Method for electrolytic water disinfection without cathodic hydrogen evolution

Abstract

The invention relates to a novel device for electrolytic disinfection of drinking water, service water and waste water using anodically generated disinfectants. The cathodic formation of hydrogen is prevented by using gas diffusion electrodes as the cathode. Atmospheric oxygen is reduced to hydroxyl ions and / or hydrogen peroxide at the gas diffusion electrodes. A permanent anode can be positioned between two gas diffusion electrodes. The latter then function alternately as a cathode or a second anode. This polarity change enables the removal of the deposits containing metal ions that form during the cathodic reaction from the gas diffusion electrodes. The substances with the disinfecting effect are produced through the use of different electrode materials for the anode and the diffusion electrode either at both anodes or at the anode and cathode.

Description

CROSS-REFERENCE TO RELATED APLICATIONS [0001] This application is a continuation of, U.S. patent application Ser. No.10 / 381,756 filed Mar. 26, 2003, which is based from International Patent Application No. PCT / EP01 / 11287, International Filing Date 27 Sep. 2001.BACKGROUND OF THE INVENTION [0002] The invention relates to a device for electrolytic disinfection of drinking water, service water and waste water, using anodically generated disinfectants, wherein the undesired formation of hydrogen during the partial cathodic reaction is avoided. [0003] Electrolytic water disinfection is an efficient and cost-effective method of disinfecting water. It can be defined roughly as follows, killing of micro-organisms in water to be treated, through the action of an electric current introduced into the water via electrodes. This electric current can lead both to the anodic generation of disinfectant substances from the water itself or from substances dissolved in it, and also to the direct killin...

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Benefits of technology

[0017] According to a further feature of the invention, the metal wire netting or expanded metal consists of titanium or some other valve metal since these have a particularly high electrochemical stability.

Problems solved by technology

A large number of devices for electrolytic water disinfection are known according to prior art (e.g. the publications DE3430616, EP515628, U.S. Pat. No. 5,807,473, EP711730, DE19534736, WO97 / 11908, DE19633342), but all of these have the decided disadvantage that during the electrolytic treatment of the water to be disinfected, hydrogen is produced at the cathodes in accordance with

In particular, in cooperation with oxygen produced during electrolysis at the anode in accordance with equation (6), the hydrogen can lead to the formation of a dangerous explosive oxyhydrogen gas mixture.

Furthermore, the accumulation of quite large amounts of hydrogen in pipeline systems in which water circulates can lead to disruption of water circulation.

Hydrogen can penetrate into many metals and lead to specific forms of corrosion or embrittlement.

However, hydrogen peroxide has a lower oxidation potential by comparison with most of the substances formed at the anode according to equations 1 to 5, and therefore often only leads to unsatisfactory results.

Also, hydrogen peroxide is not permitted in every case as a disinfectant.

What is also disadvantageous is that the hydrogen peroxide formed at the oxygen-consuming cathode can react with the anodically formed free chlorine according to

A further disadvantage of oxygen-consuming cathodes of the type mentioned in DE19631842 is the fact that only the oxygen dissolved in the water can be used for the reactions as per equations 8 and 9.

Therefore, the possible reaction speeds and consequently the applicable current densities are very low, if one does not wish to accept the cathodic formation of hydrogen.

For this reason, electrolytic devices for water disinfection using oxygen-consuming cathodes according to DE19632842 have also not been able to become established to a greater extent in practice.

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