BIOLOGICAL TREATMENT METHOD OF CALCIUM-CONTAINING WASTE WATER

摘要

PROBLEM TO BE SOLVED: To efficiently separate calcium carbonate from sludge containing calcium carbonate formed when calcium-containing waste water is biologically treated to perform stable and good biological treatment. SOLUTION: An acid is added to calcium carbonate-containing sludge separated in a sedimentation tank 2 into which biologically treated water is introduced from an aeration tank 1 in a pH adjusting tank 3 to adjust the pH of the sludge to 5-6. The pH adjusted sludge is stagnated in a calcium carbonate separation tank 5 to separate sludge high in calcium carbonate content of a lower layer to draw the same out of the system. Biological sludge low in calcium carbonate content in an upper layer is returned to the aeration tank 1.