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Analysis of some Physical Parameters under Workers' Optimal Performance in Wet and Hot Tropical Climates; A Literature Review
Modeste Kameni Nematchoua
Issue:
Volume 6, Issue 5, September 2018
Pages:
72-85
Received:
10 September 2018
Accepted:
19 September 2018
Published:
13 October 2018
Abstract: In this decade, in the hot tropical zone, it is observed a rapid variation of the external climate which acts directly on the thermal comfort and the satisfaction of the occupants inside the buildings. The aim of this article is to analysis the influence of some indoor parameters on workers’ performance. In addition, this work reports the results of the conducted study to assess the effect of indoor environment quality on workers ‘productivity, in 102 offices distributed in 23 buildings in the coastal and central areas of Cameroon (Douala and yaounde). This research was conducted during the dry and rainy seasons, in naturally ventilated buildings using the adaptive approach, in accordance with ASHRAE 55/2004, ISO 7730 and ISO 10551. Wind speed, air temperature, relative humidity and CO2 levels were measured. While, simultaneously, 600 questionnaires were distributed. The results revealed that the temperature, and relative humidity have significant effect on the office workers’ productivity. More than 80% of the participants were working under "no stress" condition, when the Universal Thermal Climate Index varied from 22.9 to 26.3°C". The optimum performance occurred when the thermal sensation was between -0.5 and 0.5. Increasing the air temperature to 28°C and above could reduce workers’ performance by a minimum of 1.5% during both seasons.
Abstract: In this decade, in the hot tropical zone, it is observed a rapid variation of the external climate which acts directly on the thermal comfort and the satisfaction of the occupants inside the buildings. The aim of this article is to analysis the influence of some indoor parameters on workers’ performance. In addition, this work reports the results o...
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Leaching of Germanium from Zinc Residue in H2SO4/SO2 Solutions
Xuelan Wu,
Hongming Long,
Xin Li,
Yanxu Shen,
Yangyang Zhang,
Zhipeng Li,
Yiming Hu
Issue:
Volume 6, Issue 5, September 2018
Pages:
86-93
Received:
12 September 2018
Accepted:
27 September 2018
Published:
26 October 2018
Abstract: Zinc residue with high germanium, a waste solid product of hydrometallurgical zinc process is dumped continuously, causing the loss of germanium. Zinc residue was characterized by chemical analysis, X-ray diffraction, and inductively coupled plasma mass spectrometry methods. The results showed that, the mineralogical compositions of the zinc residue used in this research were zinc ferrite, gypsum, hemihydrate gypsum, anglesite, sphalerite and quartz. Approximately 58% and 20% germanium occurred in the ferrite and silicate phases, respectively. Leaching of zinc residue with high germanium was investigated as a process to recover germanium. It was found to be much more effective using sulfur dioxide as a reductant. Batch leaching tests were carried out on zinc residue with high germanium at set pressure in stirred acid solution. The effects of SO2, time, sulfuric acid concentration, temperature, liquid-to-solid ratio, and sulphur dioxide partial pressure on the germanium dissolution were studied to optimize the leaching parameters. In the presence of SO2, the results showed that the extraction of germanium was maximum of 70% while the extraction of zinc and iron were 90% and 96% under the optimal condition which was determined for 80 g of zinc residue using 56 g/L sulfuric acid, liquid-to-solid ratio of 7 mL/g and sulphur dioxide partial pressure of 200 kPa at 100°C after 120 min. Under optimal conditions, the main minerals of the reduction leaching residue were sodium iron sulfate tetrahydrate, gypsum, hemihydrate gypsum, anglesite, sphalerite and quartz. Zinc ferrite was almost entirely leached.
Abstract: Zinc residue with high germanium, a waste solid product of hydrometallurgical zinc process is dumped continuously, causing the loss of germanium. Zinc residue was characterized by chemical analysis, X-ray diffraction, and inductively coupled plasma mass spectrometry methods. The results showed that, the mineralogical compositions of the zinc residu...
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Modelling and Simulation of Waste Plastic Power Plant: A Theoretical Framework
Nsidibe-Obong Ekpe Moses,
Collins Erhianoh,
Christiana Edward Anih
Issue:
Volume 6, Issue 5, September 2018
Pages:
94-98
Received:
7 September 2018
Accepted:
25 September 2018
Published:
31 October 2018
Abstract: The high energy content of plastics can be converted to electricity. The recovery of this abundant energy helps to curb environmental concerns associated with plastic utilization. Non-recyclable plastic materials are used in areas like packaging, 3D printing, and construction. Where recycling becomes an issue, technologies that utilize the waste plastics to generate electricity can be employed. This paper presents a theoretical framework for the simulation of waste plastic power plant. A simulation model that produces electricity from the High Density Polyethylene (HDPE) waste plastics has been developed using Aspen Hysys process simulator. The pyrolysis reactor modelled as a conversion reactor was used to thermally crack 2000Kg/h of HDPE feed at a temperature of 450°C to produce a top product containing a mixture of liquid fuel oil and volatile gaseous fuel. After cooling of the top product and separation to obtain the volatile gaseous fuel from the liquid fuel oil, the volatile gaseous fuel alongside air were pressurized with a compressor and then combusted in a Gibbs free energy reactor. In this reactor, the gaseous fuel burned with excess air in the combustion chamber to produce a high temperature and pressured gas that drove the gas turbine (modelled as an expander) to generate electrical power of 1194KW. To achieve proper energy optimization, the high temperature flue gas obtained from the gas turbine after pressure loss was passed through a “Heat Recovery Steam Generator” that allowed water at 25°C to be heated up to produce steam which in turn drove a steam turbine to generate electricity of 255.3KW. In all, the waste plastic power plant generated a net power of 216.461KW at an equivalence ratio of 1.5.
Abstract: The high energy content of plastics can be converted to electricity. The recovery of this abundant energy helps to curb environmental concerns associated with plastic utilization. Non-recyclable plastic materials are used in areas like packaging, 3D printing, and construction. Where recycling becomes an issue, technologies that utilize the waste pl...
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Effect of Process Condition on the Bio-Digestion of Cow Dung for Organic Fertilizer Production
Udeh Sunday,
Ekumankama Ekuma Onu
Issue:
Volume 6, Issue 5, September 2018
Pages:
99-106
Received:
18 September 2018
Accepted:
30 September 2018
Published:
1 November 2018
Abstract: Studies were conducted on the biodigestion of cow-dung into organic fertilizer with the aim of determining the effect of process parameters on the quality of the product. The Hydrogen ion index (pH) was varied from 3.5 to 7.0 whereas the microbe: substrate (M/S) ratio was varied from 1.33 to 4.5g/kg and biodigestion time from 3 to 24hrs. The fertilizer produced was characterized by the NPK content and the production index (PI). The extent of biodigestion as indicated by the PI value, varied with the pH, ranging from 0.068 to 0.109 for pH between 3.5 to 7.0. Hydrogen ion index (pH) range of 3.5-4.0 at the temperature of 350°C, using native microbial flora were discovered to be most favorable to the biodigestion process, with PI 0.109 to 0.12. It was also discovered that the use of mixed culture (native microbe plus cultured saccharomyces cerevisiea further enhanced the result. A maximum microbe-substrate ratio of 4.5g/kg and a minimum of 2.67g/kg on mass basis were recommended. Within a bioconversion period of nine hours (9hrs), a product with N. P. K values of 2.9; 0.016, and 1.55 was obtained representing an increase in fertilizer value by 61.1% and 78.5% in Nitrogen (N) and potassium nutrient compositions respectively within the period. The fertilizer has an acceptable odour when dried and readily available to plant on application. It was also observed that the biodigestion process generated an exceeding quantity of biogas which can be trapped and upgraded for other domestic and industrial applications.
Abstract: Studies were conducted on the biodigestion of cow-dung into organic fertilizer with the aim of determining the effect of process parameters on the quality of the product. The Hydrogen ion index (pH) was varied from 3.5 to 7.0 whereas the microbe: substrate (M/S) ratio was varied from 1.33 to 4.5g/kg and biodigestion time from 3 to 24hrs. The fertil...
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The Effect of Graphene/TIO2 Nanomaterials on Photocatalytic Performance for Industrial Wastewater Treatment
Abd El-Aziz Hassanin Konsowa,
Yehia Abd El-Qadeer EL-Taweel,
Shahinaz Ibrahim Abogaliel
Issue:
Volume 6, Issue 5, September 2018
Pages:
107-120
Received:
5 September 2018
Accepted:
8 October 2018
Published:
6 November 2018
Abstract: The aim of the present work is to combine TiO2/Graphene to increase photo-catalytic activity and obtain efficient removal of direct red 23 azo dye without difficult synthesis. Many operating variables which affect the process and some design aspects were studied. Reactor geometry is the main design parameter where slurry rectangular reactor and bubble column were compared with respect to hydrodynamic regimes, overall degradation efficiency and applicability in industrial scale. The removal rate was found to increase with increase in TiO2 concentration, approaching a limiting value at catalyst loads of 3g/L. For rectangular reactor only 0.005g/L of rGO able to enhance the activity of photo-catalysis. However, the optimum concentration of rGO is decreased in the bubble column reactor to be 0.001g/L. In both reactor systems, photocatalytic activity increase significantly by decreasing wavelength of the irradiated lamp from 365 nm to 254 nm. Also, results show the ability of bubble column reactor to treat high concentrations of dye up to 200 ppm. That makes it suitable to be integrated with biological system to convert non-biodegradable contaminates into biodegradable organics. That reduces the operating cost of the process and makes it more applicable in industrial scale. Rectangular reactor has the ability to be modified to use sunlight instead of artificial lamps because of high surface exposed to sunlight. In general the performance of bubble column reactor was better than rectangular reactor because it has excellent mass transfer characteristics, which enhance the efficiency of the process.
Abstract: The aim of the present work is to combine TiO2/Graphene to increase photo-catalytic activity and obtain efficient removal of direct red 23 azo dye without difficult synthesis. Many operating variables which affect the process and some design aspects were studied. Reactor geometry is the main design parameter where slurry rectangular reactor and bub...
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