Waste in the Inner City: asset or assault?

In an unequal society, undesirable wastes often end up in the poorest and least powerful communities, becoming part of the economic and environmental milieu of the inner city. Two contradictory responses to waste reflect contrasting theoretical paradigms. Some wastes can become assets in local economic development, creating incomes through scavenging, industrial jobs in recycling plants or new businesses using locally available materials. Other wastes are an assault on the community that receives them; toxic wastes, polluting facilities and industrial by-products often create local health hazards rather than development. Waste as an asset is consistent with the free market model of economics. The inner city, 'endowed' with waste materials and low-wage labour, has a comparative advantage in labour-intensive processing of materials that the rest of society has discarded. Waste as an assault on the community is consistent with a different model of environmental risk. Some by-products of industry are so hazardous that they should not be produced, or should be tightly regulated. Each model has a realm of validity; the balance between the two depends on which wastes are hazardous, and which are just ugly resources waiting to be discovered.     

Waste in the Inner City: Asset or assault?

In an unequal society, undesirable wastes often end up in the poorest and least powerful communities, becoming part of the economic and environmental milieu of the inner city. Two contradictory responses to waste reflect contrasting theoretical paradigms. Some wastes can become assets in local economic development, creating incomes through scavenging, industrial jobs in recycling plants or new businesses using locally available materials. Other wastes are an assault on the community that receives them; toxic wastes, polluting facilities and industrial by-products often create local health hazards rather than development. Waste as an asset is consistent with the free market model of economics. The inner city, 'endowed' with waste materials and low-wage labour, has a comparative advantage in labour-intensive processing of materials that the rest of society has discarded. Waste as an assault on the community is consistent with a different model of environmental risk. Some by-products of industry are so hazardous that they should not be produced, or should be tightly regulated. Each model has a realm of validity; the balance between the two depends on which wastes are hazardous, and which are just ugly resources waiting to be discovered.     

含油污水中固体废物固化与燃煤混烧的可行性

在含油污水处理过程中易产生含油污泥、活性污泥及浮渣等固体废物,利用传统的焚烧法、分离法、填埋法、生物降解法处理这些废物具有一定的缺陷和局限性。为了利用这些废物中的油及有机质的潜在能量,大庆炼化公司对固体废物进行了脱水固化试验。结果表明,脱水后的废物可以达到较好的固化状态,并具有一定的热值。固化废物经粉碎处理后,可按一定比例与燃煤混烧。在正常生产状况下,热电厂可保证混合燃烧的效果,其总体热值不会降低。混烧后的灰渣和炉渣可作为水泥厂的原料。该方法有利于环境保护,但其工业化生产可行性有待于进一步证实。     

Glassceramics obtained from industrial waste

Large areas of Latvia are contaminated with industrial waste: metallurgical slag, fly-ash, etching refuse, peat, and coal ash as well as glass waste which often contain dangerous substances. From the environmental point of view this waste should be neutralised. As this waste also contains valuable chemical compounds, it can be considered as a raw material for the generation of new materials. One method of utilisation is to produce recycled materials — street plates, decorative tiles, or floor tiles. Dense sintered glassceramics with a water uptake of 0.34–3.23 wt.%, a final density of 2.93–3.05 g/cm³, and a bending strength of 80–96 MPa have been created from industrial waste. The mast chemically durable glassceramics contained clay additions. Thus, the material containing only waste had a durability (mass loss) of 3.02% in 0.1 N HCl, while the composition containing 30% clay addition had a durability of 0.2% in 0.1 N HCl.     

Industrial waste to energy by circulating fluidized bed combustion

Industrial waste is a good resource from the viewpoint of efficient waste management. The vital need for energy utilization and environmental protection mean it is of interest to develop circulating fluidized bed combustion (CFBC) to burn solid wastes with low pollutant emissions. The paper presents some explanatory studies on waste-to-energy in a pilot scale CFCB facility. A series of combustion/incineration tests have been carried out for the industrial wastes: petroleum coke, waste tire and sludge cakes with various moisture contents. It seems that the CFBC has feed flexibility without modifying heat transfer equipments for energy recovery. In addition, the results of experimental tests demonstrate that gas emissions from waste incineration in CFBC can be well controlled under local regulation limits.At normal operation temperature in CFBC (approx. 800°C), the heat transfer coefficient between bulk bed and bed wall is on the order of 10² W/m^2° C, which is useful to estimate the energy recovery of waste combustion by CFBC. A practical and simple guide is proposed to estimate the energy recovery from waste combustion by CFBC, and to find maximum allowable moisture content of waste if there is to be any energy recovery without auxiliary fuel.     

Study on assessment of slope stability and mixed disposal of overburden in voids of Singrauli Coalfield

The mining industry can be considered the backbone of the Indian economy as well as facilitating the power that drives most of the other industries in the company. The overburden and waste rocks produced during coal mining are major concerns in regard to the amount of land that is required for their disposal, as well as the stability of dumps for these materials, which are of increasing height. Land reclamation issues are also a concern. In this work the adverse impacts caused by the dumping of overburden on land and acidic mine water on water bodies is discussed. Remote sensing tools were used along with the laboratory experimentation to assess the various impacts. This study also shows that silt released from waste dumps, can affected the angle of repose of the overburden dump slope. The angle of repose of the overburden materials varies with particle size composition. Thus, use of in‐pit crushers in large opencast mining operations can effectively reduce the area locked under the waste dumps. The acid neutralization potential of fly ash and overburden for the treatment of acid water was tested in the laboratory by using fly ash and waste rock materials on acidic coalfield water. The results are encouraging, and fly ash may prove to be a good acid neutralizer when used in conjunction of coal overburden material.     

Chemical characterization of synthetic soil from composting coal combustion and pharmaceutical by-products

Land application of coal combustion by-products (CCBs) mixed with solid organic wastes (SOWs), such as municipal sewage sludge, has become increasingly popular as a means of productively using what were once considered waste products. Although bulk chemical and physical properties of several of these CCB-SOW materials have been reported, detailed information about their synthesis and mineralogy of the CCB-SOW materials has not been reported. In this paper, chemical and mineralogical properties of a soil-like material obtained from composting a mixture of CCBs with a pharmaceutical fermentation by-product (FB) were investigated at the laboratory and field scale. All starting materials and products were characterized by X-ray diffraction (XRD), fourier transform infrared (FFIR) spectroscopy, and elemental analyses. The results showed that the FB was strongly bound to the CCBs and could not be removed by washing. Within 2 wk of the start of a composting study, there was a rapid drop in pH from 12 to 8, an increase in temperature to 70 degrees C, and a reduction in the dissolved oxygen content, attributed to the rapid establishment of a highly active microbial population. Composting produced a soil-like material with high levels of plant nutrients, a high nutrient retention capacity, and metal contents similar to median levels of those metals reported for soils. The levels of boron and soluble salts are such that sensitive plants may initially show toxicity symptoms. However, with adequate rainfall, leaching should rapidly remove most of the B and soluble salts. With care, the material produced is safe for use as a synthetic topsoil.     

Industrial processes and waste characterization

Specific industrial processes and its waste characteristics should be known for proper management and control of the wastes produced from industries. Some industrial processes and waste characteristics are introduced to explain how to deal with the wastes for waste characterization. Evaluation methods of biodegradability of industrial wastewater were introduced in order for environmental engineers to be able to decide the proper treatment method of the industrial wastewaters. Industrial processes and characterization discussed in this section might be useful for the selection of suitable methods to prevent pollutant discharge from industrial processes.     

煤灰渣利用中对人群所产生辐射影响的评价

煤的开发与利用产生了大量的灰，渣等固体废物，占用大量土地，污染土壤和水源，成为四大公害之一，因而对煤灰，渣的治理和综合利用一直受到人们的关注。然而，由于煤灰渣中的天然放射性水平较高，因此，在煤灰渣的综合利用，尤其在用作建筑材料时，不可避免地要受到其放射性核素的危害。本文在对四川省各燃煤电厂排放灰渣中的^238U,^232Th,^220R,^40X并无然放射性核素进行分析和研究的基础上，用UNSCEAR1982年报告所推荐的计算模式估算了各电厂煤灰渣制度建材对公众所产生的附加辐射剂量，评价了煤灰制度建材对环境和人群所产生的辐射影响，并提出了控制煤灰渣在建材中的最大掺合量，为其它作用的使用煤灰渣提出了科学的理论依据。     

Critical review of industrial and medical waste practices in Dar es Salaam City

Industrial and medical wastes constitute a larger part on what is known as ‘hazardous wastes’. The production of these wastes is and will continue to be an on going phenomenon as long as human civilization persists. The health impacts of direct and indirect exposure to hazardous wastes include carcinogenic effects, reproductive system damage, respiratory effects, central nervous system effects, and many others. Today, many developed countries have legal provisions with regard to proper management of hazardous wastes. Tanzania, like many developing countries, has little emphasis on the proper handling and disposal of hazardous wastes. There is a serious inadequacy in handling industrial and medical solid wastes in the Dar es Salaam City. Improper waste deposition is increasingly becoming a potential public health risk and an environmental burden. Due to poor control of waste, industrialists and hospital owners are not well checked on how they handle and dispose of the wastes they produce with the result that many hazardous wastes reach the Vingunguti dumpsite without notice. Data on waste generation in Dar es Salaam is also inadequate, making it difficult to plan an efficient solid waste system. Promotion of public awareness, legislation and regulations enforcement and establishment of a proper sanitary landfill are considered to be principal remedial measures to ensure sound environmental maintenance. This paper summarizes the findings of the study on the practices of industrial and medical waste management in Dar es Salaam. The author aims to express the inadequacy in hazardous waste management and suggests possible measures to be applied in order to rectify the situation.     

兰炭生产过程中固体废物的产生与利用现状分析

在对国内兰炭生产工艺流程应用及现状介绍的基础上,概括总结了旧式低温干馏阶段和现阶段兰炭生产过程中固体废物的产生节点、种类、性质和主要处置方式。结果表明,旧式低温干馏阶段,兰炭生产过程中产生的固体废物主要包括煤筛分破碎工序产生的末煤和煤矸石、筛焦工序产生的焦粉、焦油冷却收集系统产生的焦油渣等;现阶段,兰炭生产过程中产生的固体废物主要包括煤筛分破碎工序产生的末煤和煤矸石以及破碎过程中经除尘器收集的煤尘、筛焦工序产生的焦粉、废水处理污泥、焦油冷却收集系统产生的焦油渣、脱硫工序产生的脱硫残液等。其中末煤、煤矸石、煤尘、焦粉作为一般工业固废全部综合利用,废水污泥、焦油渣、脱硫残液主要掺入原料煤中自行消化处置。     

Reclamation of wastes contaminated by copper,lead, and zinc

Waste materials containing toxic levels of copper, lead, and zinc, such as mine and smelter wastes, present difficult conditions for the establishment of vegetation. This article reviews the many attempts which have been made to reclaim these wastes. Inert wastes from mining and quarrying operations, such as slate quarry waste and certain colliery shales, seem to be good materials for reclaiming wastes contaminated by copper, lead, and zinc. Organic wastes, such as sewage sludge and domestic refuse, may provide only a temporary visual improvement and stabilization of the toxic materials.Nontolerant plant materials may often be planted directly on modern waste materials, which are less toxic than they were in the past. However, tolerant plant materials are needed for revegetating waste materials produced by early and more primitive extraction methods.     

南京市工业系统资源环境减量投入分析

本文将物质减量图解应用于工业系统的资源环境减量投入上,对南京市工业系统1986～2004年的资源环境的使用强度和减量化水平进行了计算和分析。结果表明,南京市工业系统的资源环境使用强度在评价期间逐年降低,2004年的工业用水、能源消耗、废水排放、废气排放和“固废”排放的强度分别为1986年的18.14%、15.14%、4.36%、14.95%、15.72%;在评价期间南京市工业系统只有工业废水实现了绝对减量排放;而水耗、能耗、废气排放和“固废”排放四项指标均没有实现绝对减量,致使在此期间南京市工业系统水耗增加了384100.66万吨,能耗增加了1409.32万标准吨煤,废气排放量增加19852018.00万立方米,“固废”增加排放603.26万吨。     

Strontium isotope study of coal utilization by-products interacting with environmental waters

Sequential leaching experiments on coal utilization by-products (CUB) were coupled with chemical and strontium (Sr) isotopic analyses to better understand the influence of coal type and combustion processes on CUB properties and the release of elements during interaction with environmental waters during disposal. Class C fly ash tended to release the highest quantity of minor and trace elements-including alkaline earth elements, sodium, chromium, copper, manganese, lead, titanium, and zinc-during sequential extraction, with bottom ash yielding the lowest. Strontium isotope ratios ((87)Sr/(86)Sr) in bulk-CUB samples (total dissolution of CUB) are generally higher in class F ash than in class C ash. Bulk-CUB ratios appear to be controlled by the geologic source of the mineral matter in the feed coal, and by Sr added during desulfurization treatments. Leachates of the CUB generally have Sr isotope ratios that are different than the bulk value, demonstrating that Sr was not isotopically homogenized during combustion. Variations in the Sr isotopic composition of CUB leachates were correlated with mobility of several major and trace elements; the data suggest that arsenic and lead are held in phases that contain the more radiogenic (high-(87)Sr/(86)Sr) component. A changing Sr isotope ratio of CUB-interacting waters in a disposal environment could forecast the release of certain strongly bound elements of environmental concern. This study lays the groundwork for the application of Sr isotopes as an environmental tracer for CUB-water interaction.     

Utilization of waste foundry sand (WFS) in concrete manufacturing

Due to ever increasing quantities of waste materials and industrial by-products, solid waste management is the prime concern in the world. Scarcity of land-filling space and because of its ever increasing cost, recycling and utilization of industrial by-products and waste materials has become an attractive proposition to disposal. There are several types of industrial by-products and waste materials. The utilization of such materials in concrete not only makes it economical, but also helps in reducing disposal concerns. One such industrial by-product is waste foundry sand (SFS). Waste foundry sand is a by-product of ferrous and nonferrous metal casting industries. Foundries successfully recycle and reuse the sand many times in a foundry. When the sand can no longer be reused in the foundry, it is removed from the foundry and is termed as waste foundry sand.Published literature has shown that WFS could be used in manufacturing Controlled Low-Strength Materials (CLSM) and concrete. This paper presents an overview of some of the research published on the use of WFS in concrete. Effect of WFS on concrete properties such as compressive strength, splitting tensile strength, modulus of elasticity, freezing-thawing resistance, and shrinkage are presented.     

采油作业“三废”控制技术研究与应用

针对采油作业产生的废酸、固废、废水处理成本高、技术不成熟等问题,研发改性废酸降压增注、深部调剖技术;高比重污泥悬浮研磨后的固废处理技术;低耗水打塞、原井液+CaCl2压井、原井液处理再利用技术,减少了"三废"的产生,解决了"三废"环保处理费高等问题,消除了环保隐患,实现了清洁生产,环境效益显著。     

China: Energy and environment

Some of China's most prominent environmental problems are related to energy The air pollution of the cities and industrial centers is caused by the inefficient combustion of coal. Deforestation is due to a certain extent to the procurement of firewood. Further problems are caused by the ash and slag from coal combustion and the oil pollution of the sea. While most of China's air is still clean, pollution levels in the cities surpass by far those of German industrial towns, and the health effects are becoming apparent The problem of deforestation must be considered still more serious because it affects whole regions. Short-term effective solutions to the problems presented are not available     

Coal Combustion Product: Nonhazardous Material for Mine Fill

As is the case in many other countries around the world, India's main source of electricity is coal‐fired power plants. In addition to providing energy, the burning of coal also results in large amounts of coal combustion products (CCP), the incombustible material, such as fly ash, left after the coal is burned. These materials are produced in large volume, and if they are not managed or utilized properly, they can pose a danger to the environment. This article discusses the uses of CCP, with a special emphasis on fly ash, and the role that it is currently playing and can continue to play as a mine filler for India's depleted opencast and underground coal mines.     

Utilization of municipal solid waste (MSW) ash in cement and mortar

Solid waste management is gaining significant importance with the ever-increasing quantities of waste materials generated these days. With increased environmental awareness and its potential hazardous effects, recycling/utilization of these materials have become an attractive alternative to disposal. Some of these waste and hazardous materials could possible be used in cement-based materials. One of such waste is municipal solid waste. Ash is obtained after incineration of MSW.This paper presents comprehensive details of the physical, chemical, and mineralogical composition, elemental analysis of ash obtained from MSW. It also covers the effect of MSW ash on the hydration characteristics, setting times, compressive strength, sulfate resistance and mass loss of cement and mortar. It also deals with the leachate analysis of MSW ash.     

Assessing determinants of industrial waste reuse: The case of coal ash in the United States

Devising effective strategies to facilitate waste reuse depends on the solid understanding of reuse behaviors. However, previous studies of reuse behavior have been limited in scope, focusing mostly on household recycling behaviors or very limited types of industrial wastes. To gain a better understanding of the business reuse behaviors, this study examined the impact of various factors in technical, economic, regulatory, and behavioral categories in the case of coal ash generated in the United States. The results of fixed effect models for fly ash and bottom ash particularly showed the significance role of the behavioral factor. In both models, a proxy variable, which represents knowledge sharing among the power plants or the utility's decision-making, turned out to be statistically significant and had the largest coefficient estimates among a group of variables. This finding may imply that the characteristics of waste reuse behavior are determined more by business decision-making behaviors than by market or institutional factors. However, the role of the behavioral variable was stronger in the bottom ash models than in the fly ash models. While the reuse of bottom ash was determined primarily by the behavioral variable, fly ash reuse was determined by more diverse factors including economic and regulatory variables. This could be explained by material characteristics in relation to competing resources and the nature of reuse applications.