Water Content Dynamics in Biofiltration: The Role of Humidity and Microbial Heat Generation

Abstract

Mass and energy balances were performed on a compost biofilter to identify the mechanisms for water content change in the compost bed material. Three mechanisms were identified: humidity fluctuations at the inlet and outlet, heat generation from microbial oxidation, and gradients in the water potential. Microbial oxidation and humidity fluctuations were the dominant mechanisms for water content changes. Time domain reflectometry was used to estimate on-line volumetric water content in the bed material. Biofiltration experiments demonstrated a moving front of temperature increase and water evaporation associated with the microbial oxidation of toluene. The localized microbial heat generation evaporated sufficient water from consecutive sections of the bed, eventually impairing degradation throughout the entire column.

Modelling shock loadings and starvation in the biofiltration of toluene and xylene

“…Assuming that in the air about 0.032% of the volume is occupied by carbon dioxide, a reading of 100% corresponded to 4 vol% of carbon dioxide in the air. To maintain the level of moisture at about 60% (checked by the dry weight method7) and to ensure that the biomass growth was not limited by nutrients, 100 cm 3 of medium B was added once a week. The composition of the solution is also given in Table 1.…”

Treatment of xylene polluted air using press mud-based biofilter

“…Water content of the media is one of the most important factors that affect the performance of the biofilter [22][23][24][25]. According to Sun et al [26,27], the optimal initial water content of the packing media treating xylene ranged from 50 to 70% and from 40 to 60%, respectively.…”

Traitement de l'air par biofiltration

“…Le gaz, en traversant le lit, a tendance à se saturer jusqu'à 100% en humidité relative à la température du lit. De plus, la chaleur dégagée par les réactions de biodégradation occasionne un gradient de température dans le biofiltre, ce qui influence le contenu d'humidité du lit (Gostomski et al 1997). Le taux de variation de l'humidité du lit causé par ce phénomène augmente à mesure que la concentration des polluants à l'entrée et la capacité d'élimination augmentent.…”