Preparation and characterization of a novel packing material for the gas-phase fluidized-bed bioreactor

Abstract

Gas-phase fluidized-beds reactor (FBR) can overcome the shortages of bed clogging and performance decline in packed-bed reactors on VOCs treatment. Ideal FBR packing materials with minimum fluidized velocity and surface characteristics are required. In this study, an expanded polystyrene (EPS) with particle size 1.0–2.0 mm was selected as the skeleton among six types of EPS and two types of expanded polypropylene (EPP). They were then physically coated with a combination of potato dextrose medium, fine wheat bran particles, and inorganic glue. Different glue concentrations and amounts of medium were tested and the optimal values of 2 % and 0.22 g∙cm−2 were achieved. The wheat-coated EPS obtained hydrophilic functional groups on the surface, and its contact angle decreased from 93° to 37° after coating. By scanning electronic microscopy, more microorganisms were observed on the surface of the coated EPS than that of the uncoated EPS. A lab-scale fluidized bioreactor was built to treat gaseous ethanol. The minimum fluidized velocity of coated packing materials was 0.2 m∙s−1 under a relative humidity of 50 ± 10 %, reaching an average elimination capacity of 681 g m-3 h−1 during the 28-days operation, while the bioreactor packed with uncoated EPS reached only 18 g m−3 h−1.