PROCESSES FOR THE TREATMENT OF FLUE GAS

PROBLEM TO BE SOLVED: To provide a method of effectively and sufficiently treating dithionic acid, N-S compounds, heavy metals, and organic COD components present in waste water of a wet flue gas desulfurizer absorbing and removing sulfur oxide in waste gas at heavy oil combustion. SOLUTION: This method of treating waste water from flue gas desulfurization includes a process 1 wherein mineral acid is added to waste water and the mixture is heated under acid condition to decompose dithionic acid and nitrogen-sulfur compounds, a process 2 wherein the waste water is regulated to pH 10-11 to make magnesium in the waste water its oxide and deposit it as flocs thereof and the flocs that catch heavy metals are separated as precipitates, a process 3 wherein a chelating agent and iron compounds are added to the waste water to regulate pH to 6-8, thereby causing formation of heavy metal chelate compounds and deposition of ferric hydroxide flocs to separate a precipitate consisting of the flocs and the chelate compounds, a process 7 wherein the waste water is treated with sand filtration to remove suspended matter, and a process 8 wherein the waste water is brought into contact with active carbon to adsorb and remove organic COD components.