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CONTENTS
Volume 3, Number 3, September 2014
 

Abstract
Efficient defluorination of perfluorooctanoic acid (PFOA) was achieved by integrating UV irradiation and Fe2+ activation of persulfate (S2O82-). It was found that the UV-Fe2+, Fe2+-S2O82-, and UV-S2O82- processes caused defluorination efficiency of 6.4%, 1.6% and 23.2% for PFOA at pH 5.0 within 5 h, respectively, but a combined system of UV-Fe2+-S2O82- dramatically promoted the defluorination efficiency up to 63.3%. The beneficial synergistic behavior between Fe2+-S2O82- and UV-S2O82- was demonstrated to be dependent on Fe2+ dosage, initial S2O82- concentration, and solution pH. The decomposition of PFOA resulted in generation of shorter-chain perfluorinated carboxylic acids (PFCAs), formic acid and fluoride ions. The generated PFCAs intermediates could be further defluorinated by adding supplementary Fe2+ and, S2O82- and re-adjusting solution pH in later reaction stage. The much enhanced PFOA defluorination in the UV-Fe2+-S2O82- system was attributed to the fact that the simultaneous employment of UV light and Fe2+ not only greatly enhanced the activation of S2O82- to form strong oxidizing sulfate radicals (SO4•-), but also provided an additional decarboxylation pathway caused by electron transfer from PFOA to in situ generated Fe3+.

Key Words
perfluorooctanoic acid; synergism; persulfate; UV; ferrous ions

Address
(1) Zhou Song, Heqing Tang:
Key Laboratory of Catalysis and Materials Science, The State Ethnic Affairs Commission and Ministry of Education, College of Chemistry and Materials Science, South-Central University for Nationalities, 182 Minyuan Road, Hongshan District, Wuhan, P.R. China;
(2) Zhou Song, Nan Wang, Xiaobo Wang, Lihua Zhu:
College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Hongshan District, Wuhan, P.R. China.

Abstract
Dewatering is an extremely important step in wastewater treatment process to reduce the final sludge volume in order to minimize the cost of sludge transportation and disposal. In the present study, the effect of different sludge solids content (1, 2 and 3.8%) on the dewaterability of anaerobically digested sludge using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was studied. The pH reduction rate was higher during initial process in the sludge having low solids content, but after 48 h of bioleaching, similar pH of below 3 was observed with all the different solids content. Bio-oxidation rate of Fe2+ was initially higher in sludge with low solids content, but 100% Fe2+ was oxidized within 60 h in all the three treatment levels. Compared to the control, specific resistance to filtration was reduced by 75, 78 and 80% in the sludge with a solids content of 1, 2 and 3.8% respectively, showing improvement in dewaterability with an increase in sludge solids content. Sludge effluent quality and sludge settling rate were also improved in treatments with higher solids content after the bioleaching process.

Key Words
acidithiobacillus ferrooxidans; acidithiobacillus thiooxidans; sludge dewaterability; bioleaching

Address
(1) Jonathan W.C. Wong, Mayur B. Kurade, Ammaiyappan Selvam:
Sino Forest Applied Research Center for Pearl River Delta Environment & Department of Biology, Hong Kong Baptist University, Hong Kong SAR;
(2) Jun Zhou, Lixiang Zhou:
College of Resources and Environment, Nanjing Agricultural University, Nanjing, PR China.

Abstract
A study was conducted to determine the phytotoxic effect of mercury on seed germination and seedling growth of an important arid legume tree Albizia lebbeck. The seeds germination and seedling growth performance of A. lebbeck responded differently to mercuric chloride treatment (1 mM, 3 mM, 5 mM and 7 mM) as compared to control. Seed germination of A. lebbeck was significantly (p < 0.05) affected by mercury treatment at 1 mM. Root growth of A. lebbeck was not significantly affected by mercury treatment at 1 mM, and 3 mM. Shoot and root length of A. lebbeck were significantly (p < 0.05) affected by 5 mM concentration of mercury treatment. Increase in concentration of mercury treatment at 5 mM and 7 mM significantly (p < 0.05) reduced seedling dry weight of A. lebbeck. The treatment of mercury at 1 mM decreased high percentage of seed germination (22%), seedling length (10%), root length (21.85%) and seedling dry weight (9%). Highest decrease in seed germination (51%), seedling (34%), root length (48%) and seedling dry weight (41%) of A. lebbeck occurred at 7 mM mercury treatment. A. lebbeck showed high percentage of tolerance (78.14%) to mercury at 1 mM. However, 7 mM concentration of mercury produced lowest percentage of tolerance (51.65%) in A. lebbeck. The seed germination potential and seedling vigor index (SVI) clearly decreased with the higher level of mercury. Plantation of A. lebbeck in mercury-polluted area will help in reducing the burden of mercury pollution. A. lebbeck can serve better in coordinating in land management programs in metal contaminated areas. The identification of the toxic concentration of metals and tolerance indices of A. lebbeck would also be helpful for the establishment of air quality standard.

Key Words
mercury; seed germination; growth; seedling vigor index; tolerance; toxicity; Albizia lebbeck; tree

Address
(1) Muhammad Zafar Iqbal, Muhammad Shafiq:
Department of Botany, University of Karachi, Karachi-75270, Pakistan;
(2) Mohammad Athar:
California Department of Food and Agriculture, 3288 Meadowview Road, Sacramento, CA 95832, USA;
(3) Mohammad Athar:
Department of Food Science and Technology, University of Karachi, Karachi-75270, Pakistan.

Abstract
The large quantity of green cull bananas has the potential of being used industrially and, thereby, to improve banana economics and eliminate the large environmental problem presented by banana waste. Wastewaters from textile, cosmetics, printing, dying, food colouring, and paper-making industries are polluted by dyes. The adsorption of basic dye by waste banana pith was investigated by varying dye concentrations, adsorbent dose, particle size and agitation rate. The adsorption capacity was found to be maximum value of removal by using 0.1 g of sorbent with particle size 1mm at mixing speed 200 rpm for initial concentration 25 mg/l to reach value of approximate 89%. The Langmuir, Temkin and Freundlich adsorption models were used for mathematical description of the adsorption equilibrium and it was found that experimental data fitted very well to these models except Langmuir model. Adsorption of dye was applied on (pseudo-first and pseudo-second-order kinetics), and the experimental data was more fitted to pseudo second order. The results of this study showed that banana pith could be employed as effective and low-cost materials for the removal of dyes from aqueous solutions.

Key Words
banana pith; isotherms; kinetics; adsorption

Address
Department of Fabrication Technology, Advanced Technology and New Materials Research Institute, City for Scientific Research and Technology Applications, Universities and Research Center District, New Borg El-Arab, Alexandria, Egypt.

Abstract
The present study examines the phosphate adsorption potential and behavior of mixture of Ground Burnt Patties (GBP), a solid waste generated from cooking fuel used in earthen stoves and Red Soil (RS), a natural substance in fixed bed column mode operation. The characterization of adsorbent was done by Proton Induced X- ray Emission (PIXE), and Proton Induced γ- ray Emission (PIGE) methods. The FTIR spectroscopy of spent adsorbent reveals the presence of absorbance peak at 1127 cm-1 which appears due to P = O stretching, thus confirming phosphate adsorption. The effects of bed height (10, 15 and 20 cm), flow rate (2.5, 5 and 7.5 mL/min) and initial phosphate concentration (5 and 15 mg/L) on breakthrough curves were explored. Both the breakthrough and exhaustion time increased with increase in bed depth, decrease in flow rate and influent concentration. Thomas model, Yoon-Nelson model and Modified Dose Response model were used to fit the column adsorption data using nonlinear regression analysis while Bed Depth Service Time model followed linear regression analysis under different experimental condition to evaluate model parameters that are useful in scale up of the process. The values of correlation coefficient (R2) and the Sum of Square Error (SSE) revealed the Modified Dose Response model as the best fitted model to the experimental data. The adsorbent mixture responded effectively to the desorption and reusability experiment. The results of this finding advocated that mixture of GBP and RS can be used as a low cost, highly efficient adsorbent for phosphate removal from aqueous solution.

Key Words
phosphate adsorption; ground burnt patties; red soil; modified dose response model; Yoon-Nelson model; thomas model; BDST model

Address
Department of Civil Engineering, School of Infrastructure, Indian Institute of Technology, Bhubaneswar - 751 013, Odisha, India.

Abstract
The quest for enhanced thermal comfort for dwellings encompasses the holistic utilization of improved building fabric, impact of weather variation and amongst passive cooling design consideration the provision of appropriate ventilation and shading strategy. Whilst thermal comfort is prime to dwellings considerations, limited research has been done in this area with the attention focused mostly on non-dwellings. This paper examines the current and future thermal comfort implications of four different standard construction specifications which show a progressive increase in thermal mass and airtightness and is underpinned by the newly developed CIBSE adaptive thermal comfort method for assessing the risk of overheating in naturally ventilated dwellings. Interactive investigation on the impact of building fabric variation, natural ventilation scenarios, external shading and varying occupants

Key Words
buildings; thermal comfort; CIBSE overheating criteria; future weather; sustainability

Address
University of West London, School of Computing and Technology, Dept. of the Built Environment, St. Mary]s Road, Ealing, London W5 5RF, United Kingdom.


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