| At the background of "Energy-saving technologies" policy implemented by nation, it has become the primary task in China's management of air pollution to reduce the total amount of sulfur dioxide in the atmosphere. Due to the high cost of desulphurization and the way out of by-product and so on, the traditional desulphurization process was restricted to its application in China. Along with the constant development of biotechnology, exploring advanced, cost-effective biological desulphurization has become a hot research of flue gas desulphurization technology. Compared with traditional desulphurization technology, bio-trickling filter FGD technology has the advantage of simple equipment, easy operation, low-cost of investment, maintenance and operation, low energy consumption, less secondary pollution and higher desulphurization efficiency, and so on.The desulphurization bacteria was isolated from the soil which stacking pyrite powder of Xi'an Longhua Industrial Co. Ltd (former Xi'an sulfuric acid plant), which was inoculated in the bio-trickling filter, and clay filler particles as the carrier drops, then bio-trickling filter flue gas desulphurization system formed. In the experiment the purification performances of bio-trickling filter were researched, and the effect of external parameters such as inlet volume load, inlet SO2 concentration, gas residence time, the spray density of recycling liquid, and temperature of recycling water in temperature control of bio-trickling filter on purification efficiency was analyzed. At the same time, the continuous run-time of bio-trickling filter, the recovery time of microbial activity and the system pressure drop were measured and an analysis was made.Experimental result shows that: The volume removal load of bio-trickling filter increases with the inlet volume load. Along with the increased inlet volume load, the volume removal load departures from 100% removal line gradually. The purification efficiency of bio-trickling filter decreases with increased inlet concentration. Gas residence time has greater effect on purification efficiency. In the circumstances of same SO2 concentration, when gas residence time extends, and purification efficient increases, and gas residence time decreases, the trend that purification efficiency decreases with inlet concentration increases gradually. At the time of low spray density of recycling liquid, with increased amount of recycling liquid purification inefficiency increases at the same time, and growth trend is significant. When spray density increases to 1.91 m3·m-2·h-1, purification efficiency reaches its highest point. With continuous increased spray liquid density, purification efficiency shows a downward trend, but the downward trend is very slow. Temperature has an effect on purification capacity of bio-trickling filter system. The optimal temperature of recycling water is about 32℃, and purification efficiency both becomes lower below or above this temperature. When temperature of recycling water is between 22℃and 37℃(actual temperature is between 20℃and 32℃in tower), the purification efficiency of bio-trickling filter for SO2 remains at a relatively high level. The purification efficiency decreases with running time. Microbial activity can recover through aeration and spraying recycling liquid, and purification efficiency increases. When inlet SO2 concentration is lower than 3000 mg/m3, higher removal efficiency of the system can be obtained within 15 minutes. |
