Formaldehyde removal from synthetic contaminated air using a biotrickling filter reactor

Abstract

Formaldehyde (FA) removal from contaminated air with biotrickling filter reactor (BTFR) has been extensively studied thus far, but the effects of different volumetric airflow rates, pH, temperature and nutrient concentration on FA removal efficiency needs to be verified to design better BTFRs with optimal operating conditions. The use of specific microorganisms to remove FA from the air still needs to be verified. This study used the laboratory scale BTFR with a volume of 3.319 L, operated at the different volumetric airflow rates to having an insight on the effect of gas retention time on FA removal efficiency. To determine the optimal retention time of contaminated airflow through the BTFR system, mathematical models were developed. The predominant microorganisms were identified as to investigate the microbiological diversity. Then the BTFR was optimized for temperature and pH as well as nitrogen and phosphorus concentration to achieve its maximum efficiency. The BTFR formaldehyde removal efficiencies of 99, 96 and 95% were verified for the volumetric airflow rates of 90, 291, 1512 L/h, respectively, and the optimal retention times of 141, 50 and 26 s were verified for the BTFR experiments operating at 90, 291 and 1512 L/h volumetric airflow rate, respectively. The optimization of the BTFR conditions for removing FA from a synthetic contaminated air stream assessed by Taghuchi method showed that the best efficiency of the BTFR could be at a neutral pH of 7, a temperature range of 40 - 45?, an ammonium concentration of 0.5 mg/L and a phosphate concentration of 1 mg/L. The predominant bacteria attached on the surface of the supporting materials were identified as five bacterial colonies i.e., Salmonella bongori, Salmonella choleraesuis subsp. arizonae, Salmonella typhimurium, Serratia entomophila and Serratia ficaria. The logarithmic and linear models were proposed as an ideal approach for determining the optimal retention time, in order to make a significant contribution for future biotechnological developments and air quality improvement analysis.