WO1998008781A1 - Upgrading purification of liquid manure - Google Patents

Abstract

The invention concerns a method which by the action of natural or concentrated humic acid on polluting fractions of the liquid manure or similar waste creates physico-chemical reactions which result in forming soluble complexes. The additives used, in particular humic acid, cause the reaction medium temperature to rise, especially when the polarisation of the particles is simultaneous. These additives and these conditions enable the instant and continuous treatment for cleansing liquid manure and consequently the production of mobile equipment provided with known mechanical components for filtering, concentrating and separating the polluting fractions of liquid manure. The methods result in obtaining humate containing ammonia and magnesium with gradual solubility for soil improvement and filtered water which can be discharged in the natural environment.

Description

 PURIFICATION RECOVERY OF MANURE

The present invention implements the methods and products which advantageously ensure the export of local surpluses of livestock waste by separating their components beforehand in organo-mineral fertilizer for dry matter and the rest in aqueous filtrate.

The intensification and the very high concentration of intensive farming, in particular in pig production often causes the practical impossibility of ensuring the purification of these farming effluents by reasoned spreading alone. Specialists have identified a number of areas with a structural surplus, that is to say within the geographical limit of which there is no longer any compatibility between the production of liquid manure and the purifying capacity of the soil available for spreading.

Numerous attempts have already been tried for this purpose with results which are often random, therefore not very industrializable or reproducible or even of limited or even zero economic interest. The chemical reactions induced by the mixture of raw raw materials necessary for these transformations in natural conditions are very long and often of the order of 20 to 50 days at temperate ambient temperatures of between 10 and 20 "C. approximately. Inspired by ancient work used in the manufacture of the first chemical fertilizers composed a few decades ago, the same approach was taken with industrial chemicals.

This is how we studied this possibility of depolluting manure with the use of phosphoric acid and then neutralizing the mixture with quicklime or calcium carbonate or ground magnesia. This technique is effectively effective in the treatment of liquid manure, since it allows the partial fixation of ammoniacal nitrogen from liquid manure in a form insoluble in water. However, this method requires still too long contact times of between 4 and 9 hours to guarantee the insolubilization of approximately 80% of the free nitrogen.

In the present invention, we first sought chemical or natural products which, mixed with slurry are essentially chosen according to their double action:

- purification of slurry through the combination with organic or mineral components which cause considerable polluting effects;

- fertilizing the soils on which they must be spread to harmoniously reintegrate the purifying cycle of the natural environment and thus partially offset the additional cost of depollution of the slurry. To guarantee these results, the fixation of the ammoniacal nitrogen present in the slurry was sought in the form of an alkaline ammonia-magnesium humate by substituting in the kinetics of the reaction described above all or part of the phosphoric acid required by 1 humic acid prepared for this purpose and favoring magnesia to neutralize the reaction media.

Obtaining the humic acid necessary for this reaction can be carried out directly by the introduction of the raw raw material, usually natural lignites, into the reactor or in the form of a more or less purified liquid industrial product which additionally allows a more precise dosage than the raw material above.

The extraction of the ammonia-magnesium humates thus obtained by filtration is greatly facilitated by their very low solubility in water.

Thus, by this new method, almost all of the polluting components are concentrated in humic complexes intended by complementary treatments to become organo-mineral fertilizers on the one hand. On the other hand, most of the initial slurry water has become a filtrate, the final purification of which by membrane techniques becomes economically possible. We can then consider the rejection of the permeates thus obtained in the natural environment. These latter operations with the use of membranes also produce liquid concentrates in very limited volume which can also be used in agricultural fertilization in this form.

Chlorination or any other method of drinking water can be used efficiently and for safety on eluates before their discharge as well as oxygenation mechanical in order to make them biologically more compatible with the natural receiving environment.

The present invention also includes adapting technical improvements which favor the regular progress and the speed of these reactions, and in particular:

- the creation of electric fields by a partial electrolysis of the aqueous medium, which causes on the one hand the migration of the colloidal particles, increases the probability of their meeting, therefore favors both the speed and the intensity of the reactions between the particles , and thereby favorably directs the flocculation. On the other hand, the emission of electrons favoring the reactions limits their duration to a few minutes;

- Continuous cleaning of the electrodes so as not to alter their operation and therefore see, in the suspensions loaded with organic matter, the useful actions of these electrodes decrease rapidly;

- the geometry of the reactors adapted to the kinetics of the physicochemical bonds sought by bringing as close as possible, for safety reasons, the distances between the electrodes reducing the duration of the reactions between 1 and 5 minutes;

- the contacting of the various components of the slurries and the chemical additives retained in this process promotes a phenomenon of natural exothermic reaction amplified by the thermal insulation of the reactors which limits the losses by radiation. It is thus possible to obtain a significant rise in the temperature of the mixture thus brought to between 50 and 70 ° C. depending on the dry extract concentrations of the mixtures.

- The present invention, by the reduction, the compactness and the reduced number of components necessary for the smooth running of the physico-chemical treatments described above with the use of the raw materials mentioned, very largely limits the size and the mass of the devices to implement and therefore makes them easily movable.

Thus, all the devices necessary for the purification of slurry according to this method can be usefully placed on a trailer or agricultural platform or road, and thus respond more specifically to the legislative provisions which recommend the on-site treatment of pollution sources to avoid the health risks that their dispersion would entail.

Claims

1./- Process for the depollution of fermentable organic waste and more particularly of recent or fermented liquid or semi-liquid animal excrement after prolonged storage. The process is characterized in that the mineral or organic chemical elements in suspension or dissolved in the aqueous phase of the waste are brought into very intimate contact with the natural humic acid of lignite or the concentrated humic acid obtained by treatment of the ore of lignite with phosphoric acid to form an organo-mineral fertilizing complex. 2./- A method of depolluting organic waste such as more or less liquid manure, characterized in that the polluting elements of these manures are brought into intimate contact with the lignite and then with phosphoric acid in a closed reactor continuously supplied with '' a mechanical system for removing solid particles. The reaction preferably being carried out in order to provide 3 to 10 minutes of contact with the additives at mixing speeds of 100 to 400 revolutions per minute. 3./- depollution process according to either of claims 1 and 2 characterized in that the conditions of contacting pollutants and additives, lignite and phosphoric acid, are sought to cause by exothermic reaction a significant increase in the temperature of all the chemical elements in contact in the reactor. 4- / ~ depollution method according to claim 3 characterized in that the temperature rise caused by the exothermic chemical reactions when the dry extract of pollutants passes from 2 to 20% approximately, increases from 10 to 30 degrees centigrade approximately, and therefore significantly shortens the reaction time. 5. / - Depollution process according to one or the other of the preceding claims, characterized in that the factors Soluble pollutants are fixed by the reactions in the form of stable, semi-insoluble organo-mineral complexes which essentially precipitate. Pollution factors based on nitrogen and phosphorus combine to form complexes of humates and ammonia-alkaline phosphates insoluble in water. 6./- depollution method according to one or other of claims 1, 2, 3, 4, 5, characterized in that the kinetics of the desired reactions is accelerated notably by the polarization of the polluting organic or chemical particles. This polarization is caused by partial electrolysis of polluted aqueous discharges. 7./- depollution method according to claim 6 characterized in that 1 * partial electrolysis of the aqueous solutions concerned can be validly ensured by the emission of a voltage current between 10 and 24 volts, with an intensity of 20 to 50 amps, for a flow of approximately 1000 liters of pig manure per hour. 8./- depollution process according to one or other of the preceding claims, characterized in that it leads to the production of organo-mineral fertilizers which are insoluble by surface water runoff. The polluting elements combined according to the methods and with the additives described in the preceding claims are only dissolved for the benefit of plants by the action of enzymes from endogenous microorganisms in the soil.