TREATMENT OF WASTE WATER

PURPOSE:To add a proper quantity of metal collecting agent and treat waste water effectively by analyzing the metal ion concentration in the waste water, and computing the necessary quantity of the metal collecting agent, basing on the result of which the adding quantity of the metal collecting agent is controlled and added. CONSTITUTION:The concentration is measured by a metal ion concentration measuring device 4 in the water in a raw water storage tank 1. Said measured value is put into a computation control device (microcomputer) 10, basing on which the quantity of a metal collecting agent to be added is computed. Then, the quantity of the metal collecting agent basing on the computation is added to the waste water transferred from the raw water storage tank 1 to a treatment tank 13 by a metal collecting agent feeding device 15 controlled by the computation control device 10, and the metal ion in the waste water is precipitated and removed. After that, said waste water is fed to a high colecular aggregating agent adding tank 16, and flocks are formed and enlarged by adding a high molecular aggregating agent in a tank 17 by an adding device 18 to the waste water in said tank 16.