The first practical applications of electroflotation were developed towards the end of the 1800s, but the first uses in (purifying) water treatment date back to the 90s of the last century. They were intended to remove metals and hydrocarbons from wastewater. Today we apply electro-flotation successfully in wastewater treatment, especially when heavy metals have to be broken down, emulsions to be broken (by reducing oils and hydrocarbons), suspended solids do be intercepted, reducing COD and BOD, in addition to often significantly reduction of most of the other pollutants.
A PROJECT OF A TREATMENT PLANT
During the electrocoagulation treatment of a wastewater, tens, sometimes hundreds, of competing reactions usually take place in reaction cells. All these reactions are in equilibrium in the (unique) liquid phase of the reaction module, with equilibria determined by the respective redox potentials, concentrations, temperature, activation energies, electrode overpotentials, etc. The current supplied by generators (in practice the electron flow), is therefore splitted in the various possible uses (hydrolysis of water, reduction of cations, development of aluminum ions, etc.) as a function of all the reaction parameters, which are always different from wastewater to wastewater. Therefore, when you are faced with a wastewater to be treated with electro-flotation, it is first of all necessary to conduct an initial analysis of the type of pollutant concentrations to be abated, assuming the reactions that are supposed to take place and calculating the reaction parameters (the specific current to be supplied, the necessary voltage, the time of residence, etc). However, it is good to admit that it is not possible to predict at the table, on the basis of the documentary analysis alone, the yield to equilibrium (of the abatement reactions, the development of oxygen and consequent oxidation, etc.). It is therefore necessary to verify the hypotheses with an experimental practical test. On the basis of the experimental results it will then be possible to predict with good approximation the abatement yields of the various pollutants obtainable with an industrial electro-flotation plant for a given wastewater to be treated.