Innovative packing material for waste gas biofiltration

Abstract Biofiltration is an established widespread air treatment technique for removing undesirable components. Packing material plays a major role in the performance, stability and long-term operation of a biotrickling filter. The aim of the work was to propound an innovative composite packing material with the representation of organic and inorganic components with good utility properties. It consisted of an equal volume fraction each of wood chips, bark, mulch, wood charcoal, crushed corn cob, wood shavings, perlite, vermiculite and zeolite, with the particle size described. The individual components and composite material were characterised in terms of selected physical and chemical properties, leaching characteristics, desiccation resistance and pH changes. Furthermore, the vitality of microorganisms after inoculation with sludge water was monitored through the total number of organisms and dehydrogenase activity. Resulting MIX 9 composite material presented water holding capacity of 120 %, bulk density of 439 kg m−3 at 100 % WHC, loss on ignition of 54.2 % and the contents of carbon, nitrogen, sulphur and phosphorus were 278 g kg −1, 1.94 g kg −1, 0.607 g kg −1, 0.743 g kg −1, respectively, with a low leachability. Total plate count and dehydrogenase activity were 4.7 107 CFU g−1 and 27 μ g g−1 h−1, respectively. pH value was 5.85. Loss of water of 50 % WHC required 3 h of desiccation under 50 °C. Decrease of pH under acidification was almost linear to the pH 3.85 and the dose required to reach this value was 0.13 mol kg −1 H + . The composite material was characterised in terms of compaction and pressure loss. MIX 9 showed resistance to bed compaction. The original fresh material had a void space of 55 % and a load of approximately 800 kg m−2 was required for reduction by 10 %. The increase in pressure drop occurred with the square of the gas flow. The dependence on time was calculated for different gas flows and a period of 1.3 years of operation for single and two-phase flow. The obtained results are very promising for a very wide practical application.