The Application Study On Odor Control By Biofilter

The environment is the foundation for human survival, and it is inevitable to bring some negative impact on human surroundings during the process of production and living. Among these questions the influence brought by odors and volatile organic compounds (VOCS) arouse more and more regards to environmental scientific researchers. The world nations are paying abroad attention to biofiltration because it has some advantages compared with some conventional methods. It will be high-cost in investment and most complexity in operation to deal with large flux and low-concentration pollutants by conventional physical and chemical means. Biofiltration has become a research hotspot because it possesses the advantages of being an environmentally friendly and cost-effective technology.Biofiltration is a process in which the contaminants are degraded or changed into innocuous or low noxious substances by microorganisms. The fillings porous surface is covered with biofilms and the contaminants are transferred into biofilms to contact with microorganisms and be degraded into water and carbon dioxide in good conditions when the waste gases are passed through the biofilter. In the same time the new organisms are formed to maintain the microbe metabolism. This technology has been widely used abroad in dealing with VOC and odor emission, and in our country this problem has not been adequately recognized, so the study on this issue is very limited.The main task of this research is to find the influence of different work conditions (different inlet flux etc.) on removal efficiency by controlling the operating parameters that have great impact on biofilter's performance and by selecting the best conditions (abundant water and oxygen etc.), and to test the elimination capacities of different fillings by correlated contrasted experiments.The research method includes to utilize the finished compost as the biofilter's main filling and the wood chips and the perlites as assistant fillings separately; to sample the gas in different parts of biofilter such as inlet point, down and up point and outlet point and to measure the gas component in laboratory; to use the shift of ammonia and hydrogen sulphide concentration to reflect the biofilter's removal capability; to adopt two means which are to alter the inlet gas flux load and to stop the running of the biofilter for a shot time to verify its capability of anti-concussion.The result of experiment has shown as follows. Firstly the biofilter that used the compost as the main media has the high ability to eliminate the ammonia and sulfurhydrogen and its outlet removal ratio can reach above 90% so that its outlet concentration can meet the nation's emission regulation. Secondly the biofilter has the good anti-concussion ability to deal with the change of its work condition. In startup period it need one or two weeks to let the filter to come to steady status, but in steady status, if stop the operation of the biofilter or change the inlet gas flux, it only need several hours to resume its ordinary removal capability. Thirdly the choosing and arrangement of the biofilter medias have the great influence on its performance. The filling made of compost and wood chips with the ratio in mass of 4:1 has high removal efficiency ,but its disadvantage is that it has high pressure drop in media and need more energy to make the gas pass through the filter; the filling made of compost and perlite with the ratio in mass of 5:1 has low pressure drop and high residence time that reduce the energy consumption. Lastly to maintain appropriate moisture content and adequate retention time are two preconditions for microorganism to degrade contaminants. The article also brings forward the direction and suggestion for further experiment and research.