A new type of poly(vinyl alcohol)/nitrocellulose/granular activated carbon/KNO3 composite bead used as a biofilter material

A new type of poly(vinyl alcohol)/nitrocellulose/granular activated carbon/KNO3 composite bead was prepared and shown to be suitable for use as a filter material in the biofiltration process. This composite bead was a porous spherical particle with a diameter of 2.4–6.0 mm and a density of 1.125 g/cm3. The amount of water-soluble nitrogen dissolved out of this composite bead was 145.5 mg N/g dry composite bead. The biochemical kinetic behaviors of n-butyl acetate in a spherical poly(vinyl alcohol) (PVA)/nitrocellulose (NC)/granular activated carbon (GAC)/KNO3 composite bead biofilter (NC biofilter) and a spherical PVA/peat/GAC/KNO3 composite bead biofilter (peat biofilter) were investigated. The values of the half-saturation constant Ks for the NC biofilter and the peat biofilter were 33.55 and 35.54 ppm, respectively. The values of the maximum reaction rate Vm for the NC biofilter and the peat biofilter were 23.83 and 22.46 ppm/s, respectively. Diffusion-limited zero-order kinetics were regarded as the most adequate biochemical reaction model for the two biofilters. The microbial growth rates and biochemical reaction rates for the two biofilters were inhibited at higher inlet concentrations. The biochemical kinetic behaviors of the two biofilters were similar. The maximum elimination capacities of the NC biofilter and the peat biofilter were 170.72 and 174.51 g C/h m3 bed volume, respectively. The PVA/nitrocellulose/GAC/KNO3 composite bead made it easier for the microbes to adjust to their new environment and secrete exocellular enzymes to break down the substrate.