DE10250533A1 - Device and method for processing liquid manure by means of electroflotation - Google Patents

Abstract

The invention relates to a device and a method for processing liquid manure from farm animal husbandry, in which the liquid manure is separated from its solid in a first step in a device provided for this purpose. The resulting thin manure is mixed with a flocculant and subjected to a separation of the flocculated substances. The thin slurry pretreated in this way then undergoes an electroflotation treatment in which the flotated solids formed are removed. The process water cleaned in this way can be discharged into the sewage system without further treatment. The solid obtained can be used to fertilize the fields without the restrictions that apply to the spreading of liquid manure.

Description

The invention relates to a device and a process for the preparation of animal husbandry Waste materials, in particular their excrement, liquid manure or with these waste materials enriched waste water.

slurry happens especially in large-scale livestock farming and consists of a mixture of feces, urine and bedding. The solid and the Water content in the manure can vary widely. The manure is collected in the factories and, as it complies with the waste regulations is subject to and therefore may not be traded as an economic good, preferably for used their own purposes. slurry but is subject to strict requirements regarding their use as fertilizer for the Fields management.

One cubic meter of pig manure contains about 3.2 kg nitrogen, 1.8 kg phosphate, 2.0 kg potassium, 0.9 kg magnesium and 3.2 kg of lime, further contamination of heavy metals as well COD and BOD relevant substances. The amount of manure in cattle is approximately 65 liters a day, in a pig about 11 liters a day. So fall in an average size pig farm with 5000 Sows annually 20,075 cubic meters of manure with the appropriate amounts of usable and harmful Fabrics.

Because of its nitrogen content manure is suitable but definitely as a fertilizer for the Field management, however, is only allowed under certain conditions be used. So the spreading of liquid manure is only allowed if the floor has sufficient absorption capacity. Manure may therefore not be spread over the fields when pools of water are visible are frozen to a depth of less than 15 cm or the thickness of the Snow cover larger than Is 15 cm. Also have to Ammoniakvertlüchtigungen largely avoided, so that the spreading above all at low temperatures, in cloudy weather, when there is no wind and close to the ground should be done.

Lately there have been attempts undertaken the manure so that they no longer meet the strict rules of waste management subject. The main focus is on the manure in this way prepare that a solid fertilizer is produced and the excess water is so detoxified that it can be reused or at least can be discharged into the sewage system.

This is how the patent application describes a procedure with the international application number PCT / DE 00/03014 for the treatment of liquid manure, Slurry and in toilet houses collected human feces, at the manure undergoes electroflotation treatment. As a product of this On the one hand, the process creates a solid that is without that for untreated Manure apply Restrictions all year round to fertilize the Fields can be used. On the other hand, through electroflotation treatment the proportion of COD and BOD relevant substances as well as heavy metals so significantly reduced in the slurry separated from the solid, that the thin manure without further after-treatment can be initiated in the sewage systems. This patent application is hereby introduced as a reference and is therefore part of the revelation.

However, it turned out that the thin manure still loaded with significant amounts of nutrients is what the efficiency of the method used reduced and on the other hand polluted the sewage to a greater extent. Furthermore, this arises in the method described above Problem that the electro flotation cell due to the high solids content the manure cannot be operated in an optimal manner. In particular, can high solids in the slurry between the electrodes baked and short circuits to lead.

From WO 95/15295 is also a device and a method for cleaning waste water are known, where the organic matter precipitates iron and aluminum hydroxides are oxidized and / or reduced. The procedure is also high Sludge concentrations applicable in wastewater and is based on the Mixing of the wastewater with compressed air, which is difficult to oxidize Fabrics in addition is mixed with ozone or hydrogen peroxide. Thus in the WO 95/15295 the addition of a gas is mandatory without the big one Mud loads cannot be floated.

Finally, WO 95/05347 is one Apparatus and a method for treating manure known that after the separation of the solid from the liquid phase and an optional Pretreatment by oxidation using ozone, hydrogen peroxide or another oxidizing substance the liquid phase through an algae pool is pumped through to a regeneration device. In this Regeneration device is an electroflotation treatment carried out, to those in the liquid Phase of existing biomass, consisting of micro-algae and bacteria using consumable electrodes made of aluminum or iron to flocculate and separate. However, the processing of the slurry is in the WO 95/05347 to carry out in two stages, whereby the electric flotation is mainly used for the to remove microorganisms introduced during the first treatment stage.

It was therefore an object of the invention to provide a device and a method for treating manure, which do not have the disadvantages of the prior art.

According to the invention this task was accomplished an apparatus with the features of claim 1 and a method solved with the features of claim 14. Advantageous configurations the invention can be found in the respective dependent claims.

A device was created in which the solids are removed in a pre-treatment of the manure and the slurry without the need for further intermediate treatment or mixing subjected to electroflotation treatment with oxidizing gases becomes. The pretreatment primarily relates to the separation the one in the manure existing solids and removal of foreign matter as well Litter or the like. That of the solid and the impurities freed thin manure then through passed through an electro flotation cell. Finally done if necessary, filtering the exiting from the electroflotation Sewage in one for that suitable filter unit.

When carrying out the method according to the invention and use of the device according to the invention becomes the manure separated into substances that are either easily recycled or can be discharged into the sewage system.

The device according to the invention enables Treatment of the manure with a particularly high degree of efficiency and particularly good utilization the - used Aggregates. The resulting wastewater and the separated solid are largely of heavy metals as well as BOD and COD-relevant substances cleaned and are not subject to the restrictions applicable to manure for the Use as a fertilizer.

It was extremely surprising for the expert that the in the manure existing pollutants can be removed even if the solids of the manure are separated before the electroflotation treatment and no longer together with the slurry must be led through the electro flotation cell. The device according to the invention allows thus the use of smaller electroflotation cells with improved Processing result, the process being particularly efficient and the electroflotation cells even when the solids content fluctuates the manure no longer clog.

It was equally surprising for the skilled person that not all of the processing work in the electro flotation cell carried out but that the system achieves a significant increase in performance, if at least one unit is used to pre-separate the solid becomes.

The device according to the invention is inexpensive and can be permanently installed on site as well as mobile, for example assembled in a freight container.

In an advantageous embodiment of the invention the solids content of the from the means for separating the solid sludge removed 20-30 %, whereby a puncture-resistant solid cake is obtained. We this advantageous solids content is clearly below, so in a particularly preferred embodiment of the invention, this solid returned to the means of separation and manure to be treated added. In an extremely advantageous embodiment of the invention, this return of the separated Solid sludge when its solids content is below 15%.

In an advantageous embodiment the invention is the means for separating the solid of the manure Centrifuge. Centrifuges for such applications, in particular, are known to the person skilled in the art Decanter centrifuges, sufficient known. In particular, these centrifuges offer compared to the for the same filter filter presses have the advantage that a significantly higher one Degree of thickening of the separated solid can be achieved. A solid is thus obtained in a particularly simple manner, which can be used as a solid fertilizer without further post-treatment.

In a preferred embodiment the device according to the invention the electro-flotation cell is a means of introducing a flocculant downstream. In a preferred embodiment of the invention this agent is attached and directed after a first centrifuge the flocculant into the thin manure. In A particularly preferred embodiment of the invention regulates this Means the supply of flocculant depending on the amount of previously generated slurry. In one extremely The preferred embodiment of the invention is the addition of flocculant from the amount of liquid manure present Solid particles dependent. In this way, optimal utilization is particularly preferred of the flocculant reached.

The flocculant is in one preferred embodiment of the invention a polymer, preferably a cationic polymer. In an extremely preferred embodiment of the invention is this cationic polymer in an aqueous solution added to the slurry. This preferred embodiment is particularly preferred Way the promotion and metering of the polymer facilitated.

In a further preferred embodiment of the invention, the flocculated by adding the flocculant Smaller and smallest fraction suspended in the first Means of separation could not be removed from the manure another means of separation from the thin manure. In one particularly This is the preferred embodiment of the device according to the invention Also a centrifuge. As a result, the device according to the invention further optimized in a simple manner. In particular that of separation the solids downstream electroflotation cell is in this preferred embodiment only for removal and / or conversion the substances dissolved in the slurry used. The solids withdrawn from the electroflotation cell can subsequently also added to the solid that was previously extracted from the manure become.

The electroflotation cell used according to the invention and the processes taking place in it are shown in of the above-mentioned international patent application with the international application number PCT / DE00 / 03014. The principle of the process is to electrolytically split the water present in the cell, which creates fine gas bubbles. The released oxygen oxidizes the substances dissolved in the treated liquid, which also form complexes with the metal ions from the sacrificial electrodes, which are carried to the surface by the gas bubbles. A foam forms on the surface of the liquid, which can be removed mechanically or in any other way.

In a preferred embodiment According to the invention, the electroflotation cell consists of a battery in relation to one another parallel and preferably vertically arranged electrode plates. The thin manure is preferably in the area introduced into the bottom of the electrophotography cell and washed around the electrode plates with a preferred direction in the direction of gravity. This makes floating in a particularly advantageous manner the floated substances supported on the treated liquid.

On the one hand, this causes constipation the electroflotation cell through between the electrode plates Baked solid safely avoided and ensures that the entire surfaces the electrode plates remain electrically active and the sacrificial electrodes wear out evenly. As a result, the life of the Electrodes optimized and the downtimes of the system on Minimum reduced.

In a particularly preferred embodiment According to the invention, the electrodes consist of one another alternately arranged plates, the anodes preferably consisting essentially of Aluminum and iron are made and the cathodes from any electrically conductive material, preferably stainless steel. In a very particularly preferred embodiment of the invention the electroflotation cells four cathode plates and three anode plates with essentially the same size and uniform base areas. In an extremely preferred embodiment of the invention have the cathode plates a thickness between 0.5 and 2 cm and the anode plate plates a thickness of 0.05-0.4 cm.

In another extremely preferred Embodiment of the invention is the voltage applied between the electrodes between 100 and 400 volts, preferably between 200 and 300 volts. This will be extremely beneficial Embodiment of the invention achieved in that the current intensity depends on the degree the pollution of those introduced into the electro-flotation cell Thin manure a certain value, preferably between 200 and 300 A. becomes. Through this extremely preferred embodiment of the invention is an optimal result electro-flotation treatment with optimal energy utilization achieved and excessive heating of the treated wastewater safely prevented.

In a preferred embodiment The process water emerging from the electroflotation cell becomes the invention at least partly in a cycle in the process. Preferably, the electro-flotated liquid manure in one Storage tank can be stored temporarily or if necessary directly or via a another intermediate container be reintroduced into the electro-flotation cell. This can in a particularly preferred embodiment of the invention for buffering particularly polluted waste water respectively. In an extremely preferred embodiment of the invention is as described Recycling for a repeated treatment of the thin manure and an associated one further purification of the waste water.

In a preferred embodiment the invention is the electro-flotated thin manure before being introduced into the Sewerage or the preferably partial return to the process one last Filtration step during which during the electroflotation resulting solids that were not withdrawn from the cell, also be removed from the electro-floated process water. In a particularly preferred embodiment of the invention, this is Filter a preferably obliquely running vacuum belt filter, in which the collected residue drained at the same time is and preferably just like the one emerging from the centrifuges Solid as a firm cake. This solid can before the manure or withdrawn from the manure Solid are added.

In a further preferred embodiment According to the invention, the device has a series of parallel ones Electro flotation cells of the same design. This will make it more preferred Way created a device in which the additional Electroflotation cells only when necessary in case of overload one of the first or the cells already in use. This creates a device in a particularly simple manner, the most varied amounts of thin slurry with optimal efficiency can process. Likewise, with redundant execution several Electroflotation cells, maintenance of the cells or an exchange used electrodes without the need to shut down the system possible.

Another aspect of the invention is a process for the treatment of slurry or waste water containing slurry, at in a first step the slurry into its components thin slurry and Solid is separated. An electro-flotation treatment is then carried out the manure, in the course of the floated solid from the treated process water is subtracted. The process water electroflotted in this way can finally in a further process step, the remaining solid, for example through a final Filtration to be withdrawn.

The method according to the invention allows a treatment of the manure, which is essentially characterized by a pre-separation of the solids of the manure and an electroflotation treatment of the thin manure is. The method according to the invention offers optimum use of the aggregates used and, on the one hand, produces a solid fertilizer that can be used in the field management without the restrictions applicable to liquid manure, and on the other hand, a process water that essentially removes the pollutants and that without further aftertreatment into the Sewerage can be initiated.

In a preferred embodiment of the method according to the invention becomes the manure the solid in a first of preferably two in succession switched centrifuges withdrawn. In a particularly preferred Design of the method according to the invention the manure becomes thin Added flocculant. The flocculates are preferably flocculated out of the thin manure Thin manure substances in one withdrawn from the second centrifuge.

In a preferred embodiment the invention that the flocculant depends on the amount of liquid manure and possibly dependent from the amount left in the thin manure Solids added. This ensures optimal use of the added polymer reached as well as an excessive load on the thin manure additional Solid safely avoided.

In a further preferred embodiment the invention, the process water after electroflotation final Filtration, preferably over an inclined filter, subjected. In a particularly preferred embodiment of the invention this process water is at least partially circulated into the Thin manure returned. In one extremely preferred embodiment of the method according to the invention takes place Repatriation in a storage tank arranged in front of the electroflotation cell. hereby a buffer is created in a particularly preferred manner, the fluctuations compensates for the slurry in the solids load and thus enables optimal use of the electroflotation cell.

The invention is explained in more detail below using an exemplary embodiment. Table 1 shows an overview of the chemical analyzes of thin manure from pig breeding after the separation of the solid (column 2), process water after electroflotation and filtration in a vacuum belt filter (column 3) as well as the collected solid from the first centrifuge, the second centrifuge and the vacuum belt filter (column 4). It can be seen that the majority of the manure pollutants are present in the thin manure and not in the solid matter and that the method according to the invention is suitable for removing almost all of the pollutant load from the manure. The process water is clear and can either be returned to the system in a circuit or fed into the sewage system without further treatment. Table 1:

The invention is described below with reference to 1 explained in more detail. However, this figure shows only a preferred embodiment of the device according to the invention and in no way limits the general inventive concept.

1 shows a schematic representation of the device according to the invention in a preferred embodiment.

In 1 a device for treating manure according to the invention is shown schematically. The manure is pumped 1 over a line 2 into the first centrifuge 3 initiated in the separation of the manure into solid 4 and manure 5 he follows. The solid 4 is about the slurry pump 6 conveyed out of the device. The thin manure 5 is in an intermediate tank 8th headed out of it by a pump 9 into the second centrifuge 10 is pumped. In this second centrifuge 10 is also powered by a pump 14 a polymer solution 11 from one with a stir 12 equipped tank 13 guided. In the centrifuge 10 the thin slurry mix 5 and the polymer solution 11 , the flocculated solid 30 is by means of the slurry pump 7 also transported from the device. The first centrifuge 3 primarily serves to separate a solid of sufficient quality from the manure, whereas the second centrifuge 10 primarily serves to optimize the properties of thin manure for electro flotation. From the centrifuge 10 occurs the thin manure 15 out and gets into one with another stir 16 equipped storage container 17 directed. In this storage container 17 If necessary, the thin manure is mixed 15 with clear process water 18 which is in the storage tank 19 is collected. By the pump 20 becomes the slurry 15 over the one valve 21 having line 22 in the bottom area of the electro flotation cell 23 directed. The electro flotation process is done by the unit 24 controlled and regulated. The process water 25 leaves the electro-flotation cell 23 in the area of its roof and becomes a stirrer in another 26 having storage container 27 directed. From this storage container 27 becomes the process water 25 via an inclined filter 28 conducted in the final filtration of the process water 25 he follows. The filtrate 29 can finally be discharged into the sewage system as clear water or as process water if required 18 in the storage container 17 be directed and there with the slurry 15 be mixed.

1

pump

2

management

3

first centrifuge

4

solid fuel

5

Manure after separating the solid

6

slurry pump

7

slurry pump

8th

intermediate tank

9

pump

10

second centrifuge

11

polymer solution

12

stir

13

tank

14

pump

15

Manure after the separation of the flocculated solids

16

stir

17

reservoir

18

process water

19

storage tank

20

pump

21

Valve

22

management

23

Elektroflotationszelle

24

control and control unit

25

process water

26

stir

27

reservoir

28

Vacuum belt filter

29

filtrate from the vacuum belt filter, process water

30

flocculated solid fuel

Claims (17)

Device for processing liquid manure with - an agent ( 3 ) to separate the solid ( 4 ) from the thin manure ( 5 ), - at least one electroflotation cell ( 23 ) for electroflotation of the thin slurry ( 5 . 15 ), and - if necessary, an agent ( 28 ) for filtering the process water emerging from the electroflotation cell ( 25 ). Device according to claim 1, characterized in that the electroflotation cell ( 23 ) an additional agent ( 14 ) to introduce a flocculant ( 11 ) and an agent ( 10 ) to separate the flocculated solids ( 30 ) is connected upstream. Device according to claim 2, characterized in that the means ( 14 ) to initiate a flo bulking agent ( 11 ) a device for the metered, preferably for flow-dependent delivery of the flocculant ( 11 ) having. Device according to one of claims 2 and 3, characterized in that the flocculant ( 11 ) is a polymer, preferably a cationic polymer. Device according to one of the preceding claims, characterized in that the means ( 3 ) consists of one or more centrifuges, preferably two centrifuges connected in series. Device according to one of the preceding claims, characterized in that the electroflotation cell ( 23 ) has a battery of anode and cathode plates arranged parallel to one another, preferably iron or aluminum plates as anodes. Apparatus according to claim 6, characterized in that the electroflotation cell ( 23 ) 4 cathode plates and three anode plates arranged between the cathode plates. Device according to one of the preceding claims 6 and 7, characterized in that the cathode plates have a thickness of 0.5-2 cm and the anode plates have a thickness of 0.05-0.4 cm. Device according to one of the preceding claims 6-8, characterized characterized in that the applied between the electrode plates Voltage between 100 and 400 V, preferably between 200 and 300 V is. Device according to one of the preceding claims, characterized in that the means ( 28 ) for filtering the process water ( 25 ) is a vacuum band filter. Device according to one of the preceding claims, characterized in that the filtrate ( 29 ) is at least partially recyclable from the filtration into the thin manure. Device according to claim 11, characterized in that the filtrate ( 29 ) at least partially into the thin slurry ( 5 . 15 ), preferably after removing the flocculated solids ( 30 ). Process for the treatment of slurry or waste water containing slurry in a device according to one of the preceding claims, with the steps: - separation of the solids present in the slurry ( 4 ) from the thin manure ( 5 ), - performing an electroflotation treatment of the thin manure ( 5 . 15 ) and separating the floated solids, and - if necessary filtering the from the electroflotation cell ( 23 ) leaking process water ( 25 ). A method according to claim 13, characterized in that after the solids ( 4 ) Flocculant ( 11 ) with the thin manure ( 5 ) are mixed and the flocculated substances ( 30 ) can also be separated. Method according to one of the preceding claims 13 and 14, characterized in that the flocculant ( 11 ) depending on the amount of thin manure ( 5 ) and if necessary depending on the amount in the thin manure ( 5 ) remaining solids is added. Method according to one of claims 14 and 15, characterized in that the flocculant ( 11 ) before the electroflotation of the thin slurry ( 5 ) is added. Method according to one of the preceding claims 13-16, characterized in that the electroflotated, preferably filtered process water ( 25 ) at least partially in the circuit in the thin manure ( 5 ) is returned.