Advanced physico-chemical treatment experiences on young municipal landfill leachates

In this study, Membrane Filtration (UF+RO), Struvite (MAP) precipitation and ammonia stripping alternatives were studied on biologically pre-treated Landfill Leachate. The results indicated that the system including the Upflow Anaerobic Sludge Blanket Reactor (UASBR) and Membrane Reactors (UF+RO) has been offered as an appropriate treatment alternative for young landfill leachates. This system provided high removals of COD, colour and conductivity (>98-99%). For ammonia removal, struvite precipitation was applied at the stoichiometric ratio (Mg:NH4:PO4=1:1:1) to anaerobically pre-treated raw landfill leachate effluent having an influent ammonium concentration of 2240 mg/l. Maximum ammonium nitrogen removal was observed as 85% at pH of 9.2. In ammonia stripping following 2 h of aeration, the removal was 72% at pH=12 while the removals were around 20% at pH=10 and pH=11. When membrane reactor, and struvite precipitation or ammonia stripping was applied to anaerobically pre-treated effluents, the results indicated that each system could be used as an appropriate post-treatment option for young landfill leachates. In economic aspect, ammonia stripping was found as the cheapest alternative with high ammonium removal. However, when both high COD and ammonium removals were to be achieved membrane technology such as UF+RO (SW) could be considered as the most appropriate system due to the fact that COD removal could be obtained very low by ammonia stripping.     

Natural Weathering of Polypropylene and Waste Tire Dust (PP/WTD) Blends

Three series of polypropylene and waste tire dust (PP/WTD) blends using three different WTD sizes were prepared, compression-molded and cut into dumbbells. The specimens were exposed to natural weathering in the northern part of Malaysia for a period of 6 months. The results show that at the same blend composition, blends with fine WTD size exhibit higher mechanical properties than that of blends with coarse WTD after exposure to natural weathering. Regardless of WTD size, the retention of tensile strength and elongation at break, E_b increases with the increase in WTD content. From the exposed surface morphology, it is apparent that the blends with fine WTD and WTD-rich blends were able to withstand weathering better than blends with coarse WTD and PP-rich blends. The DSC thermograms suggest that the overall drop in melting temperature (T_m) of the exposed blends decreases as the WTD content increases.     

Arsenic and lead in the indoor residential settings of different socio-economic status; assessment of human health risk via dust exposure

Environmental Science and Pollution Research - In the present study, occurrence of arsenic (As) and lead (Pb) is reported in rural and urban household dust (floor and AC filter dust) of the Kingdom...     

The effects of air pollution on human mortality: does gender difference matter in African countries?

The relationship between environmental factors and human health has long been a concern among academic researchers. We use two indicators of environmental pollution, namely particulate matter (PM₁₀) and carbon dioxide (CO₂) to examine the effects of poor air quality on human mortality. This study explores an issue that has largely been ignored, particularly in the African literature, where the effect of air pollution on human mortality could be influenced by gender specification. We analyse a panel data from 35 African countries and our result suggests that the elevated levels of PM₁₀ and CO₂ have a significant effect on the increasing mortality rates in infants, under-five children and adults. Although the effect of poor air quality on adults is found to differ between genders, such difference is not statistically significant. We conclude that the air pollution effects, on average, are similar between genders in the African countries.     

Numerical modeling of tracer transport in a contact tank

Chlorine is extensively used to disinfect the drinking water supply. However, the inefficient use of chlorine as a disinfectant can result in the formation of chemical compounds which can have adverse health effects. Numerical models are increasingly being used in the design of efficient chlorine contact tanks. In this paper, details are given of the application of a two-dimensional semi-time-centred implicit QUICK scheme to model the transport of a tracer in a scaled physical model of a serpentine chlorine contact disinfection tank. The model is shown to give good agreement with laboratory measurements in the compartments of the tank where the flow is relatively uniform over the depth.     

Murine Norovirus Interaction with Pseudomonas aeruginosa Biofilm in a Dynamic Bioreactor

Food and Environmental Virology - Biofilms can constitute permanent threats to food safety and public health. Bacteria and viruses lodged in biofilm can escape cleaning and sanitizing agents. The...     

Complexity,continuity and change: livelihood resilience in the Darfur region of Sudan

Darfur farming and pastoralist livelihoods are both adaptations to the environmental variability that characterises the region. This article describes this adaptation and the longer‐term transformation of these specialised livelihoods from the perspective of local communities. Over several decades farmers and herders have experienced a continuous stream of climate, conflict and other shocks, which, combined with wider processes of change, have transformed livelihoods and undermined livelihood institutions. Their well‐rehearsed specialist strategies are now combined with new strategies to cope. These responses help people get by in the short term but risk antagonising not only their specialist strategies but also those of others. A combination of factors has undermined the former integration between farming and pastoralism and their livelihood institutions. Efforts to build resilience in similar contexts must take a long‐term view of livelihood adaptation as a specialisation, and consider the implications of new strategies for the continuity and integration of livelihood specialisations.     

Persistence and bioactivity of metsulfuron-methyl in three soils

The persistence of metsulfuron-methyl (methyl 2-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl]aminosul fonyl]benzoate) in nonautoclaved and autoclaved Selangor, Lating, and Serdang series soils incubated at different temperatures and with different moisture contents was investigated under laboratory conditions using cucumber (Cucumis sativus L.) as the bioassay species. Significant degradation of metsulfuron-methyl was observed in nonautoclaved soil compared with the autoclaved soil sample, indicating the importance of microorganisms in the breakdown process. At higher temperatures the degradation rate in nonautoclaved soil improved with increasing soil moisture content. In nonautoclaved Selangor, Lating and Serdang series soils, the half-life was reduced from 4.79 to 2.78 days, 4.9 to 3.5, and from 3.3 to 1.9 days, respectively, when the temperature was increased from 20 degrees to 30 degrees C at 80% field capacity. Similarly, in nonautoclaved soil, the half-life decreased with an increasing soil moisture from 20% to 80% at 30 degrees C in the three soils studied. In the autoclaved soil, the half-life values were slightly higher than those obtained in the nonautoclaved soils, perhaps indicating that the compound may be broken down by nonbiological processes. The fresh weight of the bioassay species was reduced significantly in Serdang series soil treated with metsulfuron-methyl at 0.1 ppm. However, the reduction in fresh weight of the seedlings was least in Lating series soil, followed by Selangor series soil.     

Radionuclides in hot mineral spring waters in Jordan

Hot mineral springs in Jordan are very attractive to people who seek physical healing but they are unaware of natural radioactive elements that may be contained in the hot mineral water. The activities of the natural radioactive isotopes were measured and the concentrations of the parents of their natural radioactive series were calculated. The measured radionuclides were 234Th, 226Ra, 214Pb, 214Bi, 228Ac, 228Th, 212Pb, 212Bi and 208Tl. In addition the activities of 235U and 40K were measured. The activities ranged from 0.14 to 34.8 Bq/l, while the concentrations of parent uranium and thorium isotopes ranged from 3.0 x 10(-3) to 0.59 mg/l. The results were compared with those for drinking water.