Dissipation and mobility of permethrin in the field with repeated applications under tropical conditions

Studies on persistence, mobility and the effect of repeated application of permethrin on its half-life were carried out under field conditions. The half-life of permethrin in the top 20 cm of the soil increased from 11.5 to 23.6 days as the application rates increased from 35 to 140 g ha(-1). Induced by heavier rainfall, more residues moved downward in trial 2 than in trial 1. Repeated applications enhanced degradation rates and mobility of permethrin in the soil. The residue level in the 0-5-cm layer was reduced at day 28 after 17 consecutive applications to a level lower than after 5 applications. The half-life of permethrin was reduced from 15.9 days to 11.2 days after 5 and 17 applications, respectively. The residue reached the 15-20 cm layer much earlier (approximately 3 days after treatment) in soil that received 17 applications as compared to those with two applications.     

Investigation on the effect of sintering temperature on kaolin hollow fibre membrane for dye filtration

Despite its extraordinary price, ceramic membrane can still be able to surpass polymeric membrane in the applications that require high temperature and pressure conditions, as well as harsh chemical environment. In order to alleviate the high cost of ceramic material that still becomes one of the major factors that contributes to the high production cost of ceramic membrane, various attempts have been made to use low cost ceramic materials as alternatives to well-known expensive ceramic materials such as alumina, silica, and zirconia in the fabrication of ceramic membrane. Thus, local Malaysian kaolin has been chosen as the ceramic material in this study for the preparation of kaolin hollow fibre membrane since it is inexpensive and naturally abundant in Malaysia. Due to the fact that the sintering process plays a prominent role in obtaining the desired morphology, properties, and performances of prepared ceramic membrane, the aim of this work was to study the effect of different sintering temperatures applied (ranging from 1200 to 1500 °C) in the preparation of kaolin hollow fibre membrane via dry/wet phase inversion-based spinning technique and sintering process. The morphology and properties of membrane were then characterised by SEM, AFM, FTIR, XRD, and three-point bending test, while the performances of membrane were investigated by conducting water permeation and Reactive Black 5 (RB5) dye rejection tests. From the experimental results obtained, the sintering temperature of 1400 °C could be selected as the optimum sintering temperature in preparing the kaolin hollow fibre membrane with the dense sponge-like structure of separation layer that resulted in the good mechanical strength of 70 MPa with the appreciable water permeation of 75 L/h m² bar and RB5 rejection of 68%.     

Current and Future Strategies for Water and Wastewater Management of Istanbul City

Istanbul has experienced rapid increases in population to more than 12 million people, which has created infrastructure problems of water supply and wastewater treatment and disposal. In this article, the achievements and approaches of the Istanbul Water and Sewerage Administration (ISKI) to solve the water shortage problem and to improve services are summarized. Istanbul had a very severe water shortage problem in 1994 because of ignorance of the implementation of the needed projects. After reviewing the reasons and causes of the problem, new priority criteria adopted after 1994 are given. Following the implementation of the projects determined according to the aforementioned criteria, water supplied has exceeded the water demand. The added capacity is equal to one to three times of the capacity built up to 1994 for water treatment, service reservoirs, pumping stations, transmission lines, and the water distribution network; water quality has been improved the meet local and international potable water standards. Unaccounted for water has been reduced from 60% to 27%. The percentage of treated wastewater has been increased from 10% to 90% in 8 years, resulting in drastic improvements and rehabilitation of the Golden Horn and coastal water quality. Through improved customer services, complaints were reduced from 33% in 1994 to 0.3%. Some of the main criteria and the approaches behind this success are summarized. Published online     

Climate variability and changes in the major cities of Bangladesh: observations,possible impacts and adaptation

High population density, inadequate infrastructure and low adaptive capacity have made the urban population of Bangladesh highly vulnerable to climate change. Trends in climate and climate-related extreme events in five major cities have been analyzed in this paper to decipher the variability and ongoing changes in urban Bangladesh. An analysis of 55 years (1958–2012) of daily rainfall and temperature data using nonparametric statistical methods shows a significant increase in annual and seasonal mean daily maximum and minimum temperatures in all five cities. A significant increase in climate-related extreme events, such as heavy rainfall events (>20 mm), hot days (>32 °C) and hot nights (>25 °C), is also observed. Climate model results suggest that these trends will continue through the twenty-first century. Vulnerability of urban livelihoods and physical structures to climate change is estimated by considering certainty and timing of impacts. It has been predicted that public health and urban infrastructures, viz. water and power supply, would be the imminent affected sectors in the urban areas of Bangladesh. Adaptation measures that can be adopted to mitigate the negative impacts of climate change are also discussed.     

Method development for determination of fluroxypyr in water

Improved methods for extraction and clean up of fluroxypyr residue in water have been established. Two methods of fluroxypyr extraction were used, namely, Direct Measurement of fluroxypyr and Concentration of fluroxypyr onto A Solid Phase Extraction (SPE) Adsorbent, followed by elution with solvent before determination of fluroxypyr. The recovery for Direct Measurement of fluroxypyr in water containing 8-100 microg L(-1), ranged from 86 to 110% with relative standard deviation of 0.7 to 2.15%. For the second method, three types of SPE were used, viz. C18, C18 end-capped and polyvinyl dibenzene (ISOLUTE ENV+). The procedure involved concentrating the analyte from fluroxypyr-spiked water at pH 3, followed by elution of the analyte with 4 mL of acentonitrile. The recovery of fluroxypyr from the spiked sample at 1 to 50 microg L(-1) after eluting through either C18 or C18 end-capped ranged from 40-64% (with relative standard deviation of 0.7 to 2.15) and 41-65% (with standard deviation of 1.52 to 11.9). The use of ISOLUTE ENV+, gave better results than the C18, C18 end-capped or the Direct Measurement Methods. The recovery and standard deviation of fluroxypyr from spiked water using ISOLUTE ENV+ ranged from 91-102% and 2.5 to 5.3, respectively.     

Landfill leachate management in Istanbul: applications and alternatives

Treatment alternatives for Istanbul, Komurcuoda Landfill (KL) leachate that is currently transported to the nearest central wastewater treatment plant were comprehensively investigated with laboratory scale experiments. As flow rate of leachate increases parallel to increment in landfilled solid waste, an individual treatment will be needed to reduce the transportation cost and pollution load on central treatment. However, if the leachate is separately treated and discharged to a brook, in that case more stringent discharge standards will be valid and therefore advanced processes in addition to conventional ones should be included. In laboratory scale experiments, the young landfill leachate having BOD5/COD ratio above 0.6 was successfully treated with efficiencies above 90% in upflow anaerobic reactors if pH is kept below free ammonia inhibition level. Subsequently, nitrification of anaerobically treated leachate was performed with rates of about 8.5 mg NH4+-Ng-1 VSS h-1 and efficiencies above 99% were provided with automated pH regulation by using sodium bicarbonate. Furthermore, denitrification rates as high as 8.1 mg NOx-N g-1VSS h-1 was obtained when carbon source was externally supplied. In addition to nitrification and denitrification, air stripping and struvite precipitation were also applied to remove ammonia in leachate and in average 94% and 98% efficiencies were achieved, respectively. Finally, in average 85% of biologically inert COD was successfully removed by using either ozone or Fenton's oxidation.     

Removal and pre-concentration of phenolic species onto beta-cyclodextrin modified poly(hydroxyethylmethacrylate-ethyleneglycoldimethacrylate) microbeads

Poly(Hydroxyethylmethacrylate-Ethyleneglycoldimethacrylate), poly(HEMA-EGDMA), microbeads with 150-200 microm in size, was prepared by suspension polymerization. Beta-cyclodextrin was modified onto the polymeric microbeads using glutaraldahyde activation in an acidic medium at pH=2.5. FT-IR and TGA were used for the characterization of modified polymers and the determination of the nature of the interaction between phenolic compounds and the modified polymeric microbeads. Plain and beta-cyclodextrin modified microbeads were used in adsorption-desorption studies of phenolic species in single solution. Adsorption capacities of the phenolic species onto the plain microbeads were found to be 28.2, 17.0, 14.3, 9.8, and 1.92 mg/g polymer for o-chloro phenol, p-nitro phenol, p-chloro phenol, o-nitro phenol, and phenol, respectively. However, for beta-cyclodextrin modified microbeads, adsorption capacity of phenolic species was determined as 274, 365, 128, 182, and 87 mg/g for phenol, o-nitro phenol, p-nitro phenol, o-chloro phenol, and p-chloro phenol, respectively. Desorption ratio for the phenolic species was more than 90%, except for o-nitro phenol. Detection limits of the phenolic species were improved at least 500-fold for UV-Vis spectrophotometric detection, after the pre-concentration of all phenolic species used in this study. Adsorption time for the phenolic species onto beta-cyclodextrin-modified poly(HEMA-EGDMA) microbeads was found to be reasonable short (10-60 min) and suitable for the applications. Also, synthesized microbeads were useful for the repeated use for the removal and pre-concentration of phenolic species.     

Development of a database of landfills and dump sites in Asian countries

This article briefly summarizes the limited landfill/dump information available for developing Asian countries, and introduces a database that aims to close the information gap through collecting and sharing data. Developing nations usually try to adapt the systems and technologies of developed countries. However, this approach may not be appropriate because of differences in socioeconomic, cultural, and political backgrounds. Many waste management projects fail after operations are transferred to local authorities owing to a lack of funds to cover the high operational expenses. Some successful projects have been adapted to local conditions, although the information on these successes is not often available for others. Nevertheless, only a few developing countries even have a national inventory of their dumps/landfills, and decision-makers have little awareness of the dumps and their impacts. The database introduced here will gather landfill/dump information from each country and organize it in a comparable format, and it will then be published on the Internet.     

Study of Fatigue Life and Filler Interaction of Paper Sludge Filled Epoxidized Natural Rubber (ENR) and Maleated Natural Rubber (MNR) Composites

An investigation on the effect of epoxidation and maleated natural rubber (MNR) on fatigue and rubber-filler interaction properties of paper sludge filled natural rubber composites was elucidated. Paper sludge loading was varied from 0 to 40 phr and conventional vulcanisation system was used while compounding was carried out on a laboratory sized two roll mill. Two different types of natural rubber, SMR L and ENR 50 having 0 and 50 mole% of epoxidation were used in order to investigate the effect of epoxidation on the composites. Results indicate that, at a fixed filler loading, ENR 50 vulcanizates exhibit higher fatigue life than SMR L vulcanizates especially at filler loading below 20 phr which might be associated with better rubber-filler interaction. In the case of composites with the addition of maleated natural rubber (MNR), a higher fatigue life was observed due to presence of physical and/or chemical linkages, which increases the interfacial adhesion. Scanning electron microscopy (SEM) micrographs of fatigue fracture surfaces and rubber-filler interaction study supported the observed result on fatigue life.