矿山酸性废水治理技术及其发展趋势

矿山酸性废水在很多国家和地区都造成了严重的环境污染。本文分析矿山酸性废水的成因、特点及危害,并总结了中和法、硫化法和微生物法等经济、实用的酸性矿山废水处理技术现状,并进一步阐述了酸性矿山废水治理技术的发展趋势。     

Environmental and economic feasibility study of a total wastewater treatment network system

The synthesis of distributed wastewater treatment plants (WTPs) has been studied to reduce capital and operating costs associated with wastewater treatment. In this study, the environmental and economic feasibility of a total wastewater treatment network system (TWTNS) including distributed and terminal WTPs was estimated using life cycle assessment (LCA) and life cycle costing (LCC) methods. Wastewater sources and existing distributed and terminal WTPs in an iron and steel plant were networked. The TWTNS was generated from the optimal solution to a mathematical optimization model and compared to a conventional wastewater treatment system (CWTS). The environmental effect scores of the TWTNS were from 29.6% to 68.3% higher than those of the CWTS because of higher electricity consumption required to pump wastewater to the networked WTPs. However, the life cycle cost of the TWTNS was lower than that of the CWTS by 10.1% because of the decrease of the labor cost resulting from the closing of three distributed WTPs. Overall, the TWTNS was no more eco-efficient than the CWTS because the increase of environmental burdens outweighed the decrease of economic costs.     

澳大利亚矿山酸性废水的管理与处理

本文简要介绍了澳大利亚矿山含酸废弃物及酸性废水的管理与处理方法 ,将为我国的矿山环境保护提供借鉴作用。     

Environmental indicators for communication of life cycle impact assessment results and their applications

Life cycle impact assessment (LCIA) is performed to quantitatively evaluate all environmental impacts from products, systems, processes and services. However, LCIA does not always provide valuable information for choosing among alternatives with different specifications, functionalities and lifetimes. The objectives of this study are (1) to propose environmental indicators to evaluate environmental efficiency and value qualitatively and quantitatively on the basis of analogies to financial and economic indicators, and (2) to present the application of the indicators. Incremental evaluation using a reference is employed to obtain the environmental indicators. The environmental efficiency indicators are conceptually based on the ratios of reduced environmental burdens returned to environmental burdens required: environmental return on investment, environmental payback period and environmental internal rate of return. The environmental value indicator is the sum of all reduced and required environmental burdens: i.e., environmental net present value. All the environmental indicators can be used to compare and rank the environmental efficiencies or values of alternatives. The environmental efficiency indicators can be applied to a new environmental labeling. The concept of eco-efficiency labeling is developed by combining the environmental efficiency indicators with financial indicators. A case study is performed to illustrate the necessity and importance of the environmental indicators. These environmental indicators can help easily communicate LCIA results in the field of environmental management.     

Inorganic pigments made from the recycling of coal mine drainage treatment sludge

Continuous industrial development increases energy consumption and, consequently, the consumption of fossil fuels. Coal mineral has been used in Brazil as a solid fuel for thermoelectric generators for several years. However, coal exploitation affects the environment intensely, mainly because Brazilian coal contains excess ash and pyrite (iron disulfide). According to the local coal industry syndicate, the average annual coal run per mine is 6 million ton/year; 3.5 million ton/year are rejected and disposed of in landfills. Besides pyrite, Brazilian coal contains Mn, Fe, Cu, Pb, Zn, Ge, Se, and Co. Additionally, the water used for coal beneficiation causes pyrite oxidation, forming an acid mine drainage (AMD). This drainage solubilizes the metals, transporting them into the environment, making treatment a requirement. This work deals with the use of sedimented residue from treated coal mine drainage sludge to obtain inorganic pigments that could be used in the ceramic industry. The residue was dried, ground and calcined ( approximately 1250 degrees C). The calcined pigment was then micronized (D(50) approximately 2mum). Chemical (XRF), thermal (DTA/TG), particle size (laser), and mineralogical (XRD) analyses were carried out on the residue. After calcination and micronization, mineralogical analyses (XRD) were used to determine the pigment structure at 1250 degrees C. Finally, the pigments were mixed with transparent glaze and fired in a laboratory roller kiln (1130 degrees C, 5min). The results were promising, showing that brown colors can be obtained with pigments made by residues.     

On the usefulness of life cycle assessment of packaging

In reaction to a paper inEnvironmental Management in which the sense and sensibility of environmental assessments of packaging were questioned, it is argued that these types of assessments may be very useful, provided the relevant types of questions are posed. These boundary conditions are discussed, along with an overview of more recent methodological developments with respect to environmental assessment of products.     

Environmental impact minimization of a total wastewater treatment network system from a life cycle perspective

Synthesis of distributed wastewater treatment plants (WTPs) has focused on cost reduction, but never on the reduction of environmental impacts. A mathematical optimization model was developed in this study to synthesize existing distributed and terminal WTPs into an environmentally friendly total wastewater treatment network system (TWTNS) from a life cycle perspective. Life cycle assessment (LCA) was performed to evaluate the environmental impacts of principal contributors in a TWTNS. The LCA results were integrated into the objective function of the model. The mass balances were formulated from the superstructure model, and the constraints were formulated to reflect real wastewater treatment situations in industrial plants. A case study validated the model and demonstrated the effect of the objective function on the configuration and environmental performance of a TWTNS. This model can be used to minimize environmental impacts of a TWTNS in retrofitting existing WTPs in line with cleaner production and sustainable development.     

川北高台原区废弃煤矿枯水期矿井涌水水化学特征及成因分析

对废弃煤矿矿井涌水的水化学特征及成因进行分析,可为保护矿区地下水环境提供理论支撑.基于地质背景,通过对比枯水季节川北高台原区废弃煤矿矿井涌水与背景泉点水化学指标,并采用聚类分析方法对矿井涌水中离子指标进行统计,进而对其特征及成因进行了研究.结果表明:地层中黄铁矿中硫元素氧化是矿井涌水水化学特征变化的开端,受研究区矿井涌...     

Use of man-made impoundment in mitigating acid mine drainage in the North Branch Potomac River

The US Department of the Army, Baltimore District Corps of Engineers, oversees a long-term monitoring study to assess and evaluate effects of the Jennings-Randolph reservoir on biota in the North Branch Potomac River. The reservoir was intended, in part, to mitigate effects of acid mine drainage originating in upstream and headwater areas. The present study assessed recovery of benthos and fish in this system, six years after completion of the reservoir. Higher pH and lower iron and sulfate concentrations were observed upstream of the reservoir compared to preimpoundment conditions, suggesting better overall water quality in the upper North Branch. Water quality improved slightly directly downstream of the reservoir. However, the reservoir itself was poorly colonized by macrophytes and benthic organisms, and plankton composition suggested either metal toxicity and/or nutrient limitation. One large tributary to the North Branch and the reservoir (Stony River) was shown to have high (and possibly toxic) levels of manganese, iron, zinc, and aluminum due to subsurface coal mine drainage. Macroinvertebrate diversity and number of taxa were higher in sites downstream of the reservoir in the present study. Compared with previous years, the present study suggested relatively rapid recovery in the lower North Branch due to colonization from two major unimpacted tributaries in this system: Savage River and South Branch Potomac. Abundance of certain mayfly species across sites provided the most clear evidence of longitudinal gradients in water quality parameters and geomorphology. Fish data were consistent with macroinvertebrate results, but site-to-site variation in species composition was greater. Data collected between 1982 and 1987 suggested that certain fish species have unsuccessfully attempted to colonize sites directly downstream of the reservoir despite the more neutral pH water there. Our results show that recovery of biota in the North Branch Potomac was attributed to decreased acid inputs from mining operations and dilution from the Savage River, which contributed better water quality. Continued improvement of North Branch Potomac biota may not be expected unless additional mitigation attempts, either within the reservoir or upstream, are undertaken.     

Alternative scenarios to meet the demands of sustainable waste management

This paper analyses different alternatives for solid waste management that can be implemented to enable the targets required by the European Landfill and Packaging and Packaging Waste Directives to be achieved in the Valencian Community, on the east coast of Spain. The methodology applied to evaluate the environmental performance of each alternative is Life Cycle Assessment (LCA). The analysis has been performed at two levels; first, the emissions accounted for in the inventory stage have been arranged into impact categories to obtain an indicator for each category; and secondly, the weighting of environmental data to a single unit has been applied. Despite quantitative differences between the results obtained with four alternative impact assessment methods, the same preference ranking has been established: scenarios with energy recovery (1v and 2v) achieve major improvements compared to baseline, with scenario 1v being better than 2v for all impact assessment methods except for the EPS'00 method, which obtains better results for scenario 2v. Sensitivity analysis has been used to test some of the assumptions used in the initial life cycle inventory model but none have a significant effect on the overall results. As a result, the best alternative to the existing waste management system can be identified.     

对氨基苯胂酸的生命周期评价

本文介绍了最常用的有机胂制剂——对氨基苯胂酸的主要用途和污染特征,从生命周期的角度识别并定量评价了其生产、使用和残留过程的环境影响,评价结果表明对氨基苯胂酸在土壤中最终残留的环境骰响占其整个生命周期的99％以上,指出了常规环境影响评价在评价其环境污染上的局限性,据此提出逐步减少或禁止有机胂制剂的生产和使用、并在一些特殊的建设项目环境影响评价中推广生命周期评价的建议。     

ENVIRONMENTAL AUDITING: The Functional Unit in the Life Cycle Inventory Analysis of Degreasing Processes in the Metal-Processing Industry

1 and C₂ hydrocarbons (trichloroethane, trichloroethene, tetrachloroethene, dichloromethane). Measures aiming at the reduction of toxic emissions and ozone depletion potential (ODP) may possibly lead to a shift of environmental impacts towards higher energy consumption, emission of waste water, and volatile organic compounds (VOC) with photochemical oxidant creation potential (POCP). The present article concerns itself with a life cycle assessment of the three main degreasing processes in order to compare their integral environmental impacts with one another. This is supplemented by presenting the methodology of the life cycle inventory life cycle inventory analysis (LCI). Generally, the applicability of the established LCI method can be shown quite clearly. However, some difficulties arise, especially at the stage of the goal definition, as the use of the process and the functional unit cannot be pinned down as easily and neatly as for most other products. The definition of the use of the process and the functional unit is not as straightforward as for most products. Among the potential functional units identified are the mass of removed impurities, cleaning time, cleaning work, percentage of purity, throughput of parts, loads, mass or surface and virtual coefficients. The mass of removed impurities turned out to be the most suitable parameter for measuring the technical performance of degreasing processes. The article discusses background, purpose, scope, system boundaries, target group, process tree and representativeness of the present study.     

酸性矿山废水的处理研究

本文简要分析了酸性矿山废水的主要污染物及危害，叙述了几种主要的处理技术：中和法、硫化沉淀浮选法、微生物法和人工湿地，并介绍了它们的机理、特点及实验研究和工业应用情况，由此对我国的酸性矿山废水的治理技术进行了前景展望。     

Environmental assessment of supercritical water oxidation of sewage sludge

Environmental aspects of using supercritical water oxidation (SCWO) to treat sewage sludge were studied using a life cycle assessment (LCA) methodology. The system studied is the first commercial scale SCWO plant for sewage sludge in the world, treating sludge from the municipal wastewater treatment facility in Harlingen, TX, USA. The environmental impacts were evaluated using three specific environmental attributes: global warming potential (GWP), photo-oxidant creation potential (POCP) and resource depletion; as well as two single point indicators: EPS2000 and EcoIndicator99. The LCA results show that for the described process, gas-fired preheating of the sludge is the major contributor to environmental impacts, and emissions from generating electricity for pumping and for oxygen production are also important. Overall, SCWO processing of undigested sewage sludge is an environmentally attractive technology, particularly when heat is recovered from the process. Energy-conserving measures and recovery of excess oxygen from the SCWO process should be considered for improving the sustainability potential.     

Environmental sustainability assessment in the process industry: A case study of waste-to-energy plants in Spain

This study proposes a technical procedure based on a life cycle approach for implementation of the environmental sustainability assessment (ESA) of several waste-to-energy (WtE) plants located in Spain. This methodology uses two main variables: the natural resources sustainability (NRS) and the environmental burdens sustainability (EBS). NRS includes the consumption of energy, materials, and water, whereas EBS considers five burdens to air, five burdens to water, and two burdens to land. To reduce the complexity of ESA, all variables were normalised and weighted using the threshold values proposed in the European Pollutant Release and Transfer Register regulation. The results showed the plants studied had a greater consumption of natural resources than Spain, ranging from 1.1 to 2.0 times higher than the Spanish reference consumption. The comparison of Spain with the BREF reference on waste incineration showed that only in the variable related to materials, did Spain have a lower consumption (1.80 times lower). In terms of EBS, air and land impacts were the highest contributors to global burden. The WtE plants presented higher burdens to air and water than Spain, whereas only one plant exceeded the average burden to land of Spain. Finally, this paper demonstrated the usefulness of the ESA methodology to reduce the complexity of LCA and assist the decision-making process in choosing the best option from an environmental point of view. This procedure can be used to obtain an overview of the environmental performance of WtE plants, as well as to assess individual burdens and thereby determine the main environmental hotspots, thereby improving the critical points of the process.     

Methodological aspects of life cycle assessment of integrated solid waste management systems

Environmental life cycle assessment (LCA) developed rapidly during the 1990s and has reached a certain level of harmonisation and standardisation. LCA has mainly been developed for analysing material products, but can also be applied to services, e.g. treatment of a particular amount of solid waste. This paper discusses some methodological issues which come into focus when LCAs are applied to solid waste management systems. The following five issues are discussed. (1) Upstream and downstream system boundaries: where is the ‘cradle’ and where is the ‘grave’ in the analysed system? (2) Open-loop recycling allocation: besides taking care of a certain amount of solid waste, many treatment processes also provide additional functions, e.g. energy or materials which are recycled into other products. Two important questions which arise are if an allocation between the different functions should be made (and if so how), or if system boundaries should be expanded to include several functions. (3) Multi-input allocation: in waste treatment processes, different materials and products are usually mixed. In many applications there is a need to allocate environmental interventions from the treatment processes to the different input materials. The question is how this should be done. (4) Time: emissions from landfills will continue for a long time. An important issue to resolve is the length of time emissions from the landfill should be considered. (5) Life cycle impact assessment: are there any aspects of solid waste systems (e.g. the time horizon) that may require specific attention for the impact assessment element of an LCA? Although the discussion centres around LCA it is expected that many of these issues are also relevant for other types of systems analyses.     

Life cycle assessment of a pulverized coal power plant with post-combustion capture, transport and storage of CO2

In this study the methodology of life cycle assessment has been used to assess the environmental impacts of three pulverized coal fired electricity supply chains with and without carbon capture and storage (CCS) on a cradle to grave basis. The chain with CCS comprises post-combustion CO₂ capture with monoethanolamine, compression, transport by pipeline and storage in a geological reservoir. The two reference chains represent sub-critical and state-of-the-art ultra supercritical pulverized coal fired electricity generation. For the three chains we have constructed a detailed greenhouse gas (GHG) balance, and disclosed environmental trade-offs and co-benefits due to CO₂ capture, transport and storage. Results show that, due to CCS, the GHG emissions per kWh are reduced substantially to 243 g/kWh. This is a reduction of 78 and 71% compared to the sub-critical and state-of-the-art power plant, respectively. The removal of CO₂ is partially offset by increased GHG emissions in up- and downstream processes, to a small extent (0.7 g/kWh) caused by the CCS infrastructure. An environmental co-benefit is expected following from the deeper reduction of hydrogen fluoride and hydrogen chloride emissions. Most notable environmental trade-offs are the increase in human toxicity, ozone layer depletion and fresh water ecotoxicity potential for which the CCS chain is outperformed by both other chains. The state-of-the-art power plant without CCS also shows a better score for the eutrophication, acidification and photochemical oxidation potential despite the deeper reduction of SO_x and NO_x in the CCS power plant. These reductions are offset by increased emissions in the life cycle due to the energy penalty and a factor five increase in NH₃ emissions.