EP3016912A1

EP3016912A1 - Method for treating wastewater and device for carrying out said method

Info

Publication number: EP3016912A1
Application number: EP14745066.2A
Authority: EP
Inventors: Thomas Venier
Original assignee: Vm - Tecsystems GmbH
Current assignee: Vm - Tecsystems GmbH
Priority date: 2013-07-03
Filing date: 2014-07-01
Publication date: 2016-05-11
Also published as: CN105263867A; DE102013011395A1; US20160167985A1; WO2015000462A1

Abstract

The aim of the invention is to create a method and a device that reliably guarantee the removal of contaminants from wastewater with good energy efficiencies, whereby the purified water can be fed in as a direct discharge or in special cases can be fed to a further purification process. A further aspect of said aim is the recovery of raw materials from agricultural and municipal wastewater or raw materials from biogas plants. Said aim is achieved by a method that comprises an electrolytic treatment of the wastewater by using an anode, which contains both materials that withstand the electrolysis and sacrificial materials that are dissolved during the electrolysis, which are both simultaneously exposed to the wastewater. A device for carrying out the method comprises, as the part of the anode that withstands the electrolysis, a dimensionally stable anode cage (4) made of platinum, titanium, niobium, palladium, ruthenium, or platinized titanium, to which anode cage aluminum, iron, magnesium, calcium, or mixtures of said metals are applied as sacrificial material. The invention can be used to treat wastewater.

Description

Wastewater treatment method and apparatus for carrying out this method

The invention relates to a method for wastewater treatment and to a device for carrying out this method. Both find

in particular for the removal of solid particles, suspensions and dissolved biological contaminants as well as compounds of heavy and non-ferrous metals from the waste water application. Procedures and equipment can also be used for raw material recovery

agricultural and municipal wastewater. For example, phosphates and ammonium compounds should be selectively removed from the wastewater.

A method called "Advanced Oxidation Process" (abbreviated to "AOP"), also referred to as extended oxidation in German, uses strong ones

Oxidizing agents, such as ozone or hydrogen peroxide, for the decomposition of organic and inorganic substances in the wastewater by oxidation (Wikipedia, keyword "Advanced Oxidation Process") .This AOP process, however, sometimes does not ensure their complete purification in the treatment of heavily polluted waste water, so that a direct feed into It is also not possible because of the poor efficiency of high-voltage ozone generation.

Electrolytic processes have proven to be more favorable in terms of energy, with inorganic (ion-forming)

Impurities whose electrical conductivity is sufficient anyway. However, it has been found that highly polluted, mainly organically polluted municipal wastewater have sufficient electrical conductivity for the application of electrolytic processes.

Thus, it is known to remove organic pollutants, heavy metals and pharmaceuticals by a combination of an electrochemical AOP process, an oxidative cleaning by an electrolysis process and an oxidation by ozone from the wastewater (Deutsches

Utility model no. 20 2009 012 539 U1). Here, the additional use of ozone with the above described is mandatory economic disadvantages. The aspect of recyclable material recovery is ignored in this technical solution.

The invention has for its object to overcome the above-described deficiencies of the prior art and to provide a method and a device which reliably the removal of impurities from waste water with good energy efficiency

Guaranteed, allowing the purified water directly into waters

fed or in special cases another

Cleaning process can be supplied. Another aspect of this task is the recovery of raw materials from agricultural and municipal wastewater or those from biogas plants.

This object is solved by the features of the appended claims.

Advantageous embodiments of the invention will become apparent from the dependent and dependent claims.

The inventive method and the inventive device for wastewater treatment are used in particular for the removal of organic pollutants, suspension separation, removal of biological contamination and heavy and non-ferrous metals in wastewater, according to the invention a module for performing a fort as an AEOP (advanced electrochemical oxidation process) designated method is used.

In this case, an anode cage made of the materials platinum, titanium, niobium, palladium, ruthenium or placed titanium is used. This

Anodenkäfig is dimensionally stable and preferably made of expanded metal. We then put the sacrificial metal into this anode cage. Therefore, it is called a sacrificial anode. Since this anode cage can be filled mixed with metals, this also fulfills the function of a mixing electrode that does not exist in this form. It is also possible to add metals such as magnesium and calcium to this mixing electrode. This leads to the elimination of ammonium and phosphate in the wastewater. The removal takes place in this case as Magnesium ammonium phosphate (struvite). When using iridium oxide or tantalum oxide or mixtures thereof, a disinfection of water at a salinity of> 0.2% by mass is carried out by nascent chorus.

As sacrificial material according to the invention iron, aluminum, carbon, magnesium and calcium is used. These materials can also be mixed in the anode cage.

The above method can also be combined with membrane technologies. This has the advantage that biofouling can be avoided.

According to the invention, the waste water treatment is carried out for removal of particulate pollutants (for example suspension separation), organic ingredients, heavy metals or toxic metals in general and of pharmaceuticals. This purification method is preferably used in the form of oxidative precipitation using iron, aluminum; Calcium or magnesium applied. It can be used for many applications, such as oils and fats, small and finest dirt particles, heavy and toxic metals. As a result, the heavy metal content can be reduced up to the detection limit and the organic load by up to 75%.

With this solution according to the invention, the combination of the AEOP process with at least one other known process ensures excellent quality of the purified wastewater.

In the following, the advantageous effects of the invention will be exemplified in connection with possible applications thereof in the order of the claims.

The process is optimally conducted at current densities between 40 and 120 mA / cm ² . The voltage is 2 to 12 V and pH is preferably in the range between 5 and 9, that is to say comprises a range from acidic to neutral to basic. Since the present electrolytic conductivity depends on the ion concentration, the Current density on the voltage adjustable, with a lower limit of the electrode spacing and thus the required electrical power is given by the fact that the formed ions both signs again recombine at too small a distance. This

Minimum distance is in the case of organically polluted municipal sewage relatively low conductivity about 1 to 3 cm, but must be made mostly larger for reasons of flow resistance and to avoid blockages.

By a salt addition of 0.2% by mass to the wastewater disinfection is achieved by nascent chlorine in the process of the invention. This can be achieved particularly cost-saving by a corresponding addition of seawater near the coast. The remaining sodium ions will be with regard to another

Treatment of drinking water against common salt as well as against calcium ions, although regarded as the lesser evil, but the o.g. Addition is about a factor of 4 above the permissible under the Drinking Water Ordinance 200 mg / l sodium ions, so that a less aufendiges process for removing these sodium ions must be considered as the previously known method combined ion exchangers, which must be regenerated regularly separated.

Surprisingly, it has been found according to the invention that, especially in the treatment of predominantly organically contaminated wastewaters with their compared to inorganic polluted waste water relatively low

electrical conductivity preferred control to comparable finite levels of the cleaning effect over the treatment time in terms of total energy consumption is more favorable than a preferred control over the current density. Reference is made to the second table below (organically contaminated waste water from the food industry). A comparison of the 3rd line (20 s at 40 mA / cm ² ) with the 4th line (10s at 60 mA / cm ² ) shows that a 12.5% higher total energy consumption only just under 1% higher

Cleaning performance results.

The membrane techniques mentioned in claim 5 serve to separate the insoluble precipitates of pollutants due to their inclusion in or chemical bonding to the anodically dissolved sacrificial materials. It can also be other separation methods than those listed

be applied. After a material investigation on

dangerous ingredients, such as heavy metal compounds,

Unobjectionable, the task according to the task can be done as a fertilizer.

In the aforementioned Fenton reaction, the effect of the OH radicals formed on the materials that resist the electrolysis is catalytically enhanced, i.e., catalyzed by organic compounds, by iron compounds. this works only with iron as sacrificial material.

As a sacrificial material magnesium and calcium special applications are provided, namely in the Struvitfällung, with the very "base" calcium by Caiciumphosphat care must be taken to ensure that on contact with water no spontaneous reaction without any power supply begins.

For the treatment of the above-mentioned group of organically polluted effluents, the addition has become more electrically conductive, in relation to the occurring

Eletrolyseprozesse inert carbon particles to the sacrificial material in the anode cage proved to be advantageous. They cause a spatially more uniform distribution of electricity and thus a more even

Participation of the contents of the anode cage to the desired

Precipitates of impurities. To be able to exert this effect, the carbon particles must not be much smaller,

preferably not less than about one quarter of that of the particles of the sacrificial materials in average diameter.

The energy-saving operation according to claim 4 requires

On the facility side a longer residence of the respective amount of waste water in the electrolysis room. This would be extremely low

Flow rates can be achieved, but which have the disadvantage of a risk of clogging or settling of the precipitates within the sacrificial material. Here creates the elongated tubular reactor according to claims 11 to 13 remedy, whose length in dependence desired flow rate and flow rate can be varied within wide limits.

The invention will be explained in more detail with reference to exemplary embodiments and the accompanying drawings. Show it:

1 shows a process scheme,

2 shows an AEOP reactor,

3 shows an anode cage in side view,

Fig. 4: a schematic representation of a tubular reactor in

Cross section and

Fig. 5: a schematic representation of a tubular reactor in

partially cut longitudinal view.

The process scheme of FIG. 1 shows an AEOP precipitation reactor 1 followed by a filter unit 2, which is a

Chamber filter press or can act on an automatic filter.

FIG. 2 shows the schematic structure of the AEOP reactor 1 according to the invention. It generally has the shape of a tube 3 closed at both ends by a closure cover 7, which accommodates the anode cage 4, which is only indicated here but shown in detail in FIG. Any other geometric shape may be chosen for the AEOP reactor. In the case of an inflow 5, the wastewater to be purified is introduced and the effluent treated at an outflow 6 is withdrawn. The tube 3 is in its entirety with the exception of the end-side closure lid 7 on cathode potential, the

Cathode terminal 8 is connected. Therefore, it is to be ensured by not shown insulating spacers that no metalic contact between the tube 3 and the anode cage 4 occurs inside the tube 3, so that the intervening wastewater is subjected to the electrolytic treatment essential to the invention.

Fig. 3 shows the dimensionally stable anode cage 4 in side view. It can also any, but to the shape of the reactor vessel

adapted geometric shape can be selected. The used

Expanded metal consists, as described above, of platinum, titanium, Niobium, palladium, ruthenium or placed titanium. Inside the anode cage 4 is not specifically highlighted here, sacrificial material described in detail above.

In the table attached at the end of this description is the

Effectiveness of the method according to the invention

Test measured values, whereby a direct dependence of the cleaning effect on the current density as well as on the

Duration of treatment results, which is also plausible insofar.

Further considerations then led to the technical teaching of claim 4.

4 and 5, a tube reactor 9 is shown, which

in particular, but not exclusively for the realization of the o.g.

technical teaching of claim 4 is used. In the cross section of Fig. 4, the anode cage 4 can be seen as it is electrically insulating

Spacers 9 centered is held therein. In the longitudinal direction it extends, as indicated in Fig. 5, over the entire length of

Tube reactor 9 except for the cut right end of the same. The wall 11 of the tube reactor 9 is either itself at cathode potential or it is designed to be electrically insulating and internally coated with the cathode material. In the space between the anode cage 4 and the wall 11, the wastewater to be treated flows, of course, as intended for anodic

Treatment in the anode cage 4 penetrates. It is understood that the spacers 9 are aerodynamically designed.

Referring now to Figure 5, the further embodiment of this aspect of the invention will now be described. In the present case inclined by 9 ° relative to the horizontal tube reactor 10 from the left to be treated wastewater is introduced and treated in the manner described above electrolytically, with appropriately selected

Strtömungsgeschwindigkeit in the lower part of the Aufällungen of dissolved sacrificial anode material to which contaminants or substances are bound concentrate. At the right-hand end 12 of the

Pipe reactor 10 may now be at an upper outlet 13 according to purified wastewater and at a lower outlet 14 enriched precipitates are each taken to further treatment. The outflow of these enriched in the lower part of the tubular reactor 10 precipitations can be promoted by a knocking or vibration device 15 mounted there externally.

1. Organically contaminated wastewater (municipal wastewater)

Rganisch polluted wastewater (food industry)

3. Inorganically polluted wastewater (lead industry)

4. Inorganically polluted wastewater (arsenic)

5. Inorganically polluted wastewater (nickel)

Initial value Ni End value Treatment duration Current density 0 mg / l 0.02 mg / l 10 sec 40 mA / cm2 .0 mg / l <detection limit 10 sec 60 mA / cm2 .0 mg / l <detection limit 10 sec 80 mA / cm2

2.0 mg / l <detection limit 10 sec 100 mA / List of Bezuaszahlen used

1 AEOP precipitation reactor

2 filter unit

3 pipe

4 anode cage

5 inflow

6 outflow

7 closure lid

8 cathode connection

9 spacers

10 tubular reactor

11 wall

12 outgoing people

13 upper outlet

14 lower outlet

15 Knocking the vibration device

Claims

claims

1. A process for wastewater treatment, in particular for the removal of heavy metals, organic pollutants and pharmaceuticals from wastewater, characterized by an electrolytic treatment of the wastewater using an anode, which both the electrolysis

Resistant materials as well as in the electrolysis going into solution, so-called sacrificial materials, both of which are simultaneously exposed to the wastewater.

2. The method according to claim 1, characterized in that the electrolytic treatment takes place in a pH range of the waste water of 5 to 9 at a voltage less than 12 V.

3. The method according to claim 1 or 2, characterized in that at a more than 0.2% by mass adjusted salinity of the wastewater at the same time a disinfection thereof by nascent chlorine

is made.

4. The method according to any one of claims 1 to 3, in particular for

Treatment of waste water with high levels of organic

Contaminants, characterized in that in the characteristic field of the relative change in the COD value as a function of the treatment duration and the current density at the beginning and / or in the course of treatment, an overweighting of the treatment period is set.

5. The method according to any one of claims 1 to 4, characterized in that it is combined with membrane techniques such as microfiltration, ultrafiltration or nanofiltration.

6. The method according to any one of claims 1 to 5, characterized in that it is combined with a UV wastewater treatment using the Fenton reaction.

7. Device for carrying out the method according to one of

Claims 1 to 6, characterized in that the electrolysis resistive part of the anode is a dimensionally stable anode cage (4) made of platinum, titanium, niobium, palladium, ruthenium or platinized titanium.

8. Device according to claim 7, characterized in that the anode cage (4) consists of expanded metal.

9. Device according to claim 7 or 8, characterized in that the anode cage (4) is equipped with aluminum, iron, magnesium, calcium or in the case of a mixing anode with mixtures of these metals as sacrificial material.

10. Device according to one of claims 7 to 9, characterized

characterized in that the anode cage (4) further contains carbon particles as an electrically conductive phase.

11. Device according to one of claims 7 to 10, in particular for carrying out the method according to claim 4, characterized in that the anode cage (4) by means of spacers (9) in the central axis of a tubular reactor (10) is arranged, the wall (9). the cathode is or is lined with this inside.

12. The device according to claim 11, characterized in that the tubular reactor (10) is inclined in the flow direction in the order of about 20 degrees to the horizontal downwards and at its lower outflow end (12) has an upper outlet (13) for liquid

Components of the treated wastewater and a lower outlet (14) for the precipitates of dissolved sacrificial materials with attached thereto pollution particles or substances.

13. Device according to claim 12, characterized in that on the outside of the tubular reactor (10) a knocking or vibration device (15) for supporting the transport of the precipitates to the lower outlet (14) is mounted.