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Showing 5 results for Subject: Environment

A. Fraji, Gh. Asadollahfardi, A. Shevidi,
Volume 11, Issue 4 (12-2013)

Secondary clarifiers with large areas are widely applied in wastewater treatment plants. A pilot study was conducted to examine the possibility of applying one and two-stage inclined tube settlers instead of conventional secondary clarifiers. Tube diameter in the first stage of the two-stage settler was wide as the conventional ones, but in the second stage, it was narrow to improve the efficiency. The results indicated that in short detention times, the tube settler was more effective in shorter detention time than the conventional secondary sedimentation basin, and its effluent of TSS and turbidity was acceptable to discharge into the surface waters. The average removal of TSS, BOD5, and COD, in a 20-minute detention time in the tubes, in the one-stage tube settler pilot plants was 97.6%, 96.4%, and 96.36%, respectively, while in the conventional secondary sedimentation basin was 98.2%, 99%, and 98.6%, respectively. There was a good agreement between theoretical analyses and experimental results of the pilot plant. Two-stage tube settlers in the series could improve hydraulic condition and removal efficiency of TSS, in comparison with the one-stage tube settler. The average TSS removal, in shorter detention times than that the one-stage, was 97.8%.
S. Raut, R. Ralegaonkar, S. Mandavgane,
Volume 12, Issue 4 (12-2014)

Accumulation of unmanaged industrial solid waste, especially in developing countries has resulted in an increased environmental concern. In view of utilization of industrial solid waste the recycled paper mill waste (RPMW) – cement composite bricks were designed and developed. In order to investigate the environmental performance of sustainable construction materials two small scale model houses were designed and developed with waste-create (RPMW – cement) bricks and commercially available fly ash bricks as per the standards. In order to assess the thermal comfort for the considered sustainable building materials the temperature inside the model houses were monitored over the study location for the period of a year. The economic viability for the developed model houses was also analyzed. The recorded south facade exposed wall surface temperature readings for the developed small-scale model houses were used to estimate the thermal conduction of wall assembly. The detailed analysis revealed that the developed waste-create brick model house was more thermally comfortable and economical than fly ash brick model house. The better thermal performance capacity of the waste-create brick model house can drive the construction of energy efficient building so as to minimize energy consumption through the reduction of the thermal load of the built environment. The developed low cost sustainable construction material enhances the practical feasibility of the product as well.
N. Shariatmadari, A.h. Sadeghpour, M. Mokhtari,
Volume 13, Issue 1 (3-2015)

The physical properties of the municipal solid waste (MSW) in Kahrizak Landfill (Tehran, Iran) and its changes due to aging were investigated in this research. A study of the components of the fresh MSW in this landfill showed that more than 60% of it was made from the wastes of foods, fruits, vegetables and organic materials. Next to that, paper/cardboard and plastics, with contributions of 14% and 11%, comprised the greatest parts of the waste materials. Meanwhile, the results obtained from these studies revealed that the contribution of the organic part has been decreased during the last two decade by about 20% while the plastics and paper/cardboard contribution has been increased by the same amount. In order to investigate the effect of aging on the physical properties of MSW, waste samples of 5.5, 14 and 21 years of age were obtained by excavating the aged waste burial regions of this landfill. A study of the changes in the composition of waste materials through aging also revealed that the portion of paste was decreased from 25% to 40% due to the decomposition process, while the contribution of plastics and fabrics was increased up to 200%. Particle size became finer with the mean size being reduced from 70 mm in the fresh wastes to 20 mm in 21-year-old wastes due to the decomposition process. The moisture content of the fresh waste samples was reported to be more than 150%, which was considerably larger than that of other existing landfills. Along with the increase in the age of the waste samples, the moisture content was decreased by as much as one third of the initial value. Furthermore, since the waste mass became more homogeneous by age, the variation of the moisture content was reduced. The organic content of the 14-year-old waste was found to be 20%, which was less than 0.3 of the initial value. Moreover, the variation of the organic content in the waste samples was directly related to the moisture content of the samples with both parameters being reduced to less than one third of the initial value in the older samples. Investigation of the moisture content and the organic content of the aged samples showed that the burial location had a significant effect on the trend of variations. The average density of the fresh waste was measured to be 3.5 and 7.3 kN/m3 after production and burial, respectively. It was found that the average density of the fresh waste grew to about 12kN/m3 as the age was increased.
V.v. Sakhare, S.p. Raut, S.a. Mandavgane, R.v. Ralegaonkar,
Volume 13, Issue 4 (12-2015)

Energy conservation in buildings plays a vital role for sustainable development of societies and nations. Although, newer buildings in developing nations are being constructed using energy conservation approach, existing buildings have higher energy demand to meet the desired comfort. Excessive energy demand for cooling the built environment is a major problem over most of the arid climatic zones. The problem is predominant in all the top storied buildings which are directly under exposed roof condition. In order to reduce the overheating of the roof surface a composite combination of reflecting-cum-insulating (R-I) material was developed. The sustainable materials viz., expanded polystyrene (construction waste), saw dust (industrial waste), and the false ceiling panels prepared from industrial waste were used for the development of sustainable R-I material. The R-I material was retrofitted over the existing roof of a model room in an educational building over composite climate (Nagpur, India) and was analyzed experimentally for the period of a year. The thermal resistance of the overall roof assembly was increased from 0.28 to 0.55 m² K/W, which in turn helped to achieve 16% of the duration of the year under thermal comfort. The developed R-I material has also an advantage of low cost (INR 900 per sq. m.) of installation as well as light weight (50 kg/m²) retrofitting solution. The R-I product can further be applied on larger roof areas by the designers to reduce the cooling load of the built environment as well as increase the occupants comfort over the local climatic zone.

Laemthong Laokhongthavorn, Chalida U-Tapao,
Volume 15, Issue 2 (3-2017)

This paper has applied operation research to solid waste disposal by which two objective functions are optimized to minimize the expected operational costs (maximize revenues) and the expected net carbon dioxide equivalent (CDE) emissions. Types and uncertain amounts of solid wastes as well as costs of electricity were factored into the selection decision of solid waste disposal, i.e. landfill, incineration, composting and recycling. An optimization model was applied to the solid waste disposal of Bangkok, Thailand. In addition, a multi-objective optimization technique was proposed for a tradeoff decision-making between minimum operational costs and CDE emissions. Composting and landfill are effective alternatives for Bangkok’s solid waste disposal system. The operational costs and net CDE emissions are highly correlated with the quantity of solid waste. Policy-makers and plant operators could adopt the proposed optimization model under uncertainty in the selection of an optimal solid waste disposal.

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