Removal Of Nitrogen From Huolin Brown Coal By Microorganism

Nitrogeneous compounds in coal would be released in the form of NO_x during coal combustion. NO_x contributes to the formation of acid rain and photochemical smog, at the same time it is harmful to human health. Nitrogen in coal is in the form of nitrogen-containing aromatic compounds, such as pyridine, pyrrole etc. and its content is relatively low. At present, the research about removal of nitrogen from coal mainly focuses on the methods of thermochemistry. However, the traditional processing methods are both not effective and also produce new problems, such as environmental problems, the destruction of the earth's surface, and the treatment of solid rubbish and so on. Therefore, it is necessary to explore a new processing method of denitrification. The denitrification method by microorganism is based on the capability of degradating organic nitride.The treatment process of microorganism can usually operate at the normal temperature and pressure. Recent reports related to the removal of organic nitrogen from coal by microorganism were environment friendly and promising. It is important to screen out microorganisms of high effective denitrification.But due to the complexity of coal configuration and the low content of nitrogen in coal, it is very diffcult to screen out microorganism which can remove nitrogen from raw coal and distinguish the genuine denitrification factor from many influence parameters on account of reciprocity among these factors. So, based on the form of nitrogen in coal, pyridine which is difficult to be degraded is choosed as the model compound. Pyridine was selected as a unique nitrogen source for screening out the ideal microorganisms. According to pyridine degradation efficiency, the microorganisms which could degrade pyridine were screened and trained under anoxic circumference in this article. Then, the optimum conditions which the microorganism degrade pyridine under were considered. Finally, degradation mechanism of pyridine and study on removal of nitrogen from fractions of brown coal soluble in alkali (AS-C) were discussed primarily.Four strains were screened out from the activated sludge of a coke plant. Pyridine degradation efficiency of the strain JH-2 was the highest among four strains. According to the characterizations of Colony ,shape and biochemistry for JH-2 ,it was identified as staphylococcus. By means of single factor test, the optimum culture conditions were found. Results showed that the strain JH-2 was easy to cultivate, and the optimized degradation conditions were 35℃～40℃, the medium pH 7, glucose carbon source., relatively inoculum 8%. The highest degradation efficiency of pyridine is over 40% after 48h. The research on degradation mechanism of pyridine by the strain JH-2 showed that degradation mechanism of pyridine as nitrogen source under anoxic circumference is different from under aerobic or anaerobic circumference and also discriminated from pyridine as carbon source. The results showed that pyridine as carbon source couldn't be degraded. Nitrogen in pyridine is changed into NH₄⁺ by cellular or extracellular enzyme catalysis and then is used up during metabolism.Primary study on removal of nitrogen from AS-C by the strain JH-2 showed that microorganisms which can degrade pyridine can also select nitrogen in AS-C as growing and metabolizing nitrogen source. Denitriflcation efficiency of AS-C is over 6% after 6d treatment action. The research showed that growth and metabolism of the strain JH-2 was better in culture medium containing 4g·L^-1 AS-C. Denitriflcation efficiency is affected by the complexity of coal configuration and the multiformity of organic nitride in coal.