uestions often arise as to how much residual biodegradable matter remains in sludges from biological processes after previous treatment has been completed( EPA’s F-bio test). In one case, sludge samples were removed from two facultative lagoons. Tests were conducted to determine the methane potential remaining in the sludges and to determine if the sludges were suitable for land spreading. Samples of the sludge containing 20.5 and 22.7 g VSS were transferred to respective reaction vessels and methane production was measured over a period of 18 days. Methane production ranged from 120 mL in one sample to 160 in the second sample as shown in the Figure below. The gas production rate was high for only about 2 days and then leveled off to a rate of about 4 mL/day. The COD conversion equivalent of the produced gas was only about 0.3 to 0.4 g per sample, thereby representing VSS conversions of 1.47 and 1.76 %. The sludge was then deemed to be suitable for land application without further treatment. 微生物降解呼吸仪链接：http://www.instrument.com.cn/netshow/SH101516/C121937.htm#

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