It follows that the heavy metal Cu pre-sented activating effect on protease at the low content in B(150)
in the early period of composting. In B(150), the second peak activity of protease appeared on the 25th composting day in the late
period of composting. In A(Control) and C(300), the second peak
activities of protease appeared on the 35th composting day in
the late period of composting