Results 1 - 10 of 258
Results 1 - 10 of 258. Search took: 0.02 seconds
|Sort by: date | relevance|
[en] A successful recycling program requires several components: education and promotion, convenient collection service, and most importantly, a market for collected materials. In Washington state, domestic markets currently have, or are building, the capacity to use most of the glass, newsprint, aluminum, tin cans, and corrugated materials that are collected. Unfortunately, markets for mixed waste paper (MWP), a major component of the state's solid waste stream, have been slow to develop and are unable to absorb the tremendous volumes of material generated. The American Paper Stock Institute classifies MWP as low grade paper such as magazines, books, scrap paper, non-corrugated cardboard (boxboard/chipboard), and construction paper. When viewed as part of a curbside collection program MWP consists primarily of catalogs, binder paper, magazines, brochures, junk mail, cereal boxes, and other household packaging items. A comprehensive analysis of Washington State's solid waste stream showed that during 1988, Washington citizens generated approximately 460,000 tons of mixed waste paper. No small amount, this is equivalent to more than 10% of the total solid waste generated in the state, and is expected to increase. Current projections of MWP generation rates indicated that Washington citizens could discard as much as 960,000 tons of MWP by the year 2010 making it one of the single largest components of the state's solid waste stream. This paper reports on the use of MWP as fuel source
[en] RDF (radial distribution factor) cannot be measured directly in real space. Instead, diffraction patterns from the liquid are collected and the liquid structure factor is then obtained by a series of approximations to account for scattering (multiple and inelastic) and absorption in the sample and the experimental setup. All these issues have been known for a long time and a standard set of procedures has been developed to analyze the experimental data and extract the structure factor. Following the application of these correction procedures, the accumulating systematical error in the case of neutron scattering from heavy elements is of the order of 4-5 %(1-4). Yet, an additional error is introduced by the use of finite range in the momentum transfer, q, space introducing errors into the RDF, most notably short wavelength oscillations (i.e. numerical noise). These oscillations may affect the interpretation of the RDF, and in particular prevent identification of small changes therein. In the present work, we report on two separate studies, 5 years apart, of the structure of liquid Bi at ambient pressure that we have performed at the 7C2 diffractometer at Saclay. Using different experimental setups, we show that the structure factors obtained agree to better than 1%, thus establishing the consistency of our analysis procedures. Using this structure factor as a reference, we compare a large number of experimental studies of liquid Bi at ambient pressure in order to investigate the experimental scatter in the structure factor and find out its significance. We then explore how the errors in the experimental determination of the structure factor affect the calculated RDF, focusing on two main issues: sensitivity to convergence in the high q range and choice of qmax.
[en] Malaysia is still negotiating for the best strategies to manage her 17,000 ton/day MSW in the best manner - politically, economically and environmentally. A National Solid Waste Strategic Plan has been established since 2003, advocating and adopting the Integrated Solid Waste Management System (IWMS). Recently, MINT launched the Waste to Wealth (W2W) blue print to spearhead the idea at National level, of treating waste as resource, thus could be translated to a profitable venture. In this respect, MINT role is very much focused to technology development. However, choosing the right mix of the waste management hierarchy, and thus technology, is not simple. We believed that, a technology that embraced all aspect of waste hierarchy and meet the Best Available Technology Not Entailing Excessive Cost (BATNEEC) or Best Available Technology Suiting Socio Economic Standing (BATSSES) concept will give good promise, thus certainly answers the above cry. In the above pursuit, we developed a commercial and R and D strategies concurrently to arrive at the best compromise. The technology selected, based on RDF, was not a rocket science but innovatively developed to match the waste characteristics, local cultures and social habit, national industrial strength and business opportunities, commercial packaging and institutional support at all levels - politically, socially, commercially, technically and even among government officials. The success of the project lies also in the trusts developed between the government organization conducting R and D and the private sector as the main technology developer, which transcends beyond the normal project contract agreement-manifesting the success of smart partnership model. This paper will share some success, challenges and experience, and lessons learned, in developing the RDF technology from the R and D stage to a full 700 t/day commercial plant in Semenyih, Malaysia. Also highlighted is the impact of this project on the current thinking of various stake holders involved in the entire MSW management in Malaysia
[en] This report describes the Emissions Audit carried out on a chain-grate stoker shell boiler burning dRDF at the Senior Foster Wheeler test facility in Wakefield to provide design data for gas cleaning equipment. Sampling was therefore performed in the absence of any abatement equipment other than a standard cyclonic grit arrestor. The chain-grate stoker boiler was tested at two steam loads: 40% MCR to represent low load and, 80% MCR to represent high steam load. Acid gas concentrations in the flue gas were unacceptable. The dominant gas being HCl at 850-1000mgm-3 for both tests, was considerably higher than the guideline for new plant of 50mgm-3. HF was also measured at concentrations in excess of the guidance value. It will be necessary to install acid gas scrubbing equipment before dRDF will be acceptable as a fuel. SO2 and NOx were both present in measurable concentrations but under current guidance were no cause for concern. (author)
[en] Disposing of municipal solid waste (MSW) into a landfill is a method of the past and creates the negative environmental impact. Growing awareness of this negative impact induced the development of Refuse Derived Fuel (RDF) from MSW RDF is not simply converting waste into energy but also enable waste to be recycled into heat and power. However, during the production of RDF, there are some spillages or rejects consist of organic fraction that still can be recovered. One of the options to treat these wastes is by biological treatment, the anaerobic digestion (AD). AD process could occur either naturally or in a controlled environment such as a biogas plant. The process produces a flammable gas known as biogas that can be used for processing heating, power generation, and in internal combustion engines. In general, the process provides not only pollution prevention but can also convert a disposal problem into a new profit centre. This paper will highlight the use of anaerobic technology to treat rejects derived from the RDF production process. (Author)
[en] Highlights: • Municipal waste treatment costs are assessed for the first time in developing Asia. • A database with primary and secondary data from existing plants was prepared. • Capital and operational expenditures patterns were analyzed and discussed. • Incineration identified by large margin as the costliest approach for treating waste. • Context specific circumstances are key to explain deviations from the norm. - Abstract: The management of municipal solid waste (MSW) is one of the main costs incurred by local authorities in developing countries. According to some estimates, these costs can account for up to 50% of city government budgets. It is therefore of importance that policymakers, urban planners and practitioners have an adequate understanding of what these costs consist of, from collection to final waste disposal. This article focuses on a specific stage of the MSW value chain, the treatment of waste, and it aims to identify cost patterns associated with the implementation and operation of waste treatment approaches in developing Asian countries. An analysis of the capital (CAPEX) and operational expenditures (OPEX) of a number of facilities located in countries of the region was conducted based on a database gathering nearly 100 projects and which served as basis for assessing four technology categories: composting, anaerobic digestion (AD), thermal treatment, and the production of refuse-derived fuel (RDF). Among these, it was found that the least costly to invest, as a function of the capacity to process waste, are composting facilities, with an average CAPEX per ton of 21,493 USD2015/ton. Conversely, at the upper end featured incineration plants, with an average CAPEX of 81,880 USD2015/ton, with this treatment approach ranking by and large as the most capital intensive of the four categories assessed. OPEX figures of the plants, normalized and analyzed in the form of OPEX/ton, were also found to be higher for incineration than for biological treatment methods, although on this component differences amongst the technology groups were less pronounced than those observed for CAPEX. While the results indicated the existence of distinct cost implications for available treatment approaches in the developing Asian context, the analysis also underscored the importance of understanding the local context as a means to properly identify the cost structure of each specific plant. Moreover, even though CAPEX and OPEX figures are important elements to assess the costs of a waste treatment system, these should not be considered on a standalone basis for decision making purposes. In complement to this internal cost dimension, the broader impacts – to the economy, society and the environment – resulting from the adoption of a certain treatment approach should be properly understood and, ideally, measured and expressed in monetary terms.
[en] Increasing quantities of municipal wastes have led to the development of numerous technologies for combustion or gasification of these wastes. Under sponsorship of the Department of Energy, Battelle has completed a preliminary investigation of gasification of prepared municipal wastes [refuse derived fuel (RDF)] to produce a medium Btu gas without oxygen in its High Throughput Gasification system. A successful test program was conducted in a 12 TPD Process Research Unit (PRU) to provide data on product gas composition and production rates possible with the RDF feedstock. Test data generated during the program were compared to an extensive data base generated with wood in the research unit. Results of this test program are presented along with data on waste water characteristics from the PRU. Data generated during the experimental program were used in the generation of a process conceptual design. A preliminary economic evaluation based on this design indicates that the Battelle process provides significant economic benefits when compared to mass burn technologies
[en] This report is a technical review of the techniques available for controlling pollution from combustion processes burning fuels (over 3 MW thermal input) manufactured from or including the following: Waste and recovered oil; Refuse derived fuel; Rubber tyres and other rubber waste; Poultry litter; Wood and straw. This review forms the basis for the revision of the Chief Inspector's Guidance Notes referring to the prescribed processes listed with special emphasis on recommending achievable releases to all environmental media. In formulating achievable releases account is taken of technologies in operation in the UK and overseas. (UK)
[en] Energy recovery from municipal solid waste (MSW) is so beneficial both for the energy and for the positive environmental implications. Mainly related to the saving of primary energy derived from fossil fuel. Malaysia as a fast growing population country has the average amount of municipal solid waste (MSW) generated around 0.5-0.8 kg/person/day and it has been increased to 1.7 kg/person/day in major cities. Regarding characterization exercise, the main parts of the Malaysian MSW were found to be food, paper and plastic, which made up almost 80 % of the waste by weight. Furthermore, the average moisture content of the MSW was about 55 %, making incineration a challenging mission. In addition waste sectors in Malaysia contributes to 1.3 million ton of CH4 compare to total CH4 emission which is 2.2 MT. In order to overcome waste problem considering other technical, environmental and economical methods seems to be necessarily. Resource recovery centers recovers the maximum proportion of recyclable and recoverable resources from the mixed municipal solid waste .The resource recovery process itself is one of the step-by-step segregation and elimination of all non-combustibles , and separation of the combustibles in the desired form of fuel for good combustion. Then, a further mechanical separation process converts combustible materials to refuse derived fuel (RDF) with moisture content between 20 and 30 % and an average calorific fuel value of about 3450 kcal/kg. So, the aim of this paper is taking into account resource recovery from waste using refuse derived fuel as a secondary resource with regarding advantages and disadvantages of this kind of energy production in Malaysia as a developing country. (author)
[en] Steam gasification of two different refuse derived fuels (RDFs), differing slightly in composition as well as thermal stability, was carried out in a fixed-bed reactor at atmospheric pressure. The proximate and ultimate analyses reveal that carbon and hydrogen are the major components in RDFs. The thermal analysis indicates the presence of cellulose and plastic based materials in RDFs. H2 and CO are found to be the major products, along with CO2 and hydrocarbons resulting from gasification of RDFs. The effect of gasification temperature on H2 and CO selectivities was studied, and the optimum temperature for better H2 and CO selectivity was determined to be 725 deg. C. The calorific value of product gas produced at lower gasification temperature is significantly higher than that of gas produced at higher process temperature. Also, the composition of RDF plays an important role in distribution of products gas. The RDF with more C and H content is found to produce more amounts of CO and H2 under similar experimental conditions. The steam/waste ratio showed a notable effect on the selectivity of syngas as well as calorific value of the resulting product gas. The flow rate of carrier gas did not show any significant effect on products yield or their distribution