Abstract
In this research work, a synthetic water super absorbent polymer was included in the bed of a perlite-based biofilter for the removal of ethanol from air. The performance of this biofilter was compared with the performance of a control perlite-based biofilter lacking the water super absorbent. With the empty bed residence time of 2 min, both biofilters were able to remove more than 90% of the entering pollutant with the concentration of 1 g /m3, when regular moistening was applied. After last irrigation on day 23, the performance of the control biofilter was unchanged until day 35. From day 36 onwards, the control biofilter lost its activity gradually and became totally inactive on day 45. The performance of the super absorbent containing biofilter, however, was unchanged until day 58 before starting to lose its activity. A mechanistic model was developed to describe the performance of a biofilter under drying effects. The model could predict the trends of experimental results reasonably well. The model was also applied to predict the trends of experimental data from a published paper on the removal of hexane in a perlite/super absorbent containing biofilter.
Acknowledgement
This work was supported by Graduate University of Advanced Technology, Kerman, Iran, grant number [1.813].
Nomenclature
A | = | biofilter cross section (m2) |
a | = | specific surface area of bed particles (1/m) |
Cg | = | pollutant concentration in the gas phase (g/m3) |
Cg0 | = | pollutant concentration in the gas phase at t = 0 (g/m3) |
Cgin | = | pollutant concentration in the gas phase at z = 0 (g/m3) |
G | = | air flow rate (m3/h) |
Hg | = | air humidity (g water/g dry air) |
Hg0 | = | air humidity at t = 0 (g water/g dry air) |
Hgin | = | air humidity at z = 0 (g water/g dry air) |
Hl | = | bed moisture content (g water/g dry bed) |
Hlcrit | = | bed moisture content below which the microbial activity is affected by drying (g water/g dry bed) |
Hlmin | = | bed moisture content below which the microbial activity is zero (g water/g dry bed) |
Hs | = | saturated air humidity (g water/g dry air) |
kG | = | water mass transfer coefficient between the wet solid phase and air in biofilters (m/day) |
ks | = | half saturation constant (g/m3) |
m | = | gas liquid partition coefficient (dimensionless) |
t | = | time (day) |
vm | = | maximum bioreaction rate (g/(m3day)) |
z | = | position along the height of biofilter (m) |
= | void fraction of the bed | |
= | volume fraction of moist bed particles | |
= | volume fraction of moist bed particles before drying | |
= | bulk density of dry bed particles (kg/m3) | |
= | density of air (kg/m3) | |
= | density of liquid water (kg/m3) |