Results and Discussions
Under variable H2S loading ranging from 0.45 to 24.38 gH2S/m3-h and retention time 60 seconds the removal efficiency of hydrogen sulfide decreased as the load increased only at the bottom stage (media height 0.4 meters) of the column. At higher media height the biofilter could provide complete removal of H2S as shown in Fig. 2 while Fig. 3 shows that the maximum elimination capacity could be further extended.
100
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200
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5
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50
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25
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Fig. 2. Relationship between removal efficiency and loading rate of biofilter.
Fig 3. Relationship between elimination capacity and loading rate of biofilter.
During the experiment water was add to each stage of the filter bed in order to maintain the water content of the filter media in the range of 60-80% which helped to maintain outlet air humidity in the range of 75-95% and thus provided good filter performance [7].
Furthermore, maximum pressure drop of 27.5 mm H2O/m of bed was recorded at the top of the biofilter. This result is inline with Devinny et al.’s suggestion that optimum pressure drop should not exceed 100 mm H2O/m of media [7]. The higher pressure drop resulted from product accumulation and granulated sludge-packing [11].