Rate-limiting Of Hydrogen-producing Acetogenesis To Anaerobic Digestion Compared With Methanogenesis

The organic matter of anaerobic digestion need primary fermentative bacteria, syntrophic acetogenic bacteria, homoacetogen and methanogens and other microorganisms groups. The main microbial groups differ greatly in physiological ecology. So, maintain all kinds of main functional bacteria growth environment of coordination and balance of metabolic rate play an important role to sure the stable operation of the anerobic system, The research about identify the limiting strength of anaerobic digestion process is the key in developing the anaerobic digestion technology.In this paper, anaerobic activated sludge sampled was cultivated with a series of pH、tempreture and inoculated sludge quantity. With butyric acid, acetic acid and H₂/CO₂ as substrate, respectively, studing the ecological amplitude of pH and tempreture according to the Shelford’s law of tolerance, obtaining the substrate conversion rate of syntrophic butyrate-oxidizing bacteria（SBOB）, aceticlastic methanogens（ACM） and hydrogenotrophic methanogens（HTM）. Ilustrating the limiting strength of anaerobic digestion process by the contrast analysis.Study shows that,The ecological amplitudes of pH for SBOB, ACM and HTM were 6.19⁸.59、5.50⁷.74 and 4.39⁹.23, with an optimal pH of 7.39, 6.62 and 6.81 for their metabolism, respectively. With the optimal metabolic pH, the specific conversion rate of butyric acid, acetic acid and H₂/CO₂ by the sludge were 0.86, 1.04 and 1.09 g CODequ/g MLVSS·d.SBOB had a narrower ecological amplitude of pH and a lower substrate conversion rate than the methanogens. The ecological amplitudes of tempreture for SBOB, ACM and HTM were 23.13⁵3.70℃、29.78⁴6.86℃ and 35.17⁵3.77℃, with an optimal tempreture of 38.44℃、38.32℃and 44.47℃ for their metabolism, respectively. With the optimal metabolic tempreture, the specific conversion rate of butyric acid, acetic acid and H₂/CO₂ by the sludge were 0.69, 1.16 and 2.25 g CODequ/g MLVSS·d. SBOB had a broader ecological amplitude of tempreture. But SBOB had a lower substrate conversion rate than ACM and HTM.SBOB had a lower substrate conversion rate than the methanogens with a series of inoculated sludge quantity from3%²0%.It can be show that substrate conversion rate of SBOB is sensitive to changes of ininoculated sludge quantity Accoding to the completely random design.The result shows that Hydrogen-producing acetogenesis is sensitive to pH、tempreture and ninoculated sludge quantity.The hydrogen-producing acetogenesis had a stronger limitation on the anaerobic digestion in Anaerobic digestion process.