TREATMENT OF WASTE GAS FROM CHEMICAL FACTORY

摘要

PURPOSE:To enable recurrent use of inexpensive ferric sulfate for the treatment of cyan by arranging to absorb cyan compds. and S-compds. in the waste gas using a soln. of ferric sulfate obtd. by oxidizing ferrous sulfate soln. with iron oxidizing bacteria as absorption liquid. CONSTITUTION:A soln. contg. FeSO4 such as waste water of nonferrous metal mine, etc. is led to an oxidizing tank 1, where seed bacteria such as iron oxidiz ing bacteria is added to the soln. The bacteria are proliferated by blowing air under sulfuric acidic condition and FeSO4 is oxidized to Fe2(SO4)3. Then, the Fe2(SO4)3 soln. is conveyed to an aspirator 4 in an absorption stage via a separation tank 2, and a ferric salt feeding tank 3 to absorb HCN, H2S, COS, CS2 in the waste gas. After the absorption stage, the liquid is transferred to a settling tank 6 where generated precipitate of cyan compds. and single substance S are separated from liquid, and the separated liquid contg. reduced FeSO4 is fed back to the oxidizing tank 1 via a ferrous salt feeding tank 7 and oxidized again to Fe2(SO4)3. Thus, the liquid is used again for absorption.