Application of gaseous ozone for inactivation of Bacillus subtilis spores

The effectiveness of gaseous ozone (O3) as a disinfectant was tested on Bacillus subtilis spores, which share the same physiological characteristics as Bacillus anthracis spores that cause the anthrax disease. Spores dried on surfaces of different carrier material were exposed to O3 gas in the range of 500-5000 ppm and at relative humidity (RH) of 70-95%. Gaseous O3 was found to be very effective against the B. subtilis spores, and at O3 concentrations as low as 3 mg/L (1500 ppm), approximately 3-log inactivation was obtained within 4 hr of exposure. The inactivation curves consisted of a short lag phase followed by an exponential decrease in the number of surviving spores. Prehydration of the bacterial spores has eliminated the initial lag phase. The inactivation rate increased with increasing O3 concentration but not >3 mg/L. The inactivation rate also increased with increase in RH. Different survival curves were obtained for various surfaces used to carry spores. Inactivation rates of spores on glass, a vinyl floor tile, and office paper were nearly the same. Whereas cut pile carpet and hardwood flooring surfaces resulted in much lower inactivation rates, another type of carpet (loop pile) showed significant enhancement in the inactivation of the spores.     

Phosphate uptake and release rates with different carbon sources in biological nutrient removal using a SBR

A three-step sequencing batch reactor (SBR) was used for nutrient removal from synthetic wastewater with different glucose-organic acid mixtures (1/1). Acetic, butyric, propionic and citric acids were used as organic acids along with glucose. The operation consisted of anaerobic, anoxic and oxic (An/Ax/Ox) phases with durations of 2/1/4.5h. Sludge age was kept constant for 10 days. Phosphate release and uptake rates were determined for different glucose-organic acid mixtures in the feed wastewater. Maximum phosphate uptake (8.1mgPl(-1)h(-1)) and release rates (2.23mgPl(-1)h(-1)) were obtained with the glucose-citric acid mixture. The highest (96%) percent phosphate removal at the end of the nutrient removal cycle (7.5h) was also obtained with the glucose-citric acid mixture while the glucose-acetic acid mixture resulted in comparable percent phosphate removal (95%).     

Assessment of heavy metal concentrations in the food web of lake Beyşehir, Turkey

The accumulation of heavy metals (Cd, Pb, Hg and Cr) was measured by atomic absorption spectrophotometry in water, sediment, plankton and fish samples collected from Lake Bey?ehir, which is important bird nesting and visiting areas, and irrigation and drinking water sources. In Lake Bey?ehir, the accumulation orders of heavy metals were Cd>Pb>Cr>Hg in water, Pb>Cd>Cr>Hg in sediment, Pb>Cd>Cr>Hg in plankton, and Cd>Pb>Cr>Hg in the muscles and gills of chub, carp, tench, except for the muscle of pikeperch, in which it was Pb>Cd>Cr>Hg (P<0.05). In addition to this, accumulation orders of heavy metals in the food web was also found to be water>plankton>sediment>fish tissues, except for Cr. According to international criterias and Turkish regulations, heavy metal concentrations especially Cd and Pb in Lake Bey?ehir were markedly above the permissible levels for drinking water.     

Heavy metals in mullet, Liza abu, and catfish, Silurus triostegus, from the Atatürk Dam Lake (Euphrates), Turkey

The distribution of some heavy metals in three different organs of mullet, Liza abu, and catfish, Silurus triostegus, from Atatürk Dam Lake located on Euphrates (Turkey) was studied. Co and Mo concentrations were below limits of detection in all fish organs, whereas Ni was also below limits in organs of mullet. The metal accumulation in the liver and gill of L. abu and S. triostegus was found to be quite high in comparison with the muscle. In general, the concentrations are similar to those previously observed on other fish studied in Atatürk Dam Lake and lower than those determined in Tigris River. The analysed metals (Co, Cu, Fe, Mn, Mo, Ni and Zn) were found in fish muscle at mean concentrations under the permissible limits proposed by FAO.     

Impacts of land use conversion on soil properties and soil erodibility

Land use conversion can affect natural ecological processes such as surface runoff and erosion. Therefore, it has potential to change soil stability To investigate this process in depth, Iskalan creek catchment in the Black sea region, where excessive land use applications and erosion events have often occured, was selected as the study area. The objective was to determine the effects of land use conversion on soil properties, soil erodibility and the relationships among soil properties and some erodibility indices. Duplicate topsoil samples were taken by using steel cylinders at 100 different sampling points from three different land use types; 34 of them are in farmlands, 34 in rangelands and 32 in forestlands. Soil particle size distribution, loss of ignition, pH, electrical conductivity skeleton percentage and three erodibility indices were determined. Data were analysed by using Pearson correlation analysis (at 95% and 99% significance level), ANOVA and Tukey's test at 95 % significance level. According to study results, land use conversion affects some properties of soils significantly Loss of ignition of soils in forests was significantly higher than soils in farmlands and rangelands. Soil skeleton percentage in rangelands and farmlands were significantly different. The study results showed that there was significant difference between pH of soils in forests and farmlands (p < 0.05). Pearson correlation analysis results showed significant correlations among erodibility indices and certain soil properties such as clay and sand fraction of soils (p < 0.05 and p < 0.01). Topsoils of the study area were sensitive to erosion according to all three erodibility indices. The most sensitive soils were in farmlands.     

Airborne fungi and bacteria in indoor and outdoor environment of the Pediatric Unit of Edirne Government Hospital

This study was performed between January 2004 and December 2004 in 13 stations in the Pediatric Unit of Edirne Government Hospital in order to determine the outdoor and indoor airborne microfungal and bacterial contents. The results of air samplings revealed that 1,376 microfungal and 2,429 bacterial colonies in total were isolated. The isolated microfungal specimens were identified and 65 species from 16 genera were determined. Among these, the most frequent genus was Cladosporium with 462 colonies (33.58%) followed by Alternaria with 310 (22.53%) and Penicillium with 280 (20.35%) colonies. The isolated bacterial samples were grouped based on their Gram-staining properties. The most frequent ones were Gram (+) cocci with 1,527 colonies (62.87%) followed by Gram (+) bacilli with 828 colonies (34.09%) and Gram (−) bacilli with 74 colonies (3.05%). Staphylococcus, Bacillus, Corynebacterium, and Microccus appeared to be the common genera isolated for all months. Statistical analyses were performed in order to see if there existed a relationship between meteorological conditions and the microfungal and bacterial species and their concentrations.     

Utilization of sepiolite materials as a bottom liner material in solid waste landfills

Landfill bottom liners are generally constructed with natural clay soils due to their high strength and low hydraulic conductivity characteristics. However, in recent years it is increasingly difficult to find locally available clay soils that satisfy the required engineering properties. Fine grained soils such as sepiolite and zeolite may be used as alternative materials in the constructions of landfill bottom liners. A study was conducted to investigate the feasibility of using natural clay rich in kaolinite, sepiolite, zeolite, and their mixtures as a bottom liner material. Unconfined compression tests, swell tests, hydraulic conductivity tests, batch and column adsorption tests were performed on each type of soil and sepiolite–zeolite mixtures. The results of the current study indicate that sepiolite is the dominant material that affects both the geomechanical and geoenvironmental properties of these alternative liners. An increase in sepiolite content in the sepiolite–zeolite mixtures increased the strength, swelling potential and metal adsorption capacities of the soil mixtures. Moreover, hydraulic conductivity of the mixtures decreased significantly with the addition of sepiolite. The utilization of sepiolite–zeolite materials as a bottom liner material allowed for thinner liners with some reduction in construction costs compared to use of a kaolinite-rich clay.     

Development of adaptive neuro-fuzzy inference system model for predict trihalomethane formation potential in distribution network simulation test

Environmental Science and Pollution Research - Trihalomethanes (THMs), which is one of the major classes of DBP known to be highly cytotoxic and genotoxic, were formed and modeled under controlled...