Field test of methane fermentation system for treating swine wastes.
A methane fermentation system for treating swine wastes was developed and successfully demonstrated in a field test plant (0.5 m3/d). The system was composed of a screw-press dehydrator, a methanogenic digester, a sludge separator, an oxidation ditch (OD) and composting equipment. A performance evaluation was carried out regarding physical pre-treatment using the screw-press dehydrator, methane fermentation for pre-treated slurry, and post-treatment for digested effluent by OD. Total solids (TS) and chemical oxygen demand (CODCr) removal by the screw-press pre-treatment were 38% and 22%, respectively. Properties of the screenings were as follows: water content 57%, ignition loss 93%, specific gravity 0.33. The pretreated strong slurry was digested under mesophilic conditions. Digestion gas (biogas) production rate was 25 m3/m3-slurry (NTP) and methane content of the biogas was 67%. CODCr removal of 65% with methane fermentation treatment of the slurry operating at 35 degrees C was observed. No inhibition of methane fermentation reaction occurred at the NH4(+)-N concentration of 3,000 mg/l or less during methane fermentation by the system. Mass balance from the present pilot-scale study showed that 1 m3 of mixture of excrement and urine of swine waste (TS 90 kg/m3) was biologically converted to 25 m3/m3-slurry (NTP) of biogas (methane content 67%), 100 kg of compost (water content 40%, ignition loss 75%), and 0.80 m3 of treated water (SS 30-70 mg/l).
Kataoka
N
N
Biotechnology Laboratory, Ebara Research Co., Ltd., 2-1, Honfujisawa 4-chome, Fujisawa-shi 251-8502, Japan.
Suzuki
T
T
Ishida
K
K
Yamada
N
N
Kurata
N
N
Katayose
M
M
Honda
K
K
D000383:Agriculture; D000641:Ammonia / Q000032:analysis; D000818:Animals; D001421:Bacteria, Anaerobic / Q000502:physiology; D019149:Bioreactors; D005285:Fermentation; D005740:Gases; D008372:Manure; D008697:Methane / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D012037:Refuse Disposal / Q000379:methods*; D013552:Swine
D005740:Gases; D008372:Manure; D000641:Ammonia; D008697:Methane; D010100:Oxygen