ABSTRACT
To assess the environmental radioactivity levels and hence to determine the population exposure in Kutubdia Island, Bangladesh the sediment samples were analyzed by using gamma ray spectrometry. In those sediment samples the average activity concentration of natural radionuclides [238]U, [232]Th and [40]K were found 15.39+/-1.67, 38.35+/-0.76 and 475.51+/-21.15 Bq/kg respectively. The activity concentration of [238]U and [232]Th were less than the world average. But the activity concentration of 40K was higher than the world average values. These results were used to calculate the radiological hazard parameters like radium equivalent activities [Ra[eq]], representative level index [I[gammar]]. Due to natural radionuclides in sediment, the effective annual outdoor dose in the study area was 0.07 mSv; which is within the accepted range of 0.07 mSv. The average value of radium equivalent activities [Ra[eq]] and representative level index [Igr] were found to be 128.03+/-12.08 Bq/Kg and 0.96+/-0.09 Bq/Kg which were greater than the world average. The anthropogenic radionuclide [137]Cs was also found in few samples. The average activity concentration of [137]Cs was 1.64+/-0.20 Bq/kg which is lower than the world average. The obtained experimental data of this research work would be useful to assess the population exposure from radionuclides in sediment as well as base line data of natural radioactivity in this island
ABSTRACT
Arsenic contaminated sludge can be found from the treatment of arsenic contaminated ground water. Lake of management and reuse of this sludge can create further environmental problem as there is probability of mixing with soil and water. In this paper, an effort is taken for the use of such waste. Here, effectiveness of using this sludge in making ornamental brick has been analyzed and justified. The detailed study was made upon the suitability of sludge in making bricks. Results of different tests indicate that sludge proportion is the key factor for determining the quality of ornamental bricks/tiles. The compressive strength of ornamental bricks decreases with increase of sludge proportion. This study showed that arsenic contaminated sludge could be used safely up to 4% for making ornamental bricks. Because after that limit the quality of bricks or tiles fall markedly