Settling and dewatering characteristics of granulated methane-oxidizing bacteria

We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria (GMOB) after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristics due to changes in sludge retention time (SRT, 10, 15 and 20 days) during cultivation of GMOB was conducted. In assessing dewaterability, the specific resistance to filtration (SRF) of activated sludge and GMOB was found to be 8.21×1013-2.38×1014 and 4.88 × 1012-1.98×1013 m/kg, respectively. It was confirmed that as SRT decreased, SRF of GMOB increased. In the case of bound extracellular polymeric substance (EPS), activated sludge registered 147.5 mg/g-VSS while GMOB exhibited 171-177.2 mg/g-VSS. In the case of extracellular polymeric substance soluble EPS in effluent, activated sludge measured 62 mg/L and GMOB had 17.4-21.4 mg/L. The particle size analysis showed that mean particle diameters of GMOB were 402, 369, and 350 μm, respectively, at SRTs of 20, 15 and 10 days. In addition, it was found that GMOB had a larger mean particle diameter and exhibited much better settleability and dewaterability than activated sludge did.     

Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition

We report on very small fossil eggs from the Lower Cretaceous of Thailand, one of them containing a theropod embryo, which display a remarkable mosaic of characters. While the surficial ornamentation is typical of non-avian saurischian dinosaurs, the three-layered prismatic structure of the eggshell is currently known only in extant and fossil eggs associated with birds. These eggs, about the size of a goldfinch's, mirror at the reproductive level the retention of small body size that was paramount in the transition from non-avian theropods to birds. The egg-layer may have been a small feathered theropod similar to those recently found in China.     

Prenatal diagnosis of chinese homozygous α-thalassaemia 1 and haemoglobin H disease by analysis of α- and φζ-globin genes in chorionic villi and amniocytes

Eighty-eight high-risk pregnancies, 81 for homozygous α-thalassaemia 1 and 7 for haemoglobin (Hb) H disease, were collected in this study. Chorionic villus sampling (CVS) was done in 63 cases and amniocentesis in 25 cases to obtain fetal cells. Southern blotting and DNA hybridization with α- and φζ-globin gene probes were used to determine the α-globin gene status. In two non-informative families with non-deletional mutations, DNA analysis failed to rule out the affected condition, and fetal blood sampling (FBS) and Hb electrophoresis were used for the final diagnosis. In the 81 fetuses at risk for homozygous α-thalassaemia 1, 17 (13 by CVS and 4 by amniocentesis) were afffected, 30 were α-thalassaemia 1 heterozygotes, 19 were normal, and the remaining 15 were either normal or heterozygous. In the seven fetuses at risk for Hb H disease, one was normal, three were α-thalassaemia 1 heterozygotes, two were α-thalassaemia 2 heterozygotes, and one was affected with Hb H disease and developed hydrops fetalis. DNA analysis on fetal cells enabled us to diagnose prenatally severe α-thalassaemias, to prevent the birth of infants with Hb H disease, and to minimize maternal obstetrical complications from harbouring a fetus with Hb Bart's hydrops fetalis.     

The changes in common carp blood after short-term zinc exposure

Blood zinc level, hematological parameters and blood cell morphology were evaluated in common carp immediately after 3 h exposure to 20 mg dm(-3) of zinc (Zn0), and in 24, 48 and 96 hours after the end of it (Zn24, Zn48, Zn96). Blood zinc level in the non-exposed fish was 8 mg dm(-3), reached a maximum of 20 mg dm(-3) in Zn48, while it dropped to 9 mg dm(-3) in Zn96. Zinc caused a stress reaction in fish indicated by an increase in hematocrit value in Zn0, and elevated plasma glucose level and trombocytosis which persisted until the end of the experiment. Zinc-exposed fish showed an increased frequency of abnormal erythrocytes, and a compensatory release of immature erythrocytes to the blood stream. In zinc-treated fish, leukocyte count initially increased and subsequently decreased significantly below the control level due to a drop in lymphocyte number. Lymphocyte viability was reduced, and abnormal lymphocytes appeared. A decreased count of juvenile neutrophiles, and reduced phagocyte activity also occurred. The results indicate possible zinc-induced disturbances in both specific and non-specific immune mechanisms.     

Emission characteristics of PCDD/Fs, PCBs, chlorobenzenes, chlorophenols, and PAHs from polyvinylchloride combustion at various temperatures

The effect of temperature on polyvinylchloride (PVC) combustion using a downstream tubular furnace was investigated for the formation of polycylcic aromatic hydrocarbons (PAHs) and chlorinated compounds. As the temperature increased, higher levels of PAHs were generated. Chlorinated compounds reached a peak at 600 degrees C, with low emissions recorded at 300 and 900 degrees C. There was a close correlation (R2 = 0.97) among polychlorinated biphenyls (PCBs), hexachlorobenzene, pentachlorobenzene, and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). PAHs at all temperatures were analyzed in the gas phase. PCDD/Fs and PCBs were emitted as a solid phase at 300 and 600 degrees C and as a gas phase at 900 degrees C. For some PAHs, chlorobenzenes, and PCDD/Fs, a mathematical equation between the gas and solid phase and the reciprocal temperature in semilog proportion was derived. The proposed equation, which is log (amount in gas phase/amount in solid phase) = -A/T + B, where T is the temperature of the furnace and A and B are constants, for these species relating their gas/solid distributions showed a good relationship.     

Investigation and risk assessment modeling of As and other heavy metals contamination around five abandoned metal mines in Korea

Tailings, agricultural soils, vegetables and groundwater samples were collected from abandoned metal mines (Duckum, Dongil, Dongjung, Myoungbong and Songchun mines) in Korea. Total concentrations of arsenic (As) and heavy metals (Cd, Cu, Pb and Zn) were analyzed to investigate the contamination level. Several digestion methods (Toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), 0.1 N/1 N HCl) and sequential extraction analysis for mine tailings were conducted to examine the potential leachability of As and heavy metals from the tailings. The order of urgent remediation for the studied mines based on the risk assessment and remedial goals was suggested. The Songchun mine tailings were most severely contaminated by As and heavy metals. Total concentrations of As and Pb in the tailings were 38,600–58,700 mg/kg (av. 47,400 mg/kg) and 11,800–16,800 mg/kg (av. 14,600 mg/kg), respectively. Agricultural soils having high As concentrations were found at the all mines. Average concentrations of Cd in the vegetables exceeded the normal value at all mines areas, while As only at the Dongjung, Myoungbong, and Songchun mine area. One groundwater sample each from the Dongil and Myoungbong mines, and 4 groundwater samples from the Songchun mine had values above 10 μg/L of As concentration. The TCLP method revealed that only Pb in the Songchun tailings, 6.49 mg/L, exceeded the regulatory level (5 mg/L). Employing the 1-N HCl digestion method, the concentration of As in the Songchun mine tailings, 4,250 mg/kg, was up to 3,000 times higher than its Korean countermeasure standard. Results from the sequential extraction of As in the tailings showed that the easily releasable fraction in the Myoungbong and Songchun mine tailings was more than 30% and the residual fraction was less than 40%. Based on results showing the exposure health risk employing the hazard quotient and cancer risk of As, Cd and Zn, the Dongil mine needs the most urgent remedial action. The concentration reduction factor (CRF) of As in both soil and groundwater follows the order: Songchun>Dongjung>Dongil>Myoungbong>Duckum mine.     

A study on operation problems of hydropower plants integrated with irrigation schemes operated in Turkey

In this study, Hydroelectric Power Plants, which have been built and integrated with irrigation schemes by the State Hydraulic Works which is a government agency and private companies in Turkey, have been examined. Technical, environmental, structural and social problems encountered during their operation have been analyzed, and appropriate solution proposals have been presented in the study for a sustainable irrigation and Hydroelectric Power Plant operation. Consequently, Hydroelectric Power Plants which have been integrated with irrigation schemes should be operated efficiently and they should be operated in attenuation with the environment. However, when hydroelectric projects are developed without preparing their necessary integrated basin management plans, then this will cause environmental, operation and maintenance, administrative, monitoring and evaluation problems. In order to ensure sustainability of hydroelectricity production and also in order to use water resources more efficiently for irrigation; it is very important to find permanent solutions to these problems.     

Enrichment of PCDDs/PCDFs in peripheral utilities of the municipal solid waste incineration facility

This study was performed to suggest the improvements through measuring the amounts of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), re-synthesized in peripheral utilities (PUs) of a commercial-scale municipal solid waste incineration facility (MSWIF) where a few research results existed. The PUs examined in this study consisted of air pre-heaters (APHs) and gas/gas re-heater (GGRH) and kerosene-fired duct burner for selective catalytic reduction (SCR) process. PCDDs/PCDFs in flue gas were simultaneously measured at the inlet and outlet of PUs.Flue gas was cooled down from 380 °C to 249 °C by exchanging the heat with fresh air in APHs, and then heated up to 383 °C by GGRH and duct burner from 164 °C at the outlet of bag filter. The results showed that PCDDs/PCDFs were 3–4 times higher within this temperature range of PUs. In comparison of PCDDs/PCDFs concentrations at the inlet with those at the outlet of PUs, particulate-phase PCDDs/PCDFs were about 9.5–10 times enriched while gaseous-phase ones were decreased by about 33–41%. The PCDDs/PCDFs re-synthesized in the PUs, where PCDDs were relatively higher than PCDFs, showed somewhat different patterns compared to those formed at incinerators and emitted at stack. Through the investigations for PUs, we conclude that the PUs used in MSWIFs was a potential source for de novo synthesis of PCDDs/PCDFs.