. A decision basis that the region could use for strategic waste management planning was also developed. In addition, the study provided insights for developing a systems engineering model for waste management at the national level: the project that would follow.
An epilogue based on interviews of representatives from the four municipalities illuminates what has happened in the region since the study was completed. The interviews revealed that the study was used as input to, and influenced, the decision-making process. The study is an example of how a systems engineering model can assist in real decision-making and be useful in practical waste management.
Keywords: Waste management, energy recovery, material recovery, biological treatment, strategic planning, systems engineering model
ESTIMATING GROUNDWATER RECHARGE AT LANDFILL
312 Karen Place, Waterloo, Ontario
CANADA, N2L 6K8
Waterloo Numeric Modeling Corporation
157 Queen Street N. Kitchener, Ontario
CANADA, N2H 2H8
The software tool Visual HELP allows easy assessment of groundwater recharge at landfill sites for different climatic conditions. The effect of different Visual HELP parameters on the value of recharge has been studied for two different climates. Among surface runoff parameters, evapotranspiration and parameters of the upper lowpermeable layer, field capacity and wilting point of the upper layer have the greatest impact on recharge. A small variation of these parameters (by a factor of 2) may result in recharge estimate variations of 20-30 times. The sensitivity of recharge to these two parameters is several times higher for the Fraserburg site in South Africa with a relatively arid climate than for the Kingston Site in Canada with a humid climate. The range of recharge values determined by the Visual HELP modelling strongly affects the results of Visual MODFLOW simulations. Ignoring the possible range in recharge may lead to serious errors in groundwater modelling.
CARBONATION OF FBC AS USING SONIC ENERGY
Fluidized bed combustion (FBC) ashes from firing high-sulfur fuels with limestone addition contain elevated levels of CaO. The ashes display exothermic behavior on wetting, are subject to deleterious expansion in the landfill, and produce high-pH leachate that requires treatment. Currently, the ashes are slaked in a relatively ineffective and potentially hazardous two-stage wetting procedure. Sonic energy, both low- and high-frequency, is a highly effective method of hydrating these ashes. However, even upon hydration, FBC ashes still create expansion in the landfill site, and produce a high-pH leachate. Carbonation would be a better route, but direct attempts at quantitatively carbonating these ashes have to date been unsuccessful. By contrast sonic energy is effective in promoting the carbonation of FBC ashes. When CO2 is injected into the chamber where the FBC ashes are being sonically hydrated, near-quantitative carbonation in minutes is possible.
Keywords: CFBC, Ash Conditioning, Hydration, Carbonation and Sonochemistry
EXPERIENCES FROM THE LARGE-SCALE IMPLEMENTATIONOF SOLIDIFICATION/STABILIZATION PROCESSES
Brett Cohen�* and James G. Petrie�
Department of Chemical Engineering, University of Cape Town
�Current address for both authors:
Department of Chemical Engineering, University of Sydney
* Tel: +61 2 9351 4115, Fax: +61 2 9351 2854, email: firstname.lastname@example.org
Solidification/Stabilization (S/S) refers to a suite of technologies commonly used for the treatment of hazardous wastes prior to their consignment to landfill. In cement-based S/S, cement is mixed with a waste and make-up water where required and the fresh mixture is placed into a cell in a landfill site where it is allowed to set. The waste is contained in the resultant monolith via a combination of physical and chemical processes. This paper presents the authors’ observations with regard to mixing, transport and placement of the fresh mixture, and the design of the landfill to contain these solidified products. Comments on the costing of S/S operations are made on the basis of both literature reports and the authors’ own experience. In an attempt to reduce costs of treatment and improve the performance of the product, a proportion of the cement is sometimes substituted with additives including fly ash and calcium hydroxide. Some qualitative observations regarding the effect of these additives on product performance are made here.
Keywords: Solidification, Stabilization, S/S, landfill, fly ash, calcium hydroxide, cement
ANAEROBIC CO-DIGESTION OF SOLID RESIDUEAND WASTEWATER FROM OLIVE-OIL MILLS
Bassim Eid Abbassi
Al-Balqa’ Applied University
Anaerobic treatment of olive mill wastes (OMW) was performed to evaluate the operational conditions required to develop a feasible method for biogas production. The effect of influent organic loading (expressed as total volatile solid loading, kg TVS/m3.d) and substrate composition on the performance of continuously stirred tank pilot-scale reactor (840 L) was examined. Cow manure was also used at the initial phase of the experiment. Testing a mixture of these wastes was conducted by gradual increase of OMW proportions until complete replacement of cow manure proportion. The data, which were collected over the study period, indicated that OMW could be treated anaerobically with high efficiency in TVS reduction. The highest biogas production rate (3144 L/d) was obtained when a mixture consisted of 209 L of olive mill wastewater and 15 kg of olive seed at hydraulic retention time of 26.2 day and organic loading of 3.87 kg TVS/m3.d. The average specific biogas production rate was found to be 715 L/kg TVS.m3.d.
Keywords: Olive-mill waste; anaerobic; co-digestion; biogas
Evaluationof HETEROGENEITY AND ANISOTROPY of WASTE PROPERTIES on Leachate Recirculation in BIOREACTOR Landfills
Mazen M. Haydar1 and Milind V. Khire2
1Graduate Research Assistant and
2Assistant Professor and Corresponding Author
Department of Civil and Environmental Engineering
Michigan State University
E. Lansing, MI 48824
Leachate recirculation in municipal solid waste (MSW) landfills was modeled using HYDRUS-2D, a saturated/unsaturated flow model. The recirculation system consisted of three horizontal trenches spaced laterally at 20 m. The model was used to simulate the effect of heterogeneity and anisotropy in the hydraulic conductivity of MSW on the leachate flux that can be recirculated at steady-state flow condition. Monte Carlo analysis (MCA) was used for three sets of correlation lengths and variance using a lognormal hydraulic conductivity distribution for MSW. MCA estimated the mean leachate flux and its standard deviation. MCA was computationally time intensive. However, MCA quantified the variability and the uncertainty in the magnitude of leachate flux. The key finding is that heterogeneity and anisotropy in hydraulic conductivity of MSW allows us to recirculate greater leachate flux compared to homogeneous and isotropic waste under equivalent conditions. However, heterogeneity and anisotropy results in relatively non-uniform wetting of MSW. Hence, sufficient buffer between the landfill side slopes and the leachate injection system is needed to minimize the potential of leachate breakouts from the side slopes of the landfill. We also provide guidelines for selecting appropriate buffer to minimize leachate breakouts.
Keywords: Leachate recirculation, horizontal trench, heterogeneity, anisotropy, solid waste, Monte Carlo analysis, landfill
Issue 3, August 2004
HIGH PERFORMANCE ALKALI ASH MATERIAL
Alkali Ash Material (AAM) concrete is a new and unique material that is cost-effective because it utilizes waste fly ash, has properties superior to other concrete products and is potentially suitable for high strength construction in bridges and highways. The AAM concrete described here is produced from the addition of inexpensive chemicals to fly ash. Fly ash is by far the largest by-product of the consumption of coal for the generation of electricity. Only 30% of the 71 million tons of fly ash generated each year are recycled for use in structural fill, waste stabilization and additives to concrete.
AAM has advantages over other concrete products. AAM can be used to create high performance concrete (AAM-HPC), providing rapid strength gain and development of high ultimate strengths of more than 110 MPa. AAM has far better environmental resistance than Portland cement concrete, resisting attack from sulfuric acid (H2SO4), hydrochloric acid (HCl), and organic acids. AAM resists freeze-thaw attack and high abrasion, possesses low chloride permeability and does not exhibit alkali silica reactivity. AAM concrete is mixed and molded like ordinary Portland cement using conventional technology, adapted from existing facilities in manufacture of pipe, block and wet cast concrete products. AAM hardens with dry curing, whereas Portland cement is hydrated and requires moist curing.
Applications of AAM are blocks, pipes, median barriers, sound barriers, overlaying materials, and chemical resistant products. With further development, AAM will be suitable for bridge beams, concrete tanks, highway appurtenances, and other high strength construction products.
Keywords: Fly ash, alkali activation, recycling, high performance concrete, chemical resistant
STUDY OF PARAMETERS INFLUENCING THE PROPERTIES OF SINTERED FLY ASH AGGREGATES
Dr. K. Ramamurthy*
Building Technology and Construction Management Division
Department of Civil Engineering
Indian Institute of Technology Madras
Phone No.: +91-44-22578309 Fax: +91-44-22578281
Pelletization is a promising process for making artificial aggregates from fine-grained materials like fly ash, which facilitates its high volume utilization as lightweight aggregate in concrete. A review indicates that only limited studies are reported on pelletization of fly ash aggregates. A study on the process of pelletization for the influences of angle of pelletizer disc, moisture content, affect of fineness of fly ash, and sintering temperature and its duration was undertaken. The salient observations are; i) for a chosen diameter of the pelletizer disc and the speed of revolution, the optimal angle of pelletizer has to be determined to maximise the pelletization efficiency, ii) adjustment of moisture content results in production of pellets of different size, and iii) for a given temperature and duration of sintering, pellets made with finer fly ash yield relatively higher strength.
STABILITY OF VERTICALLY STACKED RED MUD DISPOSAL CELLS
Texas A&M University-Kingsville
This study was conducted to determine the feasibility of dry stacking bauxite waste to a height of 70 feet (21.3 m) with minimal adverse effect on the integrity of the disposal facility. Red mud samples were obtained from a disposal facility and analyzed for their geotechnical properties, (i.e. confined consolidation, unconfined shear strength, Atterberg limits, specific gravity, etc). Data from these analyses were used to predict the stability of different heights for stacking red mud in the storage facility.
Slope stability analysis using Rotational Equilibrium Analysis of Multi-Layered Embankments (REAME2k) software showed that the disposal facility is stable under the present loading condition, and at the proposed peak elevation of 70 feet (21.3 m) above mean sea level (MSL). The simplified Bishop, Spencer, and Modified Spencer methods indicated a minimum factor of safety against failure of 1.4 to 1.6. These values are somewhat above industry standard of 1.3 and indicate the facility could safely load red mud wastes to the proposed height of 70 ft (21.3 m) above MSL with diligent field monitoring during and after waste placement to confirm software output.
Keywords: Red mud; bauxite; dry stacking; slope stability; waste disposal; factor of safety
IDENTIFYING OPPORTUNITIES FOR IMPROVING THE MANAGEMENT OF WASTE WITHIN A UK, ACUTE HOSPITAL USING A SYSTEMS ANALYSIS APPROACH
Anne C. Woolridge
School of Environmental Science
Paul S. Philips
SITA Centre for Sustainable Wastes Management
University College Northampton, Park Campus
Northampton, NN2 7AL
Waste generation, segregation and disposal were monitored, using observation and interviews, in a number of general wards in an UK Acute Hospital of 650 beds. The data was analysed using a structured systems analysis approach based upon Structured Systems Analysis and Design Method (SSADM). An initial Data flow Diagram, produced using SSADM, was developed into a Waste Flow Diagram, which was used to document waste generation, flow and disposal within the hospital. The Diagram tracks the movement of waste through the system and helps identify the appropriate disposal stream for a given object. Such an approach enables managers to identify cost savings through effective identification, segregation and consignment to the appropriate disposal option. The SSADM approach produces a tool that supports the adoption of best practice, as the visual outcomes enable senior managers to devise training schemes for staff in sustainable waste management within a hospital context. This study, quickly identified savings (�28 099 per annum) that were some 18% of the clinical waste costs of the hospital. Detailed application within an UK hospital would be expected to lead to significant savings with all waste streams as well as reducing costs for general resource management such as food provision and stock control.
Keywords: Healthcare waste, clinical waste, systems analysis, hospital, waste flows
SLUDGE HOMOGENISATION FOR IMPROVED ENERGY AND REDUCED SLUDGE PRODUCTIONS
Theodore I. Onyeche
Leibniztr. 21+23, D-38678 Clausthal Zellerfeld
Sewage sludge is still a major concern to mankind. The environmental and health problems caused by the contaminants in sewage sludge have led to intensified research and development activities worldwide. Sludge is a residue/product from wastewater treatment plants and contains most of the contaminants released during man’s activities. The management of sewage sludge is one of the major challenges in the wastewater treatment industry and one of the most important economic and environmental issues for the next decade. Some stringent environmental regulations on sludge treatment and disposal have been imposed in several countries. These have resulted in an increasing interest in processes allowing the reduction in sludge and improvement in biogas production during the anaerobic digestion process. This work shows the first exploitation of valuable energy from stabilised sludge with subsequent mass reduction at technical scale after using a specially modified high-pressure homogeniser led to the success of this unique project. Results showed that about 30% 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. About 23% sludge reduction was also observed with no increase in chemical oxygen demand which confirms the earlier laboratory results already published in volume 29 (February 2003) of this same journal. This new process can produce extra energy for local electric supply, for heating the digester while the sludge reduction provides savings for the plant operators depending on the size, type and location of the plant. Concentration of sludge causes reduction in investment cost on digester as well as reduction in operational time for sludge dewatering.
Keywords: Sludge, concentration; digestion; disruption; disintegration; high-pressure homogeniser; sludge
A METHODOLOGY FOR COMMUNITY BASED WASTE MANAGEMENT DECISIONS
School of Biotechnology, Dublin City University
Glasnevin, Dublin 9
Phone: 353 1 7008515
CIMRU, NUI Galway
Nunn’s Island, Galway
Modelling of decision support for waste management is not a new idea, with the first waste management models appearing in the 1960s. For a waste management system to be sustainable, it needs to be environmentally effective, economically affordable and socially acceptable. It is shown that while most waste management models consider economic and environmental aspects, very few consider social aspects, with many concentrating on improving a decision support tool. As a result, the implementation of these models have had limited success as they have not always been accepted by the people affected by them. A decision making methodology called SWAP (Sustainable Waste Achievement Programme) is presented in this paper which addresses the shortcomings of other models identified from a full review of the literature and presented in summary form in the earlier part of the paper. The methodology is then verified and validated in the latter part of the paper. The purpose of SWAP is to assist stakeholders make the best decision possible given the circumstances, to determine the most acceptable set of actions and to determine how success can be measured. SWAP is centred on the involvement of all stakeholders in the decision making process from the beginning. The main users of the methodology will be policy makers in the area of waste management, in particular the local authorities. National departments of the environment also have a strategic role to play in supporting the use of the methodology at local authority level.
Keywords: Sustainable waste management; decision support; methodology; policy; community
Issue 2, May 2004
MANAGING WASTE AT THE RESIDENTIAL CONSTRUCTION SITE
Joseph Laquatra, Ph.D.
Mark Pierce, M.S.
Department of Design and Environmental Analysis
E-208 MVR Hall Ithaca, NY 14853-4401
This paper reports on a research project that focused on waste production, management, and reduction potential t a residential construction site in Upstate New York. A waste generation audit was conducted of all waste materials that were generated during the construction of a new, 1,900 square feet bi-level single family detatched home. Following completion of the audit, the economic and logistical feasibility of reduction, re-use and recycling strategies were investigated and tested. The study formed the basis for an educational program for homebuilders.
Keywords: Recycling; waste generation audit; C&D debris; tipping fees; landfill disposal; gypsum waste
A NEW METHOD TO SYNTHESIZE ZEOLITES FROM MUNICIPAL SOLID WASTE COMBUSTION ASH
David M. Kargbo
Civil and Environmental Engineering Department
1947 N. 12th Street, Philadelpha, PA 19122 USA
Phone: 215-204-8441 Fax: 215-204-4696 Email: email@example.com
The majority of research on the beneficial use of MSWC ash has been focused on agricultural uses and the generation of cement or pavement. Our aim was to find ways to broaden the use of MSWC ash, such as the generation of zeolites that may be used as ion exchangers in remediating contaminated soils, water and wastewater, and sequestering gasses such as SO2 and CO2. To our knowledge, generation of zeolites from MSCW ash has never been investigated. The main components of the MSCW ash used in our study are SiO2 and Al2O3, the same components that are the fundamental building blocks of zeolites. We developed a “Reflux” method of synthesizing zeolites from MSCW ash. The method appeared to perform quite well in optimizing the hydrothermal conditions for generating zeolites. Zeolite structures revealed by SEM images were verified by XRD patterns. The most common zeolites formed were zeolite Na-P1, zeolite Y, faujasites, and sodalite octahydrate.
Keywords: Zeolites, reflux method, municipal solid waste combustion (MSWC) ash, waste-to-energy (WTE) facilities, sequestration, SEM images, sodalite octahydrate
AN ESTIMATING SYSTEM FOR CONSTRUCTION AND DEMOLITION WASTE MANAGEMENT
Department of Civil and Environmental Engineering
360 Huntington Avenue
Boston, MA 02115, USA
This paper describes a computerized estimating system that can be used to quantify the generation of wood, gypsum drywall, roof asphalt shingles, and carpet wastes from building-related new construction and demolition projects. The approach for developing the estimating system is flexible and can include specific waste materials targeted for recycling. The system application requires appropriate housing statistic data which are typically readily available. An interface is created between a GIS system and the estimating tool that allows a recycling program developer to visualize the spatial distribution of construction and demolition waste within the region of interest. In addition, a methodology for estimating the waste generated from renovation/remodeling activities is presented. A case study in which the estimating system was applied to estimate the generation of construction and demolition wastes in Massachusetts is also presented.
Keywords: Construction and demolition waste, waste generation, estimating system, recycling, GIS interface
AN ASSESSMENT FOR ENERGY POTENTIAL OF SOLID WASTE FROM SHIP SCRAPING YARD AT ALANG-SOSIYA, INDIA
M. Srinivasa Reddy, H.V. Joshi, Shaik Basha and V.G. Sravan Kumar
Marine Algae & Marine Environment Divison
Central Salt and Marine Chemicals Research Institute
G.B. Marg, Bhavnagar – 364002 INDIA
Alang-Sosiya (Lat 21�5′; 21� 29′ N, Long 72�5′; 72�15’E) is the largest ship-scraping yard in the world, established in 1982. This yard has gained world prominence on account of certain topographical advantages like, high tidal range (~ 13m), gentle sloping and firm bottom etc. Every year an average of 365 ships having a mean weight of 2.10×106 � 7.82 x105 LDT (light dead weight tonnage) are scrapped. This yard generates a huge amount of combustible solid waste in the form of scrapped wood, plastic, insulation material, paper, hard wood, glass wool, thermocol pieces, sponge, oiled rope, cotton waste, rubber, etc. Hence the present study has been designed to assess the energy potential of the solid waste generated from the ship-scraping yard. Thirty different types of solid waste materials have been collected for a period of six months (May to October, 2002) covering an area of 2.52 sq. km. Their proximate and ultimate analyses were carried out by standard ASTM & IS methods and the energy content was calculated by DuLong’s equation. The average energy content calculated as collected, dry, moisture and ash free basis were 23781.03 KJ/kg, 25645.9 KJ/kg, and 28475.98 KJ/kg respectively. The average gross heating value (HHV) was 24160.34 KJ/kg. The results of this study revealed that the solid waste of the ship-scraping yard could yield energy of 90 million KJ/hr, in the form of steam energy 63 million KJ/hr and electric power 5.28 MW. The estimation of energy potential has been calculated considering the probable losses in the process of energy generation.
Keywords: Alang-Sosiya, Ship scrapping, proximate and ultimate analysis, DuLong’s equation, waste to energy and energy potential
THE CHARACTERIZATION OF SUGAR INDUSTRY SOLID WASTE AS POZZOLANIC MATERIALS: A STUDY AND MODELING OF THE REACTION KINETICS
Ernesto Villar-Coci�a*, Eduardo-Valencia Morales, Jes�s Hern�ndez-Ru�z, Jorge Vega-Leyva
Department of Physics, Central University of Las Villas
Santa Clara 54830, Villa Clara, Cuba
This paper discusses the characterization of sugar industry solid waste as pozzolanic materials. Research on the reaction kinetics between calcium hydroxide (CH) and sugar cane straw ash and bagasse ash with 20% and 30% clay, calcined at 800�C and 1000�C, is described. A simple experimental technique was utilized based on the electrical conductivity measurement of a CH/waste suspension correlated with concentration.
A mathematical model, which was elaborated by the authors in previous work, was utilized to describe the reaction kinetic process. The kinetic parameters (diffusion coefficient and reaction rate constant) of the model were determined with relative accuracy in the fitting process of the model. This procedure allowed an economical and rigorous evaluation of the pozzolanic activity of sugar can straw ash and bagasse ash and ensures their efficient use in the cement industry and in the production of low cost binders.
Keywords: Solid waste, pozzolan, kinetics, pozzolanic reaction, conductivity
EVALUATION OF THE EFFECT OF COARSE AND FINE RUBBER PARTICLES ON LABORATORY RUTTING PERFORMANCE OF ASPHALT CONCRETE MIXTURES
*Dr. Yusuf Mehta, P.E., Assistant Professor (correspondence author)
Dr. Kauser Jahan, Associate Professor, P.E.
Jim Laicovsky, Laura Miller, Devi Parikh, Alicia Licon Lozano (Students)
Department of Civil and Environmental Engineering
Glassboro, NJ 08028
Phone: (856) 256-5327, Fax: (856) 256-5242
The nation faces ecological problems due to the accumulation of waste automobile and truck tires. In this study, the effect coarse ground tire rubber (GTR) and crumb rubber on rutting performance of Superpave asphalt concrete mixtures as measured in the laboratory were evaluated. A percentage of the locally available coarse rubber, uniformly graded is used as a substitution for aggregate particles, at nine levels of rubber percentages, 0% to 4.0% at 0.5% increments, while maintaining the well-graded Superpave gradation. In addition to coarse rubber, fine crumb rubber particles (minus No 80 and No. 20 mesh) in proportions of 5% and 15% were evaluated using the compaction characteristics of the Superpave Gyratory Compactor to determine the optimum percentage of coarse and fine rubber particles that can be used in the asphalt concrete mixture. The coarse rubber particles exhibit increased rutting resistance as percentage of rubber increased up to 3.5%. On the other hand, crumb rubber dissolved in the binder and stiffened to increase its rutting resistance. Even though only up to 2.5% coarse rubber particles could be used as compared to 15% of crumb rubber, the processing cost of coarse rubber is much less than crumb rubber to make it cost effective.
Issue 1, February 2004
CHEMICAL PROPERTIES OF ALKALI ASH MATERALS
Philadelphia, PA USA
Annually, the United states produces some 90 million tons of ash, of which 55 million tons is fly ash. Only 27% of this large quantity of fly ash gets reused or recycled. The remaining 73% are dumped into landfills. Alkali Ash Material (AAM) is a novel construction material that converts fly ash into a variety of construction materials. The hardened AAM material gains up to 11,000 psi compressive strength and flexural strength (up to 1,200 psi) in two days that highly engineered ultra high strength concrete takes in months to gain. AAM also resist the corrosive impact of sulfuric acid far better than ordinary Portland cement concrete. Exposing ordinary cement concrete to a pH less than 3 causes severe damage in a short time, while AAM can resist pH as low as 0.5 for extended periods of time. AAM can be used for many municipal and industrial applications such as pipes, sumps, tanks, etc. AAM not only can solve problems that arise when infrastructure is subjected to aggressive conditions, but also helps the environment by recycling a large quantity of fly ash that otherwise would have been land filled.
LIFE CYCLE ASSESSMENT FOR MUNICIPAL SOLID WASTE MANAGEMENT IMPROVEMENTS—THE CASE OF A 100.000 INHABITANT ITALIAN TOWN
Francesco Di Maria* and Stefano Saetta
Dipartimento di Ingegneria Industriale
Via G. Duranti 1A/4, 06125 Perugia ITALY
Phone: +39 075 585 3738* – 3734 – Fax: +39 075 585 3736
Email: firstname.lastname@example.org* – email@example.com
The evaluation of environmental performances of solid urban waste management systems is a very important issue to achieve a sustainable development.
Recycling and reusing a large fraction of waste products yields environmental benefits that can be widely enhanced by adopting energy recovery systems for the remaining waste fraction.
Recovering energy from solid urban waste means reducing both fossil fuels consumption and landfill needs. Furthermore, exhaust gases from combustion process can be efficiently cleaned by adopting a modern scrubbing system. Instead, large fraction of the solid exhaust part of the combustion process can be considered quite inert.
This implies that the energy recovery process, when possible, is one of the best ways to reduce the environmental impact of waste disposal.
In this work, a real case, relative to an Italian city of 100.000 inhabitants, has been examined. Improvements, consisting of electrical power production from the wastes organic fraction anaerobic treatment, to the actual situations have been suggested.
An LCA analysis has been performed to evaluate the environmental impact of the actual situation and of the improved one.
Environmental benefits, strictly linked to the energy production increase, have been pointed out.
Keywords: LCA analysis; Eco-Indicator99; MSW management; waste to energy; gas turbine; anaerobic treatment
PROVISION OF FEEDBACK TO PROMOTE HOUSEHOLDERS’ USE OF A KERBSIDE RECYCLING SCHEME—A SOCIAL DILEMMA PERSPECTIVE
Joanne K. Lyas
Centre for Environmental Sciences, University of Southampton
Highfield, Southampton, SO17 1BJ
Peter J. Shaw
Centre for Environmental Sciences, University of Southampton
Highfield, Southampton, SO17 1BJ
Department of Psychology, University of Southampton
Highfield, Southampton, SO17 1BJ
As English local authorities develop strategies to deal with the growing volumes of municipal waste created in their districts, householder participation in recycling initiatives is becoming increasingly important. Taking a social dilemma perspective, this paper adopts an individual (psychological) strategy as a means of enhancing kerbside recycling use in the London Borough of Havering. Three groups of householders received motivational messages on recycling performance with a different bias: critical, neutral or encouraging, whilst a further group acted as a control. Although differences in recycling behaviour prior to and following intervention were not statistically significant for any treatment group, average use of the scheme was found to decrease post-leaflet in all cases, but less so for those in the ‘encouraging’ message group. Responses to a questionnaire survey indicated that householder attitudes did not vary significantly between treatment groups. The study shows that an individual (psychological) approach alone is not sufficient to enhance householder recycling behaviour in Havering over the short term. Future promotional strategies are suggested that combine both the individual and the collective approach to motivate and encourage recycling participation.
Keywords: Municipal waste; kerbside recycling; social dilemma; recycling behaviour; feedback
REEXAMINING THE DECOMPOSITION AND CROSSOVER EFFECTS IN EXPANDED THEORY OF PLANNED BEHAVIOR MODELS—A STUDY OF HOUSEHOLD WASTE RECYCLING BEHAVIOR
Pin-Yu Chu, Chi-Cheng Huang
Institute of Public Affairs Management
National Sun Yat-sen University
70 Lai-Hwai Rd., Kaohsiung, Taiwan
Expanding Ajzen’s (1988, 1991) theory of planned behavior (TPB), this study examines household waste recycling behavior among local citizens in Taiwan. Two basic TPB models and three expanded TPB models are examined. The explanatory power of each model is assessed using data from a sample of 386 community residents and is analyzed using structural equation modeling. The results indicate that dividing beliefs into multi-dimensional components and allowing for crossover effects, an expanded TPB model, which includes two other variables related to household waste recycling, namely, perceived moral obligation and competing behavioral intention, improves model prediction in household waste recycling behavior. Policy implications of the model are further discussed.
Keywords: Planned behavior modeling, recycling, reasoned action, belief structures, crossover effects, choice mechanism, perceived moral obligations.
REUSE OF FOUNDRY SANDS FOR CORE AND GLASS PRODUCTION
M.C. Zanetti, S. Fiore*, C. Clerici
Department of Georesources and Territory
Polytechnic of Turin ITALY
The reuse of reclaimed green moulding sands is considered in this work for both cold-box core production in a cast iron foundry and the production of colorless glass. The regeneration process was performed in a wet mechanical treatment plant, belonging to the Gruppo Minerali S.p.A. (Novara, Northern Italy), on spent green moulding sands obtained from the Teksid S.p.A. cast iron foundry in Crescentino (Vercelli, Northern Italy).
The recovered foundry sands were characterized through physical, chemical and mineralogical analyses, to compare the values with the parameters required for core production: the cold-box process was simulated on a laboratory scale. Several melting tests were performed using different raw material mixtures to obtain colorless glass.
The recycling of the reclaimed foundry sands allows several goals to be achieved: the reduction of landfilled industrial wastes and a saving of the raw materials, the production of good quality products and an economic advantage. The silica sand that is employed in foundry operations and in the glass industry in Italy costs around 0.05 Euro/kg, the landfilling cost of the spent foundry sands is about 0.10 Euro/kg, and the total cost of the wet mechanical regeneration treatment is about 0.03-0.04 Euro/kg. Thus, hypothesizing that the moulding sand producer (Teksid S.p.A.) would adopt the regeneration process, the potential saving could be about 0.11-0.12 Euro/kg of reclaimed foundry sand.
Keywords: Foundry wastes, reclamation, green moulding sand, cores, cold-box process, colorless glass
* Correspondence author: Dott. ssa Silvia Fiore, Dipartimento di Georisorse e Territorio, Politecnico di Torino, C.so Duca degli Abruzzi, 24, 10129 Torino, Italy – tel. +390115647632, fax +390115647699, E-mail: firstname.lastname@example.org
MATERIAL CAPTURE FROM A KERBSIDE RECYCLING SCHEME AND THE EFFECTS OF SOCIO ECONOMIC CONDITIONS ON HOUSEHOLD WASTE ARISINGS
A.D. Emery, BEng MCIWM
A.J. Griffiths, BEng Ph.D. CEng FIMechE MIEE SWIE
K.P. Williams, BSc Ph.D. CEng MIChemE
T.C. Woollam, BSc LLM
Cardiff School of Engineering
Cardiff University, Queen’s Buildings
P.O. Box 925, Cardiff, CF24 0YF, Wales
Waste is never consistent. Different areas use different materials, which give rise to waste streams that can vary widely in composition. With the increasing pressure on landfill operators and local governments over the amount and type of waste going to landfill, moves have to be taken to reduce, divert and recover materials. To do this effectively it is necessary to identify the composition of the waste stream.
This paper contains the results of two separate household waste analyses conducted in a typical unitary authority of South Wales, a traditional industrial community. A full household waste analysis was conducted to determine whether there was a connection between an areas socio-economic standing and the quantities of waste produced. A selection of three different household categories were chosen, as described by the UK’s ACORN geodemographical system. The three areas chosen were, terraced, council and semi detached properties and were selected, as they were the most dominant and easily recognised types of dwellings found in the study area. The results of the full waste analysis have been compared against a number of previous household waste characterisation studies. A recyclable waste analysis was also conducted to determine the quantities and quality of recyclable materials put out for collection by residents taking part in a kerbside collection scheme. Different methods of storing the recyclable materials at the household were also monitored.
It was found that areas of greater economic wealth purchase larger quantities of foodstuffs and hence disposes of larger quantities of waste. It was also found that the type of receptacle used to store recyclables can influence the actual quantities put out for collection. A clear bag was found to be the most effective method of storing recyclables.
Keywords: Recycling, household waste composition, socio economic, classification