METHOD FOR TREATING PAPERMAKING WASTE WATER AND METHOD FOR UTILIZING SILICA SOL IN PAPERMAKING

摘要

A method for treating a papermaking waste water which comprises adding a silica-aluminum based inorganic polymer flocculating agent having a Si/Al molar ratio of 0.2 to 1.5 to a papermaking waste water having a pH of 5 to 14 or a papermaking waste water having been adjusted to have a pH of 5 to 14 in a manner so that the concentration of the above inorganic polymer flocculating agent is 1 to 250 (mg-Al/L) in terms of aluminum, to thereby control the pH of the above papermaking waste water to be 5 to 8, and then adding an organic polymer flocculating agent. The above method for treating a papermaking waste water exhibits high efficiency in the flocculation of a suspended material, and further can carry out a flocculation treatment without the presence of a finely suspended matter and thus allows the reuse of flocculated precipitates as a valuable resource.