Lateral dispersion in deflected emergent aquatic canopies

Environmental Fluid Mechanics - Understanding the mechanism of dispersion within plants is essential for proper operation of natural and constructed treatment wetlands. Plant deflection induced by...     

An ultrasonic assisted extraction method to release heavy metals from untreated sewage sludge samples

A rapid ultrasound accelerated sequential extraction procedure has been used to develop sequential extraction proposed by BCR protocol (the community Bureau of Reference now the European Union "Measurement and Testing Programme"). The effects of the ultrasonic treatment on the extraction of Cu, Cd, Cr, Pb, Ni and Zn from untreated sewage sludge collected from industrial site of Hyderabad city (Pakistan) were compared with those obtained from conventional sequentional extraction procedure of modified BCR protocol. In BCR method, each extraction steps takes 10h, where as with the use of compromise sonication conditions in ultrasonic bath, steps 1-3 of the sequential extraction (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication) could be completed in 30, 30 and 30 min, respectively. Extractable Cd, Cr, Pb and Ni contents were obtained by both comparable methodologies were measured by electrothermal atomic absorption spectrometry (ETAAS), while for Cu and Zn Flame atomic absorption spectrometry (FAAS) was used. The validations of both methods were compared by the analysis of certified reference material of soil amended with sewage sludge (BCR 483). According to statistical evaluation of the results, the proposed accelerated extraction method is valid alternative to conventional shaking with much shorter extraction time with p value <0.05. The overall metal recoveries in steps 1-3 (excluding residual step) were 95-100% of those obtained with the conventional BCR protocol, except for Cu extracted (91.6%) as related to indicative values of Cu in BCR 483 obtained in 1-3 steps. The results of the partitioning study of untreated industrial waste water sewage sludge, indicate that more easily mobilized forms (acid exchangeable) were predominant for Cd and Zn, in contrast, the largest amount of Pb and Cr was associated with the iron/manganese oxide and organic matter/sulphide fractions.     

Heavy metals from soil and domestic sewage sludge and their transfer to Sorghum plants

We studied the mobility and transport of heavy metals such as Cu, Zn, As, Cd, Cr, Ni, and Pb, from soil and soil amended with sewage sludge to sorghum plants. The total and ethylenediaminetetraacetic acid (EDTA) extractable heavy metals in agricultural soil and untreated domestic sewage sludge (DWS) samples were determined. The correlation between the total and extractable metals in soil and sewage sludge was investigated. The total and extractable heavy metals in soil, sewage sludge and sorghum grain were analysed by flame and electro thermal atomic absorption spectrometer (FAAS/ETAAS), after digestion in microwave oven. Statistically good correlations were obtained between the total contents of all heavy metals and their respective extractable fractions in soil and domestic wastewater sludge. Transfer factors of all heavy metals from domestic sewage sludge to sorghum grains were determined.     

Industrial-waste management in developing countries: the case of Lebanon

This paper presents a critical assessment of the existing Lebanese industrial sector, namely the current status and classification of industrial establishments based on a comparative synthesis and analysis of recent nationwide surveys and studies pertaining to industrial-waste management. Characterisation of solid and liquid industrial wastes generated, including hazardous wastes, is presented together with current and projected waste loads, recycling opportunities, and export/import practices. Institutional capacity and needs pertaining to the enforcement of relevant environmental legislation, staffing and resources, monitoring schemes, and public participation are critically evaluated. Finally, realistic options for industrial-waste management in the context of country-specific institutional economic and technical limitations are outlined. The industrial sector in Lebanon consists of small-scale industries (84% employ less than 10 persons), primarily involved in light manufacturing (96%). These industries which are distributed among 41 ill-defined zones and deficient in appropriate physical infrastructure, generate solid, liquid, and hazardous waste estimated at 346,730 tons/year, 20,169,600 m3/year and between 3000 to 15,000 tons/year, respectively. Although the growth of this sector contributes significantly to the socio-economic development of the country (industry accounts for 17% of the gross domestic product), in the absence of a comprehensive environmental management plan, this expansion may not be sustained into the coming millennium. The anticipated expansion will inevitably amplify adverse environmental impacts associated with industrial activities due to rising waste volumes and improper waste handling and disposal practices. These impacts are further aggravated by a deficient institutional framework, a lack of adequate environmental laws, and lax enforcement of regulations governing industrial-waste management.