ANAEROBIC TREATMENT OF LIQUID FRACTION OF HEN MANURE IN UASB REACTORS

The anaerobic treatment of liquid fraction of hen manure was studied i n two parallel laboratory 2.61 UASB reactors at 35 degrees C. The gran ular sludge from a laboratory UASB reactor treating synthetic wastewat er was used as a seed sludge. The liquid fraction of hen manure was ob tained directly from an industrial farm located in Moscow region after separation of diluted manure in situ into solid and liquid fractions. Before feeding, the waste water was preacidified under microaerobic c onditions at laboratory ambient temperature (18-20 degrees C) for 1-2 days. The influent GOD was 10.5-20 g/l of which volatile fatty acids ( VFA) were 3.9-6.7 g COD/l, pH was between 6.2-7.1. The initial organic loading rate (OLR) was Ig COD/l day(-1) then it was stepwise increase d to the values of II-I COD/l day(-1). Under these OLR and hydraulic r etention rime of 1-2 days, both reactors demonstrated optimal stabilit y with treatment efficiencies out total COD reduction of 70-75%. The b iogas production rate at the OLR of 11-12 g COD/l day(-1);vas 3.5-3.6l /l day(-1) (methane content - 79-81%) and effluent pH of about 8. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.