ES2341529A1 - Apparatus for bioremediation of soil contaminated with organic compounds - Google Patents

Abstract

This invention relates to an apparatus for the bioremediation of soil contaminated with organic compounds, preferably meant for portable use, comprising a bioreactor tank in which the soil is placed and characterized in that the gases injected during the process by means of strong, forced aeration, having a homogeneous distribution of oxygen are recirculated, such that the tainted gas is discharged to the outside after treatment inside same apparatus. The apparatus also causes the leachates generated in sufficiently high volume to periodically recirculate in order to obtain a high humidity content and a homogeneous distribution of the humidity, the nutrients and the micro-organisms. In order to counteract resistance to oxygen diffusion owing to the soil's high humidity, high-intensity injections or recirculation are used. The combination of both types of recirculation optimizes biodegradation performance and conditions with a minimal environmental impact.

Description

Equipment for bioremediation of contaminated soils with organic compounds

Object of the invention

The invention corresponds to the technical sector of recovery processes of soils contaminated by compounds organic, specifically biological degradation processes aerobics.

Organic soil contaminants are from very variable nature (oils, oils, gasoline, phytosanitary, etc.) and its presence in soils is due to various human activities (industry, transport, agriculture, etc.).

Hydrocarbons are part of the most common contaminants in the soil due to increased use of petroleum products worldwide. These pollutants are a significant risk to human health and For the enviroment. The development of regulations regarding Decontamination and recovery of contaminated soils requires development of processes that are more efficient and less expensive.

Background of the invention

Bioremediation is one of the most common remediation processes of this type / contamination. Bioremediation techniques can be in situ or ex situ . In situ techniques include bioairration, improved biodegradation, phytoremediation, injection of compressed air and natural attenuation.

If, due to site conditions, remediation cannot be carried out on site or if you simply want to optimize the technique, alternative ex situ techniques such as composting, landfarming and biopiles can be used. These techniques can be performed on-site, at the site where it is on the ground to be treated, or off-site, at facilities located outside it. When possible, contaminated soils are usually treated more effectively if biological treatment is performed ex-situ (Alexander, M., 1999; Biodegradation and Bioremediaticn; 2nd ed, Academic Press, San Diego, California), since Addition of necessary nutrients such as nitrogen and phosphorus, moisture, surfactants, bacteria, and oxygen, as well as the monitoring of the parameters that control the evolution of the process, can be performed more easily than in situ .

One of the most studied techniques, within the Biological process of soil remediation are biopiles (Von Fahnestock, F.M .; Wickramanayake, G.B .; Kratzke, R.J .; Major, W.R .; 1997; Biopile design, operation and maintenance handbook for treating hydrocarbon-contaminated soils; United States: Battelle Press). As the common processes of bioremediation, the basic principle of action of biopiles is the transformation of biodegradable soil contaminants into harmless products, taking advantage of the action of certain microorganisms present in the soil under controlled conditions, with the particularity that the soil is excavated, conditioned and Place in batteries.

If the biopile system develops at weathering, the significant presence of organic compounds volatile and its emission into the atmosphere without prior purification, can present a non-negligible environmental impact. On the other hand, the Development of these techniques requires a lot of space, since the soil after being extracted must be stacked in an area specific for it. In order to optimize the applicability of this Technology is necessary to introduce some improvements to the system.

In order to improve the biopile technique, the bioreactor technology is one of the most appropriate since allows the controlled and efficient combination of chemical processes, physical and biological, which improve and accelerate biodegradation, of same way that allows to control the pollutant emissions of the process (Riser-Roberts, E. (1998). Remediation of petroleum contaminated soils. Lewis Publishers). As an example of what Above are the following reactors:

The Institute for Ecology of Industrial Areas of Poland (Institute of Ecology for Industrial Areas) in its Production-Scale Implementation of document Petroleum Contaminated Soils Bioreactor (2000) designs, builds and starts up a closed reactor for bioremediation of Small volumes of contaminated soil. The air is injected by the lower zone of the reactor, in which the temperature is measured, the oxygen content and soil moisture, in continuous. He experiment lasts for 97 days in which the gas outlet current. The decrease in HTP (Hydrocarbons Total Oil) is approximately 50% of the value initial.

Berry, C. (2005), Bioremediation of Petroleum and Radiological Contaminated Soil Using an Ex Situ Bioreactor. PhD thesis Georgia Institute of Technology, developed a reactor to treat soils contaminated by hydrocarbons and radiation through a system based on bioairration. The concentration of oxygen in the soil, humidity and temperature are determining parameters for this process that lasts for 22 months. The decrease in HTP is 99% of the initial value.

The Naval Facilities Engineering Service Center (NFESC) (1998) designs the technique called "Biocell". It is about of a bioremediation system in a closed container where aerobic microorganisms carry out the elimination of hydrocarbons present in the soil. In this system the compounds volatile organics generated during the process are treated with a active carbon column.

An apparatus is known from US 5249368 transportable to carry out the biological remediation of Small amounts of contaminated soil. The purpose of said apparatus is to decontaminate small amounts of soil (less than 1000 Y3 = 765 m 3) in places where there is not much space; the leachates generated in this process are not recirculated within the reactor and require a treatment; another disadvantage of this system is that the reactor exhaust gases are expelled to the atmosphere.

Patent document US 4962034 publishes a procedure for the biological treatment of contaminated soils in fixed concrete reactor. The object of the invention is control the migration of pollution to both the atmosphere and to the ground, by using a closed concrete reactor in which leachates generated are collected to be subsequently recirculated within the system through a system spraying; when the liquid is added, it drags the volatile pollutants that accumulate in the upper zone from the reactor and reintroduces them to the ground. It is a fixed reactor whose construction must be done by civil works, being considerable space requirements for your building.

It is known by the KR document 4068638-A reactor for soil remediation contaminated using a specialized inoculum. This reactor recirculates the leachate generated in the process according to moisture needs ground.

In none of the processes described is performed recirculation with reactor exhaust gases.

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Description of the invention

The present invention aims to degrade soils contaminated by organic compounds by means of ex situ -on-site technology with aerobic bioreactor that improves the reference technique (biopiles). It combines the benefits of recirculating both the leachate generated in the process and the exhaust gases. The first in order to maintain the moisture and nutrients necessary for bioremediation in the soil, avoid the migration of contamination abroad and achieve a certain degree of leachate purification. The second causes the volatile organic compounds present in the exhaust gases to be treated again by the soil itself, preventing its migration to the atmosphere; This reduces or, directly, eliminates the need for secondary treatment of the current of this gas. All of the above, in a transportable bioreactor and adaptable to the specific needs of each case.

In order to optimize the conditions of biodegradation, treatment yields and at the same time reduce their costs, the following objectives have been raised:

Decrease the time needed for bioremediation and achieve homogeneous degradation throughout the mass of soil.

Improve the degree of modularity and transportability of the reactors.

Minimize the environmental impact.

The present invention is based on knowledge of the processes of biological degradation, which is carried out in a closed bioreactor in which, by optimizing the operating parameters, biodegradation processes are accelerated aerobic For this, the design includes the features explained below compared to the parameters Operational of biopile technology:

In the biopiles the aeration is low to reduce moisture loss and volatile emission. It can facilitate the formation of preferential pathways, heterogeneity of oxygenation with the consequent heterogeneity of the degradation and creation of anoxic / anaerobic zones both at the level of macropores as at the micropore level.

Against the foregoing, the present invention is characterized by the use of forced aeration of intensity, ie instantaneous high aeration rates from the lower area of the bioreactor that allow a distribution homogeneous spatial oxygen. This minimizes the preferential path formation and homogeneity is achieved in the oxygenation (at the macropore and micropore level due to internal aerodynamics provoked).

This invention is distinguished by the incorporation of a closed gas recirculation system with a speed aeration snapshot, whose value is given depending on the type of soil. This generates a better distribution and homogenization of the air in the ground that will result in an increase in speed of degradation as a result of the decrease in probability of finding anaerobic zones, that is, reducing the possibility that oxygen is a limiting factor for Bacterial growth.

Excessive air flow favors rapid soil desiccation in addition to desorption and entrainment of gas phase contamination. This is solved with the recirculation of the gases that are made intermittently commanded by the oxygen concentration in the bioreactor floor. Thus, the oxygen incorporated into the reactor is maximized.

Thanks to this system, organic compounds trailed volatiles are re-incorporated into the bioreactor to be degraded by microorganisms. During the biodegradation it goes away producing oxygen consumption, until in a given moment the oxygen content of the gas that circulates through the bioreactor reaches a certain minimum value; to make up for it it doses external air to the system and the gas outlet of the same. In this way the stoichiometry of the process.

The minimum necessary purge of the exhaust gases from the bioreactor to the outside is done after the treatment of said gases, either with activated carbon or other purification system, to avoid the emission of pollutants into the atmosphere.

Within the meaning of the present invention, means "external oxygen supply" the feeding of atmospheric air or pure oxygen to the reactor; "recirculation of gases "the action of recirculating gases whose content of oxygen is less than ambient air; and as "gas purge" the exit of gases from the reactor that takes place during the moments of "external oxygen supply".

The present invention achieves an advantage maximum oxygen through a closed aeration system, which allows to control the needs of oxygen incorporation external. To reduce energy consumption and gas volume to treat, external oxygen supply and recirculation pumps gases are only put into operation when the concentration of oxygen in the bioreactor falls below a certain value, and it stop when a sufficient concentration is reached for the aerobic biodegradation Thanks to the recirculation system of gases, the gases that leave the bioreactor will have concentrations minors of volatile organic pollutants; therefore his treatment can be done with a simple method of depuration.

Unlike some types of biopiles in that gases are emitted without control to the atmosphere, in the The present invention proposes closed circuit aeration by recirculation of the injected air. This causes a biological treatment of volatile organic compounds present in the recirculated gases by passing them through the column of the soil itself to be treated, which in the degradation phase It would work as a biofilter.

In a conventional biopile, the application of strong aeration can cause moisture to creep from soil with the consequent drying of the biopile and the slowdown of Biodegradation In the present invention we work with a circuit closed aeration, with a gas recirculation system, so even if strong aerations are applied, the soil moisture and, therefore, biodegradation in conditions optimal.

In the present invention the incorporation of oxygen into the bioremediation process, which can be by air or with pure oxygen; this requires a periodic purge of gas that in turn drags moisture. Therefore it is considered the also periodic incorporation of moisture to maintain the amount of suitable water inside. This is achieved because the leachates generated in the filtration of water through the soil are Recirculate inside the bioreactor.

The present invention operates with a level of high humidity that produces permeate, carrying out the recirculation of water in order to avoid that in some area of the column of the soil moisture is less than optimal.

Facing a possible vertical stratification of the moisture in the biopile after a timely humidification, the present invention achieves a more homogeneous distribution of moisture vertically in the soil mass, using the system of recirculation of leachates produced.

Facing a possible application of water in low flow rates that would result in the surface distribution of the water, the present heterogeneity invention makes an application of leachate with very high instantaneous flow rates, through a recirculation system consisting of a storage tank and distribution elements that guarantee a homogeneous distribution in the surface; functions commanded by level meters located in a leachate collection tank.

Facing the possible loss of nutrients in biopiles due to the extraction or purge of the leachate, the present invention achieves the maintenance of nutrient content in the soil through the recirculation of leachate.

This recirculation system provides a uniform distribution of nutrients and microorganisms in the soil, also allowing to maintain the optimum humidity for the process.

Facing a possible drag of compounds organic by circulating water, recirculation distributes vertically the same along the ground and this one works as a bacterial bed for treatment and purification.

Facing the possible spatial heterogeneity of Microbial species in a biopile, the present invention seeks a continuous realignment and redistribution through recirculation of leachates.

Advantages of the invention

The advantages of the reactor described, due fundamentally to the use of a recirculation system of the fluids, its transportable design and its procedure operation are:

Biodegradation of the contaminant through the increase in the speed of air passage in the pores without Increase the amount of air to be treated.

Achievement of partial degradation of Exhaust gases when treated by the soil itself.

Greater degree of transportability and modularity. The treatment is carried out in a reactor of dimensions adapted for road transport, and in any way simple increase the treatment capacity by simply increasing The number of reactors.

Alternatively you can adopt the configuration of fixed reactor.

Faster in the beginning of sanitation operations. The reactor has the basic elements to start the treatment once the excavation proceeds, so that the time that would be necessary for the on-site installation of the necessary equipment to favor biodegradation in other techniques is minimized.

Emission Control The treatment is carried out in a closed reactor that facilitates collection and treatment both of the liquid and gaseous emissions product of the bioremediation process.

In addition to reducing the amount of emissions in the process also reduces the pollution of these emissions Thanks to your treatment.

Decrease in the time required for the start of bioremediation of contaminated soil.

Flexibility in the process location of bioremediation by not depending on the environmental conditions of the contaminated site

When the external conditions of the reactor do not are suitable for bioremediation, there is the possibility of thermally insulating the reactor tank to favor the increase of temperatures inside and the speed of degradation, by a jacketed thermal coating, to example mode.

Description of the figures

To complement the description that is being performing and in order to help a better understanding of the characteristics of the invention, the present specification is accompanied Descriptive drawings showing the preferred embodiment, where, for illustrative and non-limiting purposes, it has been represented the next:

Figure 1.- Scheme of operation of the team.

Figure 2.- Operation scheme is shown of the bioreactor with recirculation.

Figure 3.- Operation scheme of a conventional aerated biopile.

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The previous figures show what next:

one.

Waterproof tank (bioreactor)

2.

Points for sampling

3.

Oxygen probe

Four.

Humidity probe

5.

Temperature probe

6.

Signal connection module

7.

Computer with software for storing data, data processing and pump command and valves

8.

External oxygen / recirculation pump of gases

9.

Exhaust gas purification reactor

10.

Gas recirculation pipe

eleven.

Outlet Gas Duct

12.

Oxygen inlet duct external to system

13.

Leachate collection tank

14.

Leachate Recirculation Pipe

fifteen.

Leachate level meters

16.

Leachate recirculation pump self-priming

17.

Leachate distribution device

18.

Automatic valve for oxygen inlet external

19.

Automatic valve for gas purge exit

twenty.

Automatic valve for recirculation of gas

twenty-one.

False background

22

Metal grid

2. 3.

Filter material

24.

Condensate Collection Tank

25.

Water addition

26.

Leachate Purge

27.

Expansion Deposit

100 \ hskip0.15cm Pump

101 \ hskip0.3cm Valve

102 \ hskip0.05cm Data collection line

103 Air circuit

104 Water circuit - leachate

The same references represent the same elements in Figure 3 of a conventional biopile, equivalent to in this case the numbers 1 ', 2', 3 ', 4', 5 ', 6', 7 ', 8' and 9 'to their corresponding figures in Figures 1 and 2.

Preferred Embodiment of the Invention

The invention consists of a discontinuous reactor with the appropriate dimensions to allow transport conventional road coupling to a tractor unit. At reactor is carried out a biological treatment designed for the recovery of soils contaminated by organic compounds.

The mobility of the equipment allows its transport of one location to another; being able to adopt, alternatively, the fixed reactor configuration.

The bioremediation team consists of the following elements (although under certain conditions they may not employ some of them or employ someone else): a deposit waterproof (1) resistant to corrosion constitutes the bioreactor, which it contains a false bottom (21), followed by a metal grid (22), on top of which a filter material (23) is placed; a system for the recirculation of gases in the reactor equipment, cooperating in This committed elements with the function of external oxygen input and other components that allow the exit of gases.

Gas recirculation consists of a gas recirculation pipe (10) coming out of the top of the tank, having an automatic valve on its way for gas recirculation (20), a collection tank for condensates (24) and an oxygen supply pump external / gas recirculation (8), to communicate this pipe with the bottom of the reactor in its false bottom (21).

The oxygen input into the tank (1) is performed by forced aeration from the lower zone to a instantaneous high aeration speed, whose value will come determined by the type of soil. This entry can be oxygen pure or air, and is done through an oxygen supply conduit external (12) aided by the oxygen supply pump external / gas recirculation (8); regulating this entry using the automatic valve (18). The gases go abroad by the outlet duct (11) after being purged in competition with the automatic valve for purging the exhaust gases (19), going through the gas purification reactor (9) before going to the atmosphere.

The leachate recirculation system it comprises an initial supply of water that is regulated by a valve (25); water seeps through the ground, naming the liquid after this phase, leached; distribution device leachate (17) located in the upper area of the tank; tank of leachate collection (13); leachate recirculation pump self-priming (16); condensate collection tank (24) and pipe leachate recirculation (14).

Control of the gas recirculation system It is composed of: one or several oxygen probes (3), one or several humidity probes (4), one or several temperature probes (5), a signal connection module (6) of the probes, and a computer with software (7) for data storage, data processing and command of the pump (8) and the valves that determine the gas recirculation (18, 19, 20).

The leachate level meters (15) are placed in the leachate collection tank (13) that control their recirculation inside the tank (1).

The sampling points (2) are necessary in case any probe fails or simply to perform Measurements of other parameters.

Contaminated soil, previously conditioned (addition of moisture, nutrients, sponge agents, planting of microorganisms and / or any other type of pretreatment) is introduced into the tank (1). It is placed there on the filter material (23) (it can be granular filter material or a geotextile) which in turn is on a metal grid (22); These two elements will allow leachate drainage and optimal air distribution. As the soil is introduced, the oxygen probe (3) is placed to measure the oxygen consumption by the microorganisms, the humidity probe (4) and the temperature probe (5). The arrangement and number of probes within the reservoir (1) must be such that the information they generate is representative of the entire volume of the soil. This information, through the signal connection module (6), goes to a computer (7) that continuously records the data supplied by all probes, produces the results and operates the automatic valves (18, 19 and
twenty).

Through the oxygen supply pump external / gas recirculation (8) air is fed to the false bottom (twenty-one); this circulates through the metal grid (22) and the system filter (23) up and through the ground, leaving from the side upper tank (1) through the gas recirculation pipe (10) At this point the system can work in two ways:

Recirculating the gases: With the valves (18) and (19) closed and the valve (20) open, the gas arrives again by means of the pump (8) to the tank (1) through the pipe gas recirculation (10). The gas recirculation is carried out in intermittently and is commanded by oxygen concentration in the contaminated soil, such that when the oxygen in the low ground of a setpoint value is activated the system of gas recirculation for sufficient time for mixing of the gas evenly in the system (soil, all tank and gas recirculation pipe). When after this mixed oxygen concentration reaches critical values for degradation, that is, when new air is needed to enter system, the following form of work is given.

External oxygen inlet: With valves (18) and (19) open and the valve (20) closed, a discharge of stale gas into the atmosphere through the gas duct outlet (11), previously passing through the purification reactor of gases (9) consisting of a tank in which a adsorbent material of organic molecules, for example carbon active, through which the gas stream is passed, being adsorbed the remaining organic compounds present in the gas, previously purging into the valve (19) for this purpose; and the external oxygen is introduced to the system through the inlet duct of external oxygen (12) by means of the pump (8). In this way, the oxygen concentration in the contaminated soil reaches a value suitable for biodegradation and the cycles of gas recirculation

The moisture found in the pipe gas recirculation (10) condenses and goes to the tank condensate collection (24).

The gas recirculation pipe (10) Contains an expansion tank (27) in order to maintain the system in depression or over pressure.

In the initial starting condition, the ground it contains a humidity equal to the field capacity together with a volume of excess circulating water sufficient to perform the recirculation of said water in the form of leachate. The application of leachate is done with very high instantaneous flows, which ensure the surface distribution of the same with height of low waterlogging

The recirculation of leachates generated it produces the humidification of the soil, and is done intermittently in an instantaneous flow pump, depending on the maximum volume stored in the collection tank (13), the recirculation by a timer or by the values collected by the level meters (15) or by the humidity probes, or by the combination of the variables and components mentioned. Recirculation leachate (14) is carried out by means of the pump (16) and its dispersion inside the bioreactor tank (1) it is done from top to bottom, by means of the distribution device (17) located in the area top of the bioreactor. The organic compounds contained in the leachate are percolating along the ground, functioning as a bacterial bed for treatment and purification.

The leachate falls to the false bottom (21) that will present a punctual or permanent inclination that will allow its collection in the leachate collection tank (13). Cited tilt can be designed on the false bottom (21) of the tank permanent mode, or, as in the case of the planes shown, achieve the unevenness only at specific times when precise this leachate output function, by light lifting of the trailer where it is transported or, in the case of a reactor fixed, with a chock element that causes this position.

In case of external weather conditions unfavorable, the bioreactor may have a system of heating that can be, by gas heating system, of leachate or from the deposit itself.

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Example of realization

The operation of a pilot plant of the described process (Figure 2), comparing it with the operation of the biopile technique process, (Figure 3), with the following particularities:

Two pilot scale models have been arranged composed of methacrylate columns that function as Deposit; column A, (Figure 2), and B, (Figure 3). Both have the same pollution conditions, organic matter, nutrients, external temperature, etc., and only differ from each other in the process of Aeration and initial moisture. Column A corresponds to a Bioreactor with Recirculation, object of the invention and column B It is an aerated Conventional Biopila. In both cases the Air flow is ascending. The measurements of the columns are: diameter 200 mm and height 800 mm.

Contaminated soil is introduced into the tank of the reactor (1, 1 '), columns A and B, respectively. In the holes in each column have holes for sampling the probes (2, 2 ').

At the top of each column is introduce the process control elements: probe or probes oxygen (3, 3 '), humidity probe or probes (4, 4') and probe or probes of temperature (5, 5 '), which are located inside the ground contaminated as the columns are filled. The information generated by the probes, through the module signal connection (6, 6 '), goes to a computer (7, 7') that registers continuously the data supplied by all probes, elaborates the results and triggers the various automatic valves.

In column A the oxygen supply pump external / gas recirculation (8) introduces air through the ground by the bottom of the tank (1); this air leaves the tank at the top through the recirculation pipe of gases (10). At this point the system can operate in two forms, with recirculation of gases or with the entry of oxygen external, according to the parameters and exposed operation previously.

Leachate collection is carried out in the leachate collection tank (13). The recirculation of the leachate (14) is commanded by the soil probes, by a timer, by level meters (15) or by a combination of the above elements, in competition with the bomb recirculation (16).

Leachate recirculation (14) is performed by means of the pump (16) and its distribution inside the tank of the bioreactor (1) is made from above by means of the device distribution (17).

In the case of column B, the aeration is performs in open circuit; an aeration pump (8 ') introduces external oxygen to the system through the lower area of the tank reactor (1 '). Aeration is commanded by the concentration of oxygen in the contaminated soil; when reaching a minimum of oxygen established the external oxygen supply pump (8 ') is operated, and when it reaches the maximum set it stops. The outlet gas is treats in the gas purification reactor (9 ') before being discharged into the atmosphere No recirculation, either of gases or of leachate is done in this reactor.

The pumps used for oxygen supply External / gas recirculation (8, 8 ') in both columns are pumps of emptiness. The leachate recirculation pump (16) of the column A is a peristaltic pump.

Both columns were introduced in a room with controlled temperature and in darkness.

The main operational data are indicated at continuation. A soil was used for experimentation whose Dry composition was 96.4% sand and 3.6% humus, and it was mixed with commercial diesel (initial contamination value 10000 mg / kg dry weight). The empirical formula obtained for diesel was C16H34 and its aliphatic / aromatic ratio 84/16. Before entering it in the columns, the ground was kept in contact with the diesel in deposits closed for four months, after which a average value of H.T.P of 7000 mg / kg. A speed was applied aeration snapshot of 12.7 m / h in column A and 0.44 m / h in column B. The nutrients added to the soil for both columns were nitrogen and phosphorus in a Carbon ratio, Nitrogen, Phosphorus (C: N: P) 100: 10: 2; and the initial humidities were 15% w / w in column A and 8% w / w for column B. The daily recirculation of leachates generated in the pilot plant of the process object of invention (column A) was 75% of the volume Total generated The external working temperature for both columns remained close to 30 ° C throughout the experimentation.

The results are shown in the Table below. shows below, indicating the accumulated oxygen consumption in both columns over 11 weeks of experimentation.

Curve 1 represents the cumulative consumption of oxygen for column A, and curve 2 the cumulative consumption of oxygen for column B. The horizontal axis represents the time in weeks and oxygen consumption is expressed in grams. Taking into account the stoichiometry of the reactions involved in the process, theoretically it is possible to study the evolution of the degradation through the measurement of oxygen consumption (methods respirometric). Each gram of H.T.P. (Total Hydrocarbons of Petroleum) consumes 3.47 grams of oxygen in its degradation aerobic

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one

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Both curves (1 and 2) experience an increase charged with oxygen consumed in week 1, this due possibly to the degradation of organic matter easily biodegradable (humus) by means of soil microorganisms. In column A, as can be seen in curve 1, oxygen consumption experience acceleration during weeks 2, 3, 4, 5, and 6. A from there the oxygen consumption slows down and tends to stabilize throughout weeks 7, 8, 9, 10 and 11 of experimentation. In the case of column B, (curve 2) the speed consumption during weeks 2 to 6 is lower than in the case anterior (column A) and remains almost constant for practically the entire period of experimentation.

Comparing the above with the H.T.P. values measured throughout the experiment is note that in week 6 the percentage of decrease in H.T.P. in column A was 61% of the initial value, which meant approximately 90% of the decrease in TPH in the entire Experimentation period After six weeks of experimentation, the floor of column A shows a decrease in the speed of degradation, so an option to reduce costs of treatment would be to remove it from the bioreactor and proceed to its treatment under less demanding control conditions. The Results obtained indicate that the design and construction of the Bioreactor with Recirculation (Column A) together with the system process monitoring should provide a useful tool for the remediation of soil contaminated by organic compounds, in this case, hydrocarbons.

Claims (19)

1. Equipment for bioremediation of contaminated soils with organic compounds, by aerobic biodegradation, of the that work with a leachate recirculation system, which understands: a sealed tank (1), a gas recirculation system, external oxygen supply conduit (12), gas outlet components. 2. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that the lower part of the tank (1) contains a false bottom (21), on top of which a metal grid (22) is arranged, being placed above the grid a filter material (23). 3. Equipment for bioremediation of contaminated soils, according to the preceding claims, characterized in that the gas recirculation system is composed of a gas recirculation pipe (10) that leaves the upper part of the tank (1); presenting a recirculation valve (20), a condensate collection tank (24) and an external oxygen supply pump (8); said pipe communicating with the bottom of the tank in the false bottom (21). 4. Equipment for bioremediation of contaminated soils, according to the preceding claims, characterized in that the gas recirculation pipe (10) has an expansion tank (27), in order to keep the system in depression or overpressure. 5. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that both pure oxygen and air can be introduced through the oxygen supply duct to the system, cooperating with a contribution pump at this inlet (8), regulating this contribution by means of an automatic valve (18). 6. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that the gas outlet is composed of a conduit (11) that has an automatic valve (19) that purges these outlet gases, passing through a purification reactor for these gases (9) consisting of a reservoir in which an adsorbent material of organic molecules is introduced. 7. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that the entry of oxygen into the tank (1) is carried out by means of forced aeration from the lower area of the tank at an instantaneous high aeration rate. 8. Equipment for bioremediation of contaminated soils, according to the preceding claims, characterized by treating the volatile organic compounds present in the gases recirculated to the system, by passing them through the soil column, which in the degradation phase operates as a biofilter 9. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that within the mass of soil that is placed inside the tank (1) are provided probes for measuring oxygen (3), humidity (4) and temperature (5). 10. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that the gas recirculation system is intermittent and is controlled by the concentration of oxygen measured in the soil; when this concentration falls below a setpoint, the gas recirculation is activated for a sufficient time for mixing the gas throughout the system (soil, tank and gas recirculation pipe). 11. Equipment for bioremediation of contaminated soils, according to the preceding claim, characterized in that when, after mixing caused by the recirculation of gases, the concentration of oxygen falls below a certain level, the external oxygen enters the system (12 ) by means of the input pump (8), with the exit of a volume of gas through the outlet duct (11). 12. Equipment for bioremediation of contaminated soils, according to the preceding claims, characterized in that the data provided by the probes introduced in the soil (3, 4 and 5) are processed in a computer (7) for the start-up of the pumps and valves of the gas recirculation system. 13. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that the wetting of the soil is carried out by means of the recirculation of the leachates generated, this being carried out intermittently, by means of a pumping of instantaneous flow dispersed by a distribution device (17) located in the upper area of the bioreactor tank (1). 14. Equipment for bioremediation of contaminated soils, according to the preceding claim, characterized in that the generation of said leachates is achieved with the presence in the soil of a humidity equal to the field capacity together with a sufficient volume of excess circulating water for perform the recirculation of said water in the form of leachate; realizing the application of leachate to the ground with very high instantaneous flows, which ensure the distribution of the leachate over the entire surface of the soil, generating a low pooling height. 15. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that it has an external leachate collection tank (13) for storing the leachates generated in the process. 16. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that the frequency and volume of leachate recirculation is commanded by a timer or by the values collected by the level meters (15), or by the marked values by the probes, or, in a combination of the above parameters, which coordinate the operation of a pump (16). 17. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that it can be a transportable modular reactor or be fixed in a location. 18. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that it has a heating system produced by heating the gas, the leachate or the tank itself. 19. Equipment for bioremediation of contaminated soils, according to claim 1, characterized in that the tank can be thermally insulated.