Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Exhaust gas processing and utilization

Study on the Removal of Nitric Oxide Using Trickling Biofilter by Denitrification

Author LiuZhiFei
Tutor GaoHuiWang
School Ocean University of China
Course Environmental Science
Keywords Biological trickling filter method Nitrogen oxides Kinetic model Filler Denitrification
CLC X701
Type PhD thesis
Year 2008
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NO x is one of the major air pollutants, not only harmful to human health, but also cause acid rain, photochemical smog, and one of the main causes of climate change. The the traditional NO x Governance is complex, difficult, expensive, and countries around the world are struggling to find and study NO x control and governance of the new method. This thesis is based on the denitrification principle using biological trickling filter to remove NO gas, to study biological trickling filter denitrification under anaerobic conditions to remove the effect of NO in the exhaust gas. This thesis, using sodium nitrite as the sole nitrogen source, activated sludge sewage treatment plant domestication denitrifying flora inoculated into hanging film on activated carbon and ceramic fillers. Experimental study on the impact of carbon sources on the removal efficiency; different filler, gas flow rate, the amount of spray liquid inlet concentration, oxygen content and packing height and other factors on the removal of the effect of; removal process momentum The school conducted the analysis, and verified with the experimental data; system outage idle recovery performance test, to examine the system's resistance to impact load; electron micrograph taken late in the test, activated carbon and ceramic filler biofilm the biological phase were observed and analyzed. The experimental results are as follows: (1) carbon source of biological trickling filter to remove obvious impact effect for two fillers methanol denitrification rates were significantly higher than ethanol and glucose, methanol is the most suitable to be used as denitrification process carbon source. (2) The NO gas concentration less than 1200 mg / m the 3 conditions, the amount of recirculating spray liquid to 0.05-0.15 L / min of the test range, whether based on activated carbon for filler biological trickling filter to the ceramsite for filler biological trickling filter, the amount of spray liquid purifying effect of the filter bed is not significantly affected. (3), in the NO gas concentration is less than 1200 mg / m 3 under the conditions, the influence of the gas flow rate and the inlet NO concentration of NO removal was significantly. For the activated carbon as a filler biological trickling filter, when the gas flow rate of 0.3 m 3 / h, imports NO concentration is less than 1200 mg / m 3 , NO removal basic 90%; When the gas flow rate increases to 0.9 m 3 / h imports NO concentration of 1000 mg / m 3 , NO removal rate is reduced to about 85%. Ceramsite filler biological trickling filter, when the gas flow rate of 0.3 m 3 / h, imports NO concentration is less than 1200mg / m 3 , NO removal substantially more than 87%; gas flow rate increases to 0.9 m 3 / h, imports of NO gas concentration of 1000 mg / m 3 , NO removal was reduced to about 80%. (4) packing layer height affect the removal efficiency, either activated carbon the filler or ceramisite filler lowermost filler highest removal efficiency, the removal efficiency of the remaining layers decrease in order, with the increase in height of the filler layer, the total The removal efficiency increases. Lowermost layer of filler on the exhaust of the experimental device degradation of up to 50% or more. (5) After the system is running 11 months, activated carbon packing pressure drop than the ceramsite the large, two trickling filter total pressure drop are small, the largest not more than 300 Pa. (6) for the two kinds of fillers, when the intake gas oxygen content lt; 4%, the purification efficiency of the trickling filter change is small, 4%, the purification efficiency of the trickling filter is decreased rapidly when the oxygen content gt; . (7) in the outage period, the system stops to pass into the NO gas the normal circulating fluid spray (L = 0.05L/min). During recovery, the test conditions is set to Q = the 0.3 m 3 / h L = 0.05 L / min, inlet concentration of NO was maintained at 800 mg / m 3 < / sup> or so, the test results show that: within outage 16h, the removal effect of the system is not affected; outage less than 48 h, and the removal efficiency of the system to restore to more than 90% before the outage; outage less than 360 h , the removal efficiency of the system recoverable to the outage before about 70%. (8) by two filler biofilm electron micrograph shows that the biological activated carbon biofilm than the the ceramsite rich, and the number of more Ceramisite. Activated carbon biofilm bacteria bacilli, filamentous bacteria and nematodes, ceramsite biofilm bacteria bacillus and filamentous bacteria strains are silk, two fillers biofilm main like bacteria. (9) by the induction of experimental results, a kinetic model based biodegradable relatively good agreement with experimental data. For activated carbon filler NO process of the exhaust gas purification, ξ. α / Q inlet concentration C gi relationship (ξ · α) / Q = 44561exp (C gi / 2000), The applicable range Zhou C g < / sub> ≤ 1200 mg / m 3 . For the NO exhaust purification ceramisite filler, ξ. α / Q inlet concentration C gi relationship (ξ · α) / Q = 44721exp (C gi / 2000), the scope of application Cg ≤ 1200 mg / m < sup> 3 . This test shows that the use of the biotrickling filter denitrifying mixed cultures remove exhaust gases NO, is technically feasible, the technology specified in the further application of industrial research directions.

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