WASTEWATER TREATMENT METHOD

PROBLEM TO BE SOLVED: To remove heavy metals, such as lead, thallium, selenium and the like, from wastewater generated by washing incineration ash and the like with water, at a low cost to perform purification treatment. SOLUTION: In a wastewater treatment method for removing heavy metals from wastewater generated when washing incineration ash, after adding a sulfidizing agent in a state that the pH of the wastewater is 10 or more, a ferrous compound or a ferric compound is added to the wastewater, and deposits are separated from the wastewater to which the ferrous compound or the ferric compound has been added. The deposits may be separated by filtration from the wastewater to which the ferrous compound or the ferric compound has been added, or may be settled and separated after adding a polymer coagulant. Lead, zinc, copper, thallium, selenium, and the like can be removed from wastewater, and heavy metals can be removed from wastewater generated when washing incineration ash and chlorine bypass dust at the same time. COPYRIGHT: (C)2009,JPO&INPIT