(174d) Treatment of a Dynamic Mixture of n-Hexane and Benzene in a Trickle-Bed Air Biofilter Integrated with Cyclic Adsorption/Desorption Beds

One of the main challenges facing biological treatment of contaminated gas streams is the inconsistency of contaminants' concentrations in the gas feed. The microorganisms responsible of the biodegradation process are very delicate to influent concentration changes. This adds an extra constraint for the other difficulties encountered in the biodegradation process.

Previous research in our laboratories focused on enhancing the degradation of hydrophobic contaminants. A mixture of two compounds, namely, n-hexane (hydrophobic compound) and benzene (sparingly soluble compound), are fed into two parallel trickling bed air biofilters (TBABs). TBAB ?A? was preceded by an integrated system of a cyclic 2-bed adsorption/desorption unit. The primary goal of the study was to maintain long-term, stable consistent high performance of volatile organic compounds (VOCs) degradation in the TBAB.

Both TBABs were fed with a square wave change in the influent concentration. The average concentration of VOCs in the feed applied to both TBABs was within the allowable limits as studied in an earlier study. TBAB ?A? was receiving a constant feed of the average value of the square wave as its influent, while TBAB ?B? (the control) was directly subjected to the high and low peaks.

Experimental results have shown that TBAB ?A? was operating at a constant acceptable behavior, while TBAB ?B? did not show satisfactory performance even at the time of low peak. The results further revealed that the 2-bed adsorption unit can serve as: 1) polishing unit during initial acclimation of the biofilter, 2) buffering unit under fluctuating volatile organic compounds (VOCs) loading, and 3) feeding unit during non-emission periods encountered during shut down in industries.