DE19936341C2 - Process for the treatment of manure - Google Patents

Abstract

The invention is based on the problem of developing a process for the treatment of liquid manure in which a largely odor-free process water is obtained by obtaining the valuable materials contained in the liquid manure, the deposition of solids on the evaporator surfaces is avoided and thus a trouble-free evaporation process is possible. DOLLAR A The problems with the evaporation of liquid manure, which are caused by precipitating solids and which lead to crust formation and blockages in the evaporator systems, can be avoided if the liquid manure is treated with peroxodisulfuric acid or its directly or after the coarse solids (straw and hair) have been separated Salts such as ammonium or magnesium peroxodisulfate and magnesium hydroxide are added and heated to temperatures above 60 (preferably 90 to 100) degrees Celsius. An easily separable precipitate is formed, which can be dried and stored easily and can be used as a high-quality plant or soil fertilizer. It is also a good idea to compost the solid, use it to manufacture bricks or to extract natural materials. DOLLAR A The proposed method can be used for all types of manure. Liquid manure or liquid manure is a mixture of faeces, urine, bedding, leftovers and water.

Description

Liquid manure or liquid manure is a mixture of faeces, urine, bedding, food residues as well as water and is used worldwide as plant and soil fertilizer. The nutrient content of the manure depends on the animal species, animal husbandry and feeding.

The expansion of animal production that has taken place in the past few decades while at the same time Concentration on ever larger animal husbandry units has led to locally large ones Amounts of manure are generated. Because of the limited storage capacity and the uneconomical Transport of the manure to areas in which a meaningful application would be possible are the Farmers are therefore often forced to either make the manure a disadvantage for the crops To apply time or in too large a quantity. The environmental problems caused by this like the pollution of groundwater and surface water with nitrogen and phosphorus, but also harmful gas emissions are known and led u. a. in many countries, the further To limit the expansion of animal production through appropriate approval procedures and limit the spreading of the manure to agrotechnologically favorable spreading dates. Regardless of this, new solutions for environmentally compatible slurry Processing wanted [P. Weiland: Status and perspective of slurry processing. In: Federal Working Paper 242 ministries of education, science, research and technology (1997), pp. 136-147]. Biological, mechanical, thermal and chemical processes are used to process manure described.

An overview and critical evaluation of the well-known slurry processing methods was provided by Gebel publishes [J. Gebel: Possibilities for environmentally friendly and economical treatment of liquid manure. In Rubbish and Waste, 9 (1991), pp. 518-528].

Some of the slurry ingredients can be used with sieve belts, screen drum presses or centrifuges separated and composted. This does not solve the slurry problem. A local over-fertilization of agricultural areas and related environmental damage cannot be avoided in this way (Weiland, pp. 137-138). It was because of that suggested adding a portion of the by adding phosphoric acid and magnesium oxide Precipitate ammonium salts in the manure filtrate as magnesium ammonium phosphate. This The precipitation process is technically very complex (Gebel, p. 521).  

When the liquid manure is evaporated, liquid manure components separate out on the evaporator surfaces Surfactants can cause heavy foaming. Even if before Evaporation from the manure solids such. B. straw or hair are separated, form during thermal treatment again difficult to remove substances that are reliable Disrupt the operation of evaporation plants.

It was also suggested that the saline solutions be cleaned using reverse osmosis. The disadvantage is that solids are already on the membranes after a short operating time stop and disrupt the separation process. Those caused by cleaning the membranes Business interruptions and the unfavorable mass ratio between permeate and Concentrate of 1: 4 on average leaves the process for practical use only to a limited extent seem suitable (Weiland, p. 140).

The invention is based on the problem of a method for treating manure develop a largely by extracting the valuable materials contained in the manure odorless process water obtained, the separation of solids on the Evaporator surfaces avoided and thus a trouble-free evaporation process possible becomes.

These problems are solved by the method described in claim 1. The problems with the evaporation of liquid manure, which are caused by separating solids and which can lead to crusting and blockages in the evaporator systems Avoid if the manure directly or after separation of the coarse solids (straw and hair) with peroxodisulfuric acid or its salts, such as ammonium or Magnesium peroxodisulfate or ammonium peroxodisulfate and magnesium hydroxide and heated to temperatures above 60 (preferably 90 to 100) degrees Celsius. An easily separated precipitate is formed, which can be dried and easily stored and can be used as a high-quality plant or soil fertilizer. It also offers to compost the solid, for brick production or for the extraction of natural materials to use.

Already with the addition of 4 g / l peroxodisulfuric acid or its salts and heating to above At 60 ° C there is a rapid separation of the solids contained in the manure. We give it less than 2 g / l peroxodisulfate, the effect is reduced. An addition of more than 10 g / l brings no significant improvement in the separation effect. Particularly favorable results achieved with an addition of 5 g / l to 7 g / l peroxodisulfate, since in this area a can be achieved with a relatively low use of peroxodisulfate.  

It is beneficial to add the peroxodisulfate ions before heating. Also one Activation of the peroxodisulfate ions by radiation or catalysts is possible. The slurry can also be split under pressure.

Liquid manure pretreated with peroxodisulfate ions, which is free of solid and cloudy substances can be evaporated without problems, the evaporation preferably as a relaxation evaporation realized and to avoid fouling in the radiator tubes of the Evaporator of the slurry flow is superimposed on an oscillating movement of the fluid. From the condensed vapor of the evaporation, ammonia can be prepared by known methods be separated. The ammonia obtained can u. a. as a raw material for the production of Ammonium peroxodisulfate can be used.

Biogas extraction is also possible after solid and turbid separation.

The biogas can be burned and converted into electricity in a combined heat and power plant Hot water of the cooling circuit for heating the evaporation system and for heating the Manure is used.

The method according to the invention can be used for all types of manure. The one with the invention Achievable advantages are also that in addition to the return of the water Extensive material and energetic use of the slurry ingredients is possible. In the Peroxodisulfate treatment also disinfects the manure and annoying odors are dismantled.

example

In a cattle barn with 140 dairy cows, 8 tons of liquid manure fall dry each day substance content of 7.5% dry matter and there are an additional 8 tons of rinsing water for used to flush the stables. The manure accumulation one day was a discharge of solids fed where 40% of the solids were separated as fertilizer.

After the solids had been separated off, 15.4 m ^{3 of} pre-cleaned liquid manure were mixed with about 60 kg of ammonium peroxodisulfate and heated to 90.degree. 360 kg of dry matter separated out. What remained was a solution with 0.12% dry matter, which was processed in a biogas plant with subsequent evaporation to produce higher-quality rinsing water or process water. The ammonia contained in the vapor condensate was stripped with steam in a stripping column with an integrated rectifying section. The vapor condensate with an ammonia content of <0.1% by mass was fed in via the stripping section of the column and trickled through the packed bed from top to bottom. The stripping steam flowed through the column in countercurrent to the liquid phase. Ammonia was stripped from the water at an operating temperature of approx. 110 ° C and moderate overpressure (approx. 0.4 bar).

The water withdrawn from the sump had a residual ammonia concentration of <10 ppm on. The ammonia-containing vapors were in one after the stripping section of the column concentrated reinforcement area and left the column head with a Concentration of approx. 10 mass%.

Claims (8)

1. A process for the preparation of liquid manure with recovery of valuable material, characterized in that the liquid manure is mixed with at least 0.4% by weight peroxodisulfuric acid and / or its salts, heated to a temperature of over 60 degrees Celsius, the solid which separates out and ammonia is obtained from the remaining solution. 2. The method according to claim 1, characterized in that ammonium and / or magnesium peroxodisulfate or ammonium peroxodisulfate and Magnesium hydroxide can be added to the manure. 3. The method according to claim 2, characterized in that 5 to 7 g / l Ammonium and / or magnesium peroxodisulfate or ammonium peroxodi sulfate and magnesium hydroxide are added to the manure. 4. The method according to any one of claims 1 to 3, characterized in that is heated to 90 to 100 ° C. 5. The method according to any one of claims 1 to 4, characterized in that the remaining solution with thermophilic microorganisms for extraction is treated by methane-rich fuel gas. 6. The method according to any one of claims 1 to 5, characterized in that the ammonia obtained for the production of manure processing ammonium peroxodisulfate to be added is used. 7. The method according to any one of claims 1 to 6, characterized in that the separated solid is used as fertilizer. 8. The method according to any one of claims 1 to 6, characterized in that the separating solid as an additive for the production of bricks is used.