Mineral‐induced degradation of halogentated organic pollutants from aquatic systems

Several laboratory tests were conducted to examine Fe(II) as an enhancing agent in the dehalogenation of CHC1₃ in batch mode. The CHC1₃ degradation was found to be negligible when only Fe(II) is present as a reductant in the (aqueous) reaction system. However, in the presence of Fe(II) coated goethite, the rate of CHC1₃ degradation was enhanced to some extent. This observation can be explained by considering a surface mediated electron transfer step in the overall process. Substantial increase of the degradation rate was observed when the goethite particles first coated with fulvic acid were employed in the adsorption of Fe(II) for the degradation of CHC1₃.     

Monitoring of bacterial community changes in leachate and wetland soil using T‐RFLP analysis

The removal of toxic materials in municipal solid waste (MSW) can be carried out within both bioreactors and constructed wetlands. In this study, the microbial community was analysed to monitor populations related to leachate. Wetland soil samples of two landfill sites were analysed and the microbial communities were compared during organic matter removal processes. The extracted DNA was amplified using FAM63F and HEX518R primers and T‐RFLP analysis was carried on with AluI digested terminal fragments. The bacterial populations of the wetland soil from Bury and Beccles landfill sites were absolutely dissimilar in the beginning of the treatment processes. But after four weeks of treatment the similarity was 45%. These community shifts can explain the effect of leachate on bacterial population. The T‐RFLP electropherograms indicated that the bacterial population of the bioreactor was very similar to the constructed wetland’s population in recent samples. The similarity within both sites might increase as the treatment process continues.     

Effects of water content and interface roughness on the shear strength of silt–cement mortar interface

Although the shear behaviors of silt–structure interfaces are critical in engineering practice, they have not been extensively investigated systematically. In this study, the influence of the silt water content and interface roughness on the shear behaviors of silt–cement mortar interfaces is investigated. Forty–eight silt–cement mortar structure interface tests and 18 silt direct shear tests were carried out. The results indicated that as the water content of the silt gradually increased to saturation, the interface shear stress–displacement curves changed from strain softening to strain hardening, and the interface shear strength decreased significantly. The shear strength of the rough interface was found to be significantly greater than of the silt, and the shear strength of the smooth interface was found to be lower than that of the silt. The interface shear strength gradually increased with the surface roughness, but the increase tended to be gentle. A large shear deformation was observed, and this increased with the decrease in soil water content and the increase (up to a point) in interface roughness. A model of the interface shear strength between unsaturated soil and structures considering the influence of water content and interface roughness was established and verified.     

Removal of bisphenol A and 17α-ethinyl estradiol from landfill leachate using single-walled carbon nanotubes

In this study, the adsorption of bisphenol A (BPA) and 17α-ethinyl estradiol (EE2) from landfill leachate onto single-walled carbon nanotubes (SWCNTs) was investigated. Different leachate solutions were prepared by altering the pH, ionic strength, and dissolved organic carbon (DOC) in the solutions to mimic the varying water conditions that occur in leachate during the various stages of waste decomposition. The youngest and oldest leachate solutions contained varying DOC and background chemistry and were represented by leachate Type A (pH = 5.0; DOC = 2500 mg/L; conductivity = 12,500 μS/cm; [Ca²⁺] = 1200 mg/L; [Mg²⁺] = 470 mg/L) and Type E (pH = 7.5; DOC = 250 mg/L; conductivity = 3250 μS/cm; [Ca²⁺] = 60 mg/L; [Mg²⁺] = 180 mg/L). These solutions were subsequently combined in different ratios to produce intermediate solutions, labeled B-D, to replicate time-dependent changes in leachate composition. Overall, a larger fraction of EE2 was removed as compared to BPA, consistent with its higher log K_OW value. The total removal of BPA and EE2 decreased in older leachate solutions, with the adsorptive capacity of SWCNTs decreasing in the order of leachate Type A > Type B > Type C > Type D > Type E. An increase in the pH from 3.5 to 11 decreased the adsorption of BPA by 22% in young leachate and by 10% in old leachate. The changes in pH did not affect the adsorption of EE2 in the young leachate, but did reduce adsorption by 32% in the old leachate. Adjusting the ionic strength using Na⁺ did not significantly impact adsorption, while increasing the concentration of Ca²⁺ resulted in a 12% increase in the adsorption of BPA and a 19% increase in the adsorption of EE2. DOC was revealed to be the most influential parameter in this study. In the presence of hydrophilic DOC, represented by glucose in this study, adsorption of the endocrine disrupting compounds (EDCs) onto the SWCNTs was not affected. In the absence of SWCNTs, hydrophobic DOC (i.e., humic acid) adsorbed 15-20% of BPA and EE2. However, when the humic acid and SWCNTs were both present, the overall adsorptive capacity of the SWCNTs was reduced. Hydrophobic (π-π electron donor-acceptor) interactions between the EDCs and the constituents in the leachate, as well as interactions between the SWCNTs and the EDCs, are proposed as potential adsorption mechanisms for BPA and EE2 onto SWCNTs.     

Comparison of fibrous insulations – Cellulose and stone wool in terms of moisture properties resulting from condensation and ice formation

Cellulose fibres are often used as thermal insulation in buildings. The organic nature of cellulose fibres, however, makes the insulation sensitive to high moisture content. This study investigates the moisture performance of cellulose insulation when exposed to a subzero environment. The paper is focused on the condensation and freezing in the material and includes comparison with the authors previous studies on stone-wool insulation. While the used stone-wool samples were water-repellent due to resin binders, cellulose is a typical representative for hydrophilic thermal insulation to which any contact with water condensate can be crucial.Test specimens of loose-fill cellulose were placed in a special laboratory device providing high moisture load. During a period of 100 h the specimens were subjected to a continuous load of moisture at atmospheric conditions on one side while the other side of the specimen faced a surrounding temperature of 0, −10 and −20 °C and the laboratory tests were repeated three times for each set of the specific thermal conditions (T_i = +20 °C, T_e = 0, −10 and −20 °C). The results indicate that there are minor changes in the water vapour permeability of the specimens. The experimental data from the investigation is compared with a mathematical model that simulates moisture diffusivity of cellulose together with accumulation due to sorption and freezing, using the actual climatic data.     

Erring with high‐level nuclear waste disposal: a case study of the precautionary principle

Increasingly, the “Precautionary Principle” is being discussed as a basis for decision‐making to protect environmental and human health where there are risks of serious or irreversible damage but where there are gaps in knowledge and uncertainties to demonstrate conclusively either the existence of the risks or their levels. Many analyses of the precautionary principle focus on the abstract or philosophical theories of the principle. Here, I provide a more practical case study to demonstrate some of the prospects and problems of the principle. While the case study focuses specifically on the disposal of high‐level radioactive waste at a potential repository at Yucca Mountain, Nevada, it also provides insight to other problems of complex technologies and the protection of health.     

‘Unfolding from within’: modern architecture and the dream of organic totality

With the proclamation of the Turkish Republic, in October, 1923, Ankara became the laboratory and showcase of the nation-building project led by Mustafa Kemal Atatürk. A number of European architects, planners and artists were involved in the transformation of this small Anatolian town into the political and symbolic centre of the ‘New Turkey’: as the Republic was also known. At the same time, European observers were drawn to witness a place that was described as ‘the most extraordinary capital in the world’. At a crucial juncture, in which the geopolitical space of the Orient was radically reconfigured, Ankara provided an unexpected terrain of cross-cultural encounters between East and West. This essay explores the historical traces of these encounters that emerge from an uncharted body of sources, ranging from early-1920s' travel writings to the first comprehensive accounts of the new capital published in the mid-1930s. A tropological analysis of this rich and diverse literature shows that Ankara destabilised the discursive frame through which the West had hitherto constructed the Orient as its irreducible ‘other’. The accounts of this modernist experiment reasserted the hegemony of western culture while revealing, in the process, its inner fractures and contradictions.     

Behavior and strength of steel reinforced concrete beam–column joints with single-side force inputs

Five large-scale beam–column subassemblies were fabricated and tested under cyclic loading to investigate the behavior of SRC Type I exterior and Type II corner beam–column joints. In addition, the applicability of strength superposition method on joint shear strength was assessed. It was found that: (1) the strength superposition method was able to estimate the SRC beam–column joint shear strength with reasonable accuracy; (2) the anchorage position of beam longitudinal bars has an obvious influence on the joint shear strength and crack pattern; (3) increased depth of cross-sectional steel leads to a higher shear strength for the beam–column joint; and (4) a combination of corner stirrups and shaped steel cross-sections was able to provide sufficient lateral support to longitudinal steel bars and adequate confinement to the concrete in the joint to replace the need for closed hoops.     

Engineers and equity: The political economy of high‐speed roads in the 1960s and 1990s

Abstract

This paper examines the cultural and political origins of Melbourne's Metropolitan Transportation Plan of 1969, especially its proposal to build over 600 kilometres of freeways. It gives particular attention to the influence of American paradigms of transport planning, and to the experiences of the cohort of young Australian traffic engineers who attended the Yale traffic engineering course in the 1950s and 1960s. It concludes with a comparison between the transport planning regime of the 1960s and the privatised expressways of the 1990s.     

Performance-based assessment of roadway maintenance and rehabilitation activities from user’s perception in Taiwan

In Taiwan, even though the highway agencies have been making effort to improve the overall serviceability of the road system, more often than not, road users were not satisfied with the performance of the maintenance and rehabilitation (M&R) activities. This paper focuses on the performance of M&R activities in Taiwan from the road users’ perspective. Surveys were conducted to collect the users’ perception (serving as the performance) of the M&R activities. The Decision Making Trial and Evaluation Laboratory (DEMATEL) and Analytic Network Process (ANP) are jointly used to quantify the performance of M&R activities. DEMATEL is employed to understand the influence among the criteria/elements, and ANP is used to determine the relative weights of the elements. It is found that the respondents were most concerned about unsafe conditions due to manhole covers, damaged manhole covers, insufficient street lighting, potholes and bumps on pavements, and uneven pavements. Furthermore, the performance of M&R activities implemented on six major road types in Taiwan is analysed using the Formal Concept Analysis (FCA) method. Based on the concept lattice and association rules derived from FCA, directions for the improvement of M&R activities are proposed.     

Volatile organic compounds from building products—Results from six round robin tests with emission test chambers conducted between 2008 and 2018

Emission testing of volatile organic compounds (VOC) from materials and products is commonly based on emission test chamber measurements. To ensure the comparability of results from different testing laboratories, their measurement performance must be verified. For this purpose, Bundesanstalt für Materialforschung und -prüfung (BAM) organizes an international proficiency test (round robin test, RRT) every two years using well-characterized test materials (one sealant, one furniture board, and four times a lacquer) with defined VOC emissions. The materials fulfilled the requirements of homogeneity, reproducibility, and stability. Altogether, 36 VOCs were included of which 33 gave test chamber air concentrations between 13 and 83 µg/m³. This is the typical concentration range to be expected and to be quantified when performing chamber tests. Three compounds had higher concentrations between 326 and 1105 µg/m³. In this paper, the relative standard deviations (RSD) of BAM round robin tests since 2008 are compared and the improvement of the comparability of the emission chamber testing is shown by the decrease of the mean RSD down to 28% in 2018. In contrast, the first large European interlaboratory comparison in 1999 showed a mean RSD of 51%.     

Chromium speciation in tannery effluent—I. An assessment of techniques and the role of organic Cr(III) complexes

Three methods of chromium speciation were assessed in relation to possible interferences from Cr(III)-organic complexes. They were, namely: 1,5-diphenyl-carbazide (DPC) spectrophotometry, organic extraction with methyl isobutyl ketone (MIBK) and co-precipitation with iron and bismuth salts. Initially, a number of organic ligands, i.e. proteins, amino acids and organic acids were reacted with Cr(III) and only those complexes with solubility levels above that of ionic Cr(III) were assessed further. The spectrophotometric method was found to suffer minor interferences which were attributable to a non-specific turbidity effect. In comparison, two methods of MIBK extraction were found to suffer severe interferences with Cr(III)-protein complexes. Also, co-precipitation with iron salts resulted in high levels of contamination by Cr(III)-organic complexes in the ionic chromium fractions. Due to the poor solubility of bismuth salts, this method was discarded. The results demonstrate that chromium speciation in the presence of organic complexes can lead to erroneous results. However, with recognition of the presence of such complexes, corrections can be made. Since the co-precipitation behaviour of organic Cr(III) appears to be relatively specific, a scheme is described for the speciation of Cr(III) in tannery contaminated waterways. In addition, it is recommeded that a separate determination of Cr(VI) is conducted using a modification of the DPC method.     

America's high‐level nuclear waste repository: a case study of environmental science and public policy

The disposal of high‐level commercial nuclear wastes, the so‐called spent fuel, is one of the most politically and ethically complex environmental issues. A series of actions taken over past decades has resulted in plans to dispose of spent fuels in geologic repositories. This decision has ignited numerous controversies, especially concerning where the repositories should be located. This siting controversy has been “settled” for the time being by a federal law that designates Yucca Mountain in southern Nevada as the preferred location. However, the decision: (a) is inconsistent with the National Environmental Act as a comprehensive policy act, (b) does not reflect full consideration of value‐laden public policy issues, and (c) adds to credibility problems confronting the US Department of Energy and therefore contributes to controversies surrounding the agency's decisions. Aspects of how this decision came about and how it is being implemented provide an interesting case study of how our society is presently dealing with scientifically, politically, and ethically complex technological problems.     

Emissions and efficiency of a prototype natural gas‐fired domestic cooktop burner with insert

This paper reports on the performance of a prototype natural gas‐fired cooktop burner which was developed for lower NO₂ emissions and improved thermal efficiency. A circular ring insert was part of the prototype burner. It was made from 6 mm stainless steel rod and placed at the side of the burner slightly below the ports. The prototype burner had a 42% lower NO₂ emission per unit useful energy compared to a commercially available burner at 3.3 kW. The relative improvement in thermal efficiency was 19%. The prototype burner was tested over the full range of thermal input, from 3.3 kW down to 0.66 kW. The insert did not cause any problem for emissions or efficiency at any thermal input within the range, provided it was appropriately located relative to the burner ports. As the burner was turned down, the NO₂ emission decreased and thermal efficiency increased, as normally observed with gas cooktop burners.     

Strength and abrasive properties of andesite: relationships between strength parameters measured on cylindrical test specimens and micro-Deval values—a tool for durability assessment

Bulletin of Engineering Geology and the Environment - Aggregates are necessary materials for the construction industry. Owing to their favourable properties, andesites are frequently used rock...     

Lead and cadmium in teeth,bone and kidneys of rats with a standard Pb‐Cd supply

Male Wistar rats received a combination of 25 ppm PbCl₂ and 5 ppm CdCl₂ in drinking water at different developmental stages. Pb and Cd levels of incisors, molars, epiphyses, diaphyses and kidney cortex were recorded by atomic absorption spectrophotometry. The results confirmed that Pb has an affinity for hard tissue and especially to teeth, but it also accumulated in soft tissues under the above conditions. In addition, the results indicated none or only a moderate placental or mammary barrier for Pb, and suggested a high absorption of lead from the intestine of sucklings. The results also confirmed that kidney cortex is a primary target for Cd, and indicated that Cd has crossed the placental and mammary barriers to some degree. The positive significant correlation between Cd levels in molars and kidney cortex suggested that rodent molars indicate a degree of Cd absorption, whereas incisors do not. It is supposed that rodent molars are comparable to human deciduous teeth. It is thus confirmed that human deciduous teeth indicate previous lead exposure. It is further inferred that they also can be used as indicators of previous Cd‐exposures.     

Urban and semi‐urban planning in developing countries from a water and waste water treatment point of view

Several appropriate technology alternatives are suggested for water and wastewatei treatment in less developed countries. Large‐scale water supply systems employing conventional water treatment methods should be replaced by several small‐scale water treatment units utilizing appropriate water treatment methods.

Conventional sewerage systems should be replaced by low cost on‐site sanitation systems and several other low‐cost wastewater treatment methods such as oxidation ponds, aerated lagoons and anaerobic lagoons. Wastewater renovation and re‐use should be actively encouraged in view of dwindling water resources in these countries.     

Dynamism and abundance of water hyacinth in the Winam Gulf of Lake Victoria: evidence from remote sensing and seasonal‐climate data

Aquatic plant infestations impede lake traffic through navigable waterways, block ports and passenger ferry terminals. Timely, accurate information on aquatic plant dynamism, distributions and density is required both by public agencies and by private companies engaged in aquatic plant control efforts and the local population whose economic livelihood depends on the lake. This study combined the interpretation of remote sensing and climatic variability data in understanding the seasonal dynamism and abundance of water hyacinth in Winam Gulf of Lake Victoria. The results showed a direct relationship between the hyacinth geographic and density distribution and seasonal‐climatic patterns. Gentle currents, moderate rainfall and modest but stable temperatures propagated the rapid blooming and aggregation of the hyacinth mats especially in the sheltered bays. Relatively high rainfall and high temperatures do not favor the proliferation of the weed; hence disintegration and mobility as the strengths of the currents increase in magnitude.     

The effect of temperature on the emission of formaldehyde and volatile organic compounds (VOCs) from laminate flooring — case study

The effect of temperatures of 23, 29, 50°C on formaldehyde and volatile organic compounds (VOCs) emission from laminate flooring Type A (with particleboard as substrate) and Type B (with high density fibre (HDF)) was examined. At 23 and 29°C the measurements did not show any emissions of formaldehyde and very low emissions of VOCs. At a temperature of 50°C, Type A showed a high initial emission of formaldehyde and VOCs, which decreased with time. The emission from Type B was much lower. In conclusion, some laminate flooring may affect the chemical contamination of indoor air with the use of floor heating.