Waste Management & Research recent issues

Editorial

Vallini, G. — Wed, 23 Sep 2009 03:12:06 PDT

Drivers of sustainable waste management in Asia

Agamuthu, P., Khidzir, K.M., Hamid, F. S. — Wed, 23 Sep 2009 03:12:06 PDT

Drivers of sustainable waste management are defined as groups of related factors that influence the development (or lack thereof) of industry. There has been no attempt to reasonably list the drivers that influence sustainable waste management in Asia. In this review, four groups of drivers of sustainable waste management, specifically of Asia, are explained. The four groups of drivers consist of three human elements (human, economic and institutional) and the environment as a single driving group. Typically, the first three groups have been very influential, with the environment driver, noticeably, only considered when preceded by other groups of drivers. The interconnectedness of the drivers and neglect of the environment driver is discussed. It is concluded that while the essence of the four groups of drivers can be found all over Asia, each driving group must be investigated in a local context and all information combined to devise sustainable waste management policies or strategies.

Technology selection for MSW treatment in Altiplano areas using FMDM

Jiang, J., Lou, Z., Hg, S., Duo, J., Li, Z. — Wed, 23 Sep 2009 03:12:06 PDT

There are special requirements for municipal solid waste (MSW) treatment caused by lower oxygen content and atmospheric pressure on the Altiplano. The intention of this paper was to analyse the applicability of various technologies to MSW treatment in the Altiplano and select the best one based on the current MSW collection modes and technical levels, using the Fuzzy Mathematical Decision Method (FMDM). Technologies including landfill, incineration, composting, and anaerobic digestion (AD) were compared. The results of the studies showed that AD technology is a new technology which is attractive in economic terms and helpful for environmental harmony. AD can solve the difficulties caused by a high content of organic matter in the MSW, lower atmospheric pressure and oxygen content on the Altiplano. Moreover, it can achieve reduction and recycling of the waste, thereby saving space for treatment and disposal. Using this technology, renewable energy can be recovered to save conventional fuel consumption and the emission of greenhouse gases can be reduced to improve the conservation of the local ecosystem. Putting AD into practice in the Altiplano may be the preferred method of MSW treatment.

Developing a fuzzy decision support system to determine the location of a landfill site

Alves, M. C. M., Lima, B. S. L. P., Evsukoff, A. G., Vieira, I. N. — Wed, 23 Sep 2009 03:12:06 PDT

This paper presents two case studies of municipal solid waste site location using a decision-support system based on fuzzy logic. This problem is very complex, as it requires the evaluation of different criteria, which involve environmental, social and economic data. Such data deal with a wide range of information that presents not only quantitative, but also qualitative knowledge. In order to deal with this characteristic, the developed system employs fuzzy rules due to its ability to treat linguistic variables and the human way of thinking. Conventional approaches tend to be less effective in dealing with the imprecise or vague nature of the linguistic assessment. A case study for selecting the location of a new municipal solid waste landfill for the city of Petropolis in Rio de Janeiro is presented. Testing of the proposed method was carried out using data from the municipal solid waste location for another municipality in Rio de Janeiro, Brazil.

Diesel consumption in waste collection and transport and its environmental significance

Larsen, A. W., Vrgoc, M., Christensen, T. H., Lieberknecht, P. — Wed, 23 Sep 2009 03:12:06 PDT

Use of diesel in collection trucks is presumably the most important environmental burden from waste collection because of the emission of exhaust gases from the combustion process. The environmental impact depends not only on the amount of diesel used, but also the on the cleanness of the exhaust gas that is regulated by emission standards. We measured the diesel consumption for 14 different collection schemes in two municipalities in Denmark, yielding a total of 254 measurements. Collection was defined as driving and loading of waste from the first to the final stop on the collection route. All other distances covered were defined as transport of waste, which was modelled in generic transport simulation models. The diesel consumption per tonne of waste in the specified collection schemes turned out to be related to the type of housing and to the amount of waste collected per stop. The observations showed a considerable variation between different collection schemes, ranging from 1.4— 10.1 L diesel tonne^{— 1} of waste. Assessment of the potential environmental impact by a life-cycle-assessment method showed a substantial decrease over the last decade because of implementation of European emissions standard for diesel trucks. The paper also discusses the importance of energy used for collection and transport in relation to the potential energy savings from waste treatment. In many cases, the net savings exceed significantly the use of diesel.

Behaviour of heavy metals immobilized by co-melting treatment of sewage sludge ash and municipal solid waste incinerator fly ash

Lin, K.-L., Huang, W.-J., Chen, K.-C., Chow, J.-D., Chen, H.-J. — Wed, 23 Sep 2009 03:12:06 PDT

This study elucidates the behaviour of heavy metals in slag produced from four different sewage sludge ashes mixed with municipal solid waste incinerator fly ash and then co-melted. Experimental results indicate that sewage sludge ashes consisted of SiO₂, CaO, and Al₂O₃. Fly ash consisted of CaO, Na₂O and SO₃. The speciation of sewage sludge ashes indicates that the ashes contained quartz and AlPO₄. The speciation in fly ash consisted of anhydrite, microcline, calcium chloride, sylvite and halite. The leaching behaviours of sewage sludge ashes met the Taiwan Environmental Protection Administration’s regulatory standards. The fly ash had high concentrations of Zn and Pb; however, the leaching of these metals was low. The major components of synthetic slags were SiO₂ (33.5—54.0%), CaO (21.4—36.7%), and Al₂O₃ (8.1—15.7%). The X-ray diffraction patterns of co-melted slags demonstrate that the slags contained significant amounts of glass. Most heavy metals can be fixed in a net-like structure; thus, they can not be extracted easily. The toxicity characteristic leaching procedure (TCLP) leaching concentrations for target metals in all slags met the Taiwan Environmental Protection Administration’s regulatory standards.

Soil aluminium uptake and accumulation by Paspalum notatum

Huang, J., Xia, H., Li, Z., Xiong, Y., Kong, G., Huang, J. — Wed, 23 Sep 2009 03:12:06 PDT

Paspalum notatum Flugge has been widely utilized for the purpose of ecological restoration of degraded land in the tropics and subtropics, where soil active aluminium (Al) is usually high as a result of acidification. Pot experiments were conducted to determine Al toxicity on P. notatum and to compare its potential to remove Al with another three plant species, Vetiveria zizanioides, Tristania conferta and Schima wallichii. In the Al addition experiment, the biomass of P. notatum and Al accumulation significantly decreased as the added Al concentration increased, but Al concentration in the plant markedly increased. A parallel experiment was conducted with the above four species, grown in lateritic soil and in oil shale waste containing high concentration of active Al. The biomasses of all four species were reduced obviously in the waste compared to in the soil. The effects of substrate on Al concentration, accumulation and translocation efficiency differed among species, and plants had significantly higher Al accumulation factors when grown in the soil than in the waste. Most of the Al taken up by P. notatum was transferred to above-ground parts; as a result, Al concentration in stems and leaves became quite high, over 1000 or even 3000 mg kg^—1; whereas for the other three species, Al concentration in shoots was much lower than in roots. Paspalum notatum was therefore much higher than the other three species with regard to Al translocation efficiency and therefore P. notatum may be regarded as both an effective Al hyper-accumulator and a potential Al hyper-remover.

Unlocking the resource potential of organic waste: a South African perspective

Greben, H. A., Oelofse, S. H. H. — Wed, 23 Sep 2009 03:12:06 PDT

In many countries, especially on the Asian continent, waste is considered a valuable renewable energy resource. At present 40% of waste generated in South Africa comprises organic material which, when digested supplies biogas. The biogas produced can either be used as it is, or it can be delivered as electricity using gas turbines. The electricity generated can be added to the national grid. In light of the increased demand for energy in South Africa, alternative sources of energy are required. When taking the examples of the Asian countries, where anaerobic digestion of waste is applied in rural areas to produce energy for cooking and lighting, it can be hypothesized that this technology could be transferred especially to the rural areas of South Africa. Small-scale anaerobic digestion is presently being implemented by a private company in Ivory Park, South Africa, illustrating that anaerobic digestion in South Africa may be a means of unlocking the energy potential of organic waste. This paper evaluates the requirements for an enabling governance environment to unlock the full potential of organic waste as renewable energy resource.

Report: Factors affecting the content of potentially toxic elements in the biodegradable fraction of autoclaved household waste

Papadimitriou, E. K., Barton, J. R. — Wed, 23 Sep 2009 03:12:06 PDT

A total of 3.4 tonnes of household waste (HW) that had a controlled composition were autoclaved in the presence of saturated steam for 1 h at the nominal temperature levels of 130, 160 and 200°C. The levels of Cd, Cr, Cu, Pb, Hg, Ni, and Zn were examined in samples of the fibrous, predominantly-biodegradable fraction (floc) derived from the autoclaved HW, aqueous extracts from floc, and the condensate from steam that was released from the reactor. This data was used to study the impact of the overall levels of potential toxic elements (PTEs) in HW feed and autoclaving process parameters on the levels of PTEs in floc. No consistent correlation was found to exist between the levels of PTEs in HW feed and those in the produced floc. This was primarily attributed in the inherent variability of PTEs in waste materials. Autoclaving temperature, pressure and mixing were all found to affect the mobilization and removal of PTEs from HW and their presence in floc. Temperature/pressure appeared to increase PTE removal through the condensate path, although that removal had only a negligible impact on the contents of PTEs in floc. Autoclaving temperature correlated positively, although not significantly at a 95% confidence level, with the levels of Pb and Zn in floc. On the other hand, it correlated negatively with the Hg content in floc. Increasing temperature/pressure also increased the water extraction of PTEs from floc, with the exception of Cr. However, in the context of producing high quality compost, the extraction rates were too low to bring about a substantial decrease of PTEs in floc.

Editorial

Agamuthu, P. — Fri, 07 Aug 2009 06:26:20 PDT

Production, characterization and properties of chloridized mesoporous activated carbon from waste tyres

Fri, 07 Aug 2009 06:26:20 PDT

In this study, chloridized mesoporous activated carbons (ClMAC) were prepared from used tyres. Their pore structure, surface chemistry and adsorptive capacities of toluene were investigated with nitrogen gas adsorption, Fourier transform infrared spectroscopy (FT-IR) and bench adsorptive experiments. A series of activated carbons were produced by pyrolysis, activation and chlorination under different temperatures. The activated carbons derived from scrap tyres had highly mesoporous volumes and surface areas, for example, the ClMAC prepared under 300 °C was 0.81 cm³ g^—1, and 1078.2 m² g^—1, respectively. (Commercial activated carbon—F-400 was 0.16 cm³ g^—1, and 1021.1 m² g^—1). The adsorptive capacities of toluene in the activated carbon-derived waste tyres were compared with the F-400 and the experimental results showed chlorinated activated carbons had exceptional characteristics for toluene adsorption in an aqueous solution; especially, the ClMAC produced in 300 °C had a 471.8 mg g^—1 maximum capacity; however, F-400 had a 255.4 mg g^{— 1} minimum capacity. In short, by using chloridized mesoporous activated carbons the authors significantly improved the toluene removal capacity in aqueous solution.

Chemical methods in the development of eco-efficient wood-based pellet production and technology

Kuokkanen, M., Kuokkanen, T., Stoor, T., Niinimaki, J., Pohjonen, V. — Fri, 07 Aug 2009 06:26:20 PDT

Up to 20 million tons of waste wood biomass per year is left unused in Finland, mainly in the forests during forestry operations, because supply and demand does not meet. As a consequence of high heat energy prices, the looming threat of climate change, the greenhouse effect, and due to global as well as national demands to considerably increase the proportion of renewable energy, there is currently tremendous enthusiasm in Finland to substantially increase pellet production. As part of this European objective to increase the eco- and cost-efficient utilization of bio-energy from the European forest belt, the aim of our research group is — by means of multidisciplinary research, especially through chemical methods — to promote the development of Nordic wood-based pellet production in both the qualitative and the quantitative sense. Wood-based pellets are classified as an emission-neutral fuel, which means that they are free from emission trading in the European Union. The main fields of pellet research and the chemical toolbox that has been developed for these studies, which includes a new specific staining and optical microscope method designed to determine the cross-linking of pellets in the presence of various binding compounds, are described in this paper. As model examples illustrating the benefits of this toolbox, experimental data is presented concerning Finnish wood pellets and corresponding wood-based pellets that include the use of starch-containing waste potato peel residue and commercial lignosulfonate as binding materials. The initial results concerning the use of the developed and optimized specific staining and microscopic method using starch-containing potato peel residue as binding material are presented.

Reuse of waste glass in building brick production

Demir, I. — Fri, 07 Aug 2009 06:26:20 PDT

The main objective of this study was to investigate the effect of waste glass addition on the properties of fired clay brick. Milled waste glass was added into brick clay at a ratio of 0% (control sample), 2.5, 5 and 10%. Four different series of test samples were produced by extrusion pressing. Samples were fired at 850, 950 and 1050 °C. The microstructures of the fired samples were investigated by scanning electron microscopy. The compressive strength of the fired samples was significantly improved by the addition of waste glass. It was concluded that the amorphous nature of waste glass particles enhanced the sintering action and this led to better strength behaviour.

Compressibility and shear strength of municipal solid waste under short-term leachate recirculation operations

Fri, 07 Aug 2009 06:26:20 PDT

This paper describes a comprehensive laboratory study performed to investigate the compressibility and shear strength properties of 1.5-year-old municipal solid waste (MSW) exhumed from a landfill cell where low amounts of leachate were recirculated. The study results are compared with results from a previous study on fresh MSW collected from the same landfill and data from previous studies with known MSW age to assess the variation in properties due to degradation. Laboratory testing was conducted on shredded landfilled and fresh MSW that consisted of similar particle-size distribution, with maximum particle size less than 40 mm and approximately 80% of the waste consisting of particles ranging from 10 to 20 mm. Standard Proctor, compressibility, direct shear, and triaxial consolidated undrained (CU) shear tests were conducted in general accordance with the American Society of Testing and Materials Standard Procedures. These tests were conducted with samples at an in-situ moisture content of 44% (dry weight basis) as well as elevated moisture contents of 60, 80 and 100% (dry weight basis). Standard Proctor compaction tests yielded a maximum dry density of 600 kg/m³ at 77% optimum moisture content for landfilled MSW compared to the 420 kg/m³ maximum dry density at 70% optimum moisture content for fresh MSW. Compression ratio values for landfilled MSW varied in a close range of 0.19—0.24 with a slight increasing trend with increase in moisture content; however, for fresh waste they were in the close range of 0.24—0.33 with no definitive correlation with moisture content. Based on direct shear tests, drained cohesion and friction angle were varied in the range of 12—64 kPa and 31—35° for landfilled MSW and 31—64 kPa and 26—30° for fresh MSW. Neither cohesion nor friction angle demonstrated any correlation with the moisture content. Based on triaxial CU tests, the average total strength parameters (TSP) were found to be 39 kPa and 12° for landfilled MSW and 32 kPa and 12° for fresh MSW, while effective strength parameters (ESP) were 34 kPa and 23° for landfilled MSW and 32 kPa and 16° for fresh MSW. This study was limited to small-scale laboratory testing using MSW samples with the specimen size relative to the maximum particle size in the range of 1.6 to 2.6; therefore, large-scale laboratory and field studies are recommended to systematically assess the influence of composition, particle size distribution and specimen size on the geotechnical properties of MSW.

Use of disposed waste ash from landfills to replace Portland cement

Rukzon, S., Chindaprasirt, P. — Fri, 07 Aug 2009 06:26:20 PDT

In this study, waste ash was utilized as a pozzolanic material in blended Portland cement in order to reduce negative environmental effects and landfill volume required to dispose of waste ash. The influence of waste ash, namely palm oil fuel ash, rice husk ash and fly ash on compressive strength and sulfate resistance in mortar were studied and evaluated by some accelerated short–term techniques in sodium sulfate solutions. Ordinary Portland cement (OPC) was partially replaced with ground palm oil fuel ash (POA), ground rice husk ash (RHA) and classified fly ash (FA). Single pozzolan and a blend of equal weight portions of POA, RHA and FA were also used. The resistance to sulfate attack of mortar improves substantially with partial replacement of OPC with POA, RHA and FA. The use of a blend of equal weight portions of FA and POA or RHA produced mixes with good strength and resistance to sulfate attack. POA, RHA and FA have a high potential to be used as a pozzolanic material.

Electrical resistivity and induced polarization tomography in identifying the plume of chlorinated hydrocarbons in sedimentary formation: a case study in Rho (Milan -- Italy)

Cardarelli, E., Di Filippo, G. — Fri, 07 Aug 2009 06:26:20 PDT

Resistivity and induced polarization surveying were originally developed for mineral exploration but are now finding new applications in the field of environmental and engineering geophysics. The present article reports the results of a geophysical survey performed with the aim of identifying a plume of chlorinated hydrocarbons in sedimentary formations of the Pandania plain. The tested site is characterized by three sand and gravel aquifers containing a quantity of clay particles which influence the overall bulk resistivity and chargeability. According to data obtained using shallow boreholes, mainly dense non-aqueous phase liquids were found as contaminants in the first and second aquifer. The aforementioned geo-electrical methods were applied in both two- and three-dimensional approaches. Steel and copper electrodes were used in the process of field data acquisition and the results of the survey were compared. The geophysical survey revealed some anomalies that could be explained by the presence of dense non-aqueous phase liquids in the soil medium. The concept of normalized chargeability facilitates the interpretation of detected induced polarization anomalies. The shape of the plume was inferred from maps of resistivity and chargeability to a depth of 25 m below the surface of the ground.

Conversion of organic material by black soldier fly larvae: establishing optimal feeding rates

Diener, S., Zurbrugg, C., Tockner, K. — Fri, 07 Aug 2009 06:26:20 PDT

Larvae of the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), are voracious feeders of organic material and may thus be used in simple engineered systems to reduce organic waste in low- and middle-income countries. Controlled feeding experiments with standard fodder were conducted to assess the optimum amount of organic waste to be added to a CORS system (Conversion of Organic Refuse by Saprophages). A daily feeding rate of 100 mg chicken feed (60% moisture content) per larva resulted in an optimum trade-off between material reduction efficiency (41.8%, SE 0.61) and biomass production (prepupal dry weight: 48.0 mg, SE 2.0). Applied to market waste and human faeces, this corresponds to a potential daily feeding capacity of 3—5 kg/m² and 6.5 kg/m², respectively. In addition, H. illucens prepupae quality was assessed to determine their suitability to substitute fishmeal in animal feed production. The chitin-corrected crude protein content ranged from 28.2 to 42.5%, depending on the amount of food provided to the larvae. Based on our study, a waste processing unit could yield a daily prepupal biomass of 145 g (dry mass) per m². We conclude that larvae of the black soldier fly are potentially capable of converting large amounts of organic waste into protein-rich biomass to substitute fishmeal, thereby contributing to sustainable aquaculture.

Report: Potential environmental impact of exempt site materials -- a case study of bituminous road planings and waste soils

Bark, M., Bland, M., Grimes, S. — Fri, 07 Aug 2009 06:26:20 PDT

The use of waste materials for ecological benefit, agricultural improvement or as part of construction works are often exempt from waste management control in order to maximize the reuse of material that would otherwise be disposed of to landfill. It is important, however, to determine whether there is potential for such waste to cause environmental harm in the context of the basis for granting exemptions under the relevant framework objective to ensure that waste is recovered or disposed of without risk to water, air, soil, plants or animals. The potential for environmental harm was investigated by leaching studies on two wastes commonly found at exempt sites: bituminous road planings and waste soils. For bituminous road planings, the organic components of the waste were identified by their solubility in organic solvents but these components would have low environmental impact in terms of bioavailability. Leaching studies of the heavy metals copper, lead and zinc, into the environment, under specific conditions and particularly those modelling acid rain and landfill leachate conditions showed that, except for copper, the amounts leached fell within Waste Acceptance Criteria compliance limits for defining waste as inert waste. The fact that the amount of copper leached was greater than the Waste Acceptance Criteria level suggests that either additional testing of wastes regarded as exempt should be carried out to ensure that they are in analytical compliance or that legislation should allow for the potential benefits of reuse to supersede deviations from analytical compliance.

Report: Atmospheric pollutants discharged from municipal solid waste incineration and gasification-melting facilities in Japan

Inoue, K., Yasuda, K., Kawamoto, K. — Fri, 07 Aug 2009 06:26:20 PDT

This article reports on the discharge of particulate matter, acid gases, nitrogen oxides, and dioxins from 107 municipal solid waste incineration and gasification-melting facilities in Japan between the years 2001 and 2003; the pollution control methods and the operational data are summarized. The knowledge on amounts of slaked lime used and the emission of acid gases is reported, the emission concentrations did not exceed the limit values in all facilities. In Japan, the regulation of dioxin emissions by the revised Waste Management and Public Cleansing Law (Ministry of the Environment, Government of Japan 2007) has been enforced since December 1997. Bag filters have been installed in all facilities constructed after this time, and catalytic reactors have been installed in 66% of these facilities. The regulated values for combustion temperature, the cooling temperature of gases discharged from furnaces and the concentration of carbon monoxide in the gases discharged from stacks were satisfactory in almost all facilities. In facilities constructed since December 1997, the dioxin concentrations in the discharged gases were considerably lower than in those constructed before this time. All facilities met the emission limit values for particulate matter, acid gases, nitrogen oxides and dioxins.

Sanitary landfills, foundation of the waste hierarchy inverted pyramid

Navia, R., Ross, D. — Tue, 28 Jul 2009 07:50:55 PDT

Microbial methane oxidation processes and technologies for mitigation of landfill gas emissions

Tue, 28 Jul 2009 07:50:55 PDT

Landfill gas containing methane is produced by anaerobic degradation of organic waste. Methane is a strong greenhouse gas and landfills are one of the major anthropogenic sources of atmospheric methane. Landfill methane may be oxidized by methanotrophic microorganisms in soils or waste materials utilizing oxygen that diffuses into the cover layer from the atmosphere. The methane oxidation process, which is governed by several environmental factors, can be exploited in engineered systems developed for methane emission mitigation. Mathematical models that account for methane oxidation can be used to predict methane emissions from landfills. Additional research and technology development is needed before methane mitigation technologies utilizing microbial methane oxidation processes can become commercially viable and widely deployed.

Influence of biological pre-treatment of municipal solid waste on landfill behaviour in Sri Lanka

Gunawardana, E. G.W., Basnayake, B. F.A., Shimada, S., Iwata, T. — Tue, 28 Jul 2009 07:50:55 PDT

Sri Lanka is an island in the Indian Ocean with an area about 65 610 km². The population of the country is around 20.2 million. Hazardous disposal of municipal solid waste (MSW) is a major concern particularly in the most urbanized areas of Sri Lanka. However, the current waste management system does not facilitate any waste pre-treatment techniques before final disposal. As a consequence, there is immense pressure to improve the waste disposal practices in the country. Under the above circumstance, this study is an attempt to examine the influence of biological pre-treatment of MSW on landfill behaviour in Sri Lanka. Field-scale lysimeters with untreated and biologically pre-treated MSW were used for this study. The data was obtained on leachate quantity, quality, and settlement. The ambient parameters were also measured at the experiment site. According to the results, the effect of rainfall incident on leachate generation was visible but the effect on pre-treated waste was comparatively less than untreated waste. The organic pollutant load in leachate of pre-treated MSW was seven times lower than that of untreated MSW. The settlement of the lysimeter with pre-treated MSW was comparatively less. It can be concluded that the process of biological pre-treatment of MSW by composting is an effective method for Sri Lanka and also it reduces the health and environmental risks by improving the behaviour of landfill.

The consideration of long-term emissions from landfills within life-cycle assessment

Laner, D. — Tue, 28 Jul 2009 07:50:55 PDT

Within a product system of a life-cycle assessment (LCA), solid waste landfills should be treated as processes, because they are considered to be a part of the technical system. Hence, their inputs and outputs should be included in the life-cycle inventory analysis and evaluated within the life-cycle impact assessment. The aim of this paper is to discuss the consideration of emissions from solid waste landfills within the LCA framework and to investigate the uncertainties in existing modelling approaches. Based on this analysis the main limitations are discussed and recommendations for incorporating long-term emissions from landfills in LCA are made. It is emphasized that the lack of consideration of spatial and temporal characteristics of long-term emissions turns out to be an important source of uncertainty when modelling the environmental impact of landfills. For toxicity categories in particular, the life-cycle impact assessment might be the dominant source of uncertainty. However, in order to understand the reliability of LCA results with respect to landfill emissions, quantitative uncertainty should be routinely included in LCA studies and sources of uncertainty need to be thoroughly discussed.

Potential environmental impacts of using refuse derived material for landfill capping

van Praagh, M., Persson, K. M., Karlsson, P. — Tue, 28 Jul 2009 07:50:55 PDT

In this study, the potential impacts on leachate emissions of applying a pretreated refuse-derived material as a capping layer on top of a municipal solid waste landfill were researched. Leachate emissions and stability against degradation were investigated with reference to the untreated material. Results from percolation leaching tests were analysed by multivariate data analysis and chemical speciation modelling. During 6 month aerobic pretreatment in composting windrows with forced aeration, the waste was stabilized against aerobic degradation measured as respiration activity down to 15% of the original value. Initial percolation leachate concentrations were reduced by 40% for As, by 50% for Co, by 60% for Ni, Pb, and total sulfur, by 40% for sulfate-sulfur, by 96% for ammonium nitrate, and by 62% for dissolved organic carbon. An increase was observed by a factor of 4 for Cd, by a factor of 150 for Cu, by a factor of 3 for Zn. Principle Component Analysis revealed that the leaching characteristics of the pretreated material developed towards those of a top soil used as reference material. Increasing the flow rate in column percolation experiments led to lower leachate concentrations at liquid to solid ratios of 10. Constructing a capping layer from the pretreated material is likely to have impacts on the leachate treatment system.

Spatial and multi-criteria decision analysis-based methodology for landfill site selection in growing urban regions

Ersoy, H., Bulut, F. — Tue, 28 Jul 2009 07:50:55 PDT

The construction of landfills is not an alternative option, since a landfill is always a necessary component of the specific waste management system that will be developed. One of the serious and growing potential problems in large urban areas is the shortage of land for waste disposal. In solid waste management programmes, use of geographic information systems (GIS) is a very significant tool because the selection of a suitable site is a very time-consuming process. The analytic hierarchy process in GIS provides objective mathematics to process the subjective preferences of individuals or groups and arrive at a decision. The present paper describes a spatial methodology which comprised several methods, such as multi-criteria analysis, that originate in different scientific fields. The final goal of the methodology was to evaluate the suitability of the studied area (Trabzon, NE Turkey) in order to optimally select a landfill site. Different constraint maps were overlaid with spatial analysis modules to obtain a final suitability map for Trabzon City and five suitable areas were identified. An analytic hierarchy process was applied to select the most suitable solid waste disposal site for municipal waste in the city among these alternative candidate sites. The Düzyurt area was found to be the most suitable solid waste disposal site. However, geotechnical investigations indicated that some remedial measures would be needed before this landfill site could be used.

The impacts of a recycling surcharge to increase landfill tipping fees in Wisconsin

Katers, J. F., Walczak, D., Burch, T. — Tue, 28 Jul 2009 07:50:55 PDT

This paper presents an analysis of using a state-imposed recycling surcharge to increase landfill tipping fees in Wisconsin, thereby impacting the disposal of out-of-state waste. Illinois and Minnesota are by far the two largest contributors of out-of-state waste to Wisconsin landfills. Accordingly, a mathematical model was developed to holistically assess the transport and disposal costs for municipal solid waste between Illinois and Minnesota and Wisconsin. The results of this model were then used to predict the effects of various increases to the existing recycling surcharge on both the volume of waste flowing into Wisconsin and the amount of revenue that could be generated for the state recycling fund. It was concluded that, aside from constitutional issues, an increased recycling surcharge would work reasonably well to divert low percentages of out-of-state waste away from Wisconsin. However, the recycling surcharge is more effective as a revenue-generating tool when the goals of revenue generation and waste diversion are balanced appropriately. Generating revenue for state waste management and recycling programmes may be more valuable than actually diverting large amounts of waste away from Wisconsin.

Hydraulic performance of a full-scale peat and ash biofilter in treatment of industrial landfill leachate

Kangsepp, P., Mathiasson, L., Dahlblom, P., Hogland, W. — Tue, 28 Jul 2009 07:50:55 PDT

The purpose of this study was to evaluate the hydraulic performance of a full-scale on-site vertical-flow biofilter, consisting of a mixture of peat and carbon-containing ash, and a 500 m³ equalization pond prior to the filter-system. The treatment plant was constructed to clean up leachate from an industrial mono-landfill that contained shredder residues of end-of-life vehicles and white goods. With the limited storage capacity of the equalization pond, peak loading rates exceeded up to five to six times the designed daily hydraulic load limit of the biofilter system. Such relatively short overloading events did not negatively affect the purification efficiency. To provide the designed annual irrigation rate on the biofilter of 97 m³ day^{— 1} (or 133 mm day^—1), with large seasonal variations in precipitation, a relatively large pond would be needed. Calculations showed that a storage volume of about 23 000 m³ would be sufficient for annual leachate volumes up to about 35 000 m³. A combination of sprinkler and drip irrigation with straw insulation of the latter made it possible to run the plant continuously even when the ambient air temperature was below zero for more than a month at a time. The grain size distribution of the biofilter medium was noticeably changed after 4 years of usage due to the loading of suspended solids from the leachate and decomposition of the peat, causing reduced hydraulic conductivity.

Effect of oxidized leachate on degradation of lignin by sulfate-reducing bacteria

Kim, J.-H., Kim, M., Bae, W. — Tue, 28 Jul 2009 07:50:55 PDT

Municipal solid waste materials (MSWs) in landfills need a long period of stabilization because lignin compounds in MSWs and leachate are not readily biodegraded, but inhibit methanogenic metabolism. Recirculation of leachate into the landfill offers the potential advantage of increasing the rate of decomposition of organic matter. However, the degradation of lignin by leachate recirculation alone is quite difficult. Several recent studies have demonstrated that sulfate-reducing bacteria (SRB) were able to degrade lignin compounds. In this study, batch tests were conducted to investigate the impacts of SRB enrichment on lignin decomposition rates as well as the decomposition of other biodegradable organics. Further, the effects of nitrite and nitrate on lignin degradation rates were also studied. A 16S rRNA assay showed that the SRB used herein, which were obtained by enriching solid waste collected from a closed MSW landfill, were Thaurea sp. and Desulfovibrio sp. Lignin was found to be biodegraded by the SRB and the rate of lignin removal per unit of waste volatile suspended solid was 2.9 mg lignin g^—1 VSS day^{— 1}. It was found that the initial degradation rate increased under higher initial lignin concentrations. However, the degradation rate during days 6—19 became slower than that during the initial 9 days because lignin consisted of complexly bonded aromatic compounds that were not readily biodegradable. Adding other organics such as lactate seemed to improve the rate and amount of lignin degradation, probably due to the increase in SRB associated with consumption of the additional organics. The lignin removal percentage decreased with increases in oxidized nitrogen (nitrite or nitrate) concentrations, indicating that oxidized nitrogen could inhibit SRB activity. Conclusively, the study verified the existence of SRB in the landfill and showed that the SRB could be activated for the degradation of lignin by the recirculation of the leachate, which is consistent with other studies showing that leachate recirculation could shorten the stabilization period of the landfill.

Tertiary treatment of landfill leachates by adsorption

Tue, 28 Jul 2009 07:50:55 PDT

The leachates produced at the municipal solid waste (MSW) landfill of Asturias (Spain) were submitted to a biological treatment consisting of a pressurized nitrification—denitrification process followed by ultrafiltration. The effluent from this treatment plant has a high chemical oxygen demand : biochemical oxygen demand (COD : BOD₅) ratio (about 25 : 1). The COD values of the effluent are above the discharge limits permitted by current legislation and therefore require a final treatment. In the present study, adsorption was investigated as a possible post-treatment. Three activated carbons (Organosorb 10, Organosorb 10MB and Filtracarb CC65/1240) were selected and equilibrium and column data were obtained. The best results were obtained with Organosorb 10MB, although adsorption capacities obtained were low and equilibrium was unfavourable. Adsorption capacities ranged between 150 and 157 mg COD g^—1 for an activated carbon dosage of 1 mg L^—1 and between 13.3 and 18.4 mg COD g^—1 for a dosage of 20 mg L^—1. As regards colour, adsorption capacities ranged between 145 and 175 UPtCo g^—1 for the lower dosage and between 16 and 29 UPtCo g^—1 for the higher dosage. Removal efficiency increased with the dosage of activated carbon employed, obtaining maximum COD and colour removals of 63 and 45%, respectively, for a dosage of 20 mg L^—1 after 5 h contact time.

Treating landfill leachate by electrocoagulation

Contreras, J., Villarroel, M., Navia, R., Teutli, M. — Tue, 28 Jul 2009 07:50:55 PDT

The determination of the optimal conditions for using electrocoagulation as a treatment for landfill leachate was carried out using surface response methodology. A central composite design was applied to investigate the effect of four control factors, namely current density, pH, time and fluid conductivity, as well as the interaction among (between) them to get an optimal turbidity removal. The independent variables were each coded at three levels and their values were selected on the basis of preliminary experimental results. The central composite design consisted of 29 experimental points with five replications at the centre point. A second order polynomial model was used for predicting the response. Regression analysis showed that more than 95% of the variation was explained by the model wherein current density with a 60.1% contribution turned out to be the factor with the most significant influence. Analysis of variance showed that time, pH, current density and the interaction time/current density had a significant influence on the turbidity removal, The optimal conditions obtained for the removal of turbidity were time 38.8 min, pH 7.6, current density 109.9 A m^—2 and NaCl 2.9 g L^{— 1}. Experimental results showed that for a 96.9% turbidity removal, similar reduction in Al (97.0%) and Fe (99.5%) concentrations; as well as 66% total Kjeldahl nitrogen removal were obtained. Furthermore, the sludge formed exhibited a good floc size, which separated in less than 10 min by classical sedimentation. The results analysis provided evidence of reduction of chemical pollutants, although the electrocoagulated leachate could not satisfy regulations for the maximum Total Kjeldahl nitrogen leachate discharge level to public wastewater collection systems in the town of Freire, Chile.

Environmental assessment of Ammassuo Landfill (Finland) by means of LCA-modelling (EASEWASTE)

Niskanen, A., Manfredi, S., Christensen, T. H., Anderson, R. — Tue, 28 Jul 2009 07:50:55 PDT

The Old Ämmässuo Landfill (Espoo, Finland) covers an area of 52 hectares and contains about 10 million tonnes of waste that was landfilled between 1987 and 2007. The majority of this waste was mixed, of which about 57% originated from households. This paper aims at describing the management of the Old Ämmässuo Landfill throughout its operational lifetime (1987—2007), and at developing an environmental evaluation based on life-cycle assessment (LCA) using the EASEWASTE-model. The assessment criteria evaluate specific categories of impact, including standard impact categories, toxicity-related impact categories and an impact categorized as spoiled groundwater resources (SGR). With respect to standard and toxicity-related impact categories, the LCA results show that substantial impact potentials are estimated for global warming (GW), ozone depletion (OD), human toxicity via soil (HTs) and ecotoxicity in water chronic (ETwc). The largest impact potential was found for SGR and amounted to 57.6 person equivalent (PE) per tonne of landfilled waste. However, the SGR impact may not be viewed as a significant issue in Finland as the drinking water is mostly supplied from surface water bodies. Overall, the results demonstrate that gas management has great importance to the environmental performance of the Old Ämmässuo Landfill. However, several chemicals related to gas composition (especially trace compounds) and specific emissions from on-site operations were not available or were not measured and were therefore taken from the literature. Measurement campaigns and field investigations should be undertaken in order to obtain a more robust and comprehensive dataset that can be used in the LCA-modelling, before major improvements regarding landfill management are finalized.

Editorial

Townend, W. K — Wed, 24 Jun 2009 07:10:35 PDT

Management of healthcare waste in circumstances of limited resources: a case study in the hospitals of Nablus city, Palestine

Al-Khatib, I. A., Al-Qaroot, Y. S., Ali-Shtayeh, M. S. — Wed, 24 Jun 2009 07:10:35 PDT

The objectives of this study were the assessment of healthcare waste management and the characterization of healthcare waste material generated in the hospitals in Nablus city, Palestine, and furthermore, to estimate the prevalence of hepatitis B among the cleaning personnel working in these hospitals. The medical waste generation rate in kg per bed per day was between 0.59 and 0.93 kg bed^{— 1} day^—1. The waste generation rate in the healthcare facilities of Nablus city hospitals was similar to some other developing countries; however, the percentage of medical wastes in the total waste stream was comparatively high. The density of medical waste at the four hospitals studied ranged between 144.9 and 188.4 kg m^{— 3} with a mean value of 166.7 kg m^—3. The waste segregation and handling practices were very poor. Other alternatives for waste treatment rather than incineration such as a locally made autoclave integrated with a shredder should be evaluated and implemented. The system of healthcare waste management in Nablus city is in need of immediate improvement and attention. Formulating rules and guidelines for medical waste and developing strategies for overcoming the obstacles related to waste management should be considered as an urgent matter.

Hospital waste management system -- a case study of a south Indian city

Hanumantha Rao, P. — Wed, 24 Jun 2009 07:10:35 PDT

It is more than 5 years since the prescribed deadline, 30 December 2002, for all categories of towns covered by the Biomedical Waste Management (BMW) Rules 1998 elapsed. Various reports indicate that the implementation of the BMW Rules is not satisfactory even in the large towns and cities in India. Few studies have looked at the `macro system' of the biomedical waste management in India. In this context the present study describes the role of the important stakeholders who comprise the `macrosystem' namely the pollution control board, common waste management facilities, municipal corporation, state government (Directorate of Medical Education and Health Systems Development Project), professional agencies such as the India Medical Association and non-governmental organizations, in the implementation of BMW rules in a capital city of a state in south India. Brief descriptions of the `micro-system' (i.e. biomedical waste management practices within a hospital) of six hospitals of different types in the study city are also presented.

National solid waste management plan for Iraq

Knowles, J. A. — Wed, 24 Jun 2009 07:10:35 PDT

After decades of turmoil and international sanctions much of the key civil infrastructure within Iraq has fallen into disrepair, leading to a considerable decline in the provision of basic and essential municipal services. This is particularly true of waste and resource management services that have seen years of underdevelopment and deterioration. This has resulted in a lack of provision of basic public services in the waste sector which have been replaced by a burgeoning unregulated informal market in waste collection, disposal and recycling. In response, a National Solid Waste Management Plan (NSWMP) for Iraq was developed in 2007, to plan for the strategic development of all aspects of waste management in the country over the coming 20 years. In particular, the NSWMP focuses on policy development and integrated planning regarding regulatory framework, economic aspects, institutional capacity, citizen and technical education, and technical and operational development. This paper summarizes the key objectives, challenges and subsequent recommendations contained in the NSWMP for Iraq.

The challenge of medical waste management: a case study in northwest Iran-Tabriz

Taghipour, H., Mosaferi, M. — Wed, 24 Jun 2009 07:10:36 PDT

This article presents the results of a descriptive cross-sectional study on medical waste management in Tabriz (Iran's fourth largest city). The study was conducted in 10 of 25 active hospitals of the city in the summer of 2007. The methodology of the present study was based on data collected from hospitals through a checklist, site visits (observation), and quantity analysis by weight. The results indicated that more than 13.59 tonnes day^—1 of total medical waste and 4.06 tonnes day^—1 of hazardous-infectious medical waste are generated by the active hospitals of the city. Currently, there are no practical instructions, or suitable supervision on different levels of waste management. The health authorities and hospital managers do not accept sufficient responsibility for the medical waste due to financial problems and the lack of awareness regarding the hazards of medical waste. Segregation and minimization of waste are not carried out correctly in any of the hospitals. The use of protective measures by staff and temporary storage areas was not in agreement with standards in 70 and 60% of the hospitals in the present study, respectively. About 50% of the hospitals had been equipped with an incinerator, but all but one (10%) of them had been phased out due to operation and maintenance problems, air pollution, etc. Almost all of the hospitals have a waste management officer, but there is not an effective training programme for the staff. Infectious-hazardous medical waste is mixed with general waste, and it is disposed of in a municipal waste landfill, which is an unsanitary dumpsite. Illegal segregation and recycling of medical waste is carried out at the final disposal site; therefore, there are concerns about environmental pollution and the transmission of infectious diseases. It is proposed that, through the allocation of increased budgets, implementation of integrated segregation, minimization of waste, and creation of a training programme in the hospitals, the quantity of medical waste would be decreased (by about 70.11%). Considering the previous unsuccessful experience of on-site incineration in Tabriz (and in Iran's other large cites), an amendment should be made to Iran's current hazardous waste regulations to have infectious-hazardous waste sent to a central off-site autoclave or incinerator for treatment. The off-site autoclave would have some advantages, such as decreased air pollution. Of course, some health officials oppose this plan. To test this plan and receive the official's approval, a central off-site autoclave can be put into practice as a pilot.

Hospital medical waste management in Shandong Province, China

Wed, 24 Jun 2009 07:10:36 PDT

Medical waste refers to those hazardous waste materials generated by healthcare activities, including a broad range of materials, and remains as an issue on both public health and environment. In China, there was inadequate information on the implementation of management systems in hospitals based on the national regulatory framework. The objectives of this study were to assess the current situation of medical waste management and to identify factors determining the implementation of a management system based on the national regulatory framework in hospitals. We investigated 23 general hospitals in both urban and rural areas of Shandong Province, China, by both quantitative and qualitative approaches. The medical waste generation rate was 0.744, 0.558 and 1.534 kg bed^{— 1} day^—1 in tertiary hospitals, urban secondary hospitals and county hospitals, respectively. There is a wide disparity between implementation in tertiary, secondary and county hospitals. With increasing financial, technological, and materials investment, a management system has been established in tertiary and secondary hospitals. Financial support and administrative monitoring by the government is urgently needed to build a sound management system in hospitals located at remote and less-developed areas. In those areas issues in the financial, administrative and technical aspects should be further examined.

Treatment of infectious waste: development and testing of an add-on set for used gravity displacement autoclaves

Stolze, R., Kuhling, J.-G. — Wed, 24 Jun 2009 07:10:36 PDT

The safe management of potentially infectious healthcare waste is gaining increasing worldwide importance. In developing countries, simple incinerators are used for the treatment of this type of waste stream. However, as these incinerators produce high emissions and represent the main generators of dioxin and furans in these countries, alternative and cost-effective solutions are needed. As steam treatment systems do not produce persistent organic pollutants, the use of existing (older) medical autoclaves could represent a solution for the treatment of infectious waste. ETLog Health EnviroTech & Logistics, the German-based consulting and engineering company carried out the first research into whether gravity air displacement autoclaves can be used for the safe decontamination of infectious waste. The research showed that it is not possible to decontaminate waste using this type of autoclave. A subsequent research and development phase might, however, make it possible to develop a new process cycle. Tests carried out on the basis of international standards and norms showed that by applying this process cycle and using an add-on set, it is possible to treat healthcare waste using the existing stock of older medical autoclaves. The process cycle and the add-on set developed were tested under existing conditions in Hanoi, Vietnam using the treatment cycle developed for a 13-year-old autoclave. All the parameters for infectious waste decontamination were reached. As modified autoclaves prevent the emission of toxic substances, this approach presents an interim solution, which avoids the impacts on human health and the environment caused by the incineration of healthcare waste.

Waste management in primary healthcare centres of Iran

Mesdaghinia, A., Naddafi, K., Amir Hossein Mahvi, , Saeedi, R. — Wed, 24 Jun 2009 07:10:36 PDT

The waste management practices in primary healthcare centres of Iran were investigated in the present study. A total of 120 primary healthcare centres located across the country were selected using the cluster sampling method and the current situation of healthcare waste management was determined through field investigation. The quantities of solid waste and wastewater generation per outpatient were found to be 60 g outpatient^—1 day^—1 and 26 L outpatient^—1 day^{— 1}, respectively. In all of the facilities, sharp objects were separated almost completely, but separation of other types of hazardous healthcare solid waste was only done in 25% of the centres. The separated hazardous solid waste materials were treated by incineration, temporary incineration and open burning methods in 32.5, 8.3 and 42.5% of the healthcare centres, respectively. In 16.7% of the centres the hazardous solid wastes were disposed of without any treatment. These results indicate that the management of waste materials in primary healthcare centres in Iran faced some problems. Staff training and awareness, separation of healthcare solid waste, establishment of the autoclave method for healthcare solid waste treatment and construction of septic tanks and disinfection units in the centres that were without access to a sewer system are the major measures that are suggested for improvement of the waste management practices.

Factors driving the development of healthcare waste management in the United Kingdom over the past 60 years

Townend, W. K., Cheeseman, C., Edgar, J., Tudor, T. — Wed, 24 Jun 2009 07:10:36 PDT

Since the creation of the National Health Service (NHS) in the United Kingdom in 1948 there have been significant changes in the way waste materials produced by healthcare facilities have been managed due to a number of environmental, legal and social drivers. This paper reviews the key changes in legislation and healthcare waste management that have occurred in the UK between 1948 and the present time. It investigates reasons for the changes and how the problems associated with healthcare wastes have been addressed. The reaction of the public to offensive disposal practices taking place locally required political action by the UK government and subsequently by the European legislature. The relatively new UK industry of hazardous healthcare waste management has developed rapidly over the past 25 years in response to significant changes in healthcare practices. The growth in knowledge and appreciation of environmental issues has also been fundamental to the development of this industry. Legislation emanating from Europe is now responsible for driving change to UK healthcare waste management. This paper examines the drivers that have caused the healthcare waste management to move forward in the 60 years since the NHS was formed. It demonstrates that the situation has moved from a position where there was no overall strategy to the current situation where there is a strong regulatory framework but still no national strategy. The reasons for this situation are examined and based upon the experience gained; suggestions are made for the benefit of countries with systems for healthcare waste management still in the early stages of development or without any provisions at all.

An overview of arisings and large-scale treatment technologies for healthcare waste in the United Kingdom

Tudor, T. L., Townend, W. K., Cheeseman, C. R., Edgar, J. E. — Wed, 24 Jun 2009 07:10:36 PDT

This paper reviews the current generation and management of healthcare waste in the United Kingdom, with a focus on that produced from healthcare provision in the National Health Service. While the current capacities of large-scale off-site treatment systems are adequate, there are a number of logistical factors that must be considered in future. These include variations in arisings from each country and from various regions within each country, the age and location of treatment/disposal facilities, the quantities, types and sources of healthcare waste, and the impact of waste minimization and recycling strategies. Managing UK healthcare waste is a complex issue that requires the correct technologies and capacities to be available. With increasing quantities and costs there is urgent need for future planning, and healthcare waste issues need to be addressed from a UK-wide perspective. Holistic strategies need to incorporate both minimization and segregation, with treatment using a combination of incineration and alternatives treatment technologies. The need for more research and accurate data to provide an evidence-base for future decision-making is highlighted.

Hospital waste management status in Iran: a case study in the teaching hospitals of Iran University of Medical Sciences

Farzadkia, M., Moradi, A., Mojtaba Shah Mohammadi, , Jorfi, S. — Wed, 24 Jun 2009 07:10:36 PDT

Hospital waste materials pose a wide variety of health and safety hazards for patients and healthcare workers. Many of hospitals in Iran have neither a satisfactory waste disposal system nor a waste management and disposal policy. The main objective of this research was to investigate the solid waste management in the eight teaching hospitals of Iran University of Medical Sciences. In this cross-sectional study, the main stages of hospital waste management including generation, separation, collection, storage, and disposal of waste materials were assessed in these hospitals, located in Tehran city. The measurement was conducted through a questionnaire and direct observation by researchers. The data obtained was converted to a quantitative measure to evaluate the different management components. The results showed that the waste generation rate was 2.5 to 3.01 kg bed^—1 day^—1, which included 85 to 90% of domestic waste and 10 to 15% of infectious waste. The lack of separation between hazardous and non-hazardous waste, an absence of the necessary rules and regulations applying to the collection of waste from hospital wards and on-site transport to a temporary storage location, a lack of proper waste treatment, and disposal of hospital waste along with municipal garbage, were the main findings. In order to improve the existing conditions, some extensive research to assess the present situation in the hospitals of Iran, the compilation of rules and establishment of standards and effective training for the personnel are actions that are recommended.

In itinere strategic environmental assessment of an integrated provincial waste system

Federico, G., Rizzo, G., Traverso, M. — Wed, 24 Jun 2009 07:10:36 PDT

In the paper, the practical problem of analysing in an integrated way the performance of provincial waste systems is approached, in the framework of the Strategic Environmental Assessment (SEA). In particular, the in itinere phase of SEA is analysed herein. After separating out a proper group of ambits, to which the waste system is supposed to determine relevant impacts, pertinent sets of single indicators are proposed. Through the adoption of such indicators the time trend of the system is investigated, and the suitability of each indicator is critically revised. The structure of the evaluation scheme, which is essentially based on the use of ambit issues and analytical indicators, calls for the application of the method of the Dashboard of Sustainability for the integrated evaluation of the whole system. The suitability of this method is shown through the paper, together with the possibility of a comparative analysis of different scenarios of interventions. Of course, the reliability of the proposed method strongly relies on the availability of a detailed set of territorial data. The method appears to represent a useful tool for public administration in the process of optimizing the policy actions aimed at minimizing the increasing problem represented by waste production in urban areas.

Life-cycle assessment of the municipal solid waste management system in Hangzhou, China (EASEWASTE)

Yan Zhao, , Wang, H.-T., Lu, W.-J., Damgaard, A., Christensen, T. H. — Wed, 24 Jun 2009 07:10:36 PDT

With the purpose of assessing the environmental impacts and benefits of the current municipal solid waste management system and two modified systems, EASEWASTE, a life-cycle-based model, was used to evaluate the waste system of Hangzhou city in China. An integrated model was established, including waste generation, collection, transportation, treatment, disposal and accompanying external processes. The results showed that CH₄ released from landfilling was the primary pollutant contributing to global warming, and HCl and NH₃ from incineration contributed most to acidification. Material recycling and incineration with energy recovery were important because of the induced savings in material production based on virgin materials and in energy production based on coal combustion. A modified system in which waste is transported to the nearest incinerators would be relatively better than the current system, mainly due to the decrease of pollution from landfilled waste and the increase in energy production from waste avoiding energy production by traditional power plants. A ban on free plastic bags for shopping was shown to reduce most environmental impacts due to saved oil resources and other materials used in producing the plastic bags. Sensitivity analysis confirmed the robustness of the results. LCA methodology and a model like EASEWASTE are very suitable for evaluating the overall environmental consequences, and can be used for decision support and strategic planning in developing countries such as China where pollution control has become increasingly important with the rapid increase of waste generation as well as the increasing public awareness of environmental protection.