INVESTIGATION INTO THE VIABILITY OF A LIQUID-FILM 3-PHASE SPOUTED BEDBIOFILTER

A variety of technologies exist for the treatment of malodorous air st reams, including adsorption, absorption, catalytic combustion, biofilt ration and bioscrubbing. Conventional packed bed biofiltration of malo dorous substances from waste gas streams has the disadvantages of larg e unit surface area and relatively uncontrolled design principles. The large bed surface area leads to difficulties in maintaining even mois ture and temperature profiles. In addition, the control of such biolog ically important parameters as pH is difficult. Novel fluidized/spoute d beds were studied for biological treatment of gases because of their high specific gas flowrate and vigorous mixing which facilitates enha nced gas-biomass contact. Trials of a range of fluidized and spouted b eds, with gas loadings of up to 14000 m(3)-gas m(-2)-bed h(-1), were c arried out on various biofilm support media including glass ballotini, rice hulls, plastic discs and granules, silica gel, molecular sieves, vermiculite, perlite, activated carbon, cork, polystyrene and expande d clay. Severe aggregation and wall adhesion restricted the operationa l range of the reactors. Particle suitability was based on a combinati on of shape, density, size, porosity and wettability, with large, heav y clay particles performing best. Limited gas-phase bacterial studies on selected media with ammonia- and nitrite-oxidizing bacteria demonst rated the potential of fluidized/spouted beds for efficient biofiltrat ion of ammonia (20-40 mg dm(-3)). (C) 1998 Society of Chemical Industr y.