Evaluation of the performance with biofilter effectiveness treating volatile organic compounds under different pH value

Abstract

The efficiency of a biofilter filled with pine bark charge was evaluated under conditions of interchanging pH. Hydrogen ion concentration is significance for the growth of microorganisms, therefore biological metabolism is strongly dependent on pH. Many micro-organisms will only grow within a particular pH range. However, it is necessary to know, which pH values suits the best for microorganisms growing, that degrades VOC in most intensive way and increase biological air treating efficiency. As a rough rule of thumb, most biological microorganisms growth occurs near a neutral pH (pH=7) and wide deviations from this will impair the efficiency of the biofilter. Tests were performed with different pH regimes (4, 5, 6, 7, 8, 9 and 10) in pine bark charge. Depending on the maintained pH, spontaneous microorganism groups were cultivated in the biocharge. Moreover, the charge of pine bark generated a basic pH whereas a neutral pH is an optimum condition for bacterial growth. The results showed, that the obtained performance results revealed that the biofilter provided high removal efficiency E=98 % treating butanol which has a concentration С=5 mg/m³, butyl acetate (C=4 mg/m³, E=96 %), and xylene (E=81 %, C=7 mg/m³). Accordingly to the different pH value treating butanol environment conditions when pH=4, E=6.9 %; when pH=5 then E=49 %, when pH=6 then E=91.1 %, when pH=8 then E=91.1 %, when pH=9 then E=49 %, when pH=10 then E=8.6 %. Therefore, different environment condition (primary concentration, layer height of charge 0.15 – 0.75 m, air flow rate 0.02–0.1 m/s) were tested to ascertain dependence on pH value and biological air treatment efficiency.