Removal of cyclohexane vapors from air in biotrickling filters: Effects of gas mixture composition and circular economy approach

Abstract

This work presents results of investigations on biotrickling filtration of air polluted with cyclohexane co-treated in binary, ternary and quaternary volatile organic compounds (VOCs) mixtures, including vapors of hexane, toluene and ethanol. The removal of cyclohexane from a gas mixture depends on the physic-ochemical properties of the co-treated VOCs and the lower the hydrophobicity of the VOC, the higher the removal efficiency of cyclohexane. In this work, the performance of biotrickling filters treating VOCs mixtures is discussed based on surface tension of trickling liquid for the first time. A mixed natural – synthetic packing for biotrickling filters was utilized, showing promising performance and limited maintenance requirements. Maximum elimination capacity of about 95 g/(m3·h) of cyclohexane was reached for the total VOCs inlet loading of about 450 g/(m3·h). This work presents also a novel approach of combining biological air treatment with management of a spent trickling liquid in the perspective of circular economy assumptions. The waste liquid phase was applied to the plant cultivation, showing a potential for e.g. enhanced production of energetic biomass or polluted soil phytoremediation.