Leaching behaviour of hazardous demolition waste

Demolition wastes are generally disposed of in unlined landfills for inert waste. However, demolition wastes are not just inert wastes. Indeed, a small fraction of demolition waste contains components that are hazardous to human health and the environment, e.g., lead-based paint, mercury-contained in fluorescent lamps, treated wood, and asbestos. The objective of this study is to evaluate the release potential of pollutants contained in these hazardous components when they are mixed with inert wastes in unlined landfills. After identification of the different building products which can contain hazardous elements and which can be potentially pollutant in landfill scenario, we performed leaching tests using three different lysimeters: one lysimeter containing only inert wastes and two lysimeters containing inert wastes mixed with hazardous demolition wastes. The leachates from these lysimeters were analysed (heavy metals, chlorides, sulphates fluoride, DOC (Dissolved Organic Carbon), phenol index, and PAH). Finally, we compared concentrations and cumulative releases of elements in leachates with the limits values of European regulation for the acceptance of inert wastes at landfill. Results indicate that limit values are exceeded for some elements. We also performed a percolation column test with only demolition hazardous wastes to evaluate the specific contribution of these wastes in the observed releases.     

Modelling the aerobic degradation of organic wastes based on slowly and rapidly degradable fractions

Several organic wastes of major production in the world (municipal solid wastes, wastewater sludge, manures and bulking agents) and some already treated organic wastes have been investigated to determine the partition among the several fractions that compose them and their kinetics of biodegradation. Different literature models have been explored for their suitability to predict the behaviour in respiration studies of these wastes. All the models presented limitations related to their simplicity or their excessive complexity, which makes them unsuitable for reliable and fast studies at real scale. A new model based on the rapid, the slowly and the inert organic fractions has been tested for all the wastes, showing excellent correlations with actual respiration activity. Finally, the kinetic parameters for this model in its application to all the wastes studied are presented.     

Optimization of separation and logistics for recycling materials from wallpaper hanging sites

It is of huge importance for sustainability to find a pragmatic solution for recycling of a variety of wastes emitted in small mass such as the case of wallpaper replacements. A combination of two-step sorting scheme and transportation of the wastes in collaboration with the wholesalers was proposed to enhance the efficiency of recycling. The two-step sorting consists of the first sorting at the wallpaper hanging sites to separate and group wastes in a way to avoid heavy additional burden on the hanging job. Secondary sorting is conducted at a Sorting Center to re-group wastes to send to an intermediate processing company for recycling. To minimize the costs for transportation, the grouped wastes emitted at the hanging sites are brought back by the hangers and kept temporally and then moved to the wholesaler(s) on the way to receive new materials. When the wastes at the wholesaler(s) become sufficiently large for economic transportation, a truck is arranged to collect the wastes to transport them to the Sorting Center. A feasibility study to test the practicality of the method confirmed that it could be operable and the cost would be comparable or lower than that currently incurred for disposal of the wastes.     

包装垃圾的分类与回收利用

包装垃圾是由废弃的包装物产生的固体垃圾,约占我国城市生活垃圾的1/3,虽然政府进行了必要回收,但仍有1/3以上的塑料、玻璃等包装物没能被有效回收利用,成了填埋场的主要填埋物,造成了环境污染和土地、石油等不可再生资源大量浪费。从回收利用和源头减量两方面提出包装垃圾的应对,一是对包装垃圾按来源、成分等进行详细分类,并建议回收处置方法;二是从制定行业政策方面来减少过度包装和扶持再生资源行业健康发展,有效处置包装垃圾等可再生资源。     

The Ümraniye-Hekimbaşi open dump accident

The open dump of Ümraniye-Hekimbaşi was the main solid disposal site of the Asiatic side of Istanbul. At this site, which was in operation since 1976, 1500–2000 tonnes of solid wastes were disposed of daily. No waste compaction was undertaken during placement. The slope formed by the solid wastes was very steep (3 vertical to I horizontal), and recently demolition wastes were disposed of on top of these wastes. On 28 April 1993, an “explosion” took place, followed by the displacement of a large mass of solid wastes which engulfed II houses causing the death of 39 people. This paper investigates the possible reasons for this accident and concludes that it was caused by the initial sliding of the solid wastes, which were not deposited in a stable way, followed by an explosion of the methane generated and retained in the landfill.     

Framework for estimating potential wastes and secondary resources accumulated within an economy – A case study of construction minerals in Japan

Material stocks in economic society are considered to represent a reserve for wastes and secondary resources. From the viewpoints of proper disposal and reutilization of stocked materials, accurate estimation of the amount of materials that will emerge as wastes or secondary resources in the future is important. We defined materials that have a high probability of emerging as wastes or secondary resources as “potential wastes and secondary resources” and estimated that amount for construction minerals in Japan as a case study. The following conclusions were drawn. (1) We classified materials that are input into economic society into four categories: potential wastes and secondary resources, potential dissipated materials, dissipatively used materials, and permanent structures. By clarifying the latter three non-potential wastes and secondary resources, we performed a more accurate assessment of the wastes and secondary resources that will emerge in the future. (2) The share of potential wastes and secondary resources was estimated to be about 30% of all construction minerals that have been input into and accumulated in Japanese economic society. (3) Information related to potential dissipated materials and dissipatively used materials will provide fundamental knowledge to support analyses of the environmental impacts and resource losses which these materials might generate.     

宁东能源化工基地工业固体废物综合利用现状分析、预测及建议

宁东能源化工基地目前以及将来都是宁夏回族自治区工业固体废物主要产生源,因此做好宁东能源基地工业固体废物污染防治工作就相当于解决了宁夏地区大部分工业固体废物问题。通过对基地在工业固体废物方面存在的问题进行剖析,提出宁东能源化工基地固体废物污染防治对策,旨在为减少宁东基地工业固体废物的产生量,提高工业固体废物的综合利用率。做好工业固体废物贮存、处置工作,提供科学指导,保证基地的高水平建设,为可持续发展提供科学依据。     

Medical wastes management in the south of Brazil

In developing countries, solid wastes have not received sufficient attention. In many countries, hazardous and medical wastes are still handled and disposed together with domestic wastes, thus creating a great health risk to municipal workers, the public and the environment. Medical waste management has been evaluated at the Vacacai river basin in the State of Rio Grande do Sul, Brazil. A total of 91 healthcare facilities, including hospitals (21), health centers (48) and clinical laboratories (22) were surveyed to provide information about the management, segregation, generation, storage and disposal of medical wastes. The results about management aspects indicate that practices in most healthcare facilities do not comply with the principles stated in Brazilian legislation. All facilities demonstrated a priority on segregation of infectious-biological wastes. Average generation rates of total and infectious-biological wastes in the hospitals were estimated to be 3.245 and 0.570 kg/bed-day, respectively.     

Pulp and paper plant wastes valorisation in bituminous mixes

Nowadays, the increasing amount of wastes is a concerning reality and the environmental aspects has become a major priority. Following this worry, the purpose of this experimental study was to investigate the possibility of using pulp and paper inorganic wastes, named dregs and grits, in bituminous mixtures as aggregate replacement to reduce environmental effects of these wastes disposal.First, the wastes were chemically and physically characterized and also tested primarily taking into account the requirements for aggregates in bituminous mixtures. Then, formulations were prepared replacing aggregates with wastes in different amounts. The mechanical properties of these mixtures containing wastes were compared with reference samples based on standard methods.According to the results it was possible to verify that grits had a good performance and it might be directly tested industrially as an aggregate in road construction. On the other hand, dregs need to be treated before incorporation to guarantee stable mixes in terms of water sensitivity.     

Hazardous chemical site remediation through capping: Problems with long-term protection

The capping of waste management units and contaminated soils is receiving increasing attention as a low-cost method for hazardous chemical site remediation. Capping is used to prevent further groundwater pollution by existing waste management units and contaminated soils through limiting the moisture that enters the wastes. In principle, for wastes located above the water table, the construction of an impermeable cap can prevent leaching of the wastes (leachate generation) and groundwater pollution. In practice, appropriately designed and constructed RCRA caps can provide for only short-term prevention of groundwater pollution. Alternative approaches are available for capping of wastes that can be effective in preventing moisture from entering the wastes and concomitant groundwater pollution. These approaches recognize the inability of the typical RCRA cap to keep wastes dry for as long as waste constituents will be a threat and, most importantly, provide the necessary funds to effectively address all plausible worst-case scenario failures that could occur at a capped waste management unit or contaminated soil area.     

内蒙古环境承载力与工业三废间关系的实证研究

在国内外学者对环境承载力与工业三废关系研究的基础上,探究了内蒙古环境承载力与工业三废间的关系.数据统计分析说明环境承载力与工业三废间存在长期稳定关系,但二者间不存在短期或长期的因果关系.实证分析说明近年来内蒙古环境承载力水平较低,但保持着稳步上升的趋势,缓解了工业三废带来的负外部效应.     

Accelerated carbonation treatment of industrial wastes

The disposal of industrial waste presents major logistical, financial and environmental issues. Technologies that can reduce the hazardous properties of wastes are urgently required. In the present work, a number of industrial wastes arising from the cement, metallurgical, paper, waste disposal and energy industries were treated with accelerated carbonation. In this process carbonation was effected by exposing the waste to pure carbon dioxide gas. The paper and cement wastes chemically combined with up to 25% by weight of gas. The reactivity of the wastes to carbon dioxide was controlled by their constituent minerals, and not by their elemental composition, as previously postulated. Similarly, microstructural alteration upon carbonation was primarily influenced by mineralogy. Many of the thermal wastes tested were classified as hazardous, based upon regulated metal content and pH. Treatment by accelerated carbonation reduced the leaching of certain metals, aiding the disposal of many as stable non-reactive wastes. Significant volumes of carbon dioxide were sequestrated into the accelerated carbonated treated wastes.     

Analyses of the recycling potential of medical plastic wastes

This study analyzed the recycling potential of plastic wastes generated by health care facilities. For this study, we obtained waste streams and recycling data from five typical city hospitals and medical centers and three animal hospitals in Massachusetts. We analyzed the sources, disposal costs and plastic content of medical wastes, and also determined the components, sources, types and amounts of medical plastic wastes. We then evaluated the recycling potential of plastic wastes produced by general city hospital departments, such as cafeterias, operating rooms, laboratories, emergency rooms, ambulance service and facilities, and animal hospitals. Facilities, laboratories, operating rooms, and cafeterias were identified as major sources of plastic wastes generated by hospitals. It was determined that the recycling potential of plastics generated in hospital cafeterias was much greater than that in other departments. This was mainly due to a very slight chance of contamination or infection and simplification of purchasing plastic components. Finally, we discuss methods to increase the recycling of medical plastic wastes. This study suggests that a classification at waste generating sources, depending upon infection chance and/or plastic component, could be a method for the improved recycling of plastic wastes in hospitals.     

Carbon dioxide and ammonia emissions during composting of mixed paper, yard waste and food waste

The objective of the work was to provide a method to predict CO2 and NH3 yields during composting of the biodegradable fraction of municipal solid wastes (MSW). The compostable portion of MSW was simulated using three principal biodegradable components, namely mixed paper wastes, yard wastes and food wastes. Twelve laboratory runs were carried out at thermophilic temperatures based on the principles of mixture experimental and full factorial designs. Seeded mixed paper (MXP), seeded yard waste (YW) and seeded food waste (FW), each composted individually, produced 150, 220 and 370 g CO2-C, and 2.0, 4.4 and 34 g NH3-N per dry kg of initial substrate, respectively. Several experimental runs were also carried out with different mixtures of these three substrates. The effect of seeding was insignificant during composting of food wastes and yard wastes, while seeding was necessary for composting of mixed paper. Polynomial equations were developed to predict CO2 and NH3 (in amounts of mass per dry kg of MSW) from mixtures of MSW. No interactions among components were found to be significant when predicting CO2 yields, while the interaction of food wastes and mixed paper was found to be significant when predicting NH3 yields.     

An overview of metals recovery from thermal power plant solid wastes

Thermal power plants (TPPs) that burn fossil fuels emit several pollutants linked to the environmental problems of acid rain, urban ozone, and the possibility of global climate change. As coal is burned in a power plant, its noncombustible mineral content is partitioned into bottom ash, which remains in the furnace, and fly ash, which rises with flue gases. Two other by-products of coal combustion air-pollution control technologies are flue gas desulfurization (FGD) wastes and fluidized-bed combustion (FBC) wastes. This paper analyzed and summarized the generation, characteristics and application of TPP solid wastes and discussed the potential effects of such solid wastes on the environment. On this basis, a review of a number of methods for recovery of metals from TPP solid wastes was made. They usually contain a quantity of valuable metals and they are actually a secondary resource of metals. By applying mineral processing technologies and hydrometallurgical and biohydrometallurgical processes, it is possible to recover metals such as Al, Ga, Ge, Ca, Cd, Fe, Hg, Mg, Na, Ni, Pb, Ra, Th, V, Zn, etc., from TPP solid wastes. Recovery of metals from such wastes and its utilization are important not only for saving metal resources, but also for protecting the environment.     

A mathematical model to predict the composition and generation of hospital wastes in Iran

The aim of this study is to investigate the quality and quantity of hospital wastes in Iran. The generated hospital wastes have been estimated by the number of hospitals and the number of active beds in each province of Iran in 2001. All data and information have been gathered from: (i) Iran Statistics Center, (ii) literature review, and (iii) hospital waste investigations for an average hospital. Physical analyses have been conducted in terms of various materials (plastic, textile, paper, metal, and others) and components (biological, infectious, medical, and regular wastes). Based on the above-mentioned investigation and information, a mathematical model has been developed to calculate the generation of (infectious) hospital wastes for any desired year. Utilizing the model, generated infectious hospital wastes has been estimated as 698,937 tones for 2008 (short-term) and 3,494,387 tones for 2028 (long-term period). If the real infectious wastes are collected separately, then the generated infectious wastes will be reduced by 15.1% of the above-mentioned amount (139,787 tones for 2008, and 698,877 tones for 2028). Results of physical analysis show the components of the hospital waste as: (a) infectious, 67.3%; (b) medical, 8.8%; (c) biological, 1.8%; and (d) common municipal wastes, 22.1%. An appropriate collection method requires training the staff at hospitals along with preparation of the required facilities. Of course, both of these requirements are cost intensive.     

Optimization of cement-based stabilization/solidification of organic-containing industrial wastes using organophilic clays

The treatment of organically contaminated industrial wastes by cement-based stabilization/solidification has, in the past, been restricted by the detrimental effect of organic compounds on cement hydration. This work investigates the use of organophilic clays as adsorbents for the organic components of industrial wastes prior to conventional cement-based solidification. Three industrial wastes containing between 2–12% organic carbon and trace heavy metal contamination were treated with a quaternary ammonium salt exchanged clay. The organic component of all three wastes was well adsorbed by the clay. Solidification of the waste/clay mixes produced a monolithic mass with adequate strength and very low leaching of either the organic compounds or the metals. This study has shown that organophilic clays can act as successful adsorbents for the organic contaminants of industrial wastes and enable them to be treated by cement-based solidification.     

Healthcare waste management in the capital city of Mongolia

Inconsistencies are present in the management options for healthcare wastes in Mongolia. One of the first critical steps in the process of developing a reliable waste management plan requires the performance of a waste characterization analysis. The objectives of this study were an assessment of the current situation of healthcare waste management (HCWM) and characterization of healthcare wastes generated in Ulaanbaatar. A total about 2.65 tonnes of healthcare wastes are produced each day in Ulaanbaatar (0.78 tons of medical wastes and 1.87 tons of general wastes). The medical waste generation rate per kg/patient-day in the inpatient services of public healthcare facilities was 1.4-3.0 times higher than in the outpatient services (P<0.01). The waste generation rate in the healthcare facilities of Ulaanbaatar was lower than in some other countries; however, the percentage of medical wastes in the total waste stream was comparatively high, ranging from 12.5% to 69.3%, which indicated poor waste handling practices. Despite the efforts for the management of wastes, the current system of healthcare waste management in Ulaanbaatar city of Mongolia is under development and is in dire need of immediate attention and improvement. It is essential to develop a national policy and implement a comprehensive action plan for HCWM providing environmentally sound technological measures to improve HCWM in Mongolia.     

Medical wastes characterisation in healthcare institutions in Mauritius

This study was initiated to characterize solid and liquid wastes generated in healthcare institutions and to provide a framework for the safe management of these wastes. The project was carried at three major medical institutions, namely, the Jeetoo Hospital, the Sir Seewoosagur Ramgoolam National (SSRN) Hospital and the Clinic Mauricienne. A waste audit carried out at these sites revealed that approximately 10% of solid wastes was hazardous in nature, consisting mainly of infectious, pathological and chemical wastes. The average amount of hazardous wastes per patient per day was found to be 0.072 kg at Jeetoo hospital, 0.091 kg at SSRN hospital and 0.179 kg at the clinic. The amount of hazardous wastes generated as a function of the number of occupied beds was found to follow a relationship of type y=0.0006x-0.19, where y was the amount of hazardous wastes generated per bed per day and x was the number of occupied beds. The waste quantifying process also revealed that at SSRN Hospital, 0.654 m(3) of water was being consumed per patient per day and the amount of wastewater produced was 500 m(3)/day. Further analysis revealed that the wastewater was polluting with chemical oxygen demand (COD), biological oxygen demand (BOD(5)), total suspended solids (TSS) and coliform content well above permissible limits.     

Land disposal of mixed human and animal wastes: A review

Combining septic tank effluent and animal wastes (mixed wastes) for eventual application to land is being proposed as an alternative wastewater disposal system. Both types of waste are spread on land separately, and private practice may be to mix and spread them together, but in most of the United States mixing of these wastes for land disposal is illegal. No research has been done to assess the hazards associated with spreading mixed wastes on land. The concern is with the impact on public health of adding septic tank effluent to animal wastes for disposal as animal wastes. The effects of pathogens already present in animal waste are presumably allowed for in current U.S. regulations.Pathogens in mixed wastes include viruses, bacteria and parasites. Viruses are not always present in on-site waste disposal systems, but when present are in high numbers. Most viral particles will pass through the septic tank and will remain viable. Transmission will be prevented if these particles are retained in soil or other solids until any of several factors deprive them of infectivity. As animals are the chief reservoir of most enteric bacteria that are pathogenic to man, no additional hazards from bacteria are expected in a mixed waste system. Some parasite eggs and cysts will settle into the bottom of the septic tank, but significant numbers will pass through and will remain viable. Retention with solids will minimize transmission through food and water. In all instances it is important to match land use and waste disposal carefully.