| Summary: | 碩士 === 國立臺北科技大學 === 環境規劃與管理研究所 === 94 === There have been studies of electroplating-wastewater treatments with zero valent iron (ZVI) in recent years. Due to the expensive cost of ZVI, scrap iron, a low-cost adsorbent, were used to treat chromate from electroplating wastewater in column reactors. High Cr(VI) removal is expected to achieve and coagulant cost is expected to reduce due to the generation of ferric ion.
The influent pH values were controlled at 1.3, 1.5, 1.7 and 2.0. Cr(VI) reduction was reduced as pH increased. When pH≦1.5, the Cr(VI) removal achieved 100%. When Cr(VI) removal was increased, ferrous ion was produced and oxidation-reduction potential (ORP) was getting lower. As the retention time decreased, Cr(VI) removal were less and the operation time increased. For 20 minutes of detention time at pH1.3 or 40 minutes of detention time at pH1.5, 100% Cr(VI) removal were achieved.
Effluent pH was 3-4 for the initial stage with high turbidity due to the occurrence of iron coagulation. Hence reduction and coagulation were able to achieved for adding just one chemical (scrap iron) and the cost for the scrap/Cr(VI) was lower than ZVI/Cr(VI) process due to the generation of ferric ion to save extra ferric ion needed.
|
|---|
