Co-digestion of domestic kitchen waste and night soil sludge in a full-scale sludge treatment plant.
A study was made on the domestic kitchen waste and night soil treatment performance of a full-scale sludge treatment plant. The sludge treatment at this plant was by thermophilic methane fermentation. The initial treatment, mesophilic to thermophilic fermentation, was able to be started up within a short time by adjusting the amount of influent waste. Thermophilic methane fermentation was carried out for five months (May-October) and the performance under a mean residual time of 22 days indicated a VTS decomposition of 42%, gas generation of 54-1,610 m3/day (average: 755 m3/day), and a mean methane concentration of 60%. The methane gas was used to generate power in the plant and the amount of power generated by methane gas was highest in October (average of 1,200 kWh/day). This was equivalent to about 7% of the power consumed at the entire sludge treatment plant. The BOD/NH4-N of the activated sludge influent water was lower, compared to a case where there is no recycle flow, due to the recycle flow from the methane fermentation process. There was, therefore, a tendency for an increase in the amount of methanol charged into the secondary denitrification tank. However, the quality of the effluent was satisfactory (BOD< 10 mg/L, SS< 5 mg/L, and T-N< 25 mg/L). Study results indicated that it was possible to implement a full-scale plant for recovering organic waste.
Environmental Engineering Group, Ebara Corporation, Tokyo, Japan.
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Y
Yoneyama
K
K
Takeno
D019149:Bioreactors; D003247:Conservation of Natural Resources; D003296:Cooking; D005243:Feces; D005285:Fermentation; D008697:Methane / Q000032:analysis / Q000378:metabolism; D000432:Methanol; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage / Q000737:chemistry*; D013696:Temperature
D012722:Sewage; D008697:Methane; D000432:Methanol