EVALUATION OF CONTAMINATED AIR VELOCITY ON THE FORMALDEHYDE REMOVAL EFFICIENCY BY USING A BIOTRICKLING FILTER REACTOR

Introduction: Formaldehyde is a toxic, carcinogen, mutagen and teratogen compound that is widely released into the atmosphere worldwide. The toxicity effect of formaldehyde on microorganisms is a serious obstacle on the path of using biological treatment methods. The main objective of this study is to evaluate the effect of air velocity on the efficiency of a Biotrickling Filter Reactor (BTFR) for removal of formaldehyde from an air stream. Materials and methods: A BTFR and Bioscience Laboratory Respirometer were employed for continuous and batch experiments, respectively. Three gas flow rates including 90, 291 and 1512 L/h were used to find out the effect of velocity on the formaldehyde removal efficiency of the BTFR. Monod model was modified to be capable of predicting the BTFR cases having very high formaldehyde removal efficiency. Results: The results showed that for the gas flow rates of 90, 291 and 1512 L/h in BTFR, formaldehyde removal efficiency of 95, 97 and 99% were achieved, respectively. These results showed that higher air flow velocity lead to higher removal of formaldehyde from air in a BTFR. A very slow formaldehyde removal was observed during batch experiment where the gas velocity is set equal zero. Conclusions: This study demonstrated that the mass transfer in gas phase is an important step in formaldehyde treatment in a BTFR. Very slow formaldehyde removal in the batch system which can be ascribed to the very low mass transfer rate in gas phase confirms the fact that this rate is a controlling step in overall removal rate in BTFR.