CS210681B2 - Method of contents decreasement of contaminants in liquid manure fluid phase - Google Patents

Abstract

Dung slurry from pigs, with a water content of 85-98% is treated by adding to the slurry a coagulant, pref. based on iron trichloride and aluminium sulphate, and a flocculant, pref. a cationic polyelectrolyte. The slurry is stirred and decanted so that it separates into a solid ppte. and water with a BOD 4,000 mg/l. The amt. of coagulant is pref. 0.1-4 g/l of slurry and the amt. of flocculant is 10-250 mg/l. The decanting is pref. mechanically assisted by means of a centrifuge. The water may then be passed to a biological treatment basin where the BOD is reduced to 100 mg/l. The solids may be processed to an organic compost for agricultural or horitultural use. The process enables pig slurry to be reduced to a useful solid prod., compost and clean water.

Description

BACKGROUND OF THE INVENTION The present invention relates to a method for reducing the content of pollutants in the liquid phase of a dung, while reducing the biological (BOD) of this · liquid phase · to less than 4000 mg / l for 0 pig slurry and to less than 500 mig / l for dd cattle.

By "slurry" is meant the · part of the manure · from the stables or stables, which contains ¹ predominantly liquid substances and · a minor part of the organic residues, such as straw residues and the like.

In the following description, the term "processing" means dividing the slurry into a solid phase and a liquid phase and reducing the contaminant content in the liquid phase. The content of the polluting material is determined by the following parameters:

BOD: biological oxygen demand

COD: chemical oxygen demand

SS: suspended solids (fluxing particles)

Nnh ₄ +: ammoniacal nitrogen

Nkj: nitrogen · according to Kjeldahl

So far, the following methods have been used to reduce the pollutant content of manure:

- drying of the solid phase and evaporation of the liquid phase, - drying of the solid phase by chemical means, usually calcined with lime, - burning of manure, - biodegradation of manure.

The disadvantages of the prior art are related to the large amount of liquid phase required by the construction of large devices to purify the phase. In many cases, this phase can only be cleaned using a large amount of chemicals or using expensive chemicals, and the disposal of the waste causes real problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process which does not have the known disadvantages at the same time and gives excellent results in the treatment of fertilizers with a high liquid content, i.e. waste material, with high biological oxygen consumption.

The present invention provides a process which comprises adding flocculating agents in an amount of 10 mg to 250 mg per liter of fertilizer and coagulating agents, in an amount of 0.1 g to 4 g per liter of nodule, mixing the mixture and The solid particles are separated and, in the case of processing of manure from the cattle, aerobic sludge stabilization is introduced before said operation.

Ja ^ o. Coagulating agents are preferably aluminum chloride or aluminum sulphate or ferric chloride, and a flocculating agent of the cattonactive polyelectrolyte.

One device for carrying out the method according to the invention is schematically shown in the accompanying drawings. Giant. 1 shows the upper part of the device, FIG. 2 shows a middle part and FIG. 3 a bottom part.

The apparatus for carrying out the method according to the invention comprises a storage tank 1 for manure, which is supplied from the container 2 via a pipeline. 3. The storage tank 1 is provided with two pumps 4 and 5, to which are piped 6 and 1, which after passing through the flow regulator 8 (provided with the discharge pipe 9) and the pipe 10 under the shaking screen 11.

The drawstring screen 11, having meshes with a mesh size between 0.5 and 5 m, is positioned above a tank 12 provided with an overflow pipe 13 and a liquid-phase discharge line 13 'and a solid-phase outlet 14.

Solid phase · is transported

15 Dec

The solid phase is led in the direction indicated by the arrow 16 (see FIG. 1) to the apparatus for its storage, composting and drying, while the liquid phase is led through the discharge conduit 13 'to the coagulation tank 17 (cbr. 2).

Coolant tank 17, equipped with level controllers N ¹ and · N2,. is provided as well as! a storage tank 1 with a stirrer 18 for continuously mixing the materials processed in the coagulation tank 17.

The coagulation tank 17 is fed from the tank 20 by a metering pump 19 and through the pipes 19 'and 19' of an iron chloride or aluminum sulphate solution. Iron (III) chloride is preferably used. Water is supplied to tank 20 through line 21 which is the branch of main supply line 22 (connected and water supply W).

The tank · 20 is also equipped with a stirrer · 23 and a level controller · N.

Finally, the third tank 24 serves to supply the aqueous solution with the electrolyte poles. This tank, equipped with a · N-level regulator, is · fed with water · branch 25. The polyelectrdlyt is mixed with water by means of a stirrer 26.

This roller is forced into the conduit 28 by a metering pump 27 mounted on it. 27' — 27 ”.

Piping · 28 is · · located! for dosing! Pumps · 29—30,. The pumps 29-30 lead through the line 31 to the line 28 the liquid phase of the fertilizer to which iron chloride is admixed, the liquid phase from the tank 17.

The line 28 thus supplies both the solution from tank 17 and the solution from tank 24 to the centrifuge.

Reaction between flocculant, a. The solids are guided in the direction of the arrow 34 from the centrifuge 32 in the direction of movement of the conveyor belt 15 to the activated sludge tank 36.

In this activated sludge tank, the liquid phase is subjected to biological oxidation to reduce the BOD below the permissible maximum (,, 100 ^; mg / l).

The aerated liquid is led through line 37 to the sedimentation tank 38. In the sedimentation tank 38, the sludge is separated from the clear liquid. The sludge is extruded by means of a pump 39,. mounted on conduits 39 'a; 39 ”, db storage tank · 1 fertilizer. Piping 39 ”is provided with a recirculation branch, 40.

The clear liquid from the sedimentation tank 38 is passed through a line 41 in the direction of the arrow 41 'and meets the following requirements:

BOD: less than 100 mg / l

COD: less than 1000 mg / l

SS: less than 100 mg / l

Nkj: less than 300 mig / l

N _N h + 4 ^: less than 150 mg / l

The original features of the process according to the invention are the choice of certain groups of polyelectrolytes and the simultaneous action of the polyelectrolytes and the coagulating agent on the slurry to coagulate, flocculate and decant the cloloid particles in suspension.

As is apparent from the description of the invention, the sludge formed in the sedimentation tank 38 is fed to a manure storage tank 1 and then treated simultaneously with the manure.

In the method according to the invention, the biological purification of main operations of the cleaning process ^1. The essence of the process according to the invention consists of a physico-chemical treatment with a flocculating agent. and a coagulating agent. (99 prcc. Of suspended and flotating substances are separated by this * process stage).

No need to worry that the functions .celého · Equipment · the · ¹ was hampered by defects in equipment · · · · · biological cleaning.

Hereinafter, some details of the dimensions of certain parts of the apparatus and of the residence times of these materials in the apparatus will be given as an example. These data do not limit the scope of the invention. They should be considered as optimal values, which may vary somewhat;

The following parts may have the following dimensions or capacities:

storage tank for (1) 8 m, ³ fertilizers age 21 m3 per day amount of fertilizer (12) coagulation tank (17) 3 m ³ 30 · m3 per day tank Italy (20) 3 m ³ (coagulating agent) 0.5 m ³ per day tank (24) 3 m ³ (flocculating agent) (36) 0.5 m ³ per day tank is activated .100 · m? sludge 24 · m ³ per day sedimentation tank (38) 2 mč 24 m3 - per day

The individual agitators preferably have the following speeds:

impeller (23) 1000-3000 rpm agitator (18) 50-100 rpm agitator. ⁽ 26 ^{) 100} olives ^{k /} mmut

The above 'method' and the device is, in particular. well suited for processing pig slurry.

In the treatment of manure from cattle, such as calves, cows and steers, stabilization of the manure in the aerobic sludge stabilizer 42 (Figures 1 and 2) is included prior to the operation described above.

After decanting the mixture, the solid particles are separated to give a liquid phase consisting essentially of water with a BOD lower than 500 mg / l.

When processing manure from. bovine animals form the original features of the process of the invention the combination of aerobic sludge stabilization with physico-chemical processing (coagulation and flocculation), as well as an accurate selection of coagulating agents and foculants to remove all suspended and coagulated substances.

Of course, the invention is not limited to the above-described embodiment in which many modifications can be made without departing from the scope of the invention.

Claims (7)

SUBJECT OF THE INVENTION 1. A method for reducing the content of pollutants in the liquid phase of a manure while reducing the biological oxygen demand (BOD) of this liquid phase to less than 4000 mg / l, in the case of pig slurry, and to ^less than ⁵⁰⁰ mig / ^{l ,} goes ^- !! A manure from bovine, comprising adding to the manure a flocculating agent in an amount of 10 mg to 250 mg per liter of fertilizer and a coagulating agent in an amount of 0.1 g to 4 g per 1 1 liter of fertilizer, the mixture is mixed and allowed to decant, whereupon the solid particles are separated and, in the case of processing the fertilizer, from the cattle, aerobic sludge stabilization is introduced before said operation. 2. A method for reducing the content of contaminants in the liquid phase of pig fertilizers while at the same time. a reduction of the BOD of this liquid phase and a value of less than 4000 mg / l according to claim 1, characterized in that a fliaculant is added to the manure by an amount of 10 mg to 253 mg per liter of fertilizer and a coagulating agent in an amount of 0.1 g to 4 g per liter of fertilizer, the mixture is stirred and allowed to decant, whereupon the solid particles are separated. 3. A method for reducing the content of contaminants in the liquid phase of bovine manure while reducing the biological oxygen demand (BOD) of the liquid phase to less than 500 mg / l according to item 2, characterized in that aerobic is included before the flocculating agent is added. sludge stabilization. 4. The process of claim 1 wherein the coagulating agent is selected from the group consisting of aluminum chlorides. and aluminum sulphates. 5. The method of claim 1 wherein the coagulating agent. is FeCl3. The method of claim 1, wherein the flocculation; agent. is a cationic polyelectrolyte. 7. The method of item. 1, characterized in that the amount of coagulating agent is approximately 2 g and the flocculating agent is approximately 250 mg per liter of fertilizer. 8. A method according to any one of claims 1 to 7, wherein the aqueous phase is subjected to biological purification, for example using activated. sludge.