TY - JOUR
T1 - Feasible power production from municipal sludge using an improved anaerobic digestion system
AU - Komatsu, K.
AU - Yasui, H.
AU - Goel, R.
AU - Li, Y. Y.
AU - Noike, T.
N1 - Funding Information:
This work was carried out by Kurita Water Industries, Ltd. and Tohoku University as the research activities in NEDO (New Energy and Industrial Technology Development Organization, Japan).
PY - 2011/3
Y1 - 2011/3
N2 - Anaerobic digestion with ozonation is a promising process to enhance the digestion efficiency and reduce the sludge quantity for disposal. In this study, new process schemes by incorporating thermophilic digestion were studied for further improvements. Pilot tests were performed with three schemes having mesophilic, ther-mophilic or mesophilic-thermophilic hybrid reactors. In the process scheme with thermophilic digestion, the degradation ratio of VSS components was observed to improve by 5.5% over mesophilic digestion. The amount of ozone consumption could also be reduced by 18%. However, biogas conversion ratio was not improved due to considerable non-degradable organic fraction remaining in soluble form. In batch tests, this soluble fraction was found to readily degrade by mesophilic microorganism. Based on this observation, a mesophilic-thermophilic hybrid flow scheme was developed. In this flow scheme, thermophilic microbes rapidly degraded ozonated sludge and remaining soluble organic components were converted to biogas by mesophilic microbes. This flow scheme reduced ozone consumption as well as improved the biogas conversion of municipal sludge to 78.6%. The cost performance analysis of a municipal WWTP (population equivalent 150,000) considering electricity production resulted in electricity production cost of 5.0 JPY/kWh, lower than the current market price of 9.3 JPY/kWh.
AB - Anaerobic digestion with ozonation is a promising process to enhance the digestion efficiency and reduce the sludge quantity for disposal. In this study, new process schemes by incorporating thermophilic digestion were studied for further improvements. Pilot tests were performed with three schemes having mesophilic, ther-mophilic or mesophilic-thermophilic hybrid reactors. In the process scheme with thermophilic digestion, the degradation ratio of VSS components was observed to improve by 5.5% over mesophilic digestion. The amount of ozone consumption could also be reduced by 18%. However, biogas conversion ratio was not improved due to considerable non-degradable organic fraction remaining in soluble form. In batch tests, this soluble fraction was found to readily degrade by mesophilic microorganism. Based on this observation, a mesophilic-thermophilic hybrid flow scheme was developed. In this flow scheme, thermophilic microbes rapidly degraded ozonated sludge and remaining soluble organic components were converted to biogas by mesophilic microbes. This flow scheme reduced ozone consumption as well as improved the biogas conversion of municipal sludge to 78.6%. The cost performance analysis of a municipal WWTP (population equivalent 150,000) considering electricity production resulted in electricity production cost of 5.0 JPY/kWh, lower than the current market price of 9.3 JPY/kWh.
KW - Anaerobic Digestion
KW - Mesophilic-Thermophilic Hybrid Flow Scheme
KW - Ozonation
KW - Ozone
KW - Power Generation
KW - Sludge Treatment
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U2 - 10.1080/01919512.2011.549035
DO - 10.1080/01919512.2011.549035
M3 - Article
AN - SCOPUS:79953134748
SN - 0191-9512
VL - 33
SP - 164
EP - 170
JO - Ozone: Science and Engineering
JF - Ozone: Science and Engineering
IS - 2
ER -