Sorption equilibria of metal ions on bone char

The ability of bone char to adsorb three metal ions, namely, copper(II), zinc(II) and cadmium(II) ions from wastewater has been studied. Three single-component equilibrium systems and three binary equilibrium systems have been measured experimentally. The three single-component equilibrium data were analyzed using the Langmuir and the Sips equilibrium isotherm equations. The Sips isotherm gave a better fit of the experimental data than the Langmuir isotherm based on the sum of squares errors (SSE) analysis. The Cu-Zn, Cu-Cd and Cd-Zn binary equilibrium experimental data were examined by incorporating the Langmuir and the Sips isotherm equations into the ideal adsorbed solution theory (IAST). The solution methods and the predicted results for the three binary systems at different metal ion compositions have been evaluated. In addition, the application of the IAST to the model prediction for the fixed bed system is presented.     

Evaluation of particulate matter emissions from non-passenger diesel vehicles in Qatar

ABSTRACT

Road traffic is one of the main sources of particulate matter (PM) in the atmosphere. Despite its importance, there are significant challenges in the quantitative evaluation of its contribution to airborne concentrations. In order to propose effective mitigation scenarios, the proportions of PM traffic emissions, whether they are exhaust or non-exhaust emissions, should be evaluated for any given geographical location. In this work, we report on the first study to evaluate particulate matter emissions from all registered heavy duty diesel vehicles in Qatar. The study was applied to an active traffic zone in urban Doha. Dust samples were collected and characterized for their shape and size distribution. It was found that the particle size ranged from few to 600 μm with the dominance of small size fraction (less than 100 μm). In-situ elemental composition analysis was conducted for side and main roads traffic dust, and compared with non-traffic PM. The results were used for the evaluation of the enrichment factor and preliminary source apportionment. The enrichment factor of anthropogenic elements amounted to 350. The traffic source based on sulfur elemental fingerprint was almost 5 times higher in main roads compared with the samples from non-traffic locations. Moreover, PM exhaust and non-exhaust emissions (tyre wear, brake wear and road dust resuspension) were evaluated. It was found that the majority of the dust was generated from tyre wear with 33% followed by road dust resuspension (31%), brake wear (19%) and then exhaust emissions with 17%. The low contribution of exhaust PM₁₀ emissions was due to the fact that the majority of the registered vehicle models were recently made and equipped with efficient exhaust PM reduction technologies.

Implication: This study reports on the first results related to the evaluation of PM emission from all registered diesel heavy duty vehicles in Qatar. In-situ XRF elemental analysis from main, side roads as well as non-traffic dust samples was conducted. Several characterization techniques were implemented and the results show that the majority of the dust was generated from tyre wear, followed by road dust resuspension and then brake wear; whereas exhaust emissions were tremendously reduced since the majority of the registered vehicle models were recently made and equipped with efficient exhaust PM reduction technologies. This implies that policy makers should place stringent measures on old vehicle license renewals and encourage the use of metro and public transportation.     

压力对填埋垃圾产甲烷的影响研究

压实作用被认为是影响填埋垃圾降解过程的一个重要因素,实验通过自制的压缩降解模拟填埋反应器装置,研究了阶梯增加式压力21k Pa→42 k Pa→84 k Pa(分别在垃圾填埋后的第75、103和131 d时施加)对填埋垃圾产甲烷这一资源化重要阶段的影响,包括产气特性、渗滤液性质及固体沉降等的变化.21 k Pa和42 k Pa分别恒定了4周,垃圾最后在84 k Pa恒定压力下降解,实验总共持续了170 d.结果表明,在初始21k Pa的压力作用下,由于接种物跟垃圾接触面积的增大,甲烷日产量从第75 d的1.85 L·d-1增加到了第76 d的2.95 L·d-1,产甲烷速率提高了59.82%,42 k Pa和84 k Pa时均有所增加,但增加程度均不明显.压力还使砾石层上部积留了一定水位高度的渗滤液,渗滤液的COD和含氮量在压力作用下都有了暂时的升高.压实作用还令垃圾体产生了较大的沉降,但压力进一步增大并没有使垃圾继续发生较多的沉降.实验结果有助于更好地了解压力对填埋垃圾降解过程的影响.     

Survey of dioxin sources in the Baltic Region (extended summary)

The present paper summarises the results of the project: 'Survey of Anthropogenic Sources of Dioxins and Furans in the Baltic Region'. As a part of the project, inventories have been carried out in Estonia, Latvia, Lithuania and Poland by applying the toolkit for quantification of dioxin and furan releases developed by UNEP Chemicals. The main route of direct releases to the environment is emission to air. Total emission to air from Poland was estimated at 490 (88-1,300) g I-TEQ/year, whereas the emissions from Estonia, Latvia and Lithuania were estimated as being 14 (2.4-54), 23 (2.6-63) and 17 (2.6-38) g I-TEQ, respectively. In general, the uncertainty on the estimates is very high, and recommendations regarding further development of the inventories have been made, and measures for reducing the releases have been provided.     

A critical analysis of earthquakes and urban planning in Turkey

The land use plans and policies of developed countries that live with the threat of earthquakes are gaining importance in reducing or eliminating the long‐term threat to people and property. In developing countries, however, these plans and policies seem to increase the level of vulnerability. This paper examines the effects of the earthquakes that have occurred in Turkey since 1992, with a particular focus on urbanisation and planning policies. It is based on extensive surveys carried out on location immediately after the earthquakes in Erzincan and Kocaeli‐Gölcük in 1992 and 1999, respectively. The analysis takes into account several factors, including the height of buildings, geological conditions and the construction period. The authors conclude that land use planning can serve as a very useful instrument for mitigating the extent of disaster damage if it is part of an appropriate planning system. In the case of Turkey, the planning system needs to be reorganised for this purpose.     

Comparisons of metal leachability for various wastes by extraction and leaching methods

The objective of this research was to evaluate three extraction tests, i.e., toxicity characteristic leaching procedures (TCLP), extraction procedure (EP), and American Society for Testing and Materials (ASTM) methods, for their ability to extract metals in chemical sludge and incineration bottom ash, in terms of the precision of analytical results. Typical chemical sludges, including the electroplating and dye-stuff sludges, the municipal solid waste incineration bottom ash, the leather debris, and the steel-mill bottom residue containing Cd, Cr, Cu, Pb, and Zn were prepared for the lysimetry test (dynamic testing) to compare with the extraction results. Results show that for bottom residue and dye-stuff sludge, the concentration of metal leached was almost the same between the lysimetry leaching and the TCLP tests. The metal concentration followed the order: TCLP approximately = EP > ASTM. TCLP and EP exhibited almost the same relative standard deviation (RSD) value. Therefore, the results of the TCLP tests for bottom residue and dye-stuff sludge, which have a low metal content and alkalinity, can be used to estimate the metal concentration leached by typical acid rain in Taiwan; whereas the ASTM extraction test may be a better indicator of the lysimetry test.     

Hydration and leaching characteristics of cement pastes made from electroplating sludge

The purpose of this study was to investigate the hydration and leaching characteristics of the pastes of belite-rich cements made from electroplating sludge. The compressive strength of the pastes cured for 1, 3, 7, 28, and 90 days was determined, and the condensation of silicate anions in hydrates was examined with the ²⁹Si nuclear magnetic resonance (NMR) technology. The leachabilities of the electroplating sludge and the hardened pastes were studied with the multiple toxicity characteristic leaching procedure (MTCLP) and the tank leaching test (NEN 7345), respectively. The results showed that the electroplating sludge continued to leach heavy metals, including nickel, copper, and zinc, and posed a serious threat to the environment. The belite-rich cement made from the electroplating sludge was abundant in hydraulic β-dicalcium silicate, and it performed well with regard to compressive-strength development when properly blended with ordinary Portland cements. The blended cement containing up to 40% the belite-rich cement can still satisfy the compressive-strength requirements of ASTM standards, and the pastes cured for 90 days had comparable compressive strength to an ordinary Portland cement paste. It was also found that the later hydration reaction of the blended cements was relatively more active, and high fractions of belite-rich cement increased the chain length of silicate hydrates. In addition, by converting the sludge into belite-rich cements, the heavy metals became stable in the hardened cement pastes. This study thus indicates a viable alternative approach to dealing with heavy metal bearing wastes, and the resulting products show good compressive strength and heavy-metal stability.     

Geochemical and Geophysical Monitoring of Salinewater Intrusion in Korean Paddy Fields

The saline water intruded zone in paddy fields near the seashore can be diagnosed accurately by joint exploration with geophysical and geochemical methods. Using the electromagnetic (EM) sounding technique, the weakly consolidated zone which introduces saline water into such an area of near seashore paddy fields in Korea was detected from the variation of electrical conductivity distribution following field irrigation. Vertical electrical sounding (VES) with Schlumberger array and chemical analysis of top soils, and groundwater in the study area verified the intruded zone near the surface. The VES results showed that the intrusion of seawater occurred in the form of a channel down to 30 m below sea level. Geochemical analysis of the top soil samples for the six major elements found in seawater indicated that the region showing high concentrations is concordant with the weakly consolidated zone near the surface. The degree of contamination in the study area was investigated by comparing the soil data with those from a nearby old reclamation field. If remediation work is not done for this intrusion zone, the sodicity degree in the paddy soil is expected to increase compared with the reference site data.