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Composition and production rate of dental solid waste in Xanthi, Greece: variability among dentist groups.

The objective of this work was to determine the composition and production rate of dental solid waste, produced by dental practices in the Prefecture of Xanthi, a multicultural area in Northeast Greece with a population of 102,000. For the study, 22 private dental practices and 1 public dental practice were selected of the 48 private and 5 public dental practices in operation. The 22 private dental practices included 16 owned by Christian Greek-born dentists, 3 by Moslem dentists and 3 by Christian dentists repatriated from the former Soviet Union. Differentiation on the basis of religion is directly related to the countries from which dentists received their training, e.g., Greece-European Union, Turkey and former Soviet Union. Thus, including the one public dental practice, 4 study groups were considered. Waste collection took place for 22 working days, from 20 May to 27 June 2002. This period was considered to be a representative one for a semi-rural area, such as Xanthi. Dentists were instructed to collect the total amount of waste they produced. A total of 260 kg dental solid waste was collected during the study period and was manually separated. Dental solid waste was classified in three main categories: (1) Infectious and potentially infectious waste, accounting for 94.7% by weight. (2) Non-infectious waste accounting for 2.0%. (3) Domestic-type waste, accounting for 3.3% by weight. The category of infectious waste is classified as hazardous and includes components containing metal (8.51%), components without metal (91.18%) and amalgam (0.33%). Using the weight data, the production rate of dental solid waste for the study period in the Prefecture of Xanthi was determined to be 513 g/practice/day and of infectious and potentially infectious waste 486 g/practice/day. The latter includes the production rate of sharps (9.8 g/practice/day), non-sharps (31.6), infectious waste without metal (443) and amalgam (1.6 g/practice/day). Since dental solid waste is currently disposed of in landfills together with the municipal solid waste, the results of the study were used to suggest an appropriate management scheme. The results were also used to compare the composition and production rates of dental solid waste produced by the 4 study groups.

Data Collection↗

Worrying about waste: living close to solid waste disposal facilities in southern Ontario.

As a complement to an epidemiological survey, depth interviews were used to discover the individual level impacts of living close to waste disposal facilities in southern Ontario. The paper begins by describing the nature of the sites and reporting some of the survey findings, which the depth interviews explored. Sample selection and data analysis methods are described. A by-code analysis of the material is presented, emphasizing both within- and between-site differences in type and concern (or impact). Concern varied according to type of exposure and site context. The paper ends with a discussion which relates the study's findings on non-toxic facilities to other research on psychosocial effects, lay reasoning and risk perceptions and assessments.

Adaptation, Psychological↗

Characterization and management of municipal solid waste of Srinagar-Garhwal.

Characterization and physico-chemical composition of municipal solid waste of Srinagar-Garhwal, a hill town of Uttaranchal were carried out to know the composition of solid waste for its efficient management. A total of 28,56,500 kg (2,856.5 tonnes) of solid waste was produced per annum. A disposal site away from the open bank of Alaknanda has been suggested. 1,500 m3 volume of land will be required for the land filling of half of the solid waste generated in Srinagar town. In addition to it, 60 numbers of trenches (size 10 m x 3 m x 1 m) with clear spacing of 2.0 m will be required for the composting of remaining half of the solid waste. A list of suggestions has also been made for reducing the waste generation at source.

Conservation of Natural Resources↗

Disposal of solid waste in Istanbul and along the Black Sea coast of Turkey.

The increasing amount of solid waste arising from municipalities and other sources and its consequent disposal has been one of the major environmental problems in Turkey. Istanbul is a metropolitan city with a current population of around 14 million, and produces about 9000 ton of solid waste every day. The waste composition for Istanbul has changed markedly from 1981 to 1996 with large decreases in waste density, much of which is related to decreased amounts of ash collected in winter. In recent years, the Istanbul region has implemented a new solid waste management system with transfer stations, sanitary landfills, and methane recovery, which has led to major improvements. In the Black Sea region of Turkey, most of the municipal and industrial solid wastes, mixed with hospital and hazardous wastes, are dumped on the nearest lowlands and river valleys or into the sea. The impact of riverside and seashore dumping of solid wastes adds significantly to problems arising from sewage and industry on the Black Sea coast. Appropriate integrated solid waste management systems are needed here as well; however, they have been more difficult to implement than in Istanbul because of more difficult topography, weaker administrative structures, and the lower incomes of the inhabitants.

Cities↗

[Method for estimating the population risk attributable to a transfer station of municipal solid waste].

Due to the great volume of municipal solid waste that is produced daily in the Metropolitan Area of Mexico City a sound management has been an impossible task. This is why during the past few years solid waste transfer stations have been constructed in the City, allowing a more efficient solid waste collection. The attributable risk to the population's health for the operation of such stations needs to be assessed in order to have them working within the urbanized areas without posing a potential risk to the health of the inhabitants of the inhabitants of the surrounding areas.

Adolescent↗

Solid waste management practices in U.S. Army medical treatment facilities.

U.S. Army medical treatment facilities (MTFs) will be challenged to reduce waste as the Army internalizes as environmental ethic and privatizes solid waste management. A questionnaire was modified to survey solid waste management practices, participation in waste reduction and recycling programs, and solid waste management problems in 25 MTFs. Questionnaires were returned by 19 (76%) of the sites. Eighteen sites participated in waste reduction and recycling programs. Twelve sites used contractors to disinfect potentially infectious solid waste off site. Mean importance ratings of waste reduction and recycling were 2.00 and 1.83 (1 = very important; 5 = very unimportant), respectively. Limited staffing was ranked as the most significant waste management problem, followed by cost and regulatory compliance. More information on waste generation in MTFs is needed. The Army Medical Department should be presented as a model of environmental and natural resource stewardship for the health care industry.

Conservation of Natural Resources↗

Integrated waste management--looking beyond the solid waste horizon.

Waste as a management issue has been evident for over four millennia. Disposal of waste to the biosphere has given way to thinking about, and trying to implement, an integrated waste management approach. In 1996 the United Nations Environmental Programme (UNEP) defined 'integrated waste management' as 'a framework of reference for designing and implementing new waste management systems and for analysing and optimising existing systems'. In this paper the concept of integrated waste management as defined by UNEP is considered, along with the parameters that constitute integrated waste management. The examples used are put into four categories: (1) integration within a single medium (solid, aqueous or atmospheric wastes) by considering alternative waste management options, (2) multi-media integration (solid, aqueous, atmospheric and energy wastes) by considering waste management options that can be applied to more than one medium, (3) tools (regulatory, economic, voluntary and informational) and (4) agents (governmental bodies (local and national), businesses and the community). This evaluation allows guidelines for enhancing success: (1) as experience increases, it is possible to deal with a greater complexity; and (2) integrated waste management requires a holistic approach, which encompasses a life cycle understanding of products and services. This in turn requires different specialisms to be involved in the instigation and analysis of an integrated waste management system. Taken together these advance the path to sustainability.

Conservation of Natural Resources↗

Kinetics of accelerated solid-state fermentation of organic-rich municipal solid waste.

Biotransformation of landfill solid wastes is a slow process requiring decades for completion. Accelerated anaerobic fermentation in modulated landfill environments may alleviate or eliminate pollution of land, water and air. This research was undertaken to demonstrate the application of biphasic fermentation to a simulated laboratory-scale landfill to effect rapid biomethanation of biodegradable solids. The biphasic process consisted of solid-state, acidogenic fermentation of the organic fraction of MSW followed by biomethanation of acidic hydrolysates in a separate methane fermenter. Solid-state fermentation of the MSW with effluent recirculation resulted in rapid hydrolysis, acidification and denitrification, with soluble COD and VFA concentrations accumulating to inhibitory levels of 60,000 mg/l and 13,000 mg/l, respectively, at a pH of 4.5. The landfill gas methane concentration reached a maximum of 55 mol.%. By comparison, the methanogenic reactor produced high methane-content (70-85 mol.%) gases. The biphasic process effected carbohydrate, lipid, and protein conversion efficiencies of 90%, 49%, and 37%, respectively. Development of a Monod-type product-formation model was undertaken to predict methane formation and to determine kinetic parameters for the methanogenic processes in the simulated landfill and separate methane reactors. A first-order solids hydrolysis rate constant of 0.017 day-1 was evaluated to show that landfill solids hydrolysis was slower than the inhibited methanogenesis rate.

Bacteria, Anaerobic↗

Solid Waste Management in Nigeria: Problems and Issues.

/ This paper is a presentation of the problems of solid waste management in Nigeria and certain important issues that must be addressed in order to achieve success. At the core of the problems of solid waste management are the absence of adequate policies, enabling legislation, and an environmentally stimulated and enlightened public. Government policies on the environment are piecemeal where they exist and are poorly implemented. Public enlightenment programs lacked the needed coverage, intensity, and continuity to correct the apathetic public attitude towards the environment. Up to now the activities of the state environmental agencies have been hampered by poor funding, inadequate facilities and human resources, inappropriate technology, and an inequitable taxation system. Successful solid waste management in Nigeria will require a holistic program that will integrate all the technical, economic, social, cultural, and psychological factors that are often ignored in solid waste programs.KEY WORDS: Solid waste; Management; Problems; Solutions; Nigeria

Journal Article↗

Size charge fractionation of metals in municipal solid waste landfill leachate.

Municipal solid waste landfill leachates from 9 Norwegian sites were size charge fractionated in the field, to obtain three fractions: particulate and colloidal matter >0.45microm, free anions/non-labile complexes <0.45microm and free cations/labile complexes <0.45microm. The fractionation showed that Cd and Zn, and especially Cu and Pb, were present to a large degree (63-98%) as particulate and colloidal matter >0.45microm. Cr, Co and Ni were on the contrary present mostly as non-labile complexes (69-79%) <0.45microm. The major cations Ca, Mg, K, and Mn were present mainly as free cations/labile complexes <0.45microm, while As and Mo were present to a large degree (70-90%) as free anions/non-labile complexes <0.45microm. Aluminium was present mainly as particulate and colloidal matter >0.45microm. The particulate and colloidal matter >0.45microm was mainly inorganic; indicating that the metals present in this fraction were bound as inorganic compounds. The fractionation gives important information on the mobility and potential bioavailability of the metals investigated, in contrast to the total metal concentrations usually reported. To study possible changes in respective metal species in leachate in aerated sedimentation tanks, freshly sampled leachate was stored for 48h, and subsequently fractionated. This showed that the free heavy metals are partly immobilized during storage of leachate with oxygen available. The largest effects were found for Cd and Zn. The proportion of As and Cr present as particulate matter or colloids >0.45microm also increased.

Chemical Fractionation↗

A GIS based transportation model for solid waste disposal--a case study on Asansol municipality.

Uncontrolled growth of the urban population in developing countries in recent years has made solid waste management an important issue. Very often, a substantial amount of total expenditures is spent on the collection of solid waste by city authorities. Optimization of the routing system for collection and transport of solid waste thus constitutes an important component of an effective solid waste management system. This paper describes an attempt to design and develop an appropriate storage, collection and disposal plan for the Asansol Municipality Corporation (AMC) of West Bengal State (India). A GIS optimal routing model is proposed to determine the minimum cost/distance efficient collection paths for transporting the solid wastes to the landfill. The model uses information on population density, waste generation capacity, road network and the types of road, storage bins and collection vehicles, etc. The proposed model can be used as a decision support tool by municipal authorities for efficient management of the daily operations for transporting solid wastes, load balancing within vehicles, managing fuel consumption and generating work schedules for the workers and vehicles. The total cost of the proposed collection systems is estimated to be around 80 million rupees for the fixed cost of storage bins, collection vehicles and a sanitary landfill and around 8.4 million rupees for the annual operating cost of crews, vehicles and landfill maintenance. A substantial amount (25 million rupees/yr) is currently being spent by AMC on waste collection alone without any proper storage/collection system and sanitary landfill. Over a projected period of 15 yr, the overall savings is thus very significant.

Costs and Cost Analysis↗

[A study about the interrelation between the pH values of solid wastes and extracting solvents].

A preliminary study about the interrelation between the pH values of solid wastes and extracting solvents has been conducted. The result showed that the amount of trace metals dissolved was significantly different when the solid waste samples with different pH values were extracted by extracting solventsin different pH values. The amount of trace metals was great for acidic waste samples in the low pH(pH 2-4) extracting solvents. When the pH values of the extracting solvents were at pH 4-8, the amount of heavy metals dissolved reached their end points. For neutral solid wastes, the amount of dissolved metals were not largely effected by the pH values of the extracting solvents. For basic solid waste, there were not noticeable amount of metals were dissolved in the extracting solvents with different pH values. Moreover, the compounds's formation of the metals in the samples had a direct effect on the amount of metals dissolved. This study suggested that it could be very environmentally harmful when improperly stored or buried solid wastes were washed or immersed in acid rains. The article also suggested that regional environmental testing standards should be established based on the pH value of the precipitation in the area.

Adsorption↗

A multiple criteria analysis for household solid waste management in the urban community of Dakar.

Household solid waste management is a severe problem in big cities of developing countries. Mismanaged solid waste dumpsites produce bad sanitary, ecological and economic consequences for the whole population, especially for the poorest urban inhabitants. Dealing with this problem, this paper utilizes field data collected in the urban community of Dakar, in view of ranking nine areas of the city with respect to multiple criteria of nuisance. Nine criteria are built and organized in three families that represent three classical viewpoints: the production of wastes, their collection and their treatment. Thanks to the method PROMETHEE and the software ARGOS, we do a pair-wise comparison of the nine areas, which allows their multiple criteria rankings according to each viewpoint and then globally. Finding the worst and best areas in terms of nuisance for a better waste management in the city is our final purpose, fitting as well as possible the needs of the urban community. Based on field knowledge and on the literature, we suggest applying general and area-specific remedies to the household solid waste problems.

Belgium↗

Characterization of fuel gas products from the treatment of solid waste streams with a plasma arc torch.

This work addresses the plasma treatment of two solid waste streams and production of fuel gases from the process. In this study, carpet waste and simulated solid wastes generated by a United States Air Force Basic Expeditionary Airfield Resources Base deployment were used. Waste was treated in a furnace fitted with a 100kW plasma arc torch. The off gas was analyzed to determine its composition. The product gas was composed primarily of carbon monoxide and hydrogen, with small amounts of methane, benzene and toluene also detected. These experiments demonstrate the feasibility of producing fuel gases by plasma treatment of the solid waste streams. While the thermal energy value of the fuel gas produced in these experiments was less than the energy input, a higher waste-to-fuel gas conversion efficiency is expected in full-scale application.

Benzene↗

Application of FT-IR for assessment of the biological stability of landfilled municipal solid waste (MSW) during in situ aeration.

Disposal of untreated municipal solid waste leads to gaseous emissions as well as liquid degradation products. In situ aeration is an emerging means for remediation of abandoned landfills. It aims at an accelerated mineralization and stabilization of waste organic matter and thus reduces significantly the emission potential of the site. In order to prove the success of the technique, evaluation of the biological stability of the aerated material has been suggested. Fourier Transform Infrared Spectroscopy (FT-IR) provides comprehensive information on the chemical composition of solid waste samples. Different stages of organic matter degradation are reflected by changes in the infrared spectral pattern. In the present study the feasibility of applying FT-IR for assessment of the stability of waste material derived from abandoned landfills and for in situ aeration process control was investigated. Waste samples derived in the course of pilot-scale and lab-scale aeration experiments were characterized by FT-IR (4000-400 cm(-1), KBr-technique, transmission mode) and a set of conventional parameters describing biological stability. The occurrence of distinct indicator bands was correlated with chemical and biological waste properties using 206 solid waste samples. Visual spectra interpretation was found to be appropriate in proving a reduced emission potential of initially rather reactive waste (respiration activity over 4 days (RA(4)) > 7 mg O(2) g(-1) DM) during aeration. Furthermore, cluster analysis was applied successfully to differentiate between original and aerated waste samples, even for rather stable material (RA(4) < 7 mg O(2) g(-1) DM), when visual spectra interpretation was limited.

Cluster Analysis↗

Digestibility and utilization of energy and protein in screened swine waste solids by gestating gilts.

Two balance experiments were conducted using 24 gestating gilts in each experiment to determine the apparent digestible and metabolizable energy content, apparent digestible protein content, net protein utilization and apparent biological value of screened swine waste solids (SSWS). Waste solids were collected by screening flushed whole swine waste using a vibrating screen separator. Waste solids containing 30% dry matter were collected daily and mixed with a basal diet. In Exp. 1, SSWS were fed at a level estimated to replace 0, 25, 50 or 86% of the metabolizable energy content of the basal diet. Digestibility of the energy in the total diet decreased quadratically (85.2, 70.2, 60.7 and 58.3%, respectively, P less than .0001) with increasing SSWS. The percentages of gross energy supplied by SSWS that were digested and metabolized, as calculated by difference, were not affected significantly by the amount of SSWS fed (48.0, 48.0, 53.2% digested and 45.1, 45.2, 48.1% metabolized, respectively, for 25, 50 and 86% of gross energy intake from SSWS). The mean digestible and metabolizable energy contents of SSWS for gestating gilts were determined to be 1,998 and 1,854 kcal/kg dry matter. In Exp. 2, gilts were fed SSWS to replace 0, 25 or 50% of the crude protein in the basal diet. Apparent digestibility of the protein in the total diet decreased linearly (83.8, 66.1 and 51.1%, respectively, P less than .0001) as the amount of SSWS in the diet increased. The apparent digestibility of the crude protein in SSWS, as calculated by difference, was -4.23 and 10.1% for the 25 and 50% level of replacement.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

Solid waste treatment and disposal: effects on public health and environmental safety.

The safety and acceptability of many widely used solid waste management practices are of serious concern from the public health point of view. Such concern stems from both distrust of policies and solutions proposed by all tiers of government for the management of solid waste and a perception that many solid waste management facilities use poor operating procedures. Waste management practice that currently encompasses disposal, treatment, reduction, recycling, segregation and modification has developed over the past 150 years. Before that and in numerous more recent situations, all wastes produced were handled by their producers using simple disposal methods, including terrestrial dumping, dumping into both fresh and marine waters and uncontrolled burning. In spite of ever-increasing industrialisation and urbanisation, the dumping of solid waste, particularly in landfills, remains a prominent means of disposal and implied treatment. Major developments have occurred with respect to landfill technology and in the legislative control of the categories of wastes that can be subject to disposal by landfilling. Even so, many landfills remain primitive in their operation. Alternative treatment technologies for solid waste management include incineration with heat recovery and waste gas cleaning and accelerated composting, but both of these technologies are subject to criticism either by environmentalists on the grounds of possible hazardous emissions, failure to eliminate pathogenic agents or failure to immobilise heavy metals, or by landfill operators and contractors on the basis of waste management economics, while key questions concerning the effects of the various practices on public health and environmental safety remain unanswered. The probable and relative effects on both public health and environmental safety of tradition and modern landfill technologies will be evaluated with respect to proposed alternative treatment technologies.

Attitude to Health↗

Research on solid waste management system: to improve existing situation in Corlu Town of Turkey.

Over the past decades, uncontrolled population growth and rapid urbanization and industrialization have resulted in environmental problems in Corlu Town, Turkey. One of the most important problems is solid waste due to inadequate management practices. Nowadays, increasing public awareness of the environment compels local authorities to define and to adopt new solutions for waste management. This paper presents a general overview of current solid waste management practices in Corlu Town and principles of the recommended municipal solid waste (MSW) management system. In Corlu, 170 tonnes of municipal solid waste are generated each day, or 1.150 kg per capita per day. Approximately one-half of the municipal solid waste generated is organic material and 30% of the MSW consists of recyclable materials. The recommended system deals with maximizing recycling and minimizing landfilling of municipal solid waste, and consists of separation at source, collection, sorting, recycling, composting and sanitary landfilling. This study also analyzed the recommended system with respect to feasibility and economics. To evaluate whether the suggested system is cost effective or not, the operating cost of the recommended system and market prices of recyclable materials were compared, and the results show that the recommended system will reduce required landfill volume up to 27% of compared to the present situation. The profit of the recommended system is estimated to be about 80 million US dollars.

Conservation of Natural Resources↗