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Adsorptive Solar Refrigerators Based on Composite Adsorbents ’Silica Gel – Sodium Sulphate’

Abstract

The operation processes of adsorptive solar refrigerators based on composite adsorbents ‘silica gel - sodium sulphate’ were studied. The correlation between the adsorbent composition and the coefficient of the energy performance of the device was stated. As a consequence of the decreasing of adsorbent mass, the coefficient of performance is increased when sodium sulphate content in the composite increased. Effect of the regeneration process parameters on the composite on the coefficient of performance of the adsorptive refrigenerator was stated. The growth of the coefficient of performance is shown to result from decreasing the difference between adsorbent temperature and regeneration temperature from 85 to 55°C. The maximum values of the coefficient of performance of studied solar adsorptive refrigenerator about of 1.14 are stated for composites containing about 20 wt. % silica gel and 80 wt. % sodium sulphate.

Open access
Agglomeration of Silicon Dioxide Nanoscale Colloids in Chemical Mechanical Polishing Wastewater: Influence of pH and Coagulant Concentration

Abstract

Chemical mechanical polishing (CMP) wastewater generated from semiconductor manufacturing industries is known to contain residual organic and inorganic contaminants, i.e. photoresists, acids, including silicon dioxide (SiO2), nanoparticles (NPs) and others. Nanoscale colloids in CMP wastewater have strong inclination to remain in the suspension, leading to high turbidity and chemical oxygen demand (COD). Although various types of pre-treatment have been implemented, these nanoparticles remain diffused in small clusters that pass through the treatment system. Therefore, it is crucial to select suitable pH and coagulant type in the coagulation treatment process. In this research zeta potential and dynamic light scattering measurements are applied as preliminary step aimed at determining optimum pH and coagulant dosage range based on the observation of inter particle-particle behavior in a CMP suspension. The first phase of the conducted study is to analyze nanoscale colloids in the CMP suspension in terms of zeta potential and z-average particle size as a function of pH within a range of 2 to 12. Two types of coagulants were investigated - polyaluminum chloride (PACl) and ferrous sulfate heptahydrate (FeSO4·7H2O). Similar pH analysis was conducted for the coagulants with the same pH range separately. The second phase of the study involved evaluating the interaction between nanoscale colloids and coagulants in the suspension. The dynamics of zeta potential and corresponding particle size were observed as a function of coagulant concentration. Results indicated that CMP wastewater is negatively charged, with average zeta potential of -59.8 mV and 149 d.nm at pH value of 8.7. The interaction between CMP wastewater and PACl showed that positively charged PACl rapidly adsorbed colloids in the wastewater, reducing the negative surface charge of nanoscale clusters. The interaction between CMP wastewater and FeSO4·7H2O showed that larger dosage is required to aggregate nanoscale clusters, due to its low positive value to counter negative charges of CMP wastewater.

Open access
Application of UV/TiO2 Advanced Oxidation in Treating Oily Compost Leachate Generated During Oily Sludge Composting

Abstract

In this work, oily compost leachate (OCL) generated during oily sludge composting was treated by UV/TiO2. OCL subsamples, gathered bi-weekly from the composting process, were thoroughly mixed and then filtered to reduce the solution turbidity. The effects of initial chemical oxygen demand (COD) concentration, UV type (A and C), pH (3, 7, and 11), reaction time (30, 60, 90, and 120 min), and TiO2 concentration (0.5, 1, and 2 g L−1) on the total petroleum hydrocarbons (TPH) and COD removal from OLC were examined. The results showed that the efficiency of the process improved with the increase in TiO2 concentration and reaction time and the decrease in pH and pollutant concentration. In the optimal conditions (UV-C, TiO2 concentration of 1 mg L−1, reaction time of 90 min, and pH of 3), 52.29% of TPH was removed. Moreover, 36.69 and 48.3% of TPH was reduced by UV-A/TiO2 and UV-C/TiO2, respectively in real conditions of OCL (pH = 6.3, COD = 1501. 24 mg L−1, and TPH = 170.12 mg L−1) during the 90 min reaction time. The study verified that UV/TiO2 has the potential to be applied to treat OCL.

Open access
Defining the Mathematical Dependencies of NOx and CO Emission Generation after Biomass Combustion in Low-Power Boiler

Abstract

The paper deals with the study of the influence of various factors, which have an impact on emissions such as NOx, CO, which have been verified by measurements. Biomass in the form of wood chips as fuel of different moisture content from 9% to 25% has been tested at various boiler outputs. The presented work also defines the mathematical dependencies of NOx and CO emission generation by using regression analysis from measured data after biomass combustion in low-power boilers. The paper also describes a mathematical model of biomass combustion. The mathematical model was created to verify the measured data and prediction of emission generation in the process of biomass combustion. This model consists of combustion of stoichiometry, calculation of combustion temperatures, obtained regression equations of NOx and CO. At the end of this paper, the obtained results are compared with the calculated models as well as the results of the defined dependencies from the regression analysis.

Open access
The Effectiveness of Gas Recovery Systems for Managing Odour from Conventional Effluent Treatment Ponds in Palm Oil Mills in Malaysia

Abstract

Gas recovery systems at palm oil mills enable the curtailment of uncontrolled greenhouse gas emissions from open anaerobic pond, but can also reduce odour, an aspect which has not yet been substantiated. The objective of this study is to evaluate the odour emission from palm oil mill effluent and the effectiveness of covers and tank digester in reducing odour emission from the open lagoons. Odour samples were obtained from the cooling ponds in conjunction with in-field odour assessment performed on site. Results demonstrated that odour released from open ponding or covered lagoon were almost comparable, ranging from 33,150 – 162,000 OU/m3, and 68,705 – 102,000 OU/m3, respectively. In contrast, odour emission from cooling pond which used tank digester system seemed markedly lower, ranging between 13,000 – 76,000 OU/m3. In fact, the analysis of ambient air close to anaerobic tank digesters proved a reduction of odour emission to the surroundings (with 3.5 OU/m3, weak intensity) compared to open pond (with 2700 OU/m3, strong intensity) or covered lagoon (with 111 OU/m3, distinct intensity). In conclusion, gas recovery systems at palm oil mills should be promoted not only towards the management of greenhouse gaseous, but also as an odour impact management strategy.

Open access
Flexural Behaviour of a Cold-Formed Steel-Concrete Composite Beam with Channel Type Shear Connector – An Experimental and Analytical Study

Abstract

Steel-concrete composite structures are widely used in the current construction of bridges and multi-storey buildings. The effect of shear connectors in a cold-formed steel-composite beam was studied under flexure. The number of channel connectors in the specimen was varied and the same was compared with a specimen without shear connectors. The performance and failure of cold-formed steel-composite beams were then studied. The presence of shear connectors in the tension zone prevents the formation of cracks which are the major cause of failure in a beam subjected to bending. The load-carrying capacity is greater in a composite beam and an increase in the number of channel connectors from one to five increases the load-carrying capacity by 60 % as compared to a specimen without a connector. A composite beam with five connectors is more ductile, with a ductility factor of 14. The Composite beams were also analysed using the finite element software ANSYS and were found to have good agreement with the experimental results.

Open access
Hedonic Pricing Model for Real Property Valuation via GIS - A Review

Abstract

Hedonic pricing models in real property valuation have been frequently applied in many research studies and projects since it was introduced by Rosen in 1974. The development of Geographic Information Systems (GIS) in the recent decades has gradually supports the usage of hedonic model in the spatial data pricing model studies. Beside the basic advantages of GIS to position properties in terms of their geographic coordinates, it has the capabilities of dealing with reasonable amount of data, and wide choices of analysis that make it powerful tool to facilitate the building and implementation of the hedonic models within its framework. Many studies have employed GIS in real property valuation in their present work and for the future prediction. This paper reviews the works of literature on the GIS applications in the real property valuation employing the hedonic pricing models.

Open access
Impact of Water Quality on Concrete Mix and Hardened Concrete Parameters

Abstract

The subject of the present article is the evaluation of the use of different water types in the production of concrete mix and C20/25 class concrete (assuming the same composition). Taking as an example a selected Subcarpathia-based concrete production plant, equipped with a process water management system, the research analysed the quantity-quality parameters of drinking water, sewage water, and groundwater and evaluated them for their accordance with mixing-water quality standards. It should be emphasised that the majority of specifications recommend the use of drinking water for concrete production. The paper presents the results of research which analysed the impact of water quality on selected properties of concrete mix and concrete (consistency; compressive strength after 7, 14, and 28 days; density). The results obtained confirmed the findings of the research on the suitability of recycled water for concrete production.

Open access
Investigation on Electrically Conductive Aggregates as Grounding Compound Produced by Marconite

Abstract

Marconite is often used as alternative material to improve the performance of earth grounding system. This study aims to investigate of the physical and mechanical behaviour of conductive aggregate derived from Marconite namely, the electrical resistivity, water absorption, and crushing strength. In addition, similar tests were also conducted on mortar aggregate for comparison. The resistivity of aggregates were measured using soil box method. Test results showed that the electrical resistivity, water absorption, and crushing strength of both aggregates varied with time. These values were found to be stabilised after approximately after 14 days. The electrical resistivity for aggregates containing Marconite were found to be 39.2 Ω.m, far lower than 12700 Ω.m obtained for mortar-based aggregates. Similarly, the water absorption for Marconite aggregates were greater compared to mortar aggregates. On the other hand, the crushing strength for Marconite aggregates was to be lower. Incorporating Marconite significantly improved the electrical resistivity behaviour while maintaining acceptable mechanical properties crucial for electrical grounding purposes.

Open access
New Datings of Deposits From Odra River Valley - Stratigraphic Consequences and Interpretation at Fluvial Succession

Abstract

This paper presents organic sediments age analysis in Odra river valley in Słubice, western Poland. In this middle reach of Odra valley reach the uppermost fluvial deposits contain several alternate layers of organic sediments. These deposits have been mostly interpreted as the Holocene fluvial (floodplain) sediments, even if visible admixture of organic matter is not observed. However, there is also another hypothesis. Geotechnical studies conducted in several locations in Słubice, have questioned this interpretation. The main argument was the values of preconsolidation ratio in the range of 0.8 to 5.4, which may suggest, that the analysed sediments were covered by an ice sheet. Also, based on the presence of a clay layer devoid of organic matter impurities in the top of organic deposits, the second one presumes an interglacial (possibly Eemian) age of the discussed fluvial/organic sediments (peats and silts). To verify these hypotheses, six samples from six different boreholes drilled in the Odra river valley, in the centre of Słubice were collected. The results of 14C dating and its interpretation allowed to determine the age of the tested material. All analysed samples from Słubice (Odra river valley) were formed within the last 10,000 years - in Preboreal, Atlantic and Subboreal. Such a result contradicts the earlier stratigraphic interpretations.

Open access