Simultaneous Removal of H2S, NH3, and Ethyl Mercaptan in Biotrickling Filters Packed with Poplar Wood and Polyurethane Foam: Impact of pH During Startup and Crossed Effects Evaluation
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The present work discusses the startup and operation of different biotrickling filters during the simultaneous removal of NH3, H2S, and ethyl mercaptan (EM) for odor control, focusing on (a) the impact of pH control in the stability of the nitrification processes during reactor startup and (b) the crossed effects among selected pollutants and their by-products. Two biotrickling filters were packed with poplar wood chips (R1 and R2A), while a third reactor was packed with polyurethane foam (R2B). R2A and R2B presented a pH control system, whereas R1 did not. Loads of 2–10 g N–NH3 m−3 h−1, 5–16 g S–H2S m−3 h−1, and 1–6 g EM m−3 h−1 were supplied to the bioreactors. The presence of a pH control loop in R2A and R2B proved to be crucial to avoid long startup periods and bioreactors malfunctioning due to biological activity inhibition. In addition, the impact of the presence of different concentrations of a series of N species (NH 4 + , NO 2 − , and NO 3 − ) and S species (SO 4 2− and S2−) on the performance of the two biotrickling filters was studied by increasing their load to the reactors. Sulfide oxidation proved to be the most resilient process, since it was not affected in any of the experiments, while nitrification and EM removal were severely affected. In particular, the latter was affected by SO 4 2− and NO 2 − , while nitrification was significantly affected by NH 4 + . The biotrickling filter packed with polyurethane foam was more sensitive to crossed effects than the biotrickling filter packed with poplar wood chips.
KeywordsBiotrickling filter Organic/inorganic packing material pH control Crossed effects Pollutant mixture
The Spanish government (MEC) provided financial support through the project CICYT CTM2009-14338-C03-01. This study was partially funded by the company Ros Roca S.A. (Barcelona, Spain). The Department of Chemical Engineering at UAB (Universitat Autònoma de Barcelona) is a unit of Biochemical Engineering of the Xarxa de Referència en Biotecnologia de Catalunya (XRB), Generalitat de Catalunya.
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