Reduction of SO2 Emissions by Ammonia Gas During Staged Combustion

To reduce SO2 emissions, ammonia gas was injected into a coal-fired fluidized-bed combustor under staged commbustion condition. The combustor was 2 m high with a 30 cm static bed height and a freeboard height of 170 cm. The ammonia gas was injected at 52 cm and 65 cm above the distributor, which had a temperature of ca. 700 °C, by an uncooled stainless-steel tube injector. The experiments investigated the effects of ammonia gas injection on sulphur dioxide emissions at staged conditions, varying the: (i) excess air level, (ii) secondary air ratio, (iii) fluidizing velocity, (iv) ammonia injection position, and (v) the ammonia : sulphur dioxide molar ratio.A maximum reduction of 66% in SO2 emissions was found at 40% excess air, 65 : 35 staging, 1.5 m/s fluidizing velocity, 65 cm injection height, and an NH3 : SO2 molar ratio of 1.2. The onset of SO2 reduction occurred at an NH3 : SO2 ratio of 0.5. The fluidizing velocity, excess air, level of staging, and ammonia injection height all have a significant influence on SO2 reduction.It is difficult to determine how the SO2 reduction varies with the operating conditions when ammonia is injected in the high temperature zone of the combustor. As sulphur oxides-ammonia reactions are low temperature reactions, the findings confirm the occurrence of reactions above the freeboard or near the exit to the cyclone.     

Toxic effects of mercuric chloride on sperm and egg viability of two populations of mummichog, Fundulus heteroclitus

Exposure of mummichog (Fundulus heteroclitus) sperm from polluted Piles Creek (PC) to 0.01 ppm mercuric chloride (Hg) for 2 min caused a significant reduction in fertilization success. However, comparable exposure of sperm of mummichog from a relatively clean area in Long Island (LI) did not effect the fertilization success. Exposure of PC mummichog sperm to 0.05 ppm Hg for 2 min caused significant reduction in sperm motility. On the other hand, comparable exposure of LI mummichog sperm did not have any effect on motility. These data indicate that Hg is more toxic for PC mummichog sperm than LI mummichog sperm. Exposure of both PC and LI sperm either to 15 ppt sea water or to 0.05 ppm Hg for 15 min did not affect the morphology of the sperm, as seen by scanning electron microscopy. Exposure of PC and LI mummichog eggs to 0.05 ppm Hg up to 25 min had no effect on fertilization success, indicating that eggs are more tolerant to Hg than sperm.     

Enhancement of biomethane production from cattle manure with codigestion of dilute acid pretreated lignocellulosic biomass

It is well known that dilute sulfuric acid pretreatment of the lignicellulosisc biomass is an effective approach used for the production of the ethanol. However, there are less studies on the biogas production from the pretreated lignocellulosics and hardly data available on the codigestion of cattle manure with the pretreated lignocellulosisc material. The aim of this study was to evaluate biomethane production potential of codigestion of cattle manure with dilute acid pretreated lignocellulosic biomass. Sugarcane bagasse and rice husk was pretreated with dilute sulfuric acid or phosphoric acid at 121°C for 20 minutes and subsequently subjected to anaerobic digestion alone or codigested with cattle manure.

The results showed that codigestion of 1% phosphoric acid pretreated rice husk with cattle manure led to the highest methane production of 115 Nmlg^?1VS while monodigestion of cattle manure and phosphoric acid pretreated rice husk produced 98 and 87 Nmlg^?1VS, respectively. An inhibition was observed in anaerobic digestion of sulfuric acid pretreated rice husk and sugarcane bagasse during monodigestion and codigestion with cattle manure.

The study concludes that dilute phosphoric acid pretreated lignocellulosics like sugarcane bagasse and rice husk can be used as a cosubstrate with cattle manure in anaerobic digestion for enhanced methane production. Dilute sulfuric acid pretreatment, which is effective method for the bioethanol production, causes inhibition during anaerobic digestion of the pretreated lignocellulosics.     

Synthesis and thermoluminescence properties of rare earth-doped NaMgBO<Subscript>3</Subscript> phosphor

Rare earth (Dy³⁺ and Sm³⁺)-doped sodium magnesium borate (NaMgBO₃) is synthesized by solution combustion synthesis method keeping their thermoluminescence properties in mind. The reaction produced very stable crystalline NaMgBO₃:RE (RE?=?Dy³⁺, Sm³⁺) phosphors. The phosphors are exposed to ⁶⁰Co gamma-ray radiations dose of varying rate from 5 to 25 Gy, and their TL characteristics with kinetic parameters are studied. NaMgBO₃:Dy³⁺ phosphor shows two peaks for lower doping concentration of Dy³⁺ while it reduced to single peak for the higher concentrations of activator Dy³⁺. NaMgBO₃:Dy³⁺ shows the major glow peak around 200 °C while NaMgBO₃:Sm³⁺ phosphors show two well-separated glow peaks at 200 and 332 °C respectively. The thermoluminescence intensity of these phosphors was compare with the commercially available TLD-100 (Harshaw) phosphor. The TL responses for gamma-ray radiations dose were found to be linear from 5 to 25 Gy for both phosphors while the fading in each case is calculated for the tenure of 45 days.     

Pollution of water resources due to industrialization in arid zone of Rajasthan, India.

In arid zone of Rajasthan, India, nearly 21,900 hm2 area along Bandi River has been affected by industrial effluent discharge into the river bed. Analysis of groundwater samples collected from these sites revealed that area at the vicinity of the river is most affected. The effluent water in the river is the main source of contamination of ground water. Concentration of sodium and chloride has been higher with proportional increase in TDS and EC value in the area within zone A (river water), zone B (0-100 m), zone C (101-250 m), zone D (251-500 m) and zone E (501-1000 m). There is decreasing trend in ion concentration from zone A to zone E and F, reflecting reduced effect of effluents. The pollution of water resources has resulted in the degradation of other natural resources such as land, soil and vegetation. Nearly 4463 hm2 (20.38%) area has been very severely affected. EC value at places exceeds 20 dS/m. Soil and land have become hard, compact and saline. Cropping intensity has declined. In the area (3633 hm2) affected severely, the EC value of water varies from 10-20 dS/m. Irrigation with such water has created problem of salinity, sodicity in soils. Herbal biomass declined considerably. Double cropping has almost stopped. Almost 8494 hm2 area is affected moderately. EC of ground water varies from 5 to 10 dS/m. Fragile surface crust, declining trend of phosphorous and potassium in the soil, poor density of natural vegetation are significant manifestations. Apart from this, 5305 hm2 area is slightly affected.     

The impact of local elites on disaster preparedness planning: the location of flood shelters in northern bangladesh

Disaster relief and preparedness organisations are concerned with allocating scarce resources in unstable environments, such as those prone to flooding and river erosion. The need to understand the role of powerful elites in such disaster prone environments is illustrated through an analysis of the actual location decisions and biases involved in siting four flood shelters in four communities in northern Bangladesh. The previously unrecognised implications of the location biases for employment, shelter, access and the utilisation of the flood shelter by the powerless people in the target group demonstrate the need for disaster organisations to include an analysis of the local power structure in project preparation and appraisal.     

Some factors influencing EROD activity in winter flounder (Pleuronectes americanus) exposed to effluent from a pulp and paper mill

EROD (ethoxyresorufin-O-deethylase) activity was determined in winter flounder, a sediment-inhabiting and non-migratory fish species, living near a pulp and paper mill in Newfoundland in relation to temperature, gender, sexual maturity, and lesions in the liver. Samples of liver were taken from fish captured by SCUBA divers at 0 degrees C, 5 degrees C and 16 degrees C. Enzymic activity was detected in fish living only above 0 degrees C. Adult males and juvenile fish had higher levels of EROD activity than prespawning females at 5 degrees C. Macrophage aggregates only or occurring simultaneously with bile ductule hyperplasia and clear cell foci in the liver, did not impair EROD activity but necrosis had a negative effect. Results from this study indicate the importance of water temperature, gender, sexual maturity and liver pathology in assessing EROD activity of fish in biomonitoring programs.