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Abstract

The biochemical oxidation of two wastewater feeds, one containing at least ten times more ammonia nitrogen, and the other at least ten times more chlorinated hydrocarbons, than present in a conventional municipal wastewater stream were treated in an aerated packed bed bioreactor inoculated with microorganisms ('cells') especially cultured and acclimated to the task. Arbitrarily shaped pieces of numerous microporous synthetic resinous materials (familiarly referred to as 'porous plastics') are discovered to provide not only an excellent packing for the bioreactor, but also a peculiar catalytic function not normally associated with a bio-support. Microporous polytetrafluoroethylene (PTFE foam) appears to be too inert to generate a high level of microbial activity for either feed which was tested, while microporous polyethylene appears to be exactly what the cells ordered. Such activity cannot reasonably be correlated to the overall size of the micropores alone, because a calcined dolomite having substantially the same range of average pore sizes, exhibits a removal rate, measured as mg/min/m.sup.2 of surface, which is generally about ten times lower than the rate obtained with the plastic biosupport, all other process conditions being the same. The comparison was made by simultaneously feeding several columnar glass reactors, each having a packed bed of different porous plastic packing, and one with commercially available microporous Celite.RTM.. As one might expect, the removal rate per unit volume (liter) of packing appeared not to correlate with the removal rate per unit of surface area, since the distribution of cells over the surface, and the rate at which the substrate is fed to the cells are the determining factors for removal rate. Shape of the micropores in the packing appear to influence activity.

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