bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Cluster Random Assignment to Measure Program Impacts
Authors: Bloom Howard S. , Bos Johannes M. , Lee Suk-Won
Published: April 2009

This article explores the possibility of randomly assigning groups (or clusters) of individuals to a program or a control group to estimate the impacts of programs designed to affect whole groups. This cluster assignment approach maintains the primary strength of random assignment—the provision of unbiased impact estimates—but has less statistical power than random assignment of individuals, which usually is not possible for programs focused on whole groups. To explore the statistical implications of cluster assignment, the authors (a) outline the issues involved, (b) present an analytic framework for studying these issues, and (c) apply this framework to assess the potential for using the approach to evaluate education programs targeted on whole schools. The findings suggest that cluster assignment of schools holds some promise for estimating the impacts of education programs when it is possible to control for the average performance of past student cohorts or the past performance of individual students.
Lessons for Microenterprise Programs from a Fresh Look at the Unemployment Insurance Self-Employment Demonstration
Authors: Schreiner Mark
Published: April 2009

Microenterprise programs aim to foster self-employment among the poor, those on welfare, and the unemployed. The only experimental test of their impact is the Unemployment Insurance Self-Employment Demonstration (UISED). UISED did shorten unemployment spells, but most other impacts were small and the most disadvantaged did not choose to participate. Although UISED provides some weak evidence that long-term income support, long-term work-search waivers, and on-call advice may increase total employment (but perhaps not self-employment) more than capital infusions and up-front classes, UISED does not reveal the best design for microenterprise programs or whether such programs are good social investments.
Evaluation of Hiv Risk Reduction Intervention Programs Via Latent Growth Model
Authors: Wang Jichuan , Siegal Harvey A. , Falck Russel S. , Carlson Robert G. , Rahman Ahmmed
Published: April 2009

The latent growth model (LGM) has drawn increasing attention in behavioral studies using longitudinal data. The LGM captures the level and trajectory of behavior change, variation in both the initial status and the trend of behavior change, as well as the time-ordered covariation between the initial status and change. This study demonstrates how the LGM can be applied in the evaluation of intervention programs targeting HIV risk behavior among drug users. Multigroup piecewise latent growth models were fit to longitudinal data with three repeated response measures.
Psychosocial adjustment in age related macular degeneration
Authors: Stanford Penelope , Waterman Heather , Russell Wanda B. , Harper Robert A.
Published: April 2009

This article describes longitudinally the psychosocial adjustment to visual impairment of patients with age related macular degeneration (AMD). As part of a larger randomized controlled trial (RCT), the present study design consisted of the use of prospective qualitative diaries completed over 12 months by patients with AMD who were newly referred to a low vision clinic. Out of the patients recruited (n = 226), the completion rate of a full set of four diaries (n = 37) and one three-month diary (n = 194) was very good. Vision related to daily life in patients with AMD appears to decline over 12 months with limited psychosocial adjustment to visual loss. Seven themes were generated from the patients' accounts of their experiences, as recorded in the diaries: safety, loss of independence, isolation, support mechanisms, mood, effects of the media and psychosocial adjustment. There was little evidence in the diaries of psychosocial adjustment to visual loss. The relevance of the theory of grieving and cognitive and rational-emotional theory in the context of AMD is explored in detail.
Purification of metal finishing waste waters with zeolites and activated carbons
Authors: Leinonen Heikki , Lehto Jukka
Published: April 2009

Sixteen zeolites and 5 activated carbons were tested for the removal of nickel, zinc, cadmium, copper, chromium, and cobalt from waste simulants mimicking effluents produced in metal plating plants. The best performances were obtained from 4 zeolites: A, X, L, and ferrierite types and from 2 carbon types made from lignite and peat. The distribution coefficients for these sorbents were in the range of 10,000-440,000 ml/g. Column experiments showed that the most effective zeolites for Zn, Ni, Cu, and Cd were A and X type zeolites. The activated carbons, Hydrodarco 3000 and Norit Row Supra, exhibited good sorption properties for metals in aqueous solutions containing complexing agents.
Report: landfill alternative daily cover: conserving air space and reducing landfill operating cost
Authors: Haughey Richard D.
Published: April 2009

Title 40, Part 258 of the Code of Federal Regulations, Solid Waste Disposal Facility Criteria, commonly referred to as Subtitle D, became effective on October 9, 1993. It establishes minimum criteria for solid waste disposal facility siting, design, operations, groundwater monitoring and corrective action, and closure and postclosure maintenance, while providing EPA-approved state solid waste regulatory programs flexibility in implementing the criteria.

Section 258.21(a) [40 CFR 258.21(a)] requires owners or operators of municipal solid waste landfill (MSWLF) units to cover disposed solid waste with 30cm of earthen material at the end of the operating day, or at more frequent intervals, if necessary, to control disease vectors, fires, odours, blowing litter, and scavenging. This requirement is consistent with already existing solid waste facility regulations in many states. For many MSWLFs, applying daily cover requires the importation of soil which increases landfill operating costs. Daily cover also uses valuable landfill air space, reducing potential operating revenue and the landfill’s operating life.

40 CFR 258.21(b) allows the director of an approved state to approve alternative materials of an alternative thickness if the owner or operator demonstrates that the alternative material and thickness will control disease vectors, fires, odours, blowing litter, and scavenging without presenting a threat to human health and the environment. Many different types of alternative daily cover (ADC) are currently being used, including geosynthetic tarps, foams, garden waste, and auto shredder fluff. These materials use less air space than soil and can reduce operating costs.

This paper discusses the variety of ADCs currently being used around the country and their applicability to different climates and operating conditions, highlighting the more unusual types of ADC, the types of demonstrations necessary to obtain approval of ADC, and the impact on landfill air space and operating costs of ADC use.
An entropy based method to evaluate hazardous inorganic substance balances of waste treatment systems
Authors: Rechberger Helmut
Published: April 2009

At present, methods to assess the environmental performance of waste treatment systems are based mainly on emission standards. Since waste treatment yields also products used for recycling and/or land filling, new additional instruments are needed to analyse and evaluate the partitioning of substances during waste treatment. It is shown that in order to fulfil the goals of European Waste Management, waste treatment systems have to concentrate hazardous inorganic substances. Based on substance flow analysis and the statistical entropy function, a method is presented to classify waste treatment systems in view of their power to concentrate or dilute substances. The method allows for the determination of the Substance Concentrating Efficiency (SCE) of waste treatment systems quantitatively. The SCE approach is applied in a case study comparing waste incineration and mechanical-biological waste processing. The results show that this new tool is useful to support decisions regarding the selection of waste treatment systems.
A model for optimal operation of land-treatment sites for oily wastes
Authors: ünlü Kahraman , Kıvanç Sedat
Published: April 2009

Land treatment as a disposal technology has been extensively used for the disposal of oily wastes. Effective management of land treatment sites require optimal operation of the system in order to achieve the fastest and most complete degradation of petroleum hydrocarbons without contamination of the environment. This paper describes a model that can be used for optimising the operation of land treatment sites for oily wastes. The model is composed of system simulator and optimisation submodels. Conceptually, the system simulation submodel is composed of a waste mixing zone, lower treatment zone and aquifer modules. The system simulation model allows for periodic waste applications and determines the spatial and temporal variation of the state variables such as phase summed (total) and aqueous phase contaminant concentrations and water content in the system. The optimisation submodel coupled with the system simulator determines the optimal values of system control variables, such as waste loading rate, infiltration rate, water content, frequency of waste application and the dimensions of the land treatment site. Optimisation of these system control variables is accomplished by maximising the hydrocarbon mass removal from the waste mixing zone under the constraint of satisfying a prespecified water quality criteria in the aquifer. Selected model applications are presented to demonstrate the applicability and utility of the model. Such model applications include determination of the optimal operating conditions for the land treatment of oily wastes under various different site and soil environmental conditions and practical waste disposal scenarios.
Composition of leachate from old landfills in Denmark
Authors: Kjeldsen Peter , Christophersen Mette
Published: April 2009

The Danish counties have performed numerous investigations of old landfills. These investigations have been presented in several reports, but no comprehensive summary of the findings has been carried out. The objective of this study was to evaluate the typical composition of leachates from old smaller landfills by a comprehensive review of the investigations carried out by the counties. In total 106 landfills were selected by criteria avoiding dilution effects. A database was constructed using a standard program. Statistical evaluations showed that the leachate concentrations in general decreased with the age of the landfill, and that the leachate concentrations were lower than found in other similar studies.
Electric arc furnace dust treatment: investigation on mechanical and magnetic separation methods
Authors: Sekula Robert , Wnek Maciej , Selinger Adrian , Wróbel Miroslaw
Published: April 2009

Electric arc furnace dust (EAFD) is a major issue for processing technologies: Several million tons per year are generated, it contains both valuable and hazardous metals and yet no available treatment process has proven to be superior to all others. Processes currently applied or being developed are either of hydro or pyrometallurgical type, which are very costly.

In the paper testing of some physical separation methods of electric arc furnace dust from Polish steel industry were investigated. SEM, EDX analyses as well as grain size observations of dust particles were additionally performed. All investigations confirmed a possibility of effective magnetic and mechanical separation of EAFD particles.
A novel process using enhanced acidification and a UASB reactor for biomethanation of vegetable market waste
Authors: Rajeshwari K. V. , Lata K. , Pant D. C. , Kishore V. V. N.
Published: April 2009

The processing of solid vegetable market waste was attempted in a two-stage digester. Initially, for the hydrolysis and acidification of waste, enhanced extraction process was carried out by continuous sprinkling of water over the bed of waste in a mild steel 100 l solid bed digester. The leachate obtained after completion of acidification phase was further treated in 24.6 l UASB reactor for biogas production. The effect of waste-liquid ratio, dilution and sprinkling rate on the digestion of waste were studied. A high strength leachate, with a COD of 25,298 mg l–1 and total volatile fatty acids concentration of 11.3 g l–1, was obtained as a result of hydrolysis and acidification in a very short retention time of 40 h. The COD reduction of 94% was achieved during UASB reactor operation at organic loading rate of 19.6 kg COD m day–3. A minimum hydraulic retention time of 16 h was achieved.
Integrated analysis for pre-sorting and waste collection schemes implemented in Spanish cities
Authors: Vidal Rosario , Gallardo Antonio , Ferrer José
Published: April 2009

Over recent years, European cities have been questioning their traditional pre-sorting and waste collection practices and looking for new schemes to improve environmental problems generated by waste disposal. This paper presents an integral methodology for four pre-sorting practices that are beginning to be implemented in Spanish cities. A great effort has been made to compile information to be able to estimate a large number of valuation indexes. Based on this information, the methodology is supported by the forecasting of waste generation, the use of GIS techniques, the definition of objectives and their evaluation taking into account legal, social, performance, environmental and economic issues. Special attention is given to environmental impact, for which life cycle assessment methodology is used.
Evaluation of multifarious solid waste management systems - A goal programming approach
Authors: Shekdar A V , Mistry P B
Published: April 2009

Globally the waste management systems are becoming resource generative by incorporating energy and material recovery components in the systems. These systems are expected to meet several objectives and thus cannot be analysed effectively by optimising models using single objective like cost minimisation. To study the system’s performance under varying priority structures of the conflicting objectives an interactive goal programming model of multi-objective planning of the system is proposed. The model is applied to visualise the system performance for a typical county region and accordingly its utility has been demonstrated. The application highlights the effect of change in priority structure on the extent of meeting the objectives. The proposed analytical tool facilitates the use of the model for tactical and strategical planning not only in developed countries like the UK but would provide better insight in developing energy and material recovery units in developing countries like India.
The numerical modelling and process simulation for the fault diagnosis of rotary kiln incinerator
Authors: Roh Sung-Duk , Kim Sang-Wook , Cho Wook-Sang
Published: April 2009

The numerical modelling and process simulation for the fault diagnosis of rotary kiln incinerator were accomplished. In the numerical modelling, two models applied to the modelling within the kiln are the combustion chamber model including the mass and energy balance equations for two combustion chambers and 3D thermal model. The combustion chamber model predicts temperature within the kiln, flue gas composition, flux and heat of combustion. Using the combustion chamber model and 3D thermal model, the production-rules for the process simulation can be obtained through interrelation analysis between control and operation variables. The process simulation of the kiln is operated with the production-rules for automatic operation. The process simulation aims to provide fundamental solutions to the problems in incineration process by introducing an online expert control system to provide an integrity in process control and management. Knowledge-based expert control systems use symbolic logic and heuristic rules to find solutions for various types of problems. It was implemented to be a hybrid intelligent expert control system by mutually connecting with the process control systems which has the capability of process diagnosis, analysis and control.
Solid waste characterisation study in the Guadalajara Metropolitan Zone, Mexico
Authors: Bernache-Pérez Gerardo , Sánchez-Colón Salvador , Garmendia Ana María , Dávila-Villarreal Arturo , Sánchez-Salazar María Elena
Published: April 2009

The key findings of a solid waste characterisation study conducted at the Guadalajara Metropolitan Zone, Mexico, are reported. Objectives of the study were to estimate the daily generation rate of household (HSW) and municipal solid waste (MSW), characterise and compare their composition by type of material, determine the proportion that HSW contributes to MSW, explore changes in MSW composition through time after final disposal, and estimate the types and amount of MSW that are sorted out for recycling at final disposal sites. HSW generated during seven days by a sample of 300 households chosen through a two-stage stratified sampling design was collected, weighed and classified. MSW entering the four local disposal sites was recorded for 12 weeks, and materials’ sorting was quantified. MSW samples taken by excavating trenches in two final disposal sites were also characterised. The average per capita daily HSW generation rate was 508 g. HSW mainly consisted of putrescible waste (53%), paper (10%) and plastic (9%). The average daily generation rate of MSW was 3119.2 metric tonnes. HSW represented 55.9% of MSW, and the main difference between HSW and MSW was a lower proportion of organic materials (53% vs. 16.5%, respectively). The major changes in MSW composition through time after final disposal, were the result of the quick decomposition of putrescible materials. Only 2.2% of total MSW generated in Guadalajara (mainly package waste) was sorted for recycling.
The influence of hydraulic residence time on the treatment of cattle manure in UASB reactors
Authors: MarañóN Elena , Castrillón Leonor , Vázquez Isabel , Sastre Herminio
Published: April 2009

Cattle manure from farms in the autonomous community of Asturias, Spain, was characterised and subsequently treated, after filtration through a 1 mm sieve, in upflow anaerobic sludge blanket laboratory reactors. The volume generated per cow and day varied between 50-55 litres (obtained through a survey of 400 farms), the manure being used on Asturian farms up until now as a fertiliser. After screening, the COD of the manure employed varied between 33,000 and 56,000 mgO2l-1. The highest percentage of COD removal obtained was 75.5% for a hydraulic residence time of 22.5 days. Gas production varied between values of 0.20-0.39 m3gas kg-1 COD removed, with a methane content of up to 64%. There was a fraction refractory to biodegradation of 11%.
Comparison of methods used in the collection of source-separated household waste
Authors: Tanskanen Juha-Heikki , Kaila Juha
Published: April 2009

The efficiencies of four different waste collection methods were compared by modelling the collection of source-separated household waste in the Helsinki region, Finland. Efficiency was assessed on the basis of system costs, fuel consumption, working hours and recovery rates. The study included paper, biowaste, energy waste and mixed waste produced in households.

Both separation of new types of recyclables and increasing the coverage of separate collection increased the costs of household waste collection independently of the collection method studied. Methods in which several types of waste are collected simultaneously increased the efficiency of waste collection. High participation rates and separation efficiencies reduced the costs of waste collection.
The potential for adding plastic waste fuel at a coal gasification power plant
Authors: Campbell Petra E. , Evans Ron H. , McMullan John T. , Williams Brian C.
Published: April 2009

Plastics wastes from a municipal solid waste plant have a high energy content which make it an interesting option for co-processing with coal. The potential for adding plastic waste to a coal fired Texaco IGCC (Integrated Gasification Combined Cycle) power station is examined. The resulting efficiency increases due to the improved gasification qualities of plastic over coal. For the overall economics to be the same as the coal only case, the maximum amount that the power station can afford to spend on preparing the plastic waste for use is similar to the assumed coal cost, plus the avoided landfill cost, minus the transport cost. The location of the power station plays a key role, since this has an effect on the transport costs as well as on the landfill charges. The sensitivity of the economics of co-processing plastic waste with coal for a variety of power station operational parameters is presented.
Utilisation of bottom ash in road construction: a lysimeter study
Authors: Bruder-Hubscher V. , Lagarde F. , Leroy M. J.F. , Coughanowr C. , Enguehard F.
Published: April 2009

The incineration of municipal solid waste (MSW) results in the annual production of 2.7 million tons of bottom ash in France. Utilisation of bottom ash in road construction is encouraged in France but strictly regulated. Because the incinerator residues contain enriched concentrations of metals and salts, particular attention must be focused on the potential environmental problems. In the present study, a laboratory tool (lysimeter) has been developed to reproduce the conditions of bottom ash utilisation and to study their environmental impact via the percolates collected at the bottom of the lysimeter. Four lysimeter experiments were conducted in order to study reproducibility, as well as the influence of water flow rate and pressure on the composition of the percolates. The lysimeter experiments have been then compared with the utilisation of bottom ash under real conditions (two experimental road sections). The comparison of results of lysimeter test and those measured after performing the French standard leach test (AFNOR NF X31-210) shows a recovery of 89% for the chlorides and between 30 and 35% for the sulfates. This indicates that almost all chlorides have been dissolved, contrary to the sulfates, which are less soluble.
Study for reclamation of land occupied by solar evaporation pond at UCIL, Bhopal, India
Authors: George K. V. , Patil M. P. , Swaminathan R.
Published: April 2009

Solar Evaporation Ponds (SEP) were used by Union Carbide India Limited (UCIL), Bhopal for storage of wastewater containing high concentrations of inorganic chemicals especially chlorides. Area occupied by the SEPs had to be recovered due to closure of the plant. A prerequisite to the reclamation of the SEP area is a study of adjoining soil and groundwater, which may be contaminated due to possible leakage in the pond. Surface soil, subsurface soil and groundwater samples were collected and analysed. The electrical conductivity method was employed inside the pond to test for leak in the geo-membrane liner. This was further confirmed by physically checking the liners. Based on the wet period, total rainfall and evaporation rate of the region, drying of remaining wastewater by spreading in dry ponds followed by pond dismantling was scheduled.
Life cycle inventory for municipal solid waste management
Authors: Wilson E. J.
Published: April 2009

Evaluating the environmental performance of municipal solid waste management options is a complex task. Part 1 of this study presents the municipal solid waste management program of the Pamplona Region in Spain, exploring the institutional, operational and economic factors of the program. In Part 2, alternative waste management scenarios that include the selective collection of organic material and composting are illustrated. The use of a Life Cycle Inventory model for waste management allows for the comparison of the environmental burdens of the different scenarios. This use of a Life Cycle Inventory model for solid waste management lets program managers and decision makers include energy use, final solid waste, and Greenhouse gas emissions in the decision making process. Additionally, the different management scenarios are evaluated on their ability to fulfil Pamplona regional objectives and meet European Packaging and Landfill Directive targets.
An optimisation model for regional integrated solid waste management II. Model application and sensitivity analyses
Authors: Najm M. Abou , El-Fadel M. , Ayoub G. , El-Taha M. , Al-Awar F.
Published: April 2009

Increased environmental concerns and the emphasis on material and energy recovery are gradually changing the orientation of MSW management and planning. In this context, the application of optimisation techniques have been introduced to design the least cost solid waste management systems, considering the variety of management processes (recycling, composting, anaerobic digestion, incineration, and landfilling), and the existence of uncertainties associated with the number of system components and their interrelations. This study presents a model that was developed and applied to serve as a solid waste decision support system for MSW management taking into account both socio-economic and environmental considerations. The model accounts for solid waste generation rates, composition, collection, treatment, disposal as well as potential environmental impacts of various MSW management techniques. The model follows a linear programming formulation with the framework of dynamic optimisation. The model can serve as a tool to evaluate various MSW management alternatives and obtain the optimal combination of technologies for the handling, treatment and disposal of MSW in an economic and environmentally sustainable way. The sensitivity of various waste management policies is also addressed. The work is presented in a series of two papers: (I) model formulation, and (II) model application and sensitivity analysis.
Treatment of waste incinerator air-pollution-control residues with FeSO4: Laboratory investigation of design parameters
Authors: Jensen D. L. , Christensen T. H. , Lundtorp K.
Published: April 2009

The key design parameters of a new process for treatment of air-pollution-control (APC) residues (the Ferrox-process) were investigated in the laboratory. The optimisation involved two different APC-residues from actual incinerator plants. The design parameters considered were: amount of iron oxide supplied, the liquid-to-solid ratio of the process, the separation of solids and wastewater, the sequence of material mixing, the possibilities of reuse of water, the feasibility of using secondary (brackish) water, and simple means to improve the wastewater quality. The investigation showed that an optimum process configuration could be obtained yielding a stabilised solid product with low leaching of heavy metals and a dischargable wastewater with high contents of salts (in order to remove salts from the solid product) and low concentrations of heavy metals. The amount of iron added to the APC-residues must be optimised for each residue. The overall water use can be limited to a L/S-ratio of 3 l kg-1 including water used for washing of the treated products.
Research on the utilisation of waste chromic materials in the sodium chromate production process
Authors: Kowalski Zygmunt , Walawska Barbara
Published: April 2009

The results of investigations on the utilisation of waste chromic materials for the production of sodium chromate have been presented. The optimal parameters of the sodium chromate production, which make it possible to select the best technological solutions, have been determined. A mathematical model based on a system of equations describing the process of sodium chromate production as a function of selected process parameters has been devised. This allows the values useful for a practical estimation of the process, such as mass balances, technological indicators and especially the quantity of the produced chromic waste, to be determined.
Enhanced acidogenic fermentation of food waste in a continuous-flow reactor
Authors: Han Sun-Kee , Shin Hang-Sik
Published: April 2009

This study was performed to improve acidogenic fermentation of food waste in a continuous-flow reactor. The fermentation of food waste is affected by the fermentation constraints such as the biodegradability of substrate, the degrading capability of microorganisms and the environmental conditions. The key factors were, therefore, examined to control the fermentation constraints, such as the effect of seed inoculation and the effect of adjusting dilution rate. Acidogenic fermentation of food waste employing rumen microorganisms resulted in the enhanced efficiency (71.2%) as compared with that (59.8%) employing mesophilic acidogens. In addition, the fermentation efficiency increased from 71.2 to 82.0% by adjusting dilution rate from 3.0 to 1.0 d-1 depending on the state of the fermentation. The main component of the acidified product was shifted from butyric to acetic acid. This meant that the increase of the fermentation efficiency was mainly caused by the enhanced degradation of vegetables and meats. The control of the fermentation constraints was, therefore, very effective in improving the fermentation efficiency of food waste.
Continuous feed, on-site composting of kitchen garbage
Authors: Hwang Eung-Ju , Shin Hang-Sik , Tay Joo-Hwa
Published: April 2009

Kitchen garbage generated at a school cafeteria was treated and stabilised in a controlled on-site composting unit for volume reduction and on-site utilisation of processed garbage. The on-site composter was fed with the garbage on a daily basis during the two-months experimental period. Compost was not removed from the unit but was entirely reused as a bulking agent in order to minimise the need for additional bulking agent and compost handling. Performance of the composter under this condition was investigated. Most of the easily degradable organic matter (EDM) in the garbage was biodegraded rapidly, and the final product had a low content of EDM. Lipids, total sugar, and hemi-cellulose were degraded 96%, 81%, and 66% respectively. Free air space (FAS) was higher than 0.5 all the time, so accumulation of dry matter in the unit was not significant in reducing reaction efficiency. Other reaction parameters such as pH and MC were kept within a suitable range; however, it was advisable to maintain MC at over 46%. As a result, this method of operation was able to stabilise the garbage with low sawdust demand and little compost production.
Microbial reduction of amended sulfate in anaerobic mature fine tailings from oil sand
Authors: Salloum Myrna J. , Dudas Marvin J. , Fedorak Phillip M.
Published: April 2009

,!Bitumen extraction from oil sands has resulted in large tailings ponds, containing suspended material that requires over one hundred years to densify. The mature fine tailings (MFT) have become anaerobic and bubbles of gas are observed on the pond surface. Gypsum has been proposed as an additive to increase the rate of MFT consolidation. In a laboratory study, MFT was amended with sulfate and monitored. Pore water sulfate concentrations declined and bicarbonate concentration increased. Nitrate was depleted within 36 d and the levels of soluble iron remained below 0.8 mg L-1. Thiosulfate and sulfide were detected only near the end of the experiment. Acid volatile sulfides (AVS) increased until day 39, and then reached a plateau. Methane was not detected throughout the incubation in samples amended with sulfate. The increase in AVS supports sulfide incorporation into the solid phase, however, the plateau after 39 d suggests a secondary fate of reduced sulfide
Public-private partnerships in the siting of hazardous waste facilities: the importance of trust
Authors: Ibitayo Olurominiyi O.
Published: April 2009

As the need for hazardous waste management facilities becomes critical, several strategies including public-private partnership have been suggested and adopted by states to diffuse public opposition, and facilitate the siting of these facilities. Public-private partnership involves state ownership of the facility, and its operation by a private company. Proponents of this strategy contend that state ownership of facility and therefore an assumption of long-term liability would reduce public concerns regarding site maintenance. Also, that state or public ownership of the land on which the facility is built would thwart any local land use regulation that may be enacted to derail the site selection process. This paper, through a case study provides an analysis of this strategy, and surmised that factors identified in past research-public trust in institutions of government, in the perceived competence and integrity of the developer, and in the waste treatment technology to pose minimal risks to public health and the environment, are necessary to enhance the efficacy of public-private partnership in the siting of hazardous waste management facilities.
A study on the appearance of persistent organic pollutants (POPs) in leachate treatment processes
Authors: Kim Yongjin , Ohsako Masahiro
Published: April 2009

The presence of PCDDs/DFs, PCBs and PAHs in the adsorbed or dissolved phases (depending on the leachate treatment process) was investigated in two landfills in Japan (Landfill M and Landfill N). The results of the investigations showed that, in general, persistent organic pollutants (POPs) having high Kow such as PCDDs/DFs and PCBs tended to exist in the adsorbed phase in both Landfill M and Landfill N. Furthermore, it was confirmed that their presence depended on log Kow by the appearance of PAHs.
The production of synthetic aggregate from a quarry waste using an innovative style rotary kiln
Authors: Wainwright P. J. , Cresswell D. J. F. , van der Sloot H. A.
Published: April 2009

The large volumes of wastes generated by industrialised society has led to efforts to find practical uses for these wastes, whilst also offsetting the consumption of natural resources. This paper describes the use of an innovative rotary kiln to produce synthetic aggregates from a variety of waste streams. The main waste used was a quarry fines which was blended with either paper sludge, clay, or a dredged harbour sediment. The different combinations were extruded and fired in the kiln to produce a material suitable for natural aggregate replacement. Two of the synthetic aggregates produced were tested by incorporation in to concrete as coarse aggregate replacement. The concrete 28-day compressive strengths achieved were above 40 N mm-2 and compared favourably with control concretes made with natural aggregates and a commercially available lightweight aggregate (Lytag). Leaching tests have also been carried out to assess the potential environmental impact of utilisation. Although not finalised, these tests have also given favourable results.
Evaluation of commercial compost quality
Authors: Tomati Umberto , Belardinelli Monica , Andreu Monica , Galli Emanuela , Capitani Donatella , Proietti Noemi , De Simone Claudio
Published: April 2009

Ten commercial composts were evaluated on the basis of chemical, physical and biological characteristics and compared with a compost produced by a safe matrix in controlled conditions.

FT-IR spectra, 13C CP-MAS NMR spectra and molecular weights were also assayed on humic acids extracted from the composts. The results show that the origin of the starting materials affects the quality of the end products especially for their heavy metal content and genotoxic effect. The presence of a high percentage of low molecular weight fractions generally recorded in the humic acids from commercial composts could be due to uncorrected composting process. FT-IR and 13C CP-MAS NMR spectra agree with functional group assignments, characterising the level of humification. The results show that commercial composts can display harmful properties probably due to the origin of the starting material, therefore a regulation about both compost production and characterisation should be suitable.
Calcium hypochlorite removal of mercury and petroleum hydrocarbons from co-contaminated soils
Authors: Renneberg Adrian J. , Dudas Marvin J.
Published: April 2009

Former oil and gas processing sites are often contaminated with both mercury and petroleum hydrocarbons. Traditional methods for treating these co-contaminated soils include thermal treatments and placement in landfills (Stepan et al. 1993). This study examines a chemical oxidation treatment, calcium hypochlorite, and its effectiveness in reducing both the petroleum and mercury content of several industrial soils. A sequential extraction method was used to determine the forms of mercury removed through the hypochlorite treatment. The forms included five organic forms of mercury, mercury associated with the mineral phase, ion exchangeable mercury, water phase mercury, and mercury associated with the petroleum hydrocarbons. The hypochlorite treatment did lower the mercury content of all five soils, but failed to remove the petroleum hydrocarbons from the soils. Prior to the hypochlorite treatment the dominant form of mercury was that associated with soil organic matter while after treatment most of the mercury remaining in the soil was associated with either the petroleum hydrocarbons or the mineral phase.
Modelling for environmental assessment of municipal solid waste landfills (Part II: Biodegradation)
Authors: De Cortázar Amaya Lobo García , Lantarón Javier Herrero , Fernández Oscar Montero , Monzón Iñaki Tejero , Lamia Maria Fantelli
Published: April 2009

The biodegradation module of a simulation program for municipal solid waste landfills (MODUELO) was developed. The biodegradation module carries out the balance of organic material starting with the results of the hydrologic simulation and the waste composition. It simulates the biologic reactions of hydrolysis of solids and the gasification of the dissolved biodegradable material. The results of this module are: organic matter (COD, BOD and elemental components such as carbon, hydrogen, nitrogen, oxygen, sulfur and ash), ammonium nitrogen generated with the gas and transported by the leachates and the potential rates of methane and carbon dioxide generation. The model was calibrated by using the general tendency curves of the pollutants recorded in municipal solid waste landfills, fitting the first part of them to available landfill data. Although the results show some agreement, further work is being done to make MODUELO a useful tool for real landfill simulation.
Fluidised bed catalytic pyrolysis of scrap tyres: Influence of catalyst: tyre ratio and catalyst temperature
Authors: Williams Paul T. , Brindle Alexander J.
Published: April 2009

Pyrolysis with on-line Zeolite catalysis of scrap tyres was undertaken in a fluidised bed reactor with the aim of maximising the production of higher value single ring aromatic hydrocarbons in the derived oil. Experiments were carried out in relation to the ratio of the catalyst to tyre feedstock and the temperature of the catalyst bed. Two Zeolite catalysts were examined, a Y-type Zeolite catalyst and Zeolite ZSM-5 catalyst of differing pore size and surface activity. The composition of the oils derived from the uncatalysed fluidised bed pyrolysis of tyres showed that benzene concentration was 0.2 wt%, toluene concentration was 0.8 wt%, o-xylene was 0.3 wt%, m/p-xylenes were 1.8 wt% and limonene was 4.3 wt%. Benzene, toluene and xylenes present in the oils showed a significant increase in the presence of both of the catalysts. The maximum concentrations of these chemicals for the Y-Zeolite (CBV-400) catalyst was 1 wt% for benzene, 8wt% for toluene, 3 wt% for o-xylene and 8.5 wt% for m/p-xylenes, produced at a catalyst: tyre ratio of 1.5. There was less influence of catalyst temperature on the yield of benzene, toluene and xylenes, however, increasing the temperature of the catalyst resulted in a marked decrease in limonene concentration. The Y-type Zeolite catalyst produced significantly higher concentrations of benzene, toluene and xylenes which was attributed to the larger pore size and higher surface acidity of the Y-Zeolite catalyst compared to the Zeolite ZSM-5 catalyst.
Plasma chemical gasification of sewage sludge
Authors: Balgaranova Janetta
Published: April 2009

The possibility for plasma gasification of sewage sludge is investigated. Water steam is used as the plasma generating gas and as a chemical reagent. The experiments are carried out at a sludge to water steam ratio of 1 to 1.5 by weight, and at a plasma torch temperature of up to 2600°C. The calculated average temperature in the reactor after mixing with the sludge particles is up to 1700°C. Proximate and ultimate analyses of the sludge are given. The resulting gases are analysed by gas chromatography. High calorific gas containing mainly carbon monoxide (48% volume) and hydrogen (46% volume), as well as glass-like slag, is obtained. No water-soluble substances are detected within it. The amount of carbon dioxide produced is under 4% mass. No hydrocarbons are observed within the gas. The investigated process is environmentally safe, compact and shows a high rate of conversion.
Atmospheric methane transport near landfill sites
Authors: Tagaris Efthimios , Sotiropoulou Rafaella-Eleni P. , Pilinis Christodoulos , Halvadakis Constantinos P.
Published: April 2009

Methane production rates that have been estimated by a biogas production model (MICROGEN) are combined with an air dispersion model in order to determine the spatial distribution of methane around landfill sites. By utilising dispersion models under extreme atmospheric conditions, a maximum methane concentration around the landfills can be determined. The factors that enhance the maximum methane concentrations, using the meteorological model CALMET in conjunction with the dispersion model CALPUFF, are found to be the wind speed and the percentage of cloud cover. The rates of temperature and pressure variation, as well as the land use category seem to have no effect on the maximum methane concentrations. A rapid reduction of methane concentration is observed a few metres away from the landfill centre while a slower reduction is observed at distances greater than 300 m from it. The performance of this methodology is evaluated by comparing measured concentrations with model predictions.
Serial water balance method for predicting leachate generation in landfills
Authors: De Velásquez Ma. Teresa Orta , Cruz-Rivera Reynaldo , Rojas-Valencia Neftalí , Monje-Ramírez Ignacio , Sánchez-GóMez Jorge
Published: April 2009

This paper presents the "Serial Water Balance” method for predicting leachate generation in landfills. This procedure makes it possible to calculate the total leachate likely to be generated, by estimating an individual cell by cell water balance. This new development considers the interaction effects between cells, through the execution of simple field capacity tests on solid waste samples under different loading conditions. The procedure described in this paper simulates the effect induced by fluid percolating from a cell at an upper layer to cells in the immediately subjacent layer.

The method described here was applied to the landfill in Nuevo Laredo, Tamaulipas (Mexico), after first ascertaining information regarding: duration of construction time, exposure time, surface area, the quantity of waste, number of confining cells, and local weather conditions.

In a full-scale test case the suggested method has predicted 67% of the leachate produced in a period of 4 years. Further testing and more detailed analysis of the composition of the waste used in the calculations, may improve the accuracy in predicting leachate production.

Even though this SWB methodology was applied to a landfill subject to extreme climatological conditions (high daytime temperatures), it is possible to adapt the methodology to solid waste disposal sites in regions with more humid or moderate climates.
Technical, economic and environmental feasibility of recycling nutrients in waste in Southern Thailand
Authors: Schouw Nanette Levanius , BregnhøJ Henrik , Mosbæk Hans , Tjell Jens Christian
Published: April 2009

Technical, economic and environmental criteria were used to evaluate the feasibility of recycling plant nutrients in kitchen waste, human excreta and sullage from households in Phattalung (urban), Kuan Lang (peri urban) and Prik (rural) in Southern Thailand. The difference in situation and context of the three areas called for individual solutions, and for each area three sanitation systems were evaluated. However, in all three areas recycling human excreta and kitchen waste via composting latrines was found to be more environmental feasible than human excreta managed in septic tanks or sub surface trickle irrigation and kitchen waste disposed of at landfill sites or treated at composting plants. Sullage should in Kuan Lang and Prik be used directly on garden crops, but in Phattalung be treated in waste stabilisation ponds before discharge, to be environmentally feasible. The economic feasibility results varied among the three areas and among the involved stakeholders: farmers and Kuan Lang administration benefited from recycling waste, at the expense of other private users, Phattalung municipality and Prik municipality. The main cause of these conflicting interests was lack of cost recovery and public participation, which should therefore serve as the fundament of any future environmental and economic feasible sanitation system.
Investigation on the emission factors and removal efficiencies of heavy metals from MSW incinerators in Taiwan
Authors: Chang Moo Been , Jen Chuan Hsiung , Wu Hsiu Tung , Lin Hsin Yi
Published: April 2009

Two large-scale municipal waste incinerators (MWIs) equipped with different air pollution control devices (APCDs) were selected for conducting flue gas sampling and determination of heavy metals emissions including lead, zinc, cadmium, chromium, copper and mercury. In addition, the emission characteristics and removal efficiencies of heavy metals were evaluated via simultaneous sampling of flue gas upstream and downstream of APCDs. The average removal efficiency of particulate matter was 99.47%, and the removal efficiency of heavy metals could reach 95% or higher (except for Hg) for MWI-A. Preliminary results indicated that the average removal efficiency of particulate matter was 99.94%, and the removal efficiency of heavy metals could reach 98% or higher (except for Hg) for MWI-B. The average removal efficiencies of Hg for MWI-A and MWI-B were 47% and 30% respectively. The removal efficiencies achieved with existing APCDs were close to that reported in the US EPA document (AP-42) for MWIs. The average concentrations of heavy metals and particulate matter emitted from stack could meet current emission standards in Taiwan for both MWIs, but particulate matter, Pb and Cd concentrations of MWI-A were higher than the current emission regulations in Germany and the Netherlands.