Turbidity was measured with a Hach turbidimeter before clarification and after 3, 6 and 20 h of treatment with fining agents. Flocculating rate was calculated as reported by Yokoi, Natsuda, Hirose, Hayashi, & Takasaki, 1995. Volume of the sediment during clarification was recorded at 3, 6 and 20 h from the beginning. Absorbance at 420 and 325 nm was detected before and after the treatment (0 time and after 20 h) through a Shimadzu UV-1800 spectrophotometer and then the reduction of Abs
was calculated.
420
and Abs
325