US 6,638,432 B2Granted

Method of treating waste liquid

AssigneeNippon Shokubai Co., Ltd.

InventorsYukihiro Matsumoto, Takeshi Nishimura, Kazuto Okazaki, Kiyotaka Watanabe

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Abstract

Disclosed is a method of removing heavy metals contained in exhaust gas which has been generated by burning a waste liquid containing the heavy metals discharged in a process of producing organic compounds. The method includes the steps in the order of: (a) a combustion step of burning the waste liquid to produce exhaust gas; (b) a gas-liquid contact step of rendering a liquid containing an alkali compound in contact with the exhaust gas to collect the heavy metals in bottoms of the liquid; and (c) a coagulating step of adding a coagulant to the bottoms to coagulate the heavy metals in the bottoms for removal of the heavy metals. According to this method, the heavy metals contained in the exhaust gas can be efficiently separated and removed.

Claims6

Dependent claims

A method of removing heavy metals contained in exhaust gas generated by burning a waste liquid containing the heavy metals discharged in a process of producing organic compounds, wherein the waste liquid includes waste water and/or waste oil discharged from a process of producing (meth)acrylic acids and/or esters thereof, comprising the steps in the order of:

(a) a combustion step of burning the waste liquid to produce exhaust gas;
(b) a gas-liquid contact step of rendering a liquid containing an alkali compound in contact with the exhaust gas to precipitate the heavy metals in bottoms of the liquid, wherein, in the gas-liquid contact step, the amount of the alkali compound in the liquid is regulated to keep pH of the bottoms in the range of 4 to 10;
and
(c) a coagulating step of adding a coagulant to the bottoms to coagulate the heavy metals in the bottoms for removal of the heavy metals.

1 more element

Dependencies are inferred from the claim text.