The pH and oxidation-reduction potential (ORP) values were measured using a pH/ORPmeter (FE20, METTLER, TOLEDO, Switzerland). Total oil concen-tration in the wastewater was determined by a national standardmethod [23]. It was composed of polar organics and petroleumhydrocarbons. Polar organics were the parts of the total oil adsorbedby magnesium silicate, also determined according to the nationalstandard method. The total biogas production was measured bya wet type gas flowmeter (SHAKIC LMF-1-0.2, Changchun). Bio-gas compositions were identified with a gas chromatograph (GC,Agilent 6890) equipped with a TCD detector and a Porapakq pack-ing column. The morphology of the anaerobic sludge in the reactorwas observed with a Scanning Electron Microscope (S-3000N SEM,Hitachi, Japan) on day 0 and 285, respectively. Particle size mea-surement of the seed and acclimated anaerobic sludge in the UASBreactor was performed using a LS 200 laser diffraction particle sizeanalyzer