The adsorption characteristics of heavy metals by various particle sizes of MSWI bottom ash

The incineration rate of municipal solid waste (MSW) has been increased because of difficulty in securing a proper disposal site for MSW in Korea. The advantage of incineration is reduction of the volume of waste; however, significant amounts of bottom ash and fly ash were generated in the incineration process. Their treatment has attracted growing interest because of the potential toxicity of hazardous heavy metals. Generally, heavy metals are less released from bottom ash than from fly ash. In this study the adsorption characteristics of heavy metals were investigated using various particle sizes of MSWI bottom ash. Since bottom ash has a broad particle size distribution, it was sieved to size classes of +20, -20, -48, -80, -100 mesh. Cation exchange capacity (CEC) was analyzed by the ammonium acetate method to evaluate the potential as an adsorbent. The CEC values and surface areas increase as the range of particle size becomes finer. The adsorption experiment was conducted using synthetic (Cu and Ni) and plating rinse water as a function of reaction time (10-180 min), liquid/solid ratio (2-100) and particle size (+20 to -100 mesh), respectively. The adsorption rate increased with decreasing particle size and with increasing liquid/solid ratio; however, the removal efficiency of Cu was higher than that of Ni. In the case of plating rinse water, the adsorption rate decreased sharply at high liquid/solid ratio, and it showed over 80% of adsorption rates for Cu and Ni at an initial pH of 3.     

Municipal solid waste management in Nepal: practices and challenges

Solid waste management in Kathmandu valley of Nepal, especially concerning the siting of landfills, has been a challenge for over a decade. The current practice of the illegal dumping of solid waste on the river banks has created a serious environmental and public health problem. The focus of this study was to carry out an evaluation of solid waste management in Nepal based on published information. The data showed that > or =70% of the solid wastes generated in Nepal are of organic origin. As such, composting of the solid waste and using it on the land is the best way of solid waste disposal. This will reduce the waste volume transported to the landfill and will increase its life.     

Comparison of old and new municipal solid waste management systems in Denizli, Turkey

Rapid economic growth, increasing population and change in living standards contribute to increasing the generation rate of municipal solid waste (MSW) in Denizli city, like other Turkish cities. The improper and poor MSW management system (old system) in Denizli caused environmental problems originating from the uncontrolled release of methane and leachate. In addition, the disposal of recyclable materials in unsanitary landfills is responsible for the consumption and destruction of natural sources. This paper presents a general overview of old and new MSW management practices in Denizli. Detailed data on MSW management practices including collection, transportation, disposal and recycling have been presented. The amount of solid waste generated in Denizli over the last decade has increased steadily over the years, from 108,500 tons in 1995 to 179,495 tons in 2006. The average MSW generation rate was found to be 1.23kg/day per capita. The major constituent of MSW in Denizli is food waste, but the percentage of recyclable waste has increased significantly recently. Except for metal wastes, the percentages of recyclable waste materials in Denizli are higher than in all neighborhood cities. The objective of this study is to compare the old and new MSW management systems in Denizli city. The MSW management system has been changed entirely last five years. A dumpsite was closed and a sanitary landfill with a composting facility was constructed. In addition, source separated collection has been carried out since 2002. The quantity of recyclable waste collected increased from 195 to 1549 tons. The amount of recyclable waste will continue to be increased by expanding the source separation collection system to all the districts of the city and preventing scavenging. Thus, revenue from recyclable waste ($7227 in 2006) is expected to increase. In addition, the capacity of the composting facility will be increased. Most importantly, information to increase public participation and awareness in municipal recovery programs has to be provided.     

Management of immunization solid wastes in Kano State, Nigeria

Inadequate management of waste generated from injection activities can have a negative impact on the community and environment. In this paper, a report on immunization wastes management in Kano State (Nigeria) is presented. Eight local governments were selected randomly and surveyed by the author. Solid wastes generated during the Expanded Programme on Immunization were characterised using two different methods: one by weighing the waste and the other by estimating the volume. Empirical data was obtained on immunization waste generation, segregation, storage, collection, transportation, and disposal; and waste management practices were assessed. The study revealed that immunization offices were accommodated in either in local government buildings, primary health centres or community health care centres. All of the stations demonstrated a high priority for segregation of the infectious wastes. It can be deduced from the data obtained that infectious waste ranged from 67.6% to 76.7% with an average of 70.1% by weight, and 36.0% to 46.1% with an average of 40.1% by volume. Non-infectious waste generated ranged from 23.3% to 32.5% with an average of 29.9% by weight and 53.9% to 64.0% with an average of 59.9% by volume. Out of non-infectious waste (NIFW) and infectious waste (IFW), 66.3% and 62.4% by weight were combustible and 33.7% and 37.6% were non-combustible respectively. An assessment of the treatment revealed that open pit burning and burial and small scale incineration were the common methods of disposal for immunization waste, and some immunization centres employed the services of the state or local government owned solid waste disposal board for final collection and disposal of their immunization waste at government approved sites.     

The practice and challenges of solid waste management in Singapore

This paper presents an overview of the current solid waste management situation in Singapore and provides a brief discussion of the future challenges. Singapore is a small island city-state with a large population, warm climate and high humidity. Over the past two to three decades, rapid industrialization and economic development have caused a tremendous increase in solid waste generation. The yearly disposed solid waste increased from 0.74 million tonnes in 1972 to 2.80 million tonnes in 2000. Solid waste management in Singapore has traditionally been undertaken by the Ministry of Environment (ENV), with the participation of some private sectors in recent years. The hierarchy of solid waste management in Singapore is waste minimization (reduce, reuse and recycle or so-called 3 Rs), followed by incineration and landfill. As land is extremely scarce and only one newly constructed offshore landfill site is available, solid waste incineration has been identified as the most preferred disposal method. Waste minimization, the utilization of incineration ashes, industrial waste management are regarded to be the major challenges in the future.     

Solid waste management practices in Turkey

As an economically developing country, Turkey has very well operated integrated solid waste management applications structured on modern facilities, besides over 2,000 scattered open dump areas in the country. Integrated waste management applications seem eligible for the metropolitan cities like Istanbul and Izmit (Kocaeli). Attempts have not been encouraging for the scattered regional settlements using central storage sites due to financial shortages and received rejections from nearby settlements. Small-scale compact solid waste management systems with materials recycling and composting can be more suitable alternatives in the small-scale regional settlements. The major constituents of municipal solid waste are organic in nature and approximately a quarter of municipal solid waste is recyclable. Although paper, including cardboard, is the main constituent, the composition of recyclable waste varies strongly by the source or the type of collection point. Solid wastes need primary treatment in order to be suitable for incineration and composting. Turkey needs to give more emphasis on the usage of modern solid waste removal technologies to overcome the overgrowing solid waste disposal problems.     

Urban solid waste management in Chongqing: challenges and opportunities

The dual influences of the resource supply and protection in ecological environments will pose a significant challenge to China's sustainable development. Solid waste management offers opportunities to improve profits by conserving resources and improving environmental performance. This paper examines municipal solid waste (MSW) management in urban Chongqing, the nation's fourth largest municipality after Beijing, Shanghai and Tianjin. In this paper, we will provide information on the quantity and composition of MSW, as well as give an overview of different methods for collection, transport, treatment and disposal of MSW. At present the daily amount of MSW generated per person is about 1.08 kg; food waste accounts for about 59% of total MSW. MSW in Chongqing has a higher moisture content (64.1%) and a lower LHV (3728 kJ/kg) than other cities in Asia, which is an obstruction for incineration. Landfills are the main method of disposal in Chongqing, but pollution caused by simple landfills and lack of backup MSW disposal capacity are becoming major problems in the main districts of Chongqing. In this paper, the challenges being faced and opportunities to MSW in Chongqing are analyzed and some suggestions are given for improving the MSW system in the future.     

Treatment and disposal alternatives for health-care waste in developing countries--a case study in Istanbul, Turkey.

Efficient health-care waste management is crucial for the prevention of the exposure of health-care workers, patients, and the community to infections, toxic wastes and injuries as well as the protection of the environment (Safe Management of Wastes from Health-care Activities. World Health Organization, Geneva). The amount of health-care waste produced in the Istanbul Metropolitan City in Turkey is 30 ton day(-1) in total. The method used for the final disposal of most of the health-care waste of Istanbul is incineration. However, a great portion of the infectious waste is disposed of with the domestic waste into the sanitary landfill because of improper segregation practices applied in the health-care institutions. Therefore the alternatives for the treatment and disposal of health-care waste were evaluated. The technical information related to the available treatment technologies including incineration, microwave irradiation, mobile or stationary sterilization, etc. were also investigated. The capital investment cost, transportation/operational costs for each alternative method and the different locations for installation were compared. When the data collected were evaluated, it was found that separate handling and disposal of health-care waste generated on the European and the Asian sides of the city was the most economic and practicable solution. As a result, it was concluded that the capacity of the Kemerburgaz-Odayeri incineration plant is enough to incinerate the health-care waste generated on the European side of Istanbul, the construction of a new incineration plant or a stationary sterilization unit for the disposal of health-care waste generated on the Asian side was the most effective alternative.     

Nitrous oxide (N2O) emissions from waste and biomass to energy plants.

Following the Kyoto protocol with respect to reducing emissions of greenhouse gases emissions, and EU energy policy and sustainability in waste management, there has been an increased interest in the reduction of emissions from waste disposal operations. From the point of view of nitrous oxide (N2O) emissions, waste incineration and waste co-combustion are very acceptable methods for waste disposal. In order to achieve very low N2O emissions from waste incineration, particularly for waste with higher nitrogen content (e.g. sewage sludge), two factors are important: temperature of incineration over 900 degrees C and avoiding the selective non-catalytic reduction (SNCR) de-NO(X) method based on urea or ammonia treatments. The more modern selective catalytic reduction (SCR) systems for de-NO(X) give rise to negligible sources of N2O.     

Management of municipal solid waste in the Three Gorges region

As the fourth phase of the Three Gorges reservoir project commenced in 2008, the rate of water flow in the Yangtze River has obviously decelerated further downstream and water clarity within the storage facility has decreased. Meanwhile, the rate of urbanization in the region is adding to the amount of municipal solid waste (MSW) being generated by every day life. The composition of the waste is becoming more diversified and complicated, thereby presenting an increasing threat to the ecological environment and water resources of the Three Gorges region. This paper is a probe into MSW in terms of its characteristics as well as methods of storage, collection, transportation, recycling, treatment and disposal, the protection of environmental ecosystems. Municipal solid waste management (MSWM) is one of the major environmental problems in the Three Gorges region, and indeed the whole of China. Based on the analysis of the present situation of MSWM and its treatment/disposal, some methods of sorting, recycling, decomposing, incineration and reuse are described, sanitary landfill as the main disposal method in Chongqing city, incineration being the second. Sanitary landfill or dump was also used for MSW treatment in the Three Gorges region, and this paper also provides some suggestions for improving MSWM in the Three Gorges region.     

Municipal solid waste management in China: a comparative analysis

This paper illustrates an overview of the past and present MSWM strategies in China. A comparison is made with MSWM in China, and other developed and developing countries to identify and analyze the problems of existing MSWM, and evaluate some effective suggestion to overcome the limitations. Rapid urbanization and economic growth are the main factors of increasing MSW generation in China. The generating MSW has 55.86 % food waste with high moisture contain due to unavailable source separation. Chinese MSWM is dominated by 60.16 % landfilling, whereas incineration, untreated discharge, and other treatments are 29.84, 8.21, and 1.79 %, respectively. In 2014, a total of 604 sanitary landfills, 188 incineration plants, and 26 other units were used for MSWM. With the magnitude of timing, the increasing rate of incineration unit and disposal capacity is higher than the landfill. In 2004–2014, the disposal capacity of landfill and incineration is increased from 68.89 to 107.44 and 4.49 to 53.3 million tons, respectively. However, the heating value in the majority of Chinese incineration plants is 3000–6700 kJ/kg and the inappropriate leachate treatment can be found in 47 % landfill sites. A proper taxation system for MSW disposal is not fully implemented in China, which has a negative impact on overall MSW recycling. From the comparative study of MSWM, it is revealed that the source separation MSW collection, high energy recovery from incineration plants, appropriate leachate treatment, effective landfill location and management, increase waste recycling and proper taxation system for MSW disposal are essential to improve MSWM in China.     

Application of system dynamics modeling for evaluation of different recycling scenarios in Singapore

The influence of socioeconomic factors, such as population and rapid economic growth, and the change of consumption and living patterns make waste management in Singapore, a complex issue. Due to limited land and resources, the solid waste management scheme requires a comprehensive approach. Therefore, system dynamics (SD) modeling was applied to assess alternative strategies for solid waste management by interconnecting landfill capacity and recycling efficiency with reference to the projection on waste generation. Nine different scenarios were investigated to identify the best approach to maintain environmental sustainability without inhibiting the economic growth. Four subsystems (i.e., population, economy, waste recycling, and waste disposal) have been incorporated into the SD model to broaden the effectiveness of the waste management system. Research findings revealed that a high economic pattern and a high recycling rate are recommended to satisfy the requirements for economic growth and environmental sustainability while extending landfill capacity for waste disposal. Even though the balance of expenditure could be increased by the high recycling rate, it meets the need for long-term incineration and landfill planning.     

The future course of solid waste management in the U.S.

It is postulated that the current “garbage crisis” is due to a shortage of disposal capacity, not to burgeoning amounts of municipal solid waste (MSW). In support of this, trends in the quantity and composition of MSW, methods of waste reduction, recycling and growth of waste-to-energy capacity are examined to gain insight as to the future course of MSW management in the U.S. over about the next 15 plus years. This is the likely time to install new disposal capacity if pending legislative proposals are passed, that would enable states that provide their own disposal to ban wastes from other states.A new term, the “intensity of waste generation”, is proposed and illustrated, analogous to the intensity of mineral usage. The intensity is decreasing, implying that it is unlikely that waste generation will grow at rates projected by extrapolation or simple macroeconomic assumptions. Some other conclusions are: per capita MSW generation was nearly statistically constant from 1970 to 1984; the content of most forms of packaging in MSW are decreasing; packaging decreases the amount of food residues in MSW; and proposed national recycling targets of about 25% or more are not likely to be achieved, in part because of changes in the composition of MSW. Coupled with likely shortages of labor to process separated waste, it is forecast that there will be some future time when people will not think source separation is worth the bother and recycling will decrease. The future growth of waste-to-energy capacity is projected by assuming that a city will install capacity when others have done so, which leads to a simple quantitative model. The likely effects of impending landfill and incineration regulations are addressed.     

Biomedical solid waste management in an Indian hospital: a case study

The objectives of this study were: (i) to assess the waste handling and treatment system of hospital bio-medical solid waste and its mandatory compliance with Regulatory Notifications for Bio-medical Waste (Management and Handling) Rules, 1998, under the Environment (Protection Act 1986), Ministry of Environment and Forestry, Govt. of India, at the chosen KLE Society's J. N. Hospital and Medical Research Center, Belgaum, India and (ii) to quantitatively estimate the amount of non-infectious and infectious waste generated in different wards/sections. During the study, it was observed that: (i) the personnel working under the occupier (who has control over the institution to take all steps to ensure biomedical waste is handled without any adverse effects to human health and the environment) were trained to take adequate precautionary measures in handling these bio-hazardous waste materials, (ii) the process of segregation, collection, transport, storage and final disposal of infectious waste was done in compliance with the Standard Procedures, (iii) the final disposal was by incineration in accordance to EPA Rules 1998, (iv) the non-infectious waste was collected separately in different containers and treated as general waste, and (v) on an average about 520 kg of non-infectious and 101 kg of infectious waste is generated per day (about 2.31 kg per day per bed, gross weight comprising both infectious and non-infectious waste). This hospital also extends its facility to the neighboring clinics and hospitals by treating their produced waste for incineration.     

Combined incineration of industrial wastes with in-plant residues in fluidized-bed utility boilers--decision relevant factors.

In Austria more than 50% of the high-calorific industrial residues and wastes generated are utilized for energy recovery in industrial utility boilers. This study investigated full-scale trials of combined incineration of in-plant residues with various industrial wastes. These trials were carried out in order to learn how the alternatively used fuel influences the incineration process itself as well as the quantity and quality of the various incineration products. The currently used fuel, which consisted of in-plant residues as well as externally acquired waste wood and the refuse-derived fuel (RDF) mixtures used during the full-scale trials are characterized in terms of material composition as well as chemical and physical parameters. An input-output mass balance for the incineration plant (two fluidized bed combustion units, 20 and 30 MW, respectively) has been established, based on the data collected during the full-scale incineration trials. Furthermore, pollutant concentrations in the off-gas as well as the solid incineration residue are reported. It is not only the pollutant content but also a variety of other internal as well as external factors that have to be considered if a company is to decide whether or not to thermally utilize specific waste types. Therefore a strengths and weaknesses profile for several types of waste and the specific industrial boiler is also presented.     

Setting priorities for waste management strategies in developing countries.

This study aimed to determine whether the waste management systems, that are presently applied in affluent countries are appropriate solutions for waste management in less developed regions. For this purpose, three cities (Vienna, Damascus and Dhaka) which differ greatly in their gross domestic product and waste management were compared. The criteria for evaluation were economic parameters, and indicators as to whether the goals of waste management (protection of human health and the environment, the conservation of resources) were reached. Based on case studies, it was found that for regions spending 1-10 Euro capita(-1) year(-1) for waste management, the 'waste hierarchy' of prevention, recycling and disposal is not an appropriate strategy. In such regions, the improvement of disposal systems (complete collection, upgrading to sanitary landfilling) is the most cost-effective method to reach the objectives of solid waste management. Concepts that are widely applied in developed countries such as incineration and mechanical waste treatment are not suitable methods to reach waste management goals in countries where people cannot spend more than 10 Euro per person for the collection, treatment and disposal of their waste. It is recommended that each region first determines its economic capacity for waste management and then designs its waste management system according to this capacity and the goals of waste management.     

Municipal waste management in Sicily: practices and challenges

There are numerous problems yet to be solved in waste management and although efforts towards waste recovery and recycling have been made, landfills are still the most common method used in the EU and many other industrialised countries. Thermal disposal, particularly incineration, is a tested and viable alternative. In 2004, only 11% of the annual waste production of Italy was incinerated. Sicily, with over five million inhabitants, is the second largest region in Italy where waste management is now a critical problem. The use of landfills can no longer be considered a satisfactory environmental solution; therefore, new methods have to be chosen and waste-to-energy plants could provide an answer. This paper gives details of municipal solid waste management in Sicily following a new Waste Management Plan. Four waste-to-energy plants will generate electricity through a steam cycle; the feedstock will become the residue after material recovery, which is calculated as 20-40% weight of the collected municipal solid waste.     

Generation and distribution of PAHs in the process of medical waste incineration

After the deadly earthquake on May 12, 2008 in Wenchuan county of China, several different incineration approaches were used for medical waste disposal. This paper investigates the generation properties of polycyclic aromatic hydrocarbons (PAHs) during the incineration. Samples were collected from the bottom ash in an open burning slash site, surface soil at the open burning site, bottom ash from a simple incinerator, bottom ash generated from the municipal solid waste (MSW) incinerator used for medical waste disposal, and bottom ash and fly ash from an incinerator exclusively used for medical waste. The species of PAHs were analyzed, and the toxicity equivalency quantities (TEQs) of samples calculated. Analysis results indicate that the content of total PAHs in fly ash was 1.8 × 10³ times higher than that in bottom ash, and that the strongly carcinogenic PAHs with four or more rings accumulated sensitively in fly ash. The test results of samples gathered from open burning site demonstrate that Acenaphthylene (ACY), Acenaphthene (ACE), Fluorene (FLU), Phenanthrene (PHE), Anthracene (ANT) and other PAHs were inclined to migrate into surrounding environment along air and surface watershed corridors, while 4- to 6-ring PAHs accumulated more likely in soil. Being consistent with other studies, it has also been confirmed that increases in both free oxygen molecules and combustion temperatures could promote the decomposition of polycyclic PAHs. In addition, without the influence of combustion conditions, there is a positive correlation between total PCDD/Fs and total PAHs, although no such relationship has been found for TEQ.     

Municipal solid waste management strategies in Turkey

Municipal solid waste (MSW) is a major environmental problem in Turkey, as in many developing countries. Problems associated with municipal solid waste are difficult to address, but efforts towards more efficient collection and transportation and environmentally acceptable waste disposal continue in Turkey. Although strict regulations on the management of solid waste are in place, primitive disposal methods such as open dumping and discharge into surface water have been used in various parts of Turkey. This study presents a brief history of the legislative trends in Turkey for MSW management. The study also presents the MSW responsibility and management structure together with the present situation of generation, composition, recycling, and treatment. The results show that approximately 25 million ton of MSW are generated annually in Turkey. About 77% of the population receives MSW services. In spite of efforts to change open dumping areas into sanitary landfills and to build modern recycling and composting facilities, Turkey still has over 2000 open dumps.     

Greenhouse gases emission from municipal waste management: The role of separate collection

The municipal solid waste management significantly contributes to the emission in the atmosphere of greenhouse gases (e.g. CO₂, CH₄, N₂O) and therefore the management process from collection to treatment and disposal has to be optimized in order to reduce these emissions. In this paper, starting from the average composition of undifferentiated municipal solid waste in Italy, the effect of separate collection on greenhouse gases emissions from municipal waste management has been assessed. Different combinations of separate collection scenarios and disposal options (i.e. landfilling and incineration) have been considered. The effect of energy recovery from waste both in landfills and incinerators has also been addressed. The results outline how a separate collection approach can have a significant effect on the emission of greenhouse gases and how wise municipal solid waste management, implying the adoption of Best Available Technologies (i.e. biogas recovery and exploitation system in landfills and energy recovery system in Waste to Energy plants), can not only significantly reduce greenhouse gases emissions but, in certain cases, can also make the overall process a carbon sink. Moreover it has been shown that separate collection of plastic is a major issue when dealing with global warming relevant emissions from municipal solid waste management.