Enrichment of fungi and degrad of styrene in biofilters

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Enrichment of fungi and degrad of styrene in biofilters Powered By Docstoc
					                                                                     BIOTECHNOLOGY                       LETTERS
                                                                     Volume 15 No.7 (July 1993) pp.737-742
                                                                     Received as revised 2nd June

        ENRICHMENT          O F FUNGI A N D D E G R A D A T I O N    OF S T Y R E N E    IN B I O F I L T E R S

     H u u b H.J.    Cox*,     Jos~ H.M.      Houtman,        Hans J. Doddema,              and W i m H a r d e r

TNO Institute of Environmental Sciences, PO Box 6011, 2600 JA Delft, The


   Experiments were set up in order to enrich styrene-degrading fungi in
biofilters under conditions representative for industrial off-gas treat-
ment. From the support materials tested, polyurethane and perlite proved
to be most suitable for enrichment of styrene-degrading fungi. The bio-
filter with perlite completely degraded styrene when amounts ranging
between 290 and 675 mg/m = in the influent gas were present. An elimina-
tion capacity of at least 70 g styrene per m 3 filter bed per hour was


     Styrene        is a volatile environmental pollutant,                          emitted by styrene/-

polystyrene manufacturing                  plants and the reinforced plastics                            industry.

The styrene concentration in industrial waste gases is generally low (0-I

g/m 3 (Tossavainen,            1978)) and microbial purification of these gases may

be   economically           feasible       compared      to    chemical         and physical             treatment

methods.      Various        methods       for microbial            waste    gas        treatment        have     been

developed,          i.e.    compost       filters,     bioscrubbers           and trickle-bed                filters

(Ottengraf,          1986).     Here,     a new concept             in biofi!tration              is presented,

which is based on the application of fungi for the degradation of waste

gas compounds          in biofilters          containing        inert support materials                     for the

immobilization             of the fungi.        In principle the application                        of    fungi     in

biofilters may offer two advantages:

i. Stringent         control of the water activity and/or pH in the filter bed

     is less important,              since     fungi are generally               tolerant          to    low water

     activity and low pH.

2. Reduction of the water activity in the filter bed may improve the mass

     transfer of poorly water soluble waste gas compounds                                     like styrene.

The number of reported styrene-degrading                            fungi is low; styrene degrada-