模拟废水中钯的微生物回收及其对亚甲基蓝的催化特性

以粪肠球菌(Enterococcus faecalis)Z5菌株(CCTCC M2012445)为菌种资源,探讨了其在外源电子供体条件下以纳米颗粒形式回收溶液中钯的可能性,研究了工业废液(IW)、废旧电路板(PCBS)和废汽车催化剂(SAC)3种模拟废水中钯的回收率,分析了废水中其它离子对钯回收率的影响.结果表明,粪肠球菌Z5菌株可以从3种模拟废水中回收钯纳米颗粒.X射线衍射和透射电镜分析表明,回收产物为10 nm左右粒径的钯纳米颗粒,主要分布于细胞周质.3种废水中钯的回收率依次为IWSACPCBS,其中吸附率依次为99.8%(6 h)、99.7%(8 h)、90.3%(12 h),还原率依次为99.9%(4 h)、99.9%(6 h)、80.4%(36 h).模拟废水中Pt(Ⅳ)、Ag(Ⅰ)、Cu(Ⅱ)、Au(Ⅲ)和Fe(Ⅱ)对钯的还原和吸附过程都存在影响.具体地,钯的还原效率受影响程度依次为Au(Ⅲ)Pt(Ⅳ)Cu(Ⅱ)Ag(Ⅰ)Fe(Ⅱ).进一步将回收所得的纳米钯掺杂四氧化三铁,可应用于非均相芬顿反应中染料亚甲基蓝降解,80 min内亚甲基蓝的降解率为96.7%,显示出良好的催化性能.     

渤海海冰作为淡水资源：脱盐机理与可利用价值

我国北部沿海地区缺水问题十分严重,但冬季在渤海及黄海北部形成较大范围的海冰。海冰因其成冰过程中盐分大量析出而盐度很低,可能成为解决这些地区缺水问题的重要淡水资源。论文根据实地观测和室内不同盐度海水的实验分析,阐述了渤海海冰盐度变化和海水成冰脱盐过程,并采用二次成冰脱盐和离心脱盐等方法,分析了海冰经进一步人工淡化的可能性,探讨了海冰作为淡水资源的可利用价值。     

The amplification refractory mutation system (ARMS): A rapid and direct prenatal diagnostic technique for β-thalassaemia in Singapore

β-Thalassaemia major patients have chronic anaemia and since 3–4 per cent of Singaporeans carry the β-gene, prenatal diagnosis is essential. We evaluated the amplification refractory mutation system (ARMS) technique as a routine test for prenatal diagnosis of β-major. Six mutations along the β-gene were studied—41–42 (-TCTT), IVSII #654 (C-T), 17β (A-T), – 28 TATA (A-G), IVSI #5 (G-C), and IVSI #1 (G-T). Our results indicate that prenatal diagnosis using these mutations can be offered to 90 per cent (35/39) of our Chinese couples and 54·6 per cent (12/22) of our Malay couples at risk. Confirmation of ARMS results was carried out using allele-specific oligonucleotide hybridization. Prenatal diagnosis using ARMS was successfully carried out in nine cases which included a set of triplets and twins. The triplets were diagnosed with the β-trait carrying the 41–42 mutation. The couple with twins possessed the #654 mutation and one twin was diagnosed with the β-trait and the other with #654 homozygosity. Genomic sequencing of the undefined mutations in the Chinese couples revealed rarer mutations at − 29 and an ATG-AGG base substitution at the initiation codon for translation. In the Malay couples, genomic sequencing detected mutations at codon 15 (TGG-TAG) and codon 26 (GAG-AAG). We conclude that ARMS with its direct detection of amplified products by gel electrophoresis provides an accurate, rapid, and simpler method for our β-thalassaemia prenatal diagnosis programme in Singapore.     

Anaerobic co-digestion of fat,oil, and grease (FOG): A review of gas production and process limitations

The addition of readily available high strength organic wastes such as fats, oils, and grease (FOG) from restaurant grease abatement devices may substantially increase biogas production from anaerobic digesters at wastewater treatment facilities. This FOG addition may provide greater economic incentives for the use of excess biogas to generate electricity, thermal, or mechanical energy. Co-digestion of FOG with municipal biosolids at a rate of 10–30% FOG by volume of total digester feed caused a 30–80% increase in digester gas production in two full scale wastewater biosolids anaerobic digesters (Bailey, 2007, Muller et al., 2010). Laboratory and pilot scale anaerobic digesters have shown even larger increases in gas production. However, anaerobic digestion of high lipid wastes has been reported to cause inhibition of acetoclastic and methanogenic bacteria, substrate, and product transport limitation, sludge flotation, digester foaming, blockages of pipes and pumps, and clogging of gas collection and handling systems. This paper reviews the scientific literature on biogas production, inhibition, and optimal reactor configurations, and will highlight future research needed to improve the gas production and overall efficiency of anaerobic co-digestion of FOG with biosolids from municipal wastewater treatment.     

The performance of Electro-Fenton oxidation in the removal of coliform bacteria from landfill leachate

Leachate pollution is one of the main problems in landfilling. Researchers have yet to find an effective solution to this problem. The technology that can be used may differ based on the type of leachate produced. Coliform bacteria were recently reported as one of the most problematic pollutants in semi-aerobic (stabilized) leachate. In the present study, the performance of the Electro-Fenton process in removing coliform from leachate was investigated. The study focused on two types of leachate: Palau Borung landfill leachate with low Coliform content (200 MPN/100 m/L) and Ampang Jajar landfill leachate with high coliform content (>24 × 10⁴ MPN/100 m/L). Optimal conditions for the Electro-Fenton treatment process were applied on both types of leachate. Then, the coliform was examined before and after treatment using the Most Probable Number (MPN) technique. Accordingly, 100% removal of coliform was obtained at low initial coliform content, whereas 99.9% removal was obtained at high initial coliform content. The study revealed that Electro-Fenton is an efficient process in removing high concentrations of pathogenic microorganisms from stabilized leachate.     

Is there a commercially viable market for crop insurance in rural Bangladesh?

The study aims to assess the commercial viability of a potential crop insurance market in Bangladesh. In a large scale household survey, agricultural farm households were asked for their preferences for a hypothetical crop insurance scheme using double bounded (DB) contingent valuation (CV) method. Both revenue and production cost based indemnity payment approaches were applied to assess the commercial viability of a crop insurance program assuming a partner-agent (PA) model of insurance supply. Crop insurance is found marginally commercially viable in riverine flood plain areas. The expected indemnity payable consistently exceeds the expected insurance premium receivable by the insurer for the households living in wetland basin and coastal floodplain. We conclude that a uniform structure of crop insurance market does not exist in Bangladesh. The nature of the disaster risks faced by the farm households and the socio-economic characteristics of the rural farm communities need to be taken into careful consideration while designing such an insurance scheme.

Landscape changes of desertification in arid areas: the case of south-west Algeria

This study aims to monitor the arid Algerian High Plateaus, a key region for pastoral activities which has suffered harsh and widespread degradation from the eighties. This area is not sufficiently known by the international scientific community. For this purpose, we considered phytoecological inventories and thematic maps that have been carried out during 30 years. Available data for the study are vegetation maps derived from aerial photographs (1975-1978) and from satellite imagery (2006). The parameters considered include vegetation, flora, and soil surface properties. The study area is part of the ROSELT/OSS (ROSELT: Réseau d'Observatoires de Surveillance Ecologique à Long Terme (Long Term Ecological Monitoring Observatories Network); OSS: Observatory of the Sahara and the Sahel) network observatory (OSS 2008). To assess land degradation, we used landscape ecology parameters. These include the number and surface area of vegetation units, synthesized by the large patch index and the Shannon landscape diversity index. All parameters reflect an increase in landscape heterogeneity. The largest decline is observed for Stipa tenacissima vegetation units constituting 2/3 of the landscape in 1978 and occupied just 1/10 in 2006. Vegetation units linked to degradation, such those dominated by Salsola vermiculata, inexistent in 1978, now dominate the steppe. Another result of the ongoing landscape degradation on the plateaus between 1975 and 2006 is the decrease of vegetation cover. In 1978, 1/3 of rangelands only had low vegetation covers, inferior to 15%. Presently 9/10 present the same class cover. This can be explained by severe spells of drought combined by an exponential rise of livestock during the last 30 years. This has in turn greatly undermined the fodder potential of the steppe. Results suggest that the "greening-up" described by several authors in the Sahel over the last 40 years is not observed in the Algerian, nor in the North African steppes. On the contrary, the desertification is still ongoing and the threshold of irreversibility seems to be imminent.     

Simple graphical method for inherent occupational health assessment

The concept of inherently safer design was introduced to design a fundamentally safer process so that hazards can be avoided or minimized rather than controlled or managed. The ideology has later been extended to the environmental, but not health criteria due to its complicated underlying principles. Even though health risk methods are already established, majority are for existing plants assessment. Early consideration of health aspect starting from process design stage however, has received much less attention. This paper introduces a simple graphical method to evaluate the inherent occupational health hazards of chemical processes during the R&D stage. A survey was conducted to identify the important health parameters for the graphical method development, involving nine world inherent safety and health experts. Based on their input, process mode, material volatility, operating pressure and chemical health hazard (toxicity and adverse effect) are the significant factors affecting inherent health hazards of chemical processes. The choice of parameters was bounded by the information availability at this stage. The method was applied on six routes to methyl methacrylate and ten routes to acetic acid. The parameters were plotted for each subprocess of the alternative routes. The ‘healthiest’ route was selected based on thorough hazards assessment across all the subprocesses. The first case study reveals the tertiary butyl alcohol as the ‘healthiest’ one as it poses relatively lower, or at least comparable hazards to the other routes due to exposure and health impacts. Meanwhile the acetic acid case study indicates ethanol oxide and ethyl oxide based routes as the inherently healthier as they operate at lower operating pressure besides posing comparable hazards level for the other three parameters, compared to the other routes. The case studies show that the inherent occupational health of a chemical process can already be evaluated easily in the R&D stage with the simple graphical method proposed.     

The effects of Environmental Kuznets Curve toward environmental pollution,energy consumption on sustainable economic growth through moderate role of technological innovation

Environmental Science and Pollution Research - South Asia is a hub for encompassing air contamination, with 37 of the top tiers of the 40 most contaminated urban communities around the globe...