Studies on the Degradation of Calcium from Water using Microorganism

P. Bosco Dhanaseeli and V. Balasubramanian

Centre For Ocean Research, AMET UNIVERSITY, Kanathur, Chennai, India.

DOI : http://dx.doi.org/10.13005/bbra/1400

ABSTRACT: Cooling water system plays a vital role in thermal power plants. Cooling water system removes the heat via evaporative coolers. Its primary aim is to remove the heat absorbed in the circulating water system. Water is pumped from the tower base into cooling water routed through the process cooler and condenser. The cool water absorbs the heat from hot process system. The absorbed heat warms the circulating water, which returns to the top of cooling tower and tickles downward towards the materials inside the tower. The evaporated water leaves the dissolved salts in the water which has not been evaporated thus salt concentration is increased in water. The concentration of dissolved salts in the cooling water exceeds their solubility limits and precipitates on the water surface and forms the scale. The most common scale formers, calcium salts cause scale formation in the most sensitive areas of heat transfer. In extreme cases, enough material precipitates physically blocked the cooling water passages, resulting in the affected equipment being removed from the operation for either chemical or mechanical cleaning.. The microbes, which are ubiquitous in nature, particularly the bacteria utilises some of the substrates as sole source for their multiplication; sometime it may utilize a special component and can degrade the other substances.. Thus the production of enzyme urease by some bacteria plays a vital role in reducing calcium by utilizing the anural substrate urea. The primary role of bacteria in the precipitation process has been ascribed to their ability to create an alkaline environment through various physiological activities. Immobilization of the microbes (biocatalysts) in specific matrices will further improve the efficiency of the process.

KEYWORDS: Cooling tower; scales; calcium; immobilization; Bacillus cereus; Pseudomonas fluorescence; Staphylococcus aureus

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