| This study evaluated simultaneous removal of ethylene, sparingly soluble in water, and ammonia gases by biofiltration as influenced by liquid recirculation flow and media types. Perlite and glass beads were utilized as media in eight and two biofilters, respectively. Continuous liquid recirculation flow rates ranged from 2.7-5.4, 5.4-13, or 13-26 L/h. Two perlite biofilters were operated with the liquid recirculated at 13L/h intermittently for 10 min/hr. The empty bed residence time was 30 s in each reactor. Gas flow rate was 7 L/min for each bioreactor, and the full media depth was 50 cm.;The experimental results showed that ethylene removal efficiencies increased with microbial adaptation and growth as time elapsed, but the characteristics of ethylene removal over time was varied with reactor types. One of the two perlite biotrickling filters with low liquid recirculation flow increased ethylene removal to 90% due to low mass transfer limitations. However, other filters with medium, high, or intermittent liquid recirculation flow or with glass beads media reached only about 30-70% probably due to relatively high mass transfer limitation, poor distribution of nutrition supplies, and low specific surface areas of media, respectively. On the other hand, ammonia was almost completely removed by each reactor. No significant effect of ammonia loading rates or removal efficiency on ethylene removal efficiencies was observed. Mathematical simulation was utilized to predict ethylene degradation and understand the relevant biofiltration mechanisms. The logistic model was used to fit the S-shape increase of ethylene removal efficiencies over time, and the numerical model was to analyze physic-chemical and biological mechanisms related to ethylene removal in each reactor. |
