Abstract
Wastewater from the production of semiconductor, printed circuits, and IC parts contains chemically stable COD components and chelating heavy metals shch as lead borofluoride [Pb (BF4)2]. As conventional treatments of those components by neutralization, coagulation and biological methods are not efficient enough, we examined a treatment by oxidation together with hydrolysis. The subject is oxidized by hydrogen peroxide with iron powder catalyst and hydrolyzed by aluminium sulfate.
The article reports the results of our laboratory and field experiments. With iron powder catalyst, the subject water (COD : 4,500mg·l-1) was oxidized up to 160mg·l-1 in COD value, while the subject was oxidized only up to 270mg·l-1 in COD value with ferrous sulfate catalyst. The oxidation with iron powder is considered to be efficient since the amount of Fe-ions from iron powder was less than half of that from ferrous sulfate.
Consequently, with the iron powder catalyst, the volume of sludge from Fe-ions reduced to half of that from process with ferrous sulfate, which will contribute to reducing the volume of industrial waste. The hydrolysis of borofluoric acid with aluminium sulfate removed F- ions up to 1mg·l-1.
