英语翻译Fig.1 presents the removal efficiency and recovery time

英语翻译Fig.1 presents the removal efficiency and recovery time as a function of the preceding contaminant starvation period.The results show that when BTF was subjected to contaminant starvation for periods of 4,8,12,and 16 h,after reestablishment of the contaminant in the inlet gasstream,removal efficiency dropped from 100 to 97%,96,94,and 92%,respectively.However,after a period of 1.5 2 h,in all cases the removal efficiency climbed back to 100%.This means that the BTF used in the present study can reasonably withstand short starvation periods - such aswould occur during equipment failure,and shift work.In order to shed further light on the effect of short term starvation on the activity of the immobilized bacterial biomass in the BTF,the corresponding SOUR values of samples of immobilized biomass at the end of the starvation period was measured.The results (Fig.2) showed that there is a significant reduction in the SOUR value of immobilized biomass after 4 h of contaminant starvation,whereas further increase in the period of contaminant starvation of up to 16 h had a much smaller or no effect.The initial reduction in the aerobic activity of the immobilized biomass is related to the shift from activemetabolism to maintenance state [3].The results suggestthat T.thioparuscells are able to maintain themselveswithout a supply of H2S as an energy source for up to 16h and fairly quickly shift back to active metabolism whenH2S is resupplied to them.One reason for this phenomenoncan be the use of elemental sulfur produced in the biofiltration process [6,13].The observation of yellow deposits inside the BTF confirmed the production of sulfur during the experiments,although no data is available to confirm the usage of this sulfur during the starvation period.In the study by Cox and Deshusses [3],when BTF was subjected to contaminant starvation the removal performance of toluene also dropped but the decrease was lower than that observed in the present study.This is probably partly related to the use of heterotrophic microorganisms in thatstudy,since these types of microorganisms can utilize the products of lyses and death of other microbes as an energy source enabling them to tolerate starvation periods more easily.Another factor is the higher immobilized biofilm thickness observed in BTFs treating VOCs compared tothose treating volatile inorganic compounds such as H2S (23 µm in H2S elimination compared to at least 60 80 µm in VOC elimination) [16,25,26].This means that in the former,under certain conditions,a short-term starvation regime might actually be beneficial,as it would lead to the death of part of the microbial population and reduce