FR2748676A1 - METHOD OF CLEANING POROUS SURFACES WITH A WASHING LIQUID CONTAINING BACTERIA HAVING ENZYMATIC ACTIVITY - Google Patents

Abstract

The cleaning method involves spraying the porous surface with an aqueous preparation containing bacteria, such as pseudomonas or moraxella, with an enzymic activity producing a hydrolysis of hydrocarbons by bio-surfactants or natural surfactants. After leaving the preparation to work for an appropriate time it is rinsed off and recovered by suction, together with any residues. The area to be cleaned can be pre-treated by spraying it with a liquid at a pressure of under 90 bars and a temperature below 60 deg C, recovering the liquid after a period of some 5-20 min. The pre-treatment liquid comprises a 1-2 per cent aqueous solution of a biosurfactant complex derived from bacteria with an associated biodegradable surfactant. The enzyme and biosurfactant solutions can be produced on the spot with reactors, and the surface to be treated can be pre-cleaned mechanically with brushes if it has accumulated surface deposits.

Description

The present invention relates to a method of cleaning surfaces

  porous surfaces, in particular surface coatings such as

".

  Surface coatings, known as "drainage coatings", which are used more particularly as pavements of roads or other surfaces of

  the purpose of the rapid evacuation of rainwater in order to keep

  characteristics, particularly as regards the adhesion of vehicles

  because they prevent the risk of slipping and water surfaces

  stagnant. Usually, layers of 4 to 5 cm thick are used.

  bitumen coated with gravel with typically 0/10 or 0/14 for grain size. These porous, unsealed layers are arranged on a sealed substrate, usually made of concrete. Similar porous coatings

  have been used for tennis courts, for example.

  The draining mixes comprise, when they are put in place, empty cavities communicating with each other, preferably representing 10 to 20% of their total volume, which allow the flow of water. This type of coating however has the disadvantage that the cavities fill more or less

  waste, leading to a decrease in

  carrying the initial porosity. The filling of cavities is mainly

  by soil and sand up to 95% and by various compounds, mostly petroleum residues, rubber powder, metals, carbon, organic materials, ... often of the order of 5% . These 5% of

  various compounds agglomerate the sands by transforming them into a

  pact and waterproof. In addition, in the presence of organic materials, it has also been found that an impermeable surface layer forms on the surface of the draining mix. If the total volume of the cavities exceeds 30%, there is a risk of foul pollution by accumulation of stagnant water loaded with organic matter. It is therefore not possible to significantly increase the importance of

  cavities in order to delay their clogging.

  Whatever the nature of the draining asphalt, infiltration clogging and clogging accumulation is inevitable. Clogging is generally faster in urban areas than in open country, the nature of clogging and

  clogging mechanism being different.

  A cross-section of a draining asphalt often leads to the observation of two layers of pollution: a predominantly organic pollution

  is observed on the surface while petroleum products agglomerating

  blues and gravel are dominant in depth.

  In order to preserve the coating's initial qualities, it is necessary to carry out cleaning or maintenance operations of the draining mixes, whose purpose is the total or at least partial restoration of their porosity by eliminating the waste that has accumulated in the cavities. Similarly, pedestrian spaces, squares and other road surfaces must be treated for

  ensure their cleanliness and renovate the colors.

  Maintenance operations on draining asphalt using cleaning devices using high-pressure water began around 1990 when it was found that the draining mixes lost their ability to evacuate water over time. Traditionally, the cleaning materials used are autonomous. They have a large storage tank ranging from 2,500 to

  20,000 liters. The known principles of cleaning the draining

  on two main operations: * Spraying water at high pressure (between 40 and 250 bar) to destroy the

  cohesion between sands and agglomerating compounds.

  * Suction by a vacuum turbine capable of sucking between 20,000 and

35,000 m3 / h.

  Cleaning materials usually used can vary: * the spray pressure which is all the higher as the draining asphalt is clogged, * the flow of water, * the orientation of the jets, * the speed of progress which is all the more slow as the draining asphalt is clogged, the number of passages.

  The cleaning processes used so far all suffer from

  it is advisable to pack the sands and clogging in the cavities of the asphalt

  under the effect of the pressure of water directed more or less vertically. This gives a simple temporary improvement due to the settling effect of materials and waste filling cavities without providing a real solution to the problem.

  problem of cleaning and restoring the initial porosity of the coating

  is lying. The agglomerating products remain around the sands and gravels that do not

  their mobility and which can not be extracted during the

  ration. Due to the settlement of materials and waste that are not extracted

  by this type of cleaning, a subsequent cleaning is then all the more difficult.

  In addition, the aspirations involved that are very powerful can produce detachments of the asphalt layer, which accelerates the destruction.

  of the asphalt asphalt surface without responding to the problem.

  For example, cleaning work, according to the traditional process de-

  above, of a draining asphalt surfaced in August 1992, was carried out on the Paris ring road in November 1993, after a first cleaning in March 1993. The granulometric analysis of products capping the slow route gives the following results: : <2 pm 0.3 2-20 glm 2.6 -50 gm 1.5 -200 um 6.1 -2000 gm 32.9> 2000 gm 56.6

  We note, whatever the imperfections of the method of analysis

  lysis, which was essentially extracted from gravel and coarse sands with more than 90% of particles larger than 200 gm. These sands and gravels were agglomerated to each other by hydrocarbons, rubber powder and various organic materials.

  The only use of mechanico-hydraulic cleaning machines

  santes is therefore not satisfactory to restore the porosity of the draining mix. It is obviously impossible to proceed with a scarification of the coating because it would lose its essential qualities. The use of soaps, detergents, or solvents for the degradation of the agglomerating products is not possible, or even contraindicated or prohibited, as contrary to the requirements of environmental protection. They can also destroy the bitumens that coat the gravels of the draining asphalt. Agglomerating products are only moved but not destroyed. They can resume their negative activity. Their accumulation can

to be dangerous.

  As a result, the subject of the present invention is a cleaning method of

  porous surfaces, such as draining mixes used as

  roads or other public or private roads, which

  disadvantages of the known processes and to restore the initial porosity without

  damaging the surface and without the settling effect of materials and waste

  matting, and which allows to extract the waste by respecting the requirements of

Environmental Protection.

  In order to achieve these objectives, the present invention proposes a solution

  effective for the maintenance of draining asphalt by washing the asphalt

  followed by rinsing and aspiration of the liquids and waste released.

  The invention more specifically proposes a cleaning process which is distinguished by the following operations: * Spreading of a washing liquid from the deep zone of the porous surface

  consisting of an aqueous preparation containing bacteria having an

  enzymatic activity, the enzymes produced which hydrolyze the hy-

  hydrocarbons due to biosurfactants or natural surfactants.

  After sufficient time for the washing liquid deep zone could act, spreading a liquid rinse, and its recovery by suction, and clogged residues. According to the invention, the washing itself can be preceded

  pretreatment of the superficial zone of the porous surface,

  solubilize the hydrocarbon particles which will then be biodegraded during the wash consisting of a bacterial treatment. Prewash liquid

  is obtained by dilution in water, for example 0.2 to 1%, of a

  biosurfactant plexus derived from bacteria, combined with a biodegradable surfactant.

  The destruction of the more or less tight surface layer can be

  facilitated by mechanical brushing prior to washing or prewashing.

  The washing operation is followed by a rinsing / suction operation after a sufficient time of action of the washing liquid on the deep zone. A rinse liquid is spread and then recovered by suction together with unclogged residues. According to the invention, the rinsing liquid is preferably water under pressure, of the order of 200 to 350 bar from the feed pumps, distributed inside a rinsing bell, by a rotary arm carrying ejection nozzles which have a small angle, of the order of 30 relative to the surface to be cleaned, and which are arranged at a distance advantageously between 40 and 60 mm from the surface to be cleaned. The flow

  rinse liquid is preferably about 1.5 liters per minute and per

  square meter of ground surface of the bell. The flushing bell, enclosing the nozzle carrying arm is kept at a fixed distance from the ground, and

  is sealed by a flexible seal, for example rubber, rubbing against

  heavily on the porous surface to be cleaned.

  Thus, the process according to the invention allows the destruction of the

  surface which could have formed on the surface of the porous coating of surfaces, then of the deep layer of products agglomerating the sands which

  found in the cavities porous surfaces coatings. Sand sands

  cavities find their mobility and can then be extracted from the

by suction.

  For carrying out the cleaning process, the invention proposes the use of a washing liquid containing enzymes and bacteria which essentially destroy the agglomerating products. The washing liquid is

  composed of water in which the enzymatic and bacterial solutions are diluted

  without the addition of solvents. These solutions are preferably produced in situ. The bacteria used in the context of the invention are advantageously pseudomonas, moraxella, bacillus alone or consortium (associated) with other bacteria that have a strong appetite for hydrocarbons. The exact type of bacteria or mixture of bacteria may vary and will be determined by

  depending on the type of clogging agents, particularly the predominant type of waste

  hydrocarbons and hydrocarbons identified on the site to be treated.

  The use of an enzymatic solution according to the invention is particularly interesting. Indeed, the enzymes take off the nutrients that the bacteria need thanks to their "bio-surfactant" or "natural surfactant" power, which brings food to bacteria. There is transfer of petroleum products by formation of macro- and microemulsions that increase the solubility of the binder. Enzymes hydrolyze hydrocarbon chemical chains to allow bacteria to digest

  hydrocarbon compounds with shorter chains. Bacteria renew themselves

  slow in about twenty minutes and produce new enzymes. In end of

  cycle, the bacteria release carbon dioxide, water, undigested

  rable. Enzymes and bacteria that remain in the draining mix after cleaning according to the invention remain as long as the bacteria find food

  from new projections of organic matter and that

  nimal is maintained. They prevent the accumulation of products agglomerating sand and gravel. The bacteria selected for the washing liquid are harmless to the environment and die when they no longer have sufficient food. The organic waste and hydrocarbons that fall on the road during its use and the cycle of the seasons contribute to a

  regular supply of food. The enzymes and bacteria used are not only

  biodegradable but biodegradable.

  The invention has the advantage of allowing the extraction of sands parti-

  clean, which can be landfilled without

  tion. The liquids recovered after being used to train the products

  glomerating agents are loaded with petroleum residues, various organic residues,

  dust, sand and gravel, of carbon powder, and a low concentration of

  enzymes and bacteria that are treated, if necessary, to achieve standardized concentrations of less than 1 ppm or 10 ppm

  and bacteria used, before discharge into existing sanitation networks.

  No pollution is to be feared because of these discharges because they are cleaned by

  bacteria like in a sewage treatment plant.

  The invention will be explained in more detail during the description

  examples of implementation that will follow.

  Porous surface cleaning operations such as coating

  said draining coatings according to the invention advantageously

  while the outside temperature is preferably between C and 30 C, in: In situ production of enzymatic and biosurfactant solutions from

  reactors adapted to the constraints of the sites to be treated. It may be a reaction

  stationary located near the areas to be cleaned, with filling of

  transport and spreading equipment, or mobile reactors brought to the

  third. * The mechanical cleaning by brushing the area to be treated if it presents

  superficial accumulations of materials.

  * Spreading at a pressure below 90 bar and at a lower temperature

  less than 60 C of a prewash liquid from the superficial zone of the porous surface and its recovery as necessary after a sufficient time,

  on the order of at least 5 to 20 minutes, so that he could act.

  * The spreading of a washing liquid from the deep zone of the porous surface.

  * After sufficient time for the washing liquid from the deep zone to

  could act, spreading a rinsing liquid, and recovery by suction.

  The process according to the invention is carried out by means of a

  China cleaning with powerful mechanico-hydraulic means.

  The prewash liquid of the superficial zone of the porous surface is advantageously obtained by dilution in water, for example, in a proportion of 0.2 to 1% of a complex of biosurfactant enzymes derived from microorganisms,

  acting as neutral detergents and surfactants compatible with cultural

  bacterial res found on site. The basic preparation usefully has the following characteristics: apparent density 1 pH between 10 and 12 pH in 1% solution between 8.5 and 11.5 viscosity <400 cts fully soluble in water In some cases it may be necessary to use a basic preparation complying with the standards AFNOR 72-150 (CMB = 0.1%) and AFNOR 72-200 (tested only on Candidae Albicans) (CMB = 0.2%). By way of non-limiting example, basic preparations corresponding to the preceding specifications are marketed under the name "BIOSURF" by the so-called

  "BIONERGIES" installed in Aubagne (Bouches-du-Rhône, France).

  The washing of the deep zone of the porous surface is carried out with an aqueous preparation containing bacteria selected according to their

  appetite for agglomerating products. It can advantageously be bac-

  pseudomonas, moraxella, bacillus, alone or better in consortium (associated) with other bacteria that have a strong appetite for hy-

  drocarbures. They produce enzymes that preferentially

  lysis of hydrocarbons and excrete biosurfactants and / or natural surfactants. The basic preparation is usefully obtained by the following method:

  * Collection of bacterial strains at the site to be cleaned before the operations

  cleaning procedures. The bacteria present on the site to be cleaned are the best adapted to the pollution to fight because they have by natural selection

  eliminated most other bacteria.

  * Selection of bacteria from samples to form a strain

  bacterial example of about 100 g.

  * Pre-development for a week or so of the bacterial strain

  in a biological reactor of about 1 m3 in warm water with a

  a favorable diet, that is to say under the provision of fats and nutrients,

  tation and oxygenation for good bacterial growth and

  creation of the corresponding exogenous enzymes.

  * Development for two days in a reactor of 7 to 8 m3 in warm water with a favorable diet, that is to say under the provision of fats and nutrients, agitation and oxygenation to have a good development

  bacterial secretion and corresponding exogenous enzymes.

  Rinsing / aspiration is carried out by mechanical means which

  in three stages: * mixing enzymes and sand, * taking off sand grains,

* aspiration of grains of sand.

  The rinsing liquid is preferably pressurized water, of the order of 200 to 350 bar from the feed pumps, distributed inside rinsing bells, by a rotating arm carrying nozzles. ejection. The flow rate of the rinsing liquid is preferably 1.5 liters per minute and per square meter of floor area of the bell. These nozzles have a small angle, of the order of 30 relative to the surface to be cleaned, o o almost tangent jets

  to the surface to be cleaned, which avoids any risk of settling. The clo

  rinse tube enclosing the nozzle support arm is maintained at a dis-

  fixed relative to the porous surface to be cleaned. It is waterproof

  by a flexible joint, for example rubber, rubbing lightly on the surface.

  porous face to clean. The distance between the ground and the ejector nozzles is

  preferably between 40 and 60 mm. The rotation of the arm carrying the nozzles creates a cy-

  hydraulic clone that generates a natural depression that is large enough to draw, by its sole force, the rinsing liquid which has taken up waste and

sand.

  The quantity of sand to be sucked can become very important, for example in the case of roads leaving a construction site. It could be raised more than 10 kg

  per square meter of rolling surface of certain areas of the perimeter boulevard

  Paris. It is then necessary to carry out a powerful aspiration of

wash water laden with sand.

  After the action of the flushing bells, additional suction by ramp may be considered to improve the extraction of the rinsing liquid and sands still trapped in the draining asphalt. It is also possible to

  provide an annular suction complementary to the suction by the cyclone

  inside the cleaning bell and several parallel or successive bells.

  It is noted that an excessive suction of sand, in the presence of a

  too small a quantity of water, can lead to their accumulation in the

  of the draining asphalt. There is then formation of a compact layer which

  fills the superficial cavities of the draining asphalt and makes it watertight.

  It is obviously necessary that there be compatibility between

  prewash and wash. Moreover, if bacteria remain in the draining mix after rinsing, they reduce the hydrocarbons as

  measure and facilitate subsequent maintenance work.

  A test of cleaning of an urban site implementing the process

  according to the invention has been carried out. A draining mix with porosity

  average price of 1.26 was set in July 1991. No cleaning of the coating

  porous to restore its original characteristics has been performed

  for 38 months. The porosity measured is then zero. A cleaning with preliminary

  Vage, wash, rinse and suction, according to the invention is then performed. imme-

  after the completion of the test, an average porosity of about 0.6 was observed. Rinsing leaves bacteria on the site. Five days after the cleaning performed according to the invention, a storm occurs. A new measure of

  porosity gives an average of 1 with peaks at 1.18, that is, a po-

  almost back to its original value, and shows that the bacteria

  left on the site during the rinsing continued to feed on clogging.

Claims (3)

claims   A method for cleaning porous surfaces, in particular coatings called "draining mixes" characterized by the following operations: Spreading of a washing liquid from the deep zone of the porous surface   consisting of an aqueous preparation containing bacteria having an   enzymatic activity, the enzymes produced which hydrolyze the hy-   hydrocarbons due to biosurfactants or natural surfactants.   After sufficient time for the washing liquid of the deep zone to be able to act, spreading of a rinsing liquid, and its recovery by suction, as well as clogged residues.   A process for cleaning porous surfaces according to claim 1   rised by pretreatment of the superficial area of the porous surface which   is spread at a pressure less than 90 bar and at a temperature below 60 C of a prewash liquid from the surface area of the porous surface and its recovery as necessary after a sufficient time,   the order of at least 5 to 20 minutes, so that he could act.   A method of cleaning porous surfaces according to claims 1 and 2   characterized by a prewash liquid of the porous surface, obtained by diluting   0.2 to 1% of a biosurfactant complex derived from bacte-   associated with a bio-degradable surfactant.   4. Process for cleaning porous surfaces according to claims 1 to 3   characterized by in situ production of enzyme solutions and biosurfactant your.   A process for cleaning porous surfaces according to one of claims 1   to 4 characterized by the implementation of fixed reactors located near areas to   clean, with filling of the transport and spreading tanks.   A porous surface cleaning method according to one of claims 1   and characterized in that the prewash and / or the wash may be preceded by mechanical cleaning by brushing the area to be treated if it presents   superficial accumulations of materials.   L7, Process for cleaning porous surfaces according to one of the claims   characterized in that the rinsing liquid is preferably water under pressure, of the order of 350 bars from the feed pumps, distributed inside a rinsing bell, by an arm rotating nozzle carrying ejection nozzles which   have a small angle, of the order of 30 relative to the net surface.   and which are arranged between 40 and 60 mm from the surface to be cleaned.   * The flow rate of the rinsing liquid is preferably about 1.5 liters per minute   and per square meter of floor area of the bell.   * The flushing chamber enclosing the nozzle support arm is maintained at   a fixed distance from the ground, and is sealed by a   ple, for example rubber, rubbing lightly on the porous surface to be cleaned.   A process for cleaning porous surfaces according to claim 7   supplemented by an annular suction complementary to the inner cyclone of the clo- rinse bottle.   9 Process for cleaning porous surfaces according to one of the claims   characterized in that at least 1% of the bacteria remain after   rinsing in the cavities of the draining asphalt layer.   10. A method of cleaning porous surfaces according to one of the claims   characterized in that the bacteria used are determined according to the characteristics of the clogging agents identified on the site to be treated and are   advantageously of the pseudomonas, moraxella, bacillus type alone or in combination with   out (associated) with other bacteria that have a strong appetite for hydrocarbons.