Effects of temperature and its profile on purification performance of biotrickling bed for waste gas treatment

The effect of temperature on the purification performance of trickling biofilter for treating toluene waste gas was investigated experimentally.The results showed that temperature in trickling biofilter bed had a significant influence on purification efficiency.As the inlet temperature of circulation water increased from 10℃ to 60℃, the purification efficiency of trickling bed had a maximum value corresponding to a temperature within 30—40℃.For verifying the effect of temperature on purification efficiency, the experiments for the activity of toluene dioxygenase were conducted at various temperatures of culture fluid.The results of enzyme activity experiment showed that ambient temperature had a great effect on the microorganism enzyme activity for toluene degradation.There existed a maximum enzyme activity at the culture fluid temperature of 30℃, which was coincident with the purification experiment.The temperature profile in the packed bed of trickling biofilter was also measured in the experiments.Under co-current operation mode,the temperature of trickling biofilter bed increased gradually in gas and liquid flow directions which indicated that the metabolic biodegradation of the organic pollutants was an exothermic process.The temperature rise between the outlet and the inlet of trickling biofilter increased as the circulation liquid flow rate decreased and that of waste gas increased.A higher inlet toluene concentration led to a higher temperature rise.Meanwhile, it was also found that the operation mode had a significant effect on temperature profile in the trickling biofilter.