Research Project code：0150003099
Update date：Nov. 26, 2001
Precipitation treatment of toxic ions in wastewater by inorganic adsorbent as coagulation auxiliary agent
2000 - 2001
Investigating Researcher (3)：
The environmental criteria of fluorine 0.8mg/L, boron 1mg/L and nitrate nitrogen and nitrite nitrogen 10mg/L were decided by partial amendment of the Environmental Preservation Law by the Environmental Agency on May 22, 1999. It is difficult for the surface treatment companies using pre-treatment agents, plating agents etc. to clear these criteria by the present neutralization coagulation precipitation plant. A new treatment method must be introduced. It has been known that fluorine and boron exist as anions in wastewater and can be eliminated by strong acidic anion exchange resins. The affinity of these ions to the ion exchange resins, however, is strong and reuse of the resins is almost impossible. Both plant cost and running cost of the ion exchange resin method are high and economically disadvantageous to the industry. On the other hand, it has been known that fluorine in wastewater can only be eliminated as much as 6mg/L by calcium salt addition treatment and fluorine and boron can well be eliminated by inorganic adsorbent such as volcanic ash soil or apatite. When using them, however, the residual sludge is increased and treatment of the waste including toxic substances remains as a problem. A new treatment method is established in the fiscai year 2000 to treat fluorine and boron by adding the above inorganic adsorbent as a coagulation auxiliary agent to the present neutralization coagulation precipitation method without constructing a new processing plant.
Return to Previous Page