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.     

Waste materials for activated carbon preparation and its use in aqueous-phase treatment: a review

Commercial activated carbon is a preferred adsorbent for the removal of micropollutants from the aqueous phase; however, its widespread use is restricted due to high associated costs. To decrease treatment costs, attempts have been made to find inexpensive alternative activated carbon (AC) precursors, such as waste materials. Some reviews report the use of waste materials for the preparation of AC; however, these studies are restricted to either type of wastes, preparation procedures, or specific aqueous-phase applications. The present work reviews and evaluates literature dedicated both to the preparation of AC by recycling different types of waste materials and also to its application in various aqueous-phase treatments. It is clear that conventional (from agriculture and wood industry) and non-conventional (from municipal and industrial activities) wastes can be used to prepare AC, that can be applied in various aqueous treatment processes, namely to remove organic pollutants, dyes, volatile organic compounds, and heavy metals. Moreover, high surface areas can be obtained using either physical or chemical activation; however, combined treatments might enhance the surface properties of the adsorbent, therefore increasing its adsorption capacity. It is evident from the revision made that AC prepared from both conventional and non-conventional wastes might effectively compete with the commercial ones. This happens mostly when the activation procedures are optimized considering both the raw material used to produce the carbons and the contaminants to be removed.     

The recycling of rare earths from waste tricolor phosphors in fluorescent lamps: A review of processes and technologies

Rare earths have become the most important strategic resources, widely used as functional materials in industry and many other aspects of life due to its optical, electrical, and magnetic characteristics. As a consequence, a considerable number of wastes containing rare earths such as abandoned fluorescent lamps are generated and lost. Considering the scarcity in availability and supply of certain raw materials, waste tricolor phosphors are viewed as potential resources that can be mined in urban areas for their reutilization as rare earths. A number of studies in this area have been carried out all over the world.The purpose of this paper is to review the current status of recycling technologies of rare earths from waste tricolor phosphors in fluorescent lamps. The main characteristics of the tricolor phosphors were introduced, and also a detail review of the typical single recycling and reusing technologies with regard to waste tricolor phosphors was carried out in present paper. After that, several combined recycling processes and technologies were evaluated. Based on the review, the prospects of recycling technologies were suggested.     

强化发展工业固体废物资源

本文分析了贵州工业固体废物的现状和变化趋势,讨论了工业固体废物资源化的主要途径和发展方向;强调加快企业技术改造,发展无废少废闭路循环生产工艺;加强应用基础研究、开拓新的应用途径等问题的重要性;提出了我国开展固体废物资源化的主要对策和措施.     

Municipal solid waste generation in Kathmandu, Nepal

Waste stream characteristics must be understood to tackle waste management problems in Kathmandu Metropolitan City (KMC), Nepal. Three-stage stratified cluster sampling was used to evaluate solid waste data collected from 336 households in KMC. This information was combined with data collected regarding waste from restaurants, hotels, schools and streets. The study found that 497.3 g capita(-1) day(-1) of solid waste was generated from households and 48.5, 113.3 and 26.1 kg facility(-1) day(-1) of waste was generated from restaurants, hotels and schools, respectively. Street litter measured 69.3 metric tons day(-1). The average municipal solid waste generation rate was 523.8 metric tons day(-1) or 0.66 kg capita(-1) day(-1) as compared to the 320 metric tons day(-1) reported by the city. The coefficient of correlation between the number of people and the amount of waste produced was 0.94. Key household waste constituents included 71% organic wastes, 12% plastics, 7.5% paper and paper products, 5% dirt and construction debris and 1% hazardous wastes. Although the waste composition varied depending on the source, the composition analysis of waste from restaurants, hotels, schools and streets showed a high percentage of organic wastes. These numbers suggest a greater potential for recovery of organic wastes via composting and there is an opportunity for recycling. Because there is no previous inquiry of this scale in reporting comprehensive municipal solid waste generation in Nepal, this study can be treated as a baseline for other Nepalese municipalities.     

Sound management of brominated flame retarded (BFR) plastics from electronic wastes: State of the art and options in Nigeria

Management of flame retarded plastics from waste electrical and electronic equipment (WEEE) has been posing a major challenge to waste management experts because of the potential environmental contamination issues especially the formation of polybrominated-dioxins and -furans (PBDD/F) during processing. In Nigeria, large quantities of electronic waste (e-waste) are currently being managed—a significant quantity of which is imported illegally as secondhand electronics. As much as 75% of these illegal imports are never reused but are rather discarded. These waste electronic devices are mostly older equipment that contains brominated flame retardants (BFRs) such as penta-brominated diphenyl ethers (PBDEs), and polybrominated biphenyls (PBBs) which are presently banned in Europe under the EU WEEE and RoHS Directives. Risk assessment studies found both to be persistent, bio-accumulative and toxic. The present management practices for waste plastics from WEEE in Nigeria, such as open burning and disposal at open dumps, creates potential for serious environmental pollution. This paper reviews the options in the environmentally sound management of waste plastics from electronic wastes. Options available include mechanical recycling, reprocessing into chemicals (chemical feedstock recycling) and energy recovery. The Creasolv^® and Centrevap^® processes, which are the outcome of the extensive research at achieving sound management of waste plastics from WEEE in Europe, are also reviewed. These are solvent-based methods of removing BFRs and they presently offer the best commercial and environmental option in the sound management of waste BFR-containing plastics. Because these developments have not been commercialized, WEEE and WEEE plastics are still being exported to developing countries. The industrial application of these processes and the development of eco-friendlier alternative flame retardants will help assure sound management of WEEE plastics.     

An overview for the utilization of wastes from stainless steel industries

Significant quantities of wastes are generated as the waste materials or byproducts every day from stainless steel processes. According to the origins and characteristics, the stainless steel wastes can be mainly classified into two categories, slags and dusts. They usually contained considerable quantities of valuable metals and materials. This paper summarized and analyzed the generation, composition, characteristics and the leaching behaviors of the most of wastes obtained from the stainless steel processes. On this basis, a review of several methods for treating the various stainless steel wastes was made. It is very essential not only for recycling the valuable metals and mineral resources but also for protecting the environment.     

Utilization of coal combustion by-products in sustainable construction materials

Solid waste management is gaining significant importance with the ever-increasing quantities of industrial by-products and wastes. With the environmental awareness and scarcity of space for landfilling, wastes/by-product utilization has become an attractive alternative to disposal. Several industrial by-products are produced from manufacturing processes, service industries and municipal solid wastes. Some of these industrial by-products/waste materials could possibility be used in cement-based materials.Coal combustion by-products (CCBs) represent incombustible materials left after combustion of coal in conventional and/or advanced clean-coal technology combustors. These include fly ash, bottom ash, boiler slag, and flue gas desulfurization (FGD) by-products from advanced clean-coal technology combustors. This paper briefly describes various coal combustion products produced, as well as current best recycling use options for these materials. Materials, productions, properties, potential applications in manufacture of emerging materials for sustainable construction, as well as environmental impact are also briefly discussed.     

Recycling inorganic domestic solid wastes: results from a pilot study in Dar es Salaam City, Tanzania

Solid waste recycling and recovery approach can be a sustainable and effective waste management system in many growing cities of the least developed countries. In the course of achieving proper solid waste management, a lot of efforts in these countries have, however, been focused more on collection and disposal and ignored waste recycling which can result into income generation, employment creation and reduction of the waste quantities that will finally require disposal in the existing municipal landfills or disposal sites. This paper reports the findings of a study on solid waste recycling in a selected semi-planned settlement in Dar es Salaam City, Tanzania. The objective of the study was to describe the existing solid waste management in the study area with a view to identifying the waste generation rates, types of the wastes and determine the amount of waste from the settlement that can be recycled for the purpose of income generation and reduction of the total amount of waste to be disposed of. Findings from this study revealed that waste generation rate in the study area was 0.36 kg per person per day, and that out of the 14 600 kg of recyclable waste generated per year, 8030 kg or 55% can be recycled and generate a per capita income of Tsh 834 000 for waste recyclists which is more than twice the official minimum annual wage (Tsh 360 000) in Tanzania at the time of the study. The study also revealed that effective waste recycling in the study area would result in the reduction of the total waste that need to be transported for final disposal by 11%.     

Hospital waste management in El-Beheira Governorate,Egypt

This study investigated the hospital waste management practices used by eight randomly selected hospitals located in Damanhour City of El-Beheira Governorate and determined the total daily generation rate of their wastes. Physico-chemical characteristics of hospital wastes were determined according to standard methods. A survey was conducted using a questionnaire to collect information about the practices related to waste segregation, collection procedures, the type of temporary storage containers, on-site transport and central storage area, treatment of wastes, off-site transport, and final disposal options. This study indicated that the quantity of medical waste generated by these hospitals was 1.249 tons/day. Almost two-thirds was waste similar to domestic waste. The remainder (38.9%) was considered to be hazardous waste. The survey results showed that segregation of all wastes was not conducted according to consistent rules and standards where some quantity of medical waste was disposed of with domestic wastes. The most frequently used treatment method for solid medical waste was incineration which is not accepted at the current time due to the risks associated with it. Only one of the hospitals was equipped with an incinerator which is devoid of any air pollution control system. Autoclaving was also used in only one of the selected hospitals. As for the liquid medical waste, the survey results indicated that nearly all of the surveyed hospitals were discharging it in the municipal sewerage system without any treatment. It was concluded that the inadequacies in the current hospital waste management practices in Damanhour City were mainly related to ineffective segregation at the source, inappropriate collection methods, unsafe storage of waste, insufficient financial and human resources for proper management, and poor control of waste disposal. The other issues that need to be considered are a lack of appropriate protective equipment and lack of training and clear lines of responsibilities between the departments involved in hospital waste management. Effective medical waste management programs are multisectoral and require cooperation between all levels of implementation, from national and local governments to hospital staff and private businesses.     

Heavy metal removal and cyanide destruction in the metal plating industry: an integrated approach from egypt

Wastewater produced from a metal plating is a major environmental problem. Industrial auditing revealed that the main source of pollution mainly originated from rinsing water. The characterization of final effluent showed that it is highly contaminated with hazardous heavy metals and cyanide. The concentration of copper, hexavalent chromium, nickel, and cyanide in the rinsing water of metal plating department was 14.8, 40.9, 13.3, and 19 mg/l, respectively. The concentration of cyanide and zinc from the galvanizing department reached 60 and 80 mg/l. The remediation scheme included the application of in-plant control measures via changing the rinsing process followed by the destruction of cyanide and reduction of hexavalent chromium bearing wastes. The pretreated wastes were then mixed with other industrial wastes prior to a combined chemical coagulation-sedimentation using lime and/or lime in combination with ferric chloride. The results indicated that, after applying the waste minimization measures alone at the source, prior to final treatment of industrial waste, removal rates of cyanide, copper, nickel, and chromium concentrations were 23.2%, 14.9%, 32.3%, and 55.3%, respectively in the rinse water from metal plating department. Furthermore, the removal rates of cyanide and zinc in the galvanizing department reached 59.7% and 24.3. The integrated control measures and treatment scheme led to more than 99% removal of copper, nickel, chromium, and zinc, while the complete removal of cyanide was achieved in the final effluent.     

Liquid household hazardous wastes in the United States: Identification,disposal, and management plan

Present methods of disposal of today's hazardous household chemicals in the United States are frequently not acceptable because of pathways to groundwater, surface water, and the atmosphere. This report identifies potentially hazardous liquid waste in the household, notes current disposal practices, and recommends an improved management plan that utilizes consumer education, manufacturer cooperation, and governmental intervention. Laws requiring uniform disposal labeling on packaging are critical. Local, county, and state governments must be encouraged to coordinate the necessary infrastructure. Managing hazardous household wastes now will mitigate potential disposal problems.     

AIRPORT WASTES AND WATER QUALITY1

ABSTRACT: Waste waters from various operations at the Miami International Airport are characterized. Servicing, maintenance, overhauling, and washing of aircraft seem to be the most significant waste water producing operations. Pollutional constitutents commonly found in the airport wastes include acids, alkalis, detergents, oil, grease, and oxygen demanding substances. Phenols are of concern when stripping and repainting operations occur. Although most airport wastes may be treatable, a great reduction in influent load can be achieved by proper housekeeping methods.     

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.     

Land application of biomass residue generated from palm oil processing: its potential benefits and threats

Man’s increased demand for food and better living conditions has led to over exploitation of resources and the consequent generation of enormous amounts of liquid and solid waste materials. This is one of the global challenges for mankind. In Malaysia, palm oil mill waste (POMW) contributes the highest proportion of industrial solid wastes produced yearly. Wastes from the mills include palm oil mill effluent, decanter cake, empty fruit bunches, seed shells and the fibre from the mesocarp. Direct application of POMW into agricultural soil has resulted in a number of problems such as water pollution, leaching. However, with application rates specific for targeted plant species, land application can be employed as a permanent solution to the problem of waste from palm oil mills. This review examines the characteristics of each of the palm oil wastes and their potential for use as a future fertilizer supplement.     

浅析珠三角工业结构与环境污染物的灰色关联

根据2004—2009年珠三角地区各种工业结构、总产值以及工业“三废”排放量等数据,运用灰色关联分析研究了珠三角工业生产规模结构、轻重工业结构、行业结构、工业生产结构与不同环境污染物之间的关联程度。结果表明：珠三角3种生产规模的企业中与工业“三废”关联最大的是中型企业,其次是大型企业,小型企业最小;相对重工业,珠三角轻工业与工业“三废”的关联较大;珠三角工业主导行业与工业“三废”的关联度排序：采矿业〉制造业〉电力燃气及水的生产和供应;就产业结构来说,与污染物的灰色关联度依次是：第一产业、第二产业、第三产业。     

2010年上海世博会垃圾组分的预测

为了便于2010年上海世博会期间生活垃圾的处理与处置，选择了和世博园区垃圾性质相近似的南京路步行街为参照区，进行垃圾组分的调研，预测模拟世博园区垃圾的组成与性质。研究结果表明：南京路步行街垃圾中食物垃圾占50％左右，塑料和纸张占45％左右，而一般的城市生活垃圾中塑料和纸张只占20％～30％左右，可见对于类似的垃圾资源化程度非常高。因此对于世博园垃圾进行分选，实现各组分垃圾的分流，可以更好地实现垃圾的资源化、减量化。     

Multi-objective optimization of waste and resource management in industrial networks – Part I: Model description

This article presents a general multi-objective mixed-integer linear programming (MILP) optimization model aimed at providing decision support for waste and resources management in industrial networks. The MILP model combines material flow analysis, process models of waste treatments and other industrial processes, life cycle assessment, and mathematical optimization techniques within a unified framework. The optimization is based on a simplified representation of industrial networks that makes use of linear process models to describe the flows of mass and energy. Waste-specific characteristics, e.g. heating value or heavy metal contamination, are considered explicitly along with potential technologies or process configurations. The systems perspective, including both provision of waste treatment and industrial production, enables constraints imposed upon the systems, e.g. available treatment capacities, to be explicitly considered in the model. The model output is a set of alternative system configurations in terms of distribution of waste and resources that optimize environmental and economic performance. The MILP also enables quantification of the improvement potential compared to a given reference state. Trade-offs between conflicting objectives are identified through the generation of a set of Pareto-efficient solutions. This information supports the decision making process by revealing the quantified performance of the efficient trade-offs without relying on weighting being expressed prior to the analysis. Key features of the modeling approach are illustrated in a hypothetical case. The optimization model described in this article is applied in a subsequent paper (Part II) to assess and optimize the thermal treatment of sewage sludge in a region in Switzerland.     

Fish bioassay monitoring of waste effluents

Spills of toxic materials into bodies of water receiving industrial waste discharges can be prevented only if frequent or continuous assessments of effluent quality can be made. Currently available methods can automatically measure individual physical or chemical waste components but cannot assess toxicity caused by the interaction of components or the presence of an unsuspected material. Aquatic organisms, in contrast, respond to their total environment and in this way integrate the effects of all the various chemical and physical waste parameters.This study evaluates the possibility of using the continuously and automatically recorded responses of fish to monitor the toxicity of industrial waste effluents. A review of previously developed toxicity monitoring systems is followed by a field evaluation of a method that uses the computer-monitored ventilatory patterns of 12 bluegills (Lepomis macrochirus Rafinesque) to monitor the toxicity of an industrial waste effluent as it flows into a river. No known toxic spills occurred in the effluent during the operation of this system, but acetone added to the effluent waste caused responses from the fish at concentrations which peaked near the 96-hr LC₅₀ level. Some responses were also noted when no known toxicant was present; these were related to environmental disturbances and system design problems. Recommendations are made for the design of future biologic monitoring units.     

Introduction of a waste incineration tax: Effects on the Swedish waste flows

A tax on waste-to-energy incineration of fossil carbon in municipal solid waste from households was introduced in Sweden on July 1, 2006. The tax has led to higher incineration gate fees. One of the main purposes with the tax is to increase the incentive for recycling of materials, including biological treatment. We investigate whether and to what extent this effect can be expected. A spreadsheet model is developed in order to estimate the net marginal cost of alternative waste treatment methods, i.e., the marginal cost of alternative treatment minus avoided cost of incineration. The value of the households’ time needed for source separation is discussed and included. The model includes the nine largest fractions, totalling 85% (weight), of the household waste currently being sent to waste incineration: food waste, newsprint, paper packaging, soft and hard plastic packaging, diapers, yard waste, other paper waste, and non-combustible waste. Our results indicate that the incineration tax will have the largest effect on biological treatment of kitchen and garden waste, which may increase by 9%. The consequences of an incineration tax depend on: (a) the level of the tax, (b) whether the tax is based on an assumed average Swedish fossil carbon content or on the measured carbon content in each incineration plant, (c) institutional factors such as the cooperation between waste incinerators, and (d) technological factors such as the availability of central sorting of waste or techniques for measurement of fossil carbon in exhaust gases, etc. Information turns out to be a key factor in transferring the governing force of the tax to the households as well improving the households’ attitudes towards material recycling.