Estimation of Biogas Generation from a Uasb Reactor via Multiple Regression Model

In this study, regression analysis based an estimation model for biogas generated from an up-flow anaerobic sludge blanket (UASB) reactor treating landfill leachate is developed using several leachate parameters, such as pH, conductivity, total dissolved solids, chemical oxygen demand, alkalinity, chloride, total Kjeldahl nitrogen, ammonia, total phosphorus. These landfill leachate parameters are monitorized over a period of 1000 days at 35 ± 1°C in the UASB reactor. In order to develop the best model giving highest estimation performance, eight model equations including different input parameter combinations are analyzed. Based on the results of regression analysis, the best coefficients of the model equation are determined. As a conclusion, the developed model in this study can give accurate biogas amount prediction for the USAB reactor-based leachate treatment system.     

Airborne and soilborne microfungi in the vicinity Hamitabat Thermic Power Plant in Kirklareli City (Turkey), their seasonal distributions and relations with climatological factors

Soil and air samples of seven different localities around Hamitabat Thermic Power Plant, 10 km far away from Luleburgaz/Kirklareli (Turkey), were taken between the years 2003 and 2004 with seasonal intervals. The samples were brought to the laboratory and their microfungal identifications were done. From the air samples, 737 microfungi colonies were isolated comprising 26 species belonging to eight genera. From soil samples, 170.6 × 10⁴ colony-forming unit (CFU)/g was isolated from 33 species belonging to 16 genera. The most isolated genus from air samples was Alternaria (324 CFU, 43.96%), followed by Cladosporium (208 CFU, 25.52%) and Phoma (44 CFU, 5.40%). Penicillium was the most isolated genus from the soil samples with a value of 560,000 CFU/g (32.8%), followed by Fusarium (226,000 CFU/g, 13.12%) and Aspergillus (154,000 CFU/g, 9.03%). Among these species, Alternaria citri and Alternaria alternata are the most abundant species in air with 164 and 107 CFU, respectively, whereas Fusarium graminearum and Penicillium citrinum are the most abundant species in soil with CFU per gram values of 17.8 × 10⁴ and 1.3 × 10⁵. Correlation analysis was applied to determine whether or not there was a relationship between colony number of isolated fungal genera and meteorological factors. Some parameters of soil samples’ incontent during the research period were calculated using a computer analysis program. From the air samples, a positive correlation was found between relative humidity and Alternaria colonial counts and Cladosporium spore counts (r?=?0.912 and r?=?1.000, respectively). Similarly, with the analysis of soil samples, a positive correlation between colonial counts of Alternaria and soil pH and a positive correlation between colonial counts of Aspergillus and Penicillium and salt percentage concentration of soil were found.     

Concentration of heavy metals in the food web of Lake Egirdir, Turkey

The concentration of heavy metals (Cr, Cd, Hg and Pb,) was determined by atomic absorption spectrophotometry in sediment, water, plankton and fish samples from Lake Egirdir in South-Western Turkey. Lake Egirdir is an important bird nesting and visiting areas, and it is also used as irrigation and drinking water source. The heavy metal concentrations were in the order Cd > Pb > Cr > Hg in water, Cr > Pb > Cd > Hg in sediment, Pb > Cd > Cr > Hg in plankton, Cd > Cr > Pb > Hg in the muscle and Cd > Pb > Cr > Hg in the gills of Ctenophatyngodon idella. The significant differences of concentrations occurred in water, sediment, plankton and fish tissues (Chi square test, p < 0.05). The concentrations of the heavy metals in water and fish tissues of three years old, were above the maximum permissible level for human consumption.     

Biological nutrient removal from pre-treated landfill leachate in a sequencing batch reactor

Biological treatment of landfill leachate usually results in low nutrient removals because of high chemical oxygen demand (COD), high ammonium-N content and the presence of toxic compounds such as heavy metals. Landfill leachate with high COD content was pre-treated by coagulation-flocculation with lime followed by air stripping of ammonia at pH=12. Nutrient removal from pre-treated leachate was carried out using a lab-scale sequencing batch reactor (SBR). Three different operations consisting of different numbers of steps were tested and their performances were compared. These operations were the three-step anaerobic (An)/anoxic (Ax)/oxic (Ox); the four-step (An/Ox/Ax/Ox), and the five-step (An/Ax/Ox/Ax/Ox) operations with total residence time of seven hours each. Experiments were carried out using three consecutive operations with a total cycle time of 21 h at a constant sludge age of 10 days. The lowest effluent nutrient levels were realized by using the five-step operation which resulted in effluent COD, NH4-N and PO4-P contents of 1,400, 107 and 65 mg l(-1), respectively, at the end of 21 h. Addition of domestic wastewater (1/1, v/v) and powdered activated carbon (PAC, 1 g l(-1)) to the pre-treated leachate improved nutrient removals in the five-step SBR operation, resulting in 75% COD, 44% NH4-N and 44% PO4-P removals after 21 hours of operation.     

Applications of Venturi Principle to Water Aeration Systems

The concentration of dissolved oxygen is an important indicator of water quality because aquatic life lives on the dissolved oxygen in the water. Aeration can increase dissolved oxygen when levels become deficient. Hydraulic structures can significantly improve dissolved oxygen levels by creating turbulent conditions where small air bubbles are carried into the bulk of the flow. Recent researches have focused on developing measurement and predictive techniques for oxygen transfer at hydraulic structures to maintain and enhance water quality. However, reviewing existing studies on aeration performance of hydraulic structures, it seems that there are not too many studies on venturi aeration. The present paper shows applications of venturi principle to water aeration systems. The aeration characteristics of venturi nozzle, venturi conduit and venturi weir are analyzed. The results indicate that venturi aeration might contribute significantly to air entrainment and aeration efficiency. Therefore, venturi device can be used as highly effective aerator in aeration processes.     

Effect of specimen size and grain size on deformation in microextrusion

Miniaturization of systems and devices continues unabated, which in turn requires the production of microscale components. Similar to the macroscale process, microextrusion provides a means to fabricate metallic micropins having characteristic dimensions on the order of 1 mm or less with a lower-cost, high-throughput process. In this paper, the effect of the specimen size and grain size on deformation during microextrusion is investigated. Microhardness, microstructure, and X-ray texture analyses show that when the grain size becomes comparable to the specimen feature size, together with miniaturization, penetration of the shear deformation occurs. As a result, the coarse-grained structure has higher hardness than the fine-grained structure, especially in the central regions of the cross-section for the two smallest size extrusion cases investigated, which have Ø0.76/0.57 mm and Ø1.5/1.0 mm dimensions before and after extrusion, respectively. For the largest size extrusion case investigated, Ø2.0/1.33 mm pins, the coarse-grained structure has a lower hardness than the fine-grained one, which is typical for macroscale processes and consistent with the Hall–Petch relationship.     

Geoenvironmental behavior of foundry sand amended mixtures for highway subbases

The high cost of landfilling and the potential uses of waste foundry sands have prompted research into their beneficial reuse. Roadways have a high potential for large volume usage of the foundry sands. A laboratory testing program was conducted on soil-foundry sand mixtures amended with cement and lime to assess their applicability as highway subbase materials. The mixtures were compacted in the laboratory at a variety of moisture contents and compactive efforts and subjected to unconfined compression, California bearing ratio, and hydraulic conductivity tests. The environmental suitability of the prepared mixtures was evaluated by analyzing the effluent collected during hydraulic conductivity tests. Finally, required subbase thicknesses were calculated using the laboratory-based strength parameters. The results of the study show that the strength of a mixture is highly dependent on the curing period, compactive energy, lime or cement presence, and water content at compaction. The resistance of foundry sand-based specimens to winter conditions is generally better than that of a typical subbase reference material. Laboratory leaching tests indicated that if these mixtures later come in contact with water that has been discharged directly to the environment (e.g., drainage through asphalt pavement), the quality of water will not be affected.     

Resident perceptions of livelihood impacts arising from the Kızıldağ National Park,Turkey

In this study, perceptions, needs, expectations and participation levels in the park management of residents of the K?z?lda? National Park were investigated. It was focused on especially how residents’ livelihood was affected by establishment and management of K?z?lda? National Park. It was examined why residents do not support protection efforts. Research data were obtained with the help of a survey form prepared to determine the perceptions of residents living in the national park. For the analyses of obtained data, statistics package program (SPSS 20) was used and also independent-samples t test and one-way analyses of variance were applied. As a result, the most important negative effects were loss of income and changes in traditional lifestyle. The most affected group from these negative effects was the ones dealing with animal husbandry. For the sustainable management and protection of national park, sense of belonging should be brought to residents so as to increase participation, traditional lifestyle of residents should be conserved and new sources of income should be generated for residents. To improve the participation of residents in national park management, community engagement mechanisms can be used as a tool.     

Analysis of Atmospheric Conditions during Air Pollution Episodes in Ankara,Turkey

ABSTRACT

This paper presents a detailed analysis of the meteorological conditions that are associated with strong air pollution episodes in Ankara, Turkey. Based on climatological and air quality data [SO₂ and TSP (total suspended par-ticulates)] obtained for the winter months during 19891994, the analysis showed that the presence of weak atmospheric pressure gradients and warm air advection were the most important factors leading to high SO₂ and TSP concentrations. In addition, the onset of the high air pollution episodes was generally associated with a trend toward negative vorticity at the 850-hPa level.