Electrocoagulation removal of heavy Metals from industrial wastewater in continuous flow

Electrocoagulation (EC) treatment of industrial and municipal wastewaters has existed for over a century without getting much attention, partly because of lack of know-how from specialists who have tried to implement this technology, often chemical and civil engineers, but also because of the misunderstood simplicity of its electrolytic reactions. This doctoral research work is intended to provide clarity from the perspective of a process metallurgist, while paying special attention to the design issues of related engineering fields playing a decisive role in the successful implementation of this key technology. In doing so, aim of this work was to provide techno-economical evidence about the sustainability of EC technology for the efficient removal of heavy metals from industrial wastewater, with main focus on its online process control in continuous flow. Like this, five major issues were found to be fundamental to achieve the expected requirements: 1. selection of iron as sacrificial anode material, because of its simplified recycling path and agglomeration properties, allowing gas encapsulation and floc flotation; 2. conditioning of pH value in the neutral range for effluents to be cleaned, otherwise there is no chance for colloidal particles to build up and to agglomerate; 3. design of a concentric geometry for inline electrocoagulation reactor, due to the electromagnetic and hydrodynamic factors, avoiding mechanical energy losses; 4. use of a closed-loop process control based on online measurement of conductivity, enabling an adequate dosage of electrolytic iron from anode in real-time; 5. utilization of the synergic flotation effect produced by the simultaneous release of hydrogen gas, which still contains 50% of energy consumed by EC reactions.