Electrocoagulation is an electrochemical method of treating polluted water whereby sacrificial anodes corrode to
release active coagulant precursors (usually aluminium or iron cations) into solution. Accompanying electrolytic reactions
evolve gas (usually as hydrogen bubbles) at the cathode.
Electrocoagulation has a long history as a water treatment technology having been employed to remove a wide range
of pollutants. However electrocoagulation has never become accepted as a mainstream water treatment technology.
The lack of a systematic approach to electrocoagulation reactor design/operation and the issue of electrode reliability
(particularly passivation of the electrodes over time) have limited its implementation. However recent technical
improvements combined with a growing need for small-scale decentralised water treatment facilities have led to a reevaluation
of electrocoagulation.
Starting with a review of electrocoagulation reactor design/operation, this article examines and identifies a conceptual
framework for electrocoagulation that focuses on the interactions between electrochemistry, coagulation and flotation.
In addition detailed experimental data are provided from a batch reactor system removing suspended solids
together with a mathematical analysis based on the white water model for the dissolved air flotation process. Current
density is identified as the key operational parameter influencing which pollutant removal mechanism dominates.
The conclusion is drawn that electrocoagulation has a future as a decentralised water treatment technology. A conceptual
framework is presented for future research directed towards a more mechanistic understanding of the process.
2004 Elsevier Ltd. All rights reserved.