Search

The limited availability of natural resources, such as sand, and the need to reduce CO2 emissions, which are produced in large quantities in the production of binding materials, indicate the need to look for alternative raw materials used in construction materials. At the same time, there is a strong need to utilise waste packaging materials, the global production of which is constantly increasing. This work aims to investigate the possibility of using recycled polyethylene terephthalate (PET), utilised as a partial substitute for fine aggregate, and waste glass, implemented as powder, serving as a partial substitute for cement in the manufacturing of the cementitious composites. An experimental study was carried out to evaluate the physical and mechanical properties of the resultant cementitious composites. The incorporated PET aggregate comprised 0%, 5%, and 10% by volume of silica sand and 0%, 10%, and 20% glass powder by weight of cement. The addition of waste raw materials augmented the flow of fresh mortars, predominantly subsequent to the introduction of PET recyclate. The deployment of artificial aggregate in mortars induces a decrease in the volumetric density. Concurrently, the mechanical properties of mortars enriched with waste materials exhibited a reduction, in terms of both compressive and flexural strength, with the detriment escalating in conjunction with the content of waste raw materials. An analysis of statistical significance of effects, grounded in an analysis of variance, is delineated within this document, pinpointing the quantities of waste raw materials that can be assimilated in mortars without inducing a substantial deterioration of strength properties. Through studies on phase composition, it has been demonstrated that the utilised glass waste, possessing a grain size analogous to cement, exhibited poor pozzolanic properties. The test results indicate that it is possible to partially replace cement with glass powder, up to 10%, and fine aggregate with PET waste, up to 5%, without a significant reduction in the mechanical properties of the material. [ABSTRACT FROM AUTHOR]

Recently, in geotechnical engineering, waste utilization and management have become immensely important in terms of reducing the ratios of environmentally harmful and relatively expensive chemical soil strengthening additives. Glass manufacturing waste (GMW), among the above-stated waste materials, comes to existence as the mineralogical part required to produce glass is separated from the mined material. GMW leads to serious environmental pollution incessantly. This study aims to investigate the effects of GMW to the bearing capacity and time-dependent consolidation settlements of clayey soils (CS) in an environmentally friendly approach. In this regard, GMW, which has not yet been considered in the relevant literature, was activated with KOH, NaOH and CaO alkali activators to form geopolymer mortars. Large-scale model experiments were performed on geopolymer-CS mixtures and up to 7.35 times bearing capacity increments along with 6.90 times settlement reductions were reached compared to unimproved CS. Optimum GMW ratio was found as 25% and CaO was determined to be the most ideal alkali activator. Curing temperature and durations were examined and it was deduced that both affected the results significantly. Results were compared to those of cement and remarkably close bearing capacity and settlement improvements were achieved in an environmentally friendly approach. [ABSTRACT FROM AUTHOR]

Assessment of perception on solid waste disposal is fundamental to any proper planning of solid waste management in an area. This study assessed the value-added solid waste disposal perception in Kwamo community, Ejisu Municipality in Ghana. Two hundred and sixty (260) households were stratified into high, middle and low-class residential areas based on the type of building, access to road and income status, randomly sampled and interviewed via a structured questionnaire. This study indicated 85% of the respondents consider waste materials as potential value-added resources. Concerns on negative environmental impact of improper solid waste disposal was raised by 77.7% of the responding population, 18.5% were not aware and 3.8% not sure of the negative impacts. The awareness creation on the negative impacts of waste was effective in the following order: media (36.2%) > school (30.3%) > neighborhood (16%) > friends (12.2%). Waste segregation at source was known and practiced by 4.6% while 95.4% of the households had waste bins for storage of their wastes but do not practice segregation. About 74.6% of respondents were interested to participate in waste segregation while 71.5% had interest in adding value to waste (community-based composting). It implies that source separation of waste can be practiced as an integral part of waste management in the municipality. Waste segregation has a potential of providing cleaner materials to maximize revenue through compost preparation, recycling and land reclamation and reduce challenges with public health caused by poor management of waste. [ABSTRACT FROM AUTHOR]

The main goal of the study was to look at the properties of waste, treatment options, and disposal techniques. Furthermore, waste circulation variables in the textile and apparel sectors in Sri Lanka's Biyagama Industrial Processing Zone were calculated. The types, volumes, and per capita waste generation of ten industries were analyzed, as well as waste management activities such as trash minimization, handling, storing, recirculation, and disposal. The information was gathered using questionnaires, interviews, and field observations. According to the findings, the total industrial waste generation rate was 13792.5 tonnes per year, with 5926 tonnes per year designated as hazardous waste materials (42.9%). Furthermore, the waste generation rate per capita was 0.93 kg. The waste circulation factor was 0.38, according to the findings. The findings of the study highlight the necessity for integrated waste management methods in the textile and apparel industries. [ABSTRACT FROM AUTHOR]

Fusion has the prospect of producing only low-level radioactive waste, but the volume of this waste is potentially very large. A possible means of reducing the volume of this waste is to recycle the activated materials, e.g. within the fusion industry. In the process of steelmaking, certain impurities are removed via accumulation in slag or fumes produced during the process, and this has been successfully employed as a means of clearing surface-contaminated LWR steels (e.g. steam generators). In this work, we simulate the process applied to neutron-activated fusion reactor components including the blanket, divertors, and shielding. The process is based on a well known partitioning between melt, slag, dust, and gas that is based on the oxidation potential of the elements and their volatility. We model this partitioning of activated materials and use FISPACT-II to simulate their activation during operation; the processes are repeated cyclically to simulate the long-term accumulation of activation products in the steel and waste products. The principal findings are that most of the induced activity remains in the metal rather than accumulating in the slag, and that while the slag remains a low-level waste under the assumptions employed, its volume actually exceeds that of the recycled material, and it therefore did not constitute a successful waste volume reduction technique. [ABSTRACT FROM AUTHOR]

Scrap tires pose a significant challenge as a common and inconvenient form of waste, resulting in non-functional waste products that are difficult to dispose of effectively. With an annual production of nearly 1.5 billion tires, the environmental pollution caused by their eventual disposal in the trash stream is a pressing concern. The European Union has imposed a ban on tire dumping, emphasizing the need for tire collection and recycling instead. Pyrolysis emerges as a promising solution, enabling the dissolution of waste while simultaneously yielding valuable by-products. This process involves the transformation of tires into gas, liquid, and solid phases. The heat value of pyrolytic gases during liquefaction reaches approximately 30–40 MJ/Nm3, providing ample energy not only for sustaining the pyrolysis process but also for alternative applications. Nonetheless, the presence of excessive SO 2 in flue gases poses a significant obstacle, surpassing legal limits, while HCl, NO X , and heavy metals may also contribute to similar environmental concerns. To meet regulatory standards and optimize pyrolysis efficiency, gas cleaning techniques are indispensable for eliminating these chemicals from the dissipating gases generated during discarded tire pyrolysis. Given that pyrolysis gas exhibits excellent potential as a gaseous fuel, this article's primary objective is to comprehensively evaluate its characteristics for energy recovery, while also outlining potential consequences that need to be addressed. • Pyrolytic gas obtained from waste tires is a valuable source of energy. • Composition and properties of pyro gas varies depending on pyrolysis conditions. • The special emphasis should be focused on the collection of data on gas emissions. • Pyrolysis of waste tyres produces oil, gas, and char, and recovered steel. • Batch, screw kiln, rotary kiln, vacuum and fluidized-bed are main reactor types. [ABSTRACT FROM AUTHOR]

The recycle rate of waste flat glass is quite low in spite of higher SiO2 content and its pre‐melted characteristic. This study searched a novel approach for the fabrication of Si3N4 powder by carbo‐thermal reduction and nitridation from waste glass. For comparison, starting powder mixtures were prepared from silica and waste SLS (soda‐lime‐silica) glass. Carbo‐thermal reduction and nitridation process was conducted using two temperatures and different atmospheres. The results showed that equiaxed, micron size β‐Si3N4 particle could be synthesized from waste glass. The use of waste glass reduced the amount of fiber‐like Si3N4 particles and SiC phase by increasing the amount of the liquid phase formed. This study proved the utilization of waste flat glass as a low cost and environment friendly SiO2 source. [ABSTRACT FROM AUTHOR]

Colemanite (CaO·3B 2 O3·5H 2 ) enrichment waste material from mines was employed as an alternative to boric acid (H 3 BO 3 ) for producing opaque matt frits. The aim of the study was to reduce boric acid consumption and to substitute boron-containing waste material for H 3 BO 3 used for frit production. Laboratory and pilot-scale production was carried out based on frit production methods currently used in the ceramic industry. The frits were then used to produce commercial glossy opaque glazes using existing fabrication and sintering processes with amounts ranging between 16 and 31 wt%. The fabricated glazes successfully passed EN ISO 10545 testing, exhibiting desirable surface abrasion, chemical resistance, thermal shock resistance, and staining characteristics. [ABSTRACT FROM AUTHOR]

A large amount of waste coconut shell is generated in India from temples and industries of coconut product and its disposal need to be addressed. Researchers have proposed to utilize it as ingredient of concrete. This experimental investigation was aimed to quantify the effects of replacing partially the conventional coarse aggregate by coconut shell to produce concrete. The research work was divided into two parts. First part was aimed to observe the effect of such replacement on compressive strength and density of concrete. In the second part, the aim was to find out the additional quantity of cement required to compensate for reduction in strength of concrete resulted due to this replacement. It was found that with increasing proportion of coconut shells, there is decrement in compressive strength. Results revealed that with 40% replacement of conventional coarse aggregate by coconut shell, 7 days compressive strength of concrete decreased by 62.6%; whereas decrease in 28 days compressive strength was only 21.5%. 40% replacement makes the concrete lighter by 7.47%. Further, it was revealed that for mix design of concrete of 20 N/mm 2 characteristic strength, no additional cement is required for 5% replacement and only 3.6% additional cement was required for 10% replacement. The results confirm that although there is an increase in cost due to additional cement requirement, the advantages being many, including efficient utilization of waste coconut shell, reduction in natural source depletion etc , the use of coconut shell in concrete seems to be a feasible option. Such study will help to arrive at final decision regarding quantity of coconut shell for replacing conventional aggregates in concrete production. [ABSTRACT FROM AUTHOR]

Alum salts are commonly used in the water industry to promote coagulation in the production of clean drinking water, which results in the generation and accumulation of ‘waste’ by-product ‘alum sludge’ in large volumes. Effective and efficient management of alum sludge in an economically and environmentally sustainable manner remains a significant social and environmental concern with ever increasing demand for potable water as a result of rapidly escalating world population and urban expansion. Various intensive practices have been employed to reuse the alum sludge in an attempt to figure out how to fill the gap between successful drinking water treatment process and environmentally friendly alum sludge management for over the years. This paper primarily aimed at comprehensive review of the existing literature on alum sludge characteristics, its environmental concerns and their potential utilization, especially in agricultural and horticultural sectors leading to update our recent state of knowledge and formulate a compendium of present and past developments. Different types of alum sludge utilizations in various fields were recognized and examined. The strengths, weaknesses, opportunities and potential risks of alum sludge reuse options with particular reference to agriculture were highlighted and knowledge gaps were identified. Research priorities and future challenges that will support in the development of effective alum sludge management practices in agriculture with multi-prong strategies were discussed. [ABSTRACT FROM AUTHOR]

The calorimetric measurements were applied in testing the wastes collected from different furnaces in electric power plants as materials to be used in civil engineering. The fly ash materials were collected from two power stations based on different brown coal deposits and working with conventional and fluidized bed installation. The reactivity of high calcium fly ash from sub-bituminous coal combustion has been proved in calorimetric, conductometric, chemical shrinkage, and rheological measurements before their practical implementation on larger scale. Highly soluble components of fly ash contribute to the hydration products and structure formation, followed by setting and hardening of fly ash-cement mixture. These results have been the base of research project aimed in the innovative solutions dealing with the management of deposits of wastes generated as a result of coal combustion. The standardization and potential use on larger scale of these materials, necessary from the environmental point of view, seems to be the question of nearest future. [ABSTRACT FROM AUTHOR]

This work aims to explore the self-sustaining smoldering treatment (SSST) for the destruction of food waste. The food waste used in this work mainly consists of cereal, vegetable, and meat. To examine the processing procedures and parameters, three experimental groups (raw food waste, food-waste paste and food-waste paste blended with anthracite) and five variables (moisture content, sand size, sand-to-food waste ratio, air flow and food waste-to-coal ratio) were extensively investigated. Results show that raw food waste with 40% moisture content can be disposed by SSST with the mass destruction ratio over 90%. However, the robustness of SSST for raw food waste is constrained by the heterogeneous issue due to a variety of components and sizes of food waste. This issue is addressed through stir pre-processing of raw food waste as food-waste paste. The robustness of SSST for food waste is significantly further enhanced only if a slight mass fraction of anthracite (<20% of raw food waste) is supplemented. This provides an alternative solution for employing SSST for raw food waste with very high moisture content. [Display omitted] • SSST is an energy-efficient approach destructing food waste. • Anisotropic issue is addressed by stirring food waste into pasty material. • SSST's robustness is improved while replacing raw food waste by food-waste paste. • Slight supplementary of anthracite is an alternative to SSST for highly wetted food waste. [ABSTRACT FROM AUTHOR]

Treatment of AMD with fly ash (FA) is a promising technology but solid residues (SR) generated in the process pose a disposal challenge. This study evaluates the suitability of the SR and SR, FA/ordinary Portland cement (OPC) blends for backfill in mine voids and in-situ treatment of AMD flows. The mitigation of AMD in a mine void was simulated by addition of simulated acid mine drainage (SAMD) to FA, SR, SR + 25 % FA and SR + 6 % OPC packed columns. Acidity neutralisation in AMD was achieved over the study period. PHREEQC modelling indicated that precipitation of contaminants bearing mineral phases contributed to low levels of contaminants. Leaching of toxic trace elements and attenuation of contaminants strongly depended on the pH regime. Results revealed that backfill of coal mine voids with SR is a promising approach for large scale disposal of SR and treatment of AMD flows insitu. [ABSTRACT FROM AUTHOR]

The problems of valorisation of particleboard wastes on one hand, and contamination of aqueous effluents by phenolic compounds on the other hand, are simultaneously considered in this work. Preparation of activated carbons from a two steps thermo-chemical process, formerly designed for generating combustible gases, is suggested. The resultant carbonaceous residue is activated with steam at 800°C. Depending on the preparation conditions, surface areas within the range 800–1300m2/g are obtained, close to that of a commercial activated carbon (CAC) specially designed for water treatment and used as a reference material. The present work shows that particleboard waste-derived activated carbons (WAC) are efficient adsorbents for the removal of phenol from aqueous solutions, with maximum measured capacities close to 500mg/g. However, most of times, the adsorption capacities are slightly lower than that of the commercial material in the same conditions, i.e., at equilibrium phenol concentrations below 300ppm. Given the extremely low cost of activated carbons prepared from particleboard waste, it should not be a problem to use it in somewhat higher amounts than what is required with a more expensive commercial material. Phenol adsorption isotherms at 298K were correctly fitted by various equations modelling type I and type II isotherms for CAC and WAC, respectively. Phenol adsorption isotherms of type II were justified by a 3-stages adsorption mechanism. [Copyright &y& Elsevier]

Despite legislation governing the handling of red meat abattoirs waste in South Africa, irregularities still occur. Economic conditions in South Africa force under-privileged communities to scavenge on landfill sites, dumping grounds and abattoir disposal sites. Condemned products/carcasses are eaten by ‘scavengers’ which could lead to significant health problems, disease and death. The waste products generated and the waste disposal strategies used was determined. A condemned product waste handling model was developed, causing minimum environmental pollution, reducing health risks and adding value to these products. Waste handling practices of 78 red meat abattoirs were determined by administering questionnaires and site visits. Most condemned products were buried/burned whereas most blood was disposed of into municipal drainage systems with the waste water. Limited by-product processing, denaturing and incineration took place. Minimal amounts of stomach contents and manure were utilized as compost but were mostly dumped on municipal landfill sites or farm land. [ABSTRACT FROM AUTHOR]

The article presents an overview of the environmental protection agency's low-activity waste effort for the improvement of radioactive waste management. It states that radioactive waste disposal in the United States is marked by a fragmented regulatory system, with requirements that often focus on the origin or statutory definition of the waste, rather than the hazard of the material in question. It summarizes aspects of an approach focusing on the potential use of Resource Conservation and Recovery Act Subtitle-C hazardous waste landfills for disposal of low-activity wastes and public comments on the suggested approach.

The article presents a discussion of a collaboration of government and industry relative to the Spanish Protocol for radiological surveillance of metal recycling. When the presence of radioactive materials in scrap metal has been detected, the national authorities, involved private companies, and the main trade unions drafted a protocol for prevention of and responding to such situations. It explains that the Protocol is a voluntary agreement defining the radiological surveillance of scrap metal and its products and the duties and rights of the signatories. It mentions that 461 pieces of ferric scrap were detected including sources of radiation and contaminated metal.

The article presents a discussion of the Report No. 141 of the National Council on Radiation Protection and Measurements (NCRP) which is about management disposition of potentially radioactive scrap metal. It evaluates management policy and related issues regarding scrap metal generated in regulated facilities that have been under radiological control or have radiological issues. It estimates that more than 9 million metric tons of scrap metal of all types that have been associated with the production or use of radioactive materials will be generated during the next ten years at different facilities across the United States.

The most common form of onsite domestic wastewater treatment in the United States is the septic system. Although the design of these systems has been well established, no systematic evaluation of septic system performance exists for sloping hardpan soils. In this paper, we develop a simple hydrologic model for assessing the probability of failure for a set of hydrologic conditions, septic loading rates, and soil and landscape parameters that are readily available for sloping soils. To demonstrate the model capabilities, input data for a septic field of a two-person residence in the New York City drinking water basin in the Catskills was utilized. Our analysis showed that the saturated hydraulic conductivity, depth to the impermeable layer, and slope of the drain field are critical parameters to assess in the design and siting of these systems. We concluded that septic systems perform poorly in undulating landscapes where the hydraulic conductivity is low and the impermeable layer is close to the surface. Under prolonged rainfall conditions on these soils, the septic field and downslope field saturate, causing hydraulic failure of the septic system and saturation in the downslope field; as a result, effluent may be routed directly to streams via overland runoff. [ABSTRACT FROM AUTHOR]

Underground concrete vaults have been and are planned to be used to store contaminated materials, such as hazardous materials and radioactive waste, over long periods of time. To protect humans from exposure to the contamination, the key to this long-term storage is immobilization achieved through designing concrete vaults with enhanced hydraulic performance. This paper evaluates concrete vault design parameters including properties of soil layers surrounding the vault, vault size, slope of the vault roof, and the amount of concrete degradation under various infiltration rates. A numerical model that estimates the flow of water through the vault is used as the computer simulation tool. Conclusions from the modeling simulations are that clay layers, including sand and loam layers forming a capillary barrier and placed adjacent to the vault concrete, were found to have a better hydraulic performance. Smaller vault sizes result in lower seepage through the vault and suggest a scale effect. Roof slope has a relatively small influence on hydraulic performance. [ABSTRACT FROM AUTHOR]

Intermittent sand filtration is a common and effective method for treating septic tank effluent. However, if the loading rate is too high, clogging and ponding of the sand filter surface layer can occur due to the accumulation of excessive biomass and the deposition of suspended solids. This ponding limits the practicality of sand filtration as it makes it necessary to take the filter out of service for maintenance. The objective of this study was to develop and test, on-site, a new hybrid filter system that would reduce the risk of clogging at an organic loading rate substantially greater than the maximum recommended loading rate for intermittent sand filters. The system comprised a 0.6 m deep horizontal flow biofilm reactor (HFBR) over a 0.85 m deep stratified sand filter. The HFBR consisted of a stack of 20 horizontal corrugated polyvinyl chloride sheets, at 32 mm vertical spacings. The sheets were arranged so that the wastewater flowed over and back along alternate sheets down through the stack. The main biofilm growth formed on these sheets. The hybrid filter was loaded with septic tank effluent from an office/garage complex at the rate of 206 L/m2 day for a period of 400 days in two phases. During the first phase, the effluent volume of 600 L/day was applied in 24 doses/day for 10 min/dose, and during the second phase in 6 doses/day for 40 min/dose. Biofilms in the HFBR substantially reduced the organic and suspended solids loads that reached the sand filter surface and allowed an average total biochemical oxygen demand (BODT) loading rate, based on HFBR plan area, of 37 g BODT/m2 day to be applied to the system without clogging. This rate was substantially greater than the maximum recommended loading rate of 24 g BODT/m2 day for intermittent sand filters. During both loading phases a BODT removal of 94% was achieved and nitrification was nearly complete. The average effluent BODT was 12±4 mg/L during both phases. The hybrid filter system appeared to perform better in terms of suspended solids handling and nitrification during the more frequent dosing phase. The hybrid filtration system offers a more compact alternative to intermittent sand filtration on its own with little risk of clogging. [ABSTRACT FROM AUTHOR]

Abstract: Many attributes of present day soils can only be explained by reference to land management in the historic past. This is particularly well expressed in the plaggen soils which occur extensively on the north European plain. These deepened soils owe their dominant characteristics to the application from the 12th century of turf materials, often impregnated with dung. Similar deepening of soils can result from the disposal of urban waste. This paper discusses the results of soil research focused on a small Scottish town (Nairn). A soil survey revealed topsoils of over 1m overlying fluvioglacial sands and gravels; such deepening is explained by the use of town waste on the burgh''s arable lands from at least the 17th century up until the mid-19th century when an integrated sewerage system was installed. Micromorphological study of this deepened topsoil revealed the presence of many small black carbonaceous particles. Oxygen:carbon ratios were calculated from microprobe results as a means of confirming the carbonaceous nature of these particles. Soil phosphorus was primarily concentrated on the perimeter of these particles. The high quality of present day soils on the edge of the town is explained by the disposal of waste material, which included much carbonised material. This paper is the first to highlight the importance and potential of examining the gradation in soils from urban to rural contexts. [Copyright &y& Elsevier]

Experiments on the near-field mixing of wastewater discharged from multiport diffusers into a stationary density-stratified environment are reported for conditions typical of ocean sewage outfalls. Dilutions were measured with a microconductivity probe in which the test tank was stratified with a nonconducting solution; geometrical characteristics such as rise height and layer thickness were measured by planar laser-induced fluorescence in which the test tank was stratified with refractive-index matched fluids. The port spacing was varied over a wide range encompassing rapidly merging to nonmerging plumes. The end of the near-field occurs at a distance of order one plume rise height from the diffuser. At this point the turbulence and mixing induced by the discharge is effectively damped by the ambient stratification, and little near-field mixing occurs beyond it. The results were analyzed in terms of line and point-source parameters to deduce the ranges of port spacings for which line and point plume solutions apply. Equations to predict the near-field characteristics are presented. [ABSTRACT FROM AUTHOR]

Experiments on the near-field mixing of wastewater discharged from multiport diffusers into stratified flowing waters are reported for conditions typical of actual ocean sewage outfalls. Dilutions were measured by a newly developed three-dimensional laser-induced fluorescence system combined with refractive-index matching and by a microconductivity probe. The plume dynamics are complex. Depending on port spacing, plumes discharged from the upstream diffuser side may merge first with themselves, and then with the plumes discharged from the downstream side. Or the plumes that are horizontally opposed may first merge, followed by lateral merging. In all cases, however, the wastefield eventually becomes laterally homogeneous. The results are analyzed in terms of line or point-source parameters and it is found that they can be predicted by assuming the discharge to be a line plume when s/lb<1.0 and as point plumes for s/lb>=6.0. Semiempirical equations to predict the near-field dilution, near-field length, and plume rise height are presented. [ABSTRACT FROM AUTHOR]

Abstract: Biomass waste in the form of biomass flax fibre, produced as a by-product of the textile industry was processed via both physical and chemical activation to produce activated carbons. The surface area of the physically activated carbons were up to 840m2 g−1 and the carbons were of mesoporous structure. Chemical activation using zinc chloride produced high surface area activated carbons up to 2400m2 g−1 and the pore size distribution was mainly microporous. However, the process conditions of temperature and zinc chloride concentration could be used to manipulate the surface area and porosity of the carbons to produce microporous, mesoporous and mixed microporous/mesoporous activated carbons. The physically activated carbons were found to be a mixture of Type I and Type IV carbons and the chemically activated carbons were found to be mainly Type I carbons. The development of surface morphology of physically and chemically activated carbons observed via scanning electron microscopy showed that physical activation produced activated carbons with a nodular and pitted surface morphology whereas activated carbons produced through chemical activation had a smooth surface morphology. Transmission electron microscopy analysis could identify mesopore structures in the physically activated carbon and microporous structures in the chemically activated carbons. [Copyright &y& Elsevier]

Spent or disused sealed radiation sources—no longer needed sources—may represent a risk of radiological accident or may be a target for criminal acts in countries where final disposal options are unavailable and where an increasing number of sources are being kept in extended storage. In developing countries, thousands of radium needles, teletherapy sources, oil well logging neutron sources, and miscellaneous industrial radioactive gauges are annually collected as waste and stored in research institutes. The objectives of the study described in this paper are to inventory such sources in Brazil, including those presently in use and those already collected as waste, and to design a dedicated repository where spent sources could be disposed of properly. The inventory of sources in Brazil and the concept of the repository are presented and its feasibility is discussed. [ABSTRACT FROM AUTHOR]

Many communities face a waste management crisis. An increase in waste generation and decline in available landfill capacity have led to rapid increases in waste management costs. Using sewage sludge management in coastal New York and New Jersey as an example, this paper examines optimal multimedia waste disposal under cost uncertainty. Using expected value-variance analysis, the study looks at the effects on the optimal disposal strategy of uncertainty associated with waste-management cost and the community's risk preferences. The results indicate that, based on available cost data, the optimal strategy of a moderately risk-averse decision maker is to manage sludge through land-based facilities. These results hold over a wide range of risk-aversion parameters and even at low levels of cost uncertainty. Thus, the Ocean Dumping Ban Act of 1988 is consistent with such results. [ABSTRACT FROM AUTHOR]

A Pt catalyst supported on activated carbon (Pt/AC) was used for an environmentally friendly thermal treatment of food waste under an inert atmosphere (i.e., pyrolysis). This catalyst influenced the amounts of condensable hydrocarbons and noncondensable gases but not that of the solid remaining after the pyrolysis; in particular, it contributed to shifting the carbon distribution from the condensable hydrocarbons to the noncondensable gases for the food waste pyrolysis. Moreover, its use suppressed the generation of harmful chemical compounds, especially at high temperatures. For example, a Pt/AC-catalyzed pyrolysis at 700 °C produced about 4 times fewer benzene derivatives than the same treatment without a catalyst; this probably occurred because the Pt sites catalyzed the decyclization reaction and/or the free radical mechanism, which is dominant in the thermal cracking of carbon-containing feedstock. This study suggests that a Pt/AC-catalyzed pyrolysis would be a more environmentally benign food waste treatment method. • The Pt catalyst influenced the amounts of the products of food waste pyrolysis. • The Pt catalyst reduced the generated condensable hydrocarbon content. • The Pt catalyst increased the generated noncondensable gas content. • The Pt catalyst reduced the generated benzene derivative content. [ABSTRACT FROM AUTHOR]