Abstract
Inhibitory action of mercury to anaerobic digestion was investigated by batch experiments.
At first, the role of sulfate-reducing process in inhibition of anaerobic digestion by mercury was studied to confirm the previous suggestion. It is found that sulfate-reducing process is much more tolerable to mercury than both acidogenesis and methanogenesis and it has an ability to make mercury nontoxic by producing a lot of sulfide as a result of its own metabolism. Owing to these properties described above, it is concluded that this process may greatly contributed to protect all the process in glucose degradation from toxicity of mercury and aid them in recovering from inhibition caused by mercury.
Sensitivity of methanogenesis to inhibitory action of mercury was also studied in detail using three typical intermediates of glucose degradation or usual anaerobic digestion, i.e. acetate, propionate, and n-butyrate. It is concluded that the tolerability to toxicity of mercury (or recoverability from inhibition by mercury) is higher, as the following order, at the process of degradation of n-butyrate, that of acetate, that of propionate, and at methanogenesis from hydrogen, that from acetate.
