The disposal of pulverised fuel ash in water supply catchment areas

Laboratory and field investigations have been made of factors influencing the leaching of substances from beds of p.f.a. Results presented allow the likely pattern and quality of percolate from p.f.a. beds to be predicted. By combining these with hydrogeological data, a dumping regime can be specified so that risks will not arise to drinking, or other, water supplies.     

Genetic programming based formulation for fresh and hardened properties of self-compacting concrete containing pulverised fuel ash

Self-compacting concrete (SCC) flows into place and around obstructions under its own weight to fill the formwork completely and self-compact without any segregation and blocking. Elimination of the need for compaction leads to better quality concrete and substantial improvement of working conditions. This investigation aimed to show possible applicability of genetic programming (GP) to model and formulate the fresh and hardened properties of self-compacting concrete (SCC) containing pulverised fuel ash (PFA) based on experimental data. Twenty-six mixes were made with 0.38 to 0.72 water-to-binder ratio (W/B), 183–317 kg/m³ of cement content, 29–261 kg/m³ of PFA, and 0 to 1% of superplasticizer, by mass of powder. Parameters of SCC mixes modelled by genetic programming were the slump flow, JRing combined to the Orimet, JRing combined to cone, and the compressive strength at 7, 28 and 90 days. GP is constructed of training and testing data using the experimental results obtained in this study. The results of genetic programming models are compared with experimental results and are found to be quite accurate. GP has showed a strong potential as a feasible tool for modelling the fresh properties and the compressive strength of SCC containing PFA and produced analytical prediction of these properties as a function as the mix ingredients. Results showed that the GP model thus developed is not only capable of accurately predicting the slump flow, JRing combined to the Orimet, JRing combined to cone, and the compressive strength used in the training process, but it can also effectively predict the above properties for new mixes designed within the practical range with the variation of mix ingredients.     

用废塑料代燃料烧成水泥

作水泥烧成燃料是 废塑料利用的重要途径 利用废塑料代替水泥烧成燃料提供大部分热量,可促进废塑料的大量利用。废塑料中通常含有一定量的氯,采用通常的方法焚烧（如垃圾炉内焚烧）会造成环境的二次污染。实验证明,采用废塑料代替水泥烧成燃料时,只要窑温大于 1400℃就不会产生二恶英,而通常水泥烧成温度达 1450℃,也就是说,采用废塑料作燃料烧制水泥熟料时不会造成环境的二次污染。因此,利用废塑料作燃料烧制水泥熟料与单纯焚烧废塑料处理废塑料的方法存在根本性的区别,它是一种高效、安全的“热量再利用”的方法。 可作水泥烧成…     

Use of palm oil fuel ash as a supplementary cementitious material for producing high-strength concrete

The objective of this study is to investigate the use of ground palm oil fuel ash with high fineness (GPA) as a pozzolanic material to produce high-strength concrete. Samples were made by replacing Type I Portland cement with various proportions of GPA. Properties such as the compressive strength, drying shrinkage, water permeability, and sulfate resistance, were then investigated. After aging for 28 days, the compressive strengths of these concrete samples were found to be in the range of 59.5–64.3 MPa. At 90-day the compressive strength of concrete containing GPA 20% was as high as 70 MPa. The drying shrinkage and water permeability were lower than those of high-strength concrete made from Type I Portland cement. When the concrete samples were immersed in a 10% MgSO₄ solution for 180 days, the sulfate resistance in terms of the expansion and loss of compressive strength was improved. The results indicated that GPA is a reactive pozzolanic material and can be used as a supplementary cementitious material for producing high-strength concrete.     

粉煤灰活化剂在混凝土中的应用

介绍粉煤灰活化剂的研制，将粉煤灰活化剂应用于C30等级混凝土中，使粉煤灰取代水泥量提高到40％～60％，混凝土主要性能指标均符合相关规范。并进行了粉煤灰活化机理的探索。     

Production of rice husk ash for use in concrete as a supplementary cementitious material

Rice husk ash (RHA), rich in silica content, can be produced from rice husk using appropriate combustion technique for use in concrete as a supplementary cementitious material. This paper discusses production process of RHA from rice husk and the quality of RHA produced using rudimentary furnace of the National University of Malaysia (UKM). Three combustion methods and two grinding methods were used to investigate physical characteristics and chemical aspects of RHA produced. Combustion temperature distribution of the furnace, ash particle size, silica crystallization phase and chemical content of the produced RHA were studied using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). From the investigation, it was found that combustion period, chilling duration, and grinding process and duration are important in obtaining RHA of standard fineness and quality. In addition, air ducts in the furnace are very useful in order to supply air for proper burning of rice husk.     

Influence of rock properties on selection of design for a spent nuclear fuel repository

In Sweden, researchers are examining designs for a repository for storage of spent nuclear fuel. By the year 2010 (when nuclear power production will cease, according to parliamentary decision), approximately 10,000 m³ of spent fuel will need to be encapsulated in the repository. One such system, the KBS-3 (abbreviation for Nuclear Fuel Safety, in English), has been evaluated over the past decade. Another design, called the Very Long Hole (VLH) system, is also being considered. The main difference between the two systems is in the shape of the rock openings in the disposal areas. This paper analyzes the properties of the rock in the near field (i.e., the rock affected by the excavation of the repository) and compares them for the two repository systems.     

Potential health benefit of reducing household solid fuel use in Shanxi province, China

Indoor air pollution from solid fuel use has severe health effects. 60% of the Chinese population lives in rural areas, where most people rely on solid fuels for cooking and heating. We estimate exposure by combining information on the amount of time spent in different microenvironments and estimates of the particle concentrations (PM(10)) in these environments. According to our estimates, 70% of the exposure experienced by the rural population is due to indoor air pollution (IAP). The urban coal using population experience a 17% increase in exposure from IAP. We apply Monte Carlo simulations to quantify variability and uncertainty in the exposure, morbidity and mortality estimates. We find that applying Monte Carlo simulations reduces the estimated uncertainty compared to analytical methods based on approximate distributions and the central limit theorem. We find that annually about 4% (geometric S.D. sigma(g), 3.2) and 35% (sigma(g), 2.6) of the deaths in the urban and rural populations, respectively, could be avoided by switching to clean fuels. Upgrading the stoves in rural areas to the standard found in urban areas is estimated to reduce mortality by 23% (sigma(g), 3.1). Moreover, we estimate that chronic respiratory illness (CRI) in children can be reduced by, respectively, about 9% (sigma(g), 2.5) and 80% (sigma(g) 1.9) by switching to clean fuels in the urban and rural areas. Upgrading the stoves in rural areas is estimated to reduce CRI in children with about 58% (sigma(g) 2.3). For adults the reduction in CRI was estimated to be 6% (sigma(g) 2.4) and 45% (sigma(g) 1.8) for the urban and rural population following a fuel switch, and 31% (sigma(g) 2.4) for the rural population from stove improvements. Contrary to our expectations we find small gender differences in exposure. We ascribe that to comparable kitchen and living area concentrations and similar indoor occupation times for the genders. Young children and the elderly spend the most time indoors, and have the highest daily exposure in the coal using population. The rural population experience higher exposure than the urban population, even though the outdoor air is significantly cleaner in rural areas.     

Understanding domestic fuel use practices in an urban township

Due to the complex interactions between socio-economic, cultural and political factors, some urban households consume a portfolio of energy sources, e.g. electricity, coal, paraffin, gas and solar power. A social construction of technology perspective is used to understand the choices underlying these multiple fuel practices. Nine participants (household energy managers, consumers and users) were purposefully selected from Soshanguve, an urban township in Pretoria, South Africa. Data were collected through individual in-depth interviews and narrative analysis was used to generate findings. Stories about multiple fuel use in the household showed this practice is common and forms part of the participants’ lifestyles. Social, cultural and political meanings of fuel use are identified in the narratives. Suggested interventions to optimize multiple fuel use in this context include additional technology such as solar power, collaborations with manufacturers to improve existing fuel types that are seen as potentially hazardous, and leveraging women’s knowledge and position in the household to formalize education about multiple fuels. The role of government in providing subsidies for alternative energies and reviewing accessibility to electricity was also highlighted by the participants. This research demonstrates that policy-makers should actively involve consumers in household energy system decisions through deliberative dialogue with communities.     

A study of hydrogen as an alternative fuel

ABSTRACT

As oil prices increase, the interest in alternative fuels increases. This is evidenced by demonstration programmes and commitments by states such as India. The concern of the air quality in many areas around the world makes ?nding solutions more urgent. As the price of oil increases, alternate fuels become more ruthless. Major questions remain to be answered on which fuel or fuels will emerge and to what extent alternative sources will replace gasoline as the main product of crude oil. A combination of available alternative fuels will evolve with the most likely choices affected by a number of technical, political and market factors. In order to allow a wider application of alternative fuels, a number of obstacles have to be overcome. These include economic, technological, and infrastructural issues. In the past, gasoline has been plentiful and has had a signi?cant price advantage compared to other fuels. This could change quickly and alternative fuels would need to become more commonplace. One of the alternatives involves the more widespread use of biomass-produced fuels. In this paper describes that hydrogen as an alternative fuel. Hydrogen powered fuel cells could have wide applications, replacing batteries in many portable application, vehicle and using hydrogen for home electrical needs.     

Potential of olive mill waste and compost as biobased pesticides against weeds, fungi, and nematodes

The phytotoxic and antimicrobial properties of olive mill wastes have been widely investigated and demonstrated over the past decade. However, their potential utilization as biodegradable pesticides against plant pathogens is still poorly understood. In this study, a series of laboratory bioassays was designed to test the inhibitory effects of sterile water extracts of two-phase olive mill waste (TPOMW) and TPOMW composts with different degrees of stabilization on several different plant pathogens. Fungicidal properties of TPOMW extracts, assayed in a microwell assay format, showed that the growth of Phytophthora capsici was consistently and strongly inhibited by all TPOMW extracts diluted 1:10 (w:v). In contrast, suppression of Pythium ultimum and Botrytis cinerea by the extracts was not as strong and depended on the specific TPOMW sample. Mature compost inhibited P. capsici and B. cinerea at dilutions as great as 1:50, w:v. Neither TPOMW nor TPOMW compost extracts were able to inhibit the growth of the basidiomycete root rot agent Rhizoctonia solani. In addition, studies were conducted on the allelopathic effects of TPOMW extracts on seed germination of four highly invasive and globally distributed weeds (Amaranthus retroflexus, Solanum nigrum, Chenopodium album and Sorghum halepense). Both the TPOMW and immature TPOMW compost extracts substantially inhibited germination of A. retroflexus and S. nigrum, whereas mature composts extracts only partially reduced the germination of S. nigrum. Finally, TPOMW extracts strongly inhibited egg hatch and second-stage juvenile (J2) motility of the root-knot nematode Meloidogyne incognita. However, only higher concentrations of stage-one and stage-two TPOMW compost extracts exerted a suppressive effect on both J2 motility and on egg hatch. The study shows the high potential of naturally occurring chemicals present in TPOMW and TPOMW composts that should be further investigated as bio-pesticides for their use in sustainable agricultural systems.     

Self-compacting concrete with different levels of pulverized fuel ash

This research investigated self-compacting concrete (SCC) with levels of up to 80% cement replacement by fly ash in mixes adjusted to give constant fresh concrete properties. The hardened concrete and the relationships between hardened properties were then studied.The results show that SCC with up 80% cement replaced by fly ash is possible. To keep the filling ability constant, replacement of cement with fly ash would require an increase in water/powder (W/P) ratio and a reduction in superplasticiser dosage. They also show fly ash have negative effects on passing ability, consistence retention and hardened concrete properties such as strength. The comparison between SCC and normally vibrated concrete (NVC) shows that their material properties of are similar. The successful completion of this project can lead to the use of higher volume fly ash in SCC.     

Utilization of treated spent liquor sludge with fly ash in cement and concrete

Design mix of M-20 concrete was prepared in the laboratory by substituting cement with the treated spent liquor sludge (TSLS) and fly ash. During the study, TSLS is fixed at 7.5% by weight, and fly ash is varied as 5%, 10%, 15%, 20% and 25% to study the possibility of replacement of cement. A 15% fly ash gives the optimum compressive strength. Addition of fly ash has resulted in complete removal of toxicity as per US EPA toxicity characteristic leaching procedure (TCLP) test. A total of 7.5% sludge and 15% fly ash in M-20 concrete is expected to save Rs. 252/m³ (≈USD 5.3/m³⁾ of concrete.     

碱激发剂对不同掺量粉煤灰UHPC的影响

在UHPC材料中,通过在粉煤灰0%、20%、30%、40%的掺量下掺入不同碱激发剂(氢氧化钙、氢氧化钠、硫酸钠、硫酸钙、碳酸钠、水玻璃)测试砂浆浆体流动性、经时损失和胶砂试件抗压强度、抗折强度。结果表明:在UHPC材料中,随着粉煤灰掺量的增加,流动性改善明显,对抗压抗折强度影响较大;在粉煤灰掺量较小时,碱激发剂效果不明显,随着粉煤灰掺量的增加,碱激发剂的效果逐渐凸显出来;在粉煤灰掺量为30%、40%时,硫酸钙为最为突出的碱激发剂。     

粉煤灰在桥涵混凝土中的应用

结合平阳高速路基工程施工实践,对粉煤灰在桥涵混凝土中的应用进行了介绍,分别阐述了粉煤灰的质量指标和掺量及实际应用中的作用和机理,指出粉煤灰具有良好的社会和经济效益。     

掺加粉煤灰免振捣混凝土正交试验研究

对掺粉煤灰自密实混凝土在振捣与不振捣两种情况下，试块的抗压强度和劈拉强度进行了对比，从水灰比、砂率、粉煤灰三方面探讨了影响强度比的因素，重点探讨了粉煤灰对强度比的影响，并对试验结果进行了总结。     

The use of hospital waste as a fuel. Part one.

The total quantity of hospital waste produced in the UK has been estimated to be 430kte/yr, having a combustible content equivalent to about 190kte of coal; its average gross calorific value (GCV) depends on the type of hospital, but has been estimated to be about 14GJ/te for the teaching and general hospitals which were examined. Hospitals are obliged to incinerate some of these wastes in order to destroy any pathogens which may be present, and although several hospitals have been involved in recovering the energy from this process, a number of such projects have proved to be unsuccessful. The Glenfield General Hospital (GGH) is burning combustible hospital waste on a Corsair (Erithglen) 0.5MWt (2MBtu/h) hot water boiler, the second such installation involving a new design of plant which accepts bagged, unprepared material. Although the plant suffered inevitable commissioning and teething problems, which have led to further design improvements, it has nevertheless demonstrated its ability to dispose of hospital waste reliably, safely and efficiently; it is felt, however, that it could have performed better with improved project organisation. In the light of likely future legislation to tighten control over emissions from the combustion of hospital wastes, it is anticipated that large scale plant might prove economically and environmentally attractive under certain circumstances; such plant will, in all probability, involve power generation or combined heat and power (CHP).     

Strength and water permeability of concrete containing palm oil fuel ash and rice husk–bark ash

In this paper, palm oil fuel ash and rice husk–bark ash, which are by-products from electricity generating power plants and disposed as wastes in landfills, were used as a partial cement replacement. They were ground and incorporated into concrete at the levels of 20%, 40% and 55% by weight of binder. Compressive strength and water permeability of concretes containing ground palm oil fuel ash (GPOA) and ground rice husk–bark ash (GRBA) were investigated. From the tests, the replacement of Portland cement by both materials resulted in the higher water demand in concrete mixtures as compared to ordinary Portland cement (OPC) concrete with compatible workability. The compressive strengths of concretes containing 20% of GPOA and GRBA were as high as that of OPC concrete and were reduced as the increase in the replacement ratios. Although the compressive strengths of concrete with the replacement of GPOA or GRBA up to 40% were lower than OPC concrete, their water permeabilities were still lower than that of OPC concrete. These results indicate that both of GPOA and GRBA can be applied as new pozzolanic materials to concrete with an acceptable strength as well as permeability.     

Filler effect and pozzolanic reaction of ground palm oil fuel ash

This research examines the compressive strength of mortar and how the filler effect and pozzolanic reaction of ground palm oil fuel ash (POFA) contribute to this strength. POFA and river sand were ground to three different particle sizes and used to replace Type I Portland cement at 10–40% by weight of binder to cast the mortar. The compressive strengths of ground POFA and ground river sand mortars were determined at various ages between 7 and 90 days. The results showed that the compressive strength of mortar due to the filler effect of ground river sand was nearly constant during the 7–90 day period for a specified replacement rate of cement. However, the compressive strength of mortar due to the filler effect tended to increase slightly with increased cement replacement. The pozzolanic reaction of ground POFA increased with increasing particle fineness of ground POFA, replacement rate of cement, and age of the mortar. The compressive strength contribution from the pozzolanic reaction of ground POFA was much more pronounced than the contribution from the filler effect when the smallest sizes of both materials were considered.     

Monitoring of the evolution of an industrial compost and prediction of some compost properties by NIR spectroscopy

Sewage treatment plants produce wastes resulting from the organic matter concentration in the form of sludge. A way of jointly treating and exploiting these increasing wastes jointly is the composting. Composting makes it possible to reduce volumes and the masses of wastes all while developing them in a product usable like organic soil enrichment. In this work, the composting process of an industrial sewage sludge composting plant was monitored to study the evolution of different physico-chemical parameters (temperature, moisture, pH, organic carbon, organic and inorganic nitrogen, organic carbon/organic nitrogen ratio, humic substances) and biochemical parameters (soluble fraction, hemicellulose, cellulose, lignin). Because these analyses are expensive and time consuming, we wanted to develop an alternative method to determine the maturity of compost related to compost properties with raw samples. Acceptable predictions were found for moisture, temperature, pH, organic carbon, organic carbon/organic nitrogen ratio, total-, organic- and ammoniacal nitrogen, fulvic- and humic acids and fulvic acids/humic acids ratio, but the error values were too high for the compost age to consider a quantification model. With regard to the biochemical parameters, this study is rather a preliminary test which shows the interest of the approach, but requires to be continued. Finally, the age of compost can be evaluated with Principal Component Analysis applied to NIR spectra.