Please use this identifier to cite or link to this item:

Removal of chromium(VI) from wastewater by combined electrocoagulation-electroflotation without a filter

Authors Gao, Ping View this author's profile
Chen, Xueming
Shen, Feng
Chen, Guo Hua View this author's profile
Issue Date 2005
Source Separation and purification technology , v. 43, (2), 2005, MAY, p. 117-123
Summary A combined electrocoagulation and electroflotation process was designed to reduce Cr6+ to Cr3+ first and then to remove the total Cr from wastewater to a value below 0.5 mg/L. Acidic condition was employed in the reduction of Cr6+ and neutral conditions were found to be beneficial for the coagulation of the precipitates of Cr(OH)(3) and Fe(OH)(3). The formation of Fe(OH)(3) was ensured by sparging compressed air in the coagulation unit through a draft tube. The air not only oxidizes Fe2+ produced electrically, but also helps to mix the water for a better coagulation of the particles. The two-stage electroflotation arrangement can separate the solids from the wastewater to a value of less than 3 mg/L with total Cr less than 0.5 mg/L. The residence time required is about 1.2 h. The optimal conditions for the treatment are: charge loading about 2.5 Faradays/m(3) water, pH value in the coagulation unit is 5-8. The power consumption is less than 1 kW h/m(3) water at the conductivity of 1.5 mS/cm. When aluminum ions are either added or produced in situ in the coagulation unit, the treated wastewater can be discharged without any filtration. (C) 2004 Elsevier B.V. All rights reserved.
ISSN 1383-5866
Language English
Format Article
Access View full-text via DOI
View full-text via Web of Science
View full-text via Scopus