Electrocoagulation (EC) – Water Treatment is a process whereby dissolved metals, solids and residual organic materials can be solidified and coagulated for easy removal.
The Electrocoagulation process best lends itself to recycling and remediation fresh flowback and produced water systems. By treating low quality water sources they can be used for future fracture stimulation operations, reducing the amount of water sent out for disposal, in addition to putting less strain on limited fresh water resources.
Low voltage DC current is passed between two flat electrodes as the wastewater flows through the gap. The range of applications and target pollutants using Electrocoagulation is very broad depending on the electrode material, system configuration and operating conditions.
The reduction of target pollutants has included zinc, lead, bromide, barium, strontium, scaling compounds (calcium, magnesium, etc.), ammonia, total suspended solids (TSS), total oil and grease (TOG), iron, and sulphate reducing bacteria (SRB).
By using three plates the Electrocoagulation steps through the treatment process using Electrocoagulation , Electro Flotation, and Electro Oxidation as needed.
Electrocoagulation has been in use for over a century, and is currently gaining traction in industrial applications due to the improvement in power supply systems, absence of high risk material handling, simplification in reactor designs, and small space requirements. The chemical mechanism of reducing the surface charge of colloids is similar to conventional chemical coagulation using alum or ferric/ferrous solutions; in practice, the removal rates are superior, no risky material handling is involved, and there are no extra anions added to the waste (the conventional metal coagulants are injected as salts: the metal cations and their ionic bonded anions such as sulphates, phosphates or chlorides). In this configuration, the anode is a sacrificial metal plate: either aluminum or steel. The metal ion coagulant is liberated as the anode dissolves. We have observed excellent removal rates for suspended solids and most metals using electrocoagulation followed by electro-flotation.
Inexpensive non-consumable anodes, such as graphite, can be used in the NFE flotation separation process. Our Electro-flotation (EF) process is similar to Dissolved Air Flotation (DAF) in many ways. The main difference is that DAF operates by dissolving air into the process stream using mechanical energy and high pressure, whereas EF electrolyses water into oxygen and hydrogen gases on the molecular scale directly in the process fluid. EF produces finer bubbles and superior removal while simultaneously requiring less energy input than DAF.
Using Mixed Metal Oxide (MMO) anodes, the over potential for water hydrolysis is increased and other oxidation reactions can occur. Relatively high RedOx potentials are created at the anode, which can oxidize target pollutants either directly or indirectly. One example of indirect oxidation occurs when chlorides are present in the wastewater; chlorides are oxidized to hypochlorite, which in turn can oxidize reduced contaminants (eg. ammonia) as well as provide disinfection. This mechanism is also useful for oxidizing trace metals in aqueous solution, making them more amenable to separation.