4.3. The effect of temperature on WAS acidification under thermophilic conditons
As seen in Figure. 6, with other conditions remaining unchanged (pH 9.0, adding ratio of 25%, HRT
4d), the VFAs accumulation increased first, then decreased with the rising of temperature from 50ć to
70ć. And we can find that the soluble substrate released greatest during thermophilic anaerobic digestion
as operated at 60ć, providing more feeds to the acid-forming bacteria to improve VFAs accumulation
obviously.
The conclusion indicated that 60ć was the best choice for VFAs accumulation. Low (50ć) or
excessive (70ć) temperature would influence the final quality of the VFAs products. On one hand, lower
or higher temperatures were bound to the relesae of slouble substrate. On the other hand, activity of acidforming
bacteria was markedly inhibited under low or excessive temperatures.