Studies on biogas production for the treatment of cattle and pig waste by attached growth anaerobic digester (AGAD) and UASB reactor
1993
Mongkol Damrongsri | Pramote Sirirote | Gaysorn Dhavises | Nusara Sinbuathong (Kasetsart Univ., Bangkok (Thailand). Faculty of Engineering. Dept. of Civil Engineering)
This anaerobic study of biogas production by cattle and pig waste digestion was selected in two systems. As for cow waste, the 10.2 l reactors with supported plastic media were operated by increasing the organic volumetric loading from 5 percent to 20 percent weight by volume waste concentration in order to obtain the standard rate of anaerobic digestion. The reactors, opuated at a semi-continuous flow rate of 1.02 l/d and at an ambient temperature between 30-33 deg C gave rise to a hydraulic retention time of 10 day. As for pig waste, the 6.72 l UASB reactors, 0.10 m diameter and 1.0 m height were employed. The reactors were used to treat infloent of about 3,000 mg COD/l at continuous flow rate and ambient temperature. The reactors were operated with a hydraulic retention time of 72, 48, 24 and 12 hr. corresponding to the organic loading rate of 0.74, 1.34, 2.78 and 5.87 g COD/l-d respectively. It was found that as for cow waste, the steady state volumetric total gas and methane productivity at the optimum loading of 10 percent corresponded to BOD, COD, TS and TVS removals of 84.08 percent, 63.77 percent, 63.48 percent, 61.09 percent and produced the optimum amount of methane of 50.99 percent. The efficiency factors for the conversion of organic matter to methane were calculated as volumes per gram of organic added and removed, and were detemined as 0.044 l/g COD added and 0.071 l/g COD removed at STP. As for pig waste, over 90 percent COD removal was achieved within 24-72 hr. The percentage of methane content was 60 percent and the conversion factors were 0.129 l/g COD added and 0.144 l/g COD removed at STP.
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