New EC technology to replace sacrificial electrodes

The power of the magnetic field in aqueous metal-powder dispersion

The process has the task of simplifying electrocoagulation considerably - without the need to replace electrodes - while at the same time increasing its effectiveness through magneto-chemical effects, thus making it possible to work continuously. The iron powder replaces sacrificial anodes, polarisation/oxidation does not occur and increases effectiveness while reducing costs. Here, the layer of iron powder on a magnetic "carrier-electrode", which is dimensionally stable, is to be regarded as the stationary phase.
This is a new process for the purification of waste water by EC (electrocoagulation). What has been considered disturbing in classical EC so far is a passivation of the sacrificial anodes, which leads to an interruption of the redox reaction or, in the first step, to an increase in power consumption. This could be well recognised when using aluminium electrodes as well as other electrodes.
A polarity change only partially compensates for this, so in this case metal alloys are used that give better results with a polarity change and avoid passivation by about 100 %. However, this does not prevent the sacrificial anodes from having to be replaced after consumption. To get around this, Bioway has developed a technology in trials that uses metal powder and continuously feeds this dispersion in water. A patent application has recently been filed for this new method.
Biological, aerobic wastewater treatment is not able to remove micropollutants and unwanted ions such as NH3/NH4, NO3/NO2, SO4, F-, Cl- as well as heavy metals such as As, Pb, Sb or Cr(VI) and radioisotopes etc. and to reduce water hardness - mainly Ca, Mg. However, it releases CO2 during fermentation. For this particular reason, there is a new flexible solution: it prevents the interruption of the reaction during wastewater treatment, no more replacement of sacrificial anodes. It reduces costs considerably, prevents passivation, improves reaction kinetics through a much larger surface area, is faster and more effective in COD reduction.

Example analytical data of iron powder:
1. iron (Fe) is base; 2. C - 0.01%; 3. H2 - loss 0.14%; 4. SiO2 max 0.25%; 5. P max 0.015%; 6. S max 0.015%. The DSA electrode remains stably coated with iron powder so that no further ions are released.

The method has the task of simplifying electrocoagulation - without changing electrodes - and at the same time increasing the effectiveness by magneto-chemical effects and thus working continuously. For the first time, a special magnetic DSA electrode with magnetic iron powder is used. This leads to a higher efficiency in the purification of wastewater.
The attached iron powder reacted to form hydrogen, which was clearly visible. This was registered as a primary reaction. The special electrode was not attacked and the coating of fine powder could not be removed mechanically by brushing under running water. This means that it is clearly a dimensionally stable anode - we call it a DSA electrode. There is no comparable EC system in the world.
The theory of magnetic electrocoagulation
A 4 x 10 cm electrode plate has a surface area of 40 cm². A bulk of 20 g with 40 μm particle size on 10 x 4 cm has a surface area of about 3800 cm². However, in an electrolytic redox reaction, the 40 μm particles initially go into solution faster than primary reaction. The application of magnetic fields in electrolysis is called magneto-electrolysis.
There are positive effects of magnetic fields in magneto-electrolysis. Compared to electrolysis without an additional magnetic field, magneto-electrochemistry shows improved ion transport and thus higher current densities and greater separation rates, which has a positive effect here in the electrocoagulation process. In this process, the anions are pushed or shifted to the exit point of the electrons, the anode, while the cations are pushed in mutual induction to their entry point, the cathode. When the ions reach the electrodes in this way, they are discharged - the characteristic of electrolysis. The electrode current is therefore an induction current and the electrode potentials are so-called induced voltages.
When an electron current flows through an electrolyte solution, a magnetic field is created, just like in a metal conductor. This also causes an induction current, but it does not move the conductor, the electrolyte, but the charge carriers in it, the ions.
Electrocoagulation (EC) is widely used today. The advantages over biological wastewater treatment have been recognised. Only the problem of passivation and electrode replacement remained, which has now been solved. To solve this, Bioway has developed a technology in trials that works with metal powder and feeds it continuously.

This method has many advantages:

1 It prevents the interruption of the reaction during wastewater treatment no need to replace
sacrificial anodes
2 No storage of electrodes - no transport/unloading costs for used electrodes
3 Significant cost reduction as normal iron powder is much cheaper than electrode plates -
especially special alloy electrodes.
4 It prevents passivation and a polarity change keeps the magnetic properties of the
electrodes stable
5 It improves reaction kinetics due to a much larger surface area.
6 It is faster and more effective in COD reduction and other parameters.
7 The metal powder is dispersed directly in the wastewater and continuously fed into the
reaction chamber / EC reactor.
8 No foreign ions are introduced into the water as the iron powder has a very high purity.

Norbert Pautz, Managing Director
C./ Tirant Lo BLanc 4,3
ES-03750 Pedreguer / Alicante - Spain
Mail: contact@biowayconsulting.com
phone: 0034965030786

Bioway Consulting Ltd is the successor of Bioway GmbH / Switzerland. Bioway is an engineering company now with main emphasis of consulting in the area of water- / waster purification and cleaning / killing of air containing VOCs, Corona & Co., mircro-organisms. Bioway was founded 1992 in Germany.

This release was published on openPR.