Biofiltration using peat and a nutritional synthetic packing material: influence of the packing configuration on H2S removal

This study aims to evaluate the feasibility of using a nutritional synthetic material (UP20) combined with fibrous peat as a packing material in treating H2S (up to 280ppmv). Three identical laboratory-scale biofilters with different packing material configurations (peat only; peat+UP20 in a mixture; peat+UP20 in two layers) were used to determine the biofilter performances. The superficial velocity of the polluted gas on each biofilter was 65m/h (gas flow rate 0.5Nm(3)/h) corresponding to an empty bed residence time=57 s. Variations in elimination capacity, removal efficiency, temperature and pH were tracked during 111 d. A removal efficiency of 100% was obtained for loading rates up to 6g/m(3)/h for the biofilter filled with 100% peat, and up to 10g/m(3)/h for both biofilters using peat complemented with UP20. For higher loading rates (up to 25.5g/m(3)/h), the configuration of peat-UP20 in a mixture provided the best removal efficiencies (around 80% compared to 65% for the configuration of peat-UP20 in two layers and 60% for peat only). Microbial characterization highlighted that peat is able to provide sulfide-oxidizing bacteria. Through kinetic analysis (Ottengraf and Michaelis-Menten models were applied), it appeared that the configuration peat-UP20 in two layers (80/20 v/v) did not show significant improvement compared with peat alone. Although the configuration of peat-UP20 in a mixture (80/20 v/v) offered a real advantage in improving H2S treatment, it was shown that this benefit was related to the bed configuration rather than the nutritional properties of UP20.