Combustion behaviour of some biodesulphurized coals assessed by TGA/DTA

Thermal analysis, i.e. TGA/DTA is used to study the changes in the combustion behaviour of microbially treated coals. In view of their high sulphur content and industrial significance three samples are under consideration, i.e. one lignite and two subbituminous from different region in Bulgaria. The differences in burning profiles can be related to structural changes resulted from biological treatments. The overall biological treatment generates these changes probably due to the oxidation process. Concerning organic sulphur biodesulphurization there is no change in any drastic mannerof the thermal characteristic parameters. In general, applied biotreatments provoke a complex influence on combustion coal behaviour. From one side a better ignition performance, a minor decrease in higher heating value and diminishing peak temperature of maximum weight loss rate for all biotreated samples are observed. From other side some decrease in the combustibility indicated by an increase in the combustion time and the end of combustion temperature are obvious. Also well determined decrease of self-heating temperature after biotreatments evolves high risk of spontaneous unmanageable coal combustion

Treatment of acid drainage in a uranium deposit by means of a natural wetland

Abstract Acid drainage waters generated in the uranium deposit G-1, Western Bulgaria, were treated by means of a natural wetland located in the deposit. The waters had a pH in the range of about 2.4 3.9 and contained uranium and radium radionuclides, heavy metals (copper, zinc, cadmium, iron, manganese), arsenic and sulphates in concentrations usually much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The wetland was characterized by abundant and emergent vegetation and a diverse microflora. Typha latifolia, Typha angustifolia and Phragmites australis were the main plant species in the wetland but representatives of the genera Scirpus, Juncus, Eleocharis, Potamogeton, Carex and Poa as well as different algae were also present. The water flow through the wetland varied in the range at about 0.2 1.2 l/s reflecting water residence times in the wetland of about 10 50 hours. An efficient water cleanup took place in the wetland, even during the cold winter months at ambient temperatures close to 0°C. The removal of pollutants was due to different processes but the microbial dissimilatory sulphate reduction and the sorption of pollutants on organic matter (living and dead plant and microbial biomass) and clays present in the wetland played the main role

S_Bakalova.indd

ABSTRACT Metal working fl uids (MWF

Chapter Long-Distance LIDAR Mapping Schematic for Fast Monitoring of Bioaerosol Pollution over Large City Areas

Light detection and ranging (LIDAR) atmospheric sensing is a major tool for remote monitoring of aerosol pollution and its propagation in the atmosphere. Combining LIDAR sensing with ground-based aerosol monitoring can form the basis of integrated air-quality characterization. When present, biological atmospheric contamination is transported by aerosol particles of different size known as bioaerosol, whose monitoring is now among the basic areas of atmospheric research, especially in densely-populated large urban regions, where many bioaerosol-emitting sources exist. Thus, promptly identifying the bioaerosol sources, including their geographical coordinates, intensities, space-time distributions, etc., becomes a major task of a city monitoring system. This chapter argues in favor of integrating a LIDAR mapping schematic with in situ sampling and characterization of the bioaerosol in the urban area. The measurements, data processing, and decision-making aimed at preventing further atmospheric contamination should be performed in a near-real-time mode, which imposes certain demands on the typical LIDAR schematics, including long-range sensing as a critical parameter, especially over large areas (10 – 100 km2). In this chapter, we describe experiments using a LIDAR schematic allowing near-real-time long-distance measurements of urban bioaerosol combined with its ground-based sampling and physicochemical and biological studies

CT angiographic study of the role of both willis circle and vertebral arteries during selective cerebral perfusion - a study in 105 patients

Unilateral selective cerebral perfusion (SCP) is a method for cerebral protection in aortic arch surgery. However, variations of the circle of Willis (CoW) could vitiate its protective effect. The aim of our present work was to prospectively analyze variations of CoW and vertebral arteries using CT angiography. From January, 2008 to July, 2008, a total of 105 consecutive patients underwent CT-angiography of the CoW in the Division of Radiology, St. Ekaterina University Hospital of Sofia. There were at least six CoW configurations that could lead to significant hypo perfusion during unilateral SCP: i) type IA - hypoplasia or absence of left posterior communicating artery (PComA) (in 41.9% of the patients); ii) type IB - hypoplasia or absence of anterior communicating artery (AComA) (in 1.9%); iii) type IIA - hypoplasia or absence of both left PComA and AComA (in 6.67%); iv) type IIB - hypoplasia or absence of left P1 or right vertebral artery (VA) (in 6.67%); v) type III - hypoplasia or absence of right A1 (in 8.57%), and vi) type IV - hypoplasia or absence of both right A1 and right VA or both right A1 and left PComA (in 0.95%). All these types were present in a 66.67% of all the examined patients. Our present study showed that CoW variations are presented in significant number of patients. These results support the need of extensive preoperative examination and meticulous intraoperative monitoring of cerebral perfusion during unilateral SCP.Scripta Scientifica Medica 2012; 44(2): 73-77