AERATION EFFECTS ON BEGGIATOA IN A LABORATORY FIXED-FILM GROWTH

The enrichment of Beggiatoa was derived in a lab-scale continuous flow fixed-film growth system. Under a low aeration and high BOD organic l oading condition, the enrichment of Beggiatoa was easily achieved on t he glucose-fed slime while it took fairly long time on the acetate-fed one. An increased aeration resulted in a decrease in the Beggiatoa po pulation for the acetate-fed slime, but not for the glucose-fed slime, except slightly at very high aeration level. Sulfate removal rate in both Beggiatoa dominated slimes was generally low, between 10-30%. The glucose-fed slime showed a much higher sulfate removal at high organi c loading. The aeration effects on Beggiatoa and sulfate removal were understandable in the context of the Beggiatoa-Desulfovibrio interacti on, diffusion and uptake rate of substrate. Glucose diffusion and upta ke rate may more rapid, thus air could not penetrate as efficiently in to the sulfide-emitting anaerobic layer inhabited by sulfate reducing bacteria such as Desulfovibrio. This may have resulted in less inhibit ory effects on the sulfate reducing bacteria.