A new type synthetic filter material for biofilter: Poly(vinyl alcohol)/peat composite bead

In this study, a new type of poly(vinyl alcohol) (PVA)/peat composite bead was prepared and was proved suitable as a filter material in the biofiltration process. The composite bead is a porous spherical particle and has a diameter of 2.4-6.0 mm and a density of 0.69 kg/cm(3). It contains 3.25 mg N/g dry solid and 2.91 mg P/g dry solid. The equilibrium moisture content of the composite bead for adsorption and holding experiments is 50.5 and 66.8% by wet basis, respectively. The initial compression strength of the composite bead is 0.32 kg/cm(2). It has higher moisture holding capacity and compression strength than pig manure compost filter material. The adsorption behavior of ethyl acetate and composite bead follows the Freundlich adsorption isotherm. The composite bead has buffer capacity and could keep the filter bed at pH=6.9-7.2 during operating. The percentage of removed ethyl acetate was 99% for up to 33 days as the composite bead adsorbed nutrients. (C) 2003 Wiley Periodicals, Inc.