MXPA98006323A - Procedure and plant for the treatment of water residues - Google Patents

Abstract

The invention relates to a process for the treatment of car wash wastewater, in a stage of mechanical and biological treatment, during which the waste water is collected in a tank (3) after passing through a chamber of water. sedimentation, then it is transported to a bioreactor (8) through a filter for suspended matter (7). After the biological clarification in a container of pure water (11), the residual water is collected to be used again. The invention also refers to a plant for carrying out, in particular, said process.

Description

PROCEDURE AND PLANT FOR THE TREATMENT OF WASTEWATER BJREVE DESCRIPTION OF THE INVENTION This invention relates to a wastewater treatment of car wash in a stage of mechanical and biological treatment, and to a plant that is especially suitable for carrying out this process. method. It is known to treat residual water from car washes before it passes to the municipal sewage system by applying drainage systems in accordance with DIN 1986 and DIN 1999 in a way that satisfies the demands of the legislator and local governments. The car wash residual water is therefore mechanically purified in a sedimentation chamber, largely liberated from mineral oil hydrocarbons in a light liquid separator, collected in a tank and passed to the drainage system through a chamber. of Inspection. Other stages such as chemical and / or biological treatment can be included in the purification of wastewater and serve to reduce the need for drinking water. According to DE-A-26 51 483, the waste water from a car wash containing biodegradable cleaning agents and preservatives is purified, as well as solids by mixing the waste water with a polymeric flocculant and passing it through an area first. of sedimentation with a little reduced water and then through an absorbent. DE-C 41 16 082 describes a method for the treatment of water in carwash, where the waste water leaving is mechanically, mechanically and biologically purified and recycled to the car wash. The solids that arise during mechanical purification are collected in special waste garbage lots. The pollutants are treated mechanically and biologically in a multistage process, in this method, in such a way that the solids with hydrocarbons and with contaminants are separated from the waste water of the car wash by sedimentation and collected in a first circuit, the hydrocarbons and Contaminants with waste water containing washing substances are extracted from the washing area during collection, and mechanically rinsed wastewater is released from non-degradable fractions through flotation and through biological flotation in a second circuit. The common disadvantage of known methods is that wastewater must be treated in elaborate multi-stage processes. The solids that arise, generally from flotation and sand and the sediment that leaves the vehicles, must be discarded as garbage lots that require special treatment. The water and solids that are collected from the plant have an odor that can assume an extreme and annoying degree. The reuse of purified wastewater requires a high proportion of potable water. The excess water that leaves will be fed to the wastewater treatment of the municipality through a wastewater connection. The invention in this way is based on the problem of not only increasing the efficiency of wastewater treatment for complete reuse, but also simultaneously decontaminating the sand and sediment leaving the vehicles and treating them so that they can be easily fed. to a proper disposal cycle and that no polluting loads arise, which require special disposal and treatment, such as mineral oil hydrocarbons and flotation. It should be possible to resume treatment easily after a few times of little washing activity. This problem is solved through a method of the aforementioned type, where the waste water after running through a sedimentation chamber, is collected in a tank, then passed to a bioreactor through an aerosol filter and it is collected for reuse after biological clarification in a water cleaning tank. The method of the invention has a mechanical and biologically working treatment stage. The treatment stage consists of the sedimentation chamber where sedimentation of the coarse powder introduced occurs. This usually involves mineral particles, which are frequently contaminated by mineral oil products. The thicker mineral oil particles, for example, from the wax or coating of a motor vehicle, also pass into the sedimentation chamber. The biological treatment of the sedimentation charge also occurs in the sedimentation chamber to an important degree. The backwashing of the filtration system and the bioreactor as described below, causes the oil degradation microorganisms to repeatedly pass into the sedimentation chamber, colonize there and perform their work. A large part of the organic load of the sedimentation chamber in this way is decomposed by microorganisms. Experience has shown that the content of the sedimentation chamber is later decomposed in a few months into a mulch-like mass, which can no longer be contaminated with mineral oil components and can easily be disposed of with household waste. After running through the settling chamber, the waste water passes into a reservoir that substantially serves as a buffer where the water is continuously pumped to the bioreactor through a filtration facility. The reservoir regulator effect has two aspects, firstly, a quantitative aspect since a continuous wastewater stream must be released to the bioreactor without considering the frequency of use of the car wash. Secondly, the tank serves as a dilution tank for highly concentrated dust loads, which arise in the cleaning of especially dirty motor vehicles or some contaminated with special contaminants. The aerosol filter is a convincing filter to remove the charge of suspended matter, which consists of, for example, several alternating layers of beds of coarse and fine sand. The aerosol filter can pass through the wastewater with or against gravity and occasionally should be expelled as backwashing with e-1 clean water to clean or otherwise replace. The filling of both the aerosol filter and the bioreactor is finally carried out in perforated or similar layers under which the outlet is located. The bioreactor following the aerosol filter can also be passed through the wastewater by or against gravity and houses microorganisms in a suitable support material, which are suitable to degrade the dust load in the waste water that arises in a wash of cars. Generally these are bacteria that work aerobically, which are known in the art and can be obtained with also known selection mechanisms. The clean water that comes out of the bioreactor is then collected in a tank of clean water and fed from there to the car wash to be reused. Obviously, it can be reacted to the constant loss of recirculating water due to evaporation and dragging through washed motor vehicles by feeding clean water. It has been shown in a pilot plant that several thousand cycles can be easily achieved with the wastewater thus treated and supplemented. The bioreactor conveniently consists of a fixed bed of porous support material, which can absorb the organic ingredients from the waste water and offers sufficient support of microorganisms required for colonization. The microorganisms are formed on the surface of the support material and in the pores, a lawn that filters the residual water that flows further and takes the dust / nutrients contained there. The effect of absorption of support material promotes this effect by feeding the absorbed components of the waste water to the microorganisms. To ensure a sufficient permeability of the fixed bed for the wash water, the porous support material conveniently comes out in the form of a bed, which accommodates between the individual support particles in addition to the actual pore space. The porous support materials are, for example, coal, clay, silica gel or zeolites in the form of pellets or flakes of plastic foam with a sufficient pore volume, for example of polyurethane, polystyrene or the like. A particularly suitable material has, for example, a particle size of 1 to 10 mm, a vibration density of 0.25 to 1.0 g / cm 3, a pore volume of 0.40 to 1.0 cm 3 / g and an area of more than 500 m2 / g. However, other materials with comparable physical properties can be used. Obviously, the bioreactor, with the aerosol filter, should be washed regularly to avoid being clogged with suspended particles or blocked by excessive bacterial sediment. Both the aerosol filter and the bioreactor are washed so that the washed materials are taken back to the settling chamber, where the washed oil-degrading bacteria can do their job. It is convenient to keep the bioreactor in service through a so-called subsequent operation even in times of low frequency of washing. For this purpose, it is convenient to pass clean water back to the reservoir and from there through the aerosol filter to the bioreactor. The circuit ensures a regular flow through the bioreactor and in this way also a supply of nutrients from the tank. Simultaneously, the dust load contained in the tank can be allowed to be slowly degraded during the night, which means that the new flow that enters from residual water the next day is first diluted with relatively clean water from the tank, thus avoiding a load of sudden dirt on microorganisms. As already mentioned, the bioreactor is conveniently operated in aerobic form. The amount of oxygen contained in the wash water is generally not sufficient for this. Therefore, it is convenient to introduce oxygen or air into the bioreactor, conveniently through an air injector. Some of the water that runs outside the bioreactor can be ramified, saturated with air and recirculated to the bioreactor. However, it is also easily possible to recirculate the water to the bioreactor from the clean water tank after it has been saturated with air. The clean water tank collects the clean water that runs outside the reactor, making it available for reuse in the wash cycle. Sufficient volume ensures that sufficient water is available both for cleaning purposes and for the treatment method (backwashing, after operation). The clean water released to the car wash can first be sterilized through a disinfection facility, for example, with the help of UV radiation. Obviously, the preservatives used in the washing process do not have biostatic components or biocides and are completely biodegradable. The rate of biodegradation will be considered in the sizing of the treatment plant; The fastest degradation capacity is, the smaller the bioreactor tank and clean water tank, it can be designated, within certain limits. It has been considered that for an average car wash, the tank sedimentation chamber and the clean water tank must have a collection volume of 6 m and the filter unit and bioreactor a capacity of 1 to 1.5 m3. The materials that will be used for all pipes and tanks can be corrosion-resistant metals or plastics that meet the requirements, in particular plastic reinforced with glass fiber or HDPE. The waste water that emerges in the car wash in this manner is conveniently fed through a sedimentation chamber known in the art to a reservoir and from there through an aerosol filter to a fixed bed reactor of aerobic operation. The support material of the fixed bed reactor is porous, has a large surface area, can absorb ingredients from the water and serves to colonize special microorganisms. The water in the reactor is constantly circulated through a circulation pump and enriched with oxygen, preferably atmospheric oxygen from the ambient atmosphere, without pressure through a. suitable device, preferably an injector. The speed of circulation can be varied within wide limits. It can be so that the biofilms are not damaged. The wastewater passes from the bioreactor through an overflow control to the clean water tank. From there it is recirculated 100% towards the washing process, optionally through a disinfection facility. It is advantageous to recirculate the water from the clean water tank to the sedimentation chamber without the de-germination for the countercurrent washing of the plant or to maintain a water cycle in phases of low wash intensity. It becomes necessary to wash the bioreactor and / or the aerosol filter when the pressure difference between the inlet and outlet of the aerosol filter or the reactor vessel reaches a limiting value as a measure for the charge of retained suspended material or biology surplus, for example 0.5 bar.

It is advantageous if the preservatives used in the washing process are biodegradable in 24 hours and serve as food for the microorganisms. It can also be seen that the method of the invention is suitable for taking and treating contaminated water from the work area and the gas pump area of a gas station. Therefore, it is understood that not only waste water that comes out in a car wash, but also other waste water can be treated and purified and can be used with waste water. The method of the invention in this manner is suitable for replacing the plants required for gas stations for the treatment of atmospheric water. The advantages achieved with the method of the invention are, in particular, that the waste water returns to the washing process, purified. Drinking water consumption in this way is reduced to compensate for losses due to evaporation and introduction. In the method of the invention, only the decontaminated sedimentation chamber contents arise. No additional residual substance requires separate disposal or treatment. Excess water can easily be released into the sewer system. The invention also relates to a wastewater treatment plant, which is particularly suitable for treating and recirculating waste water from car washes, shops and / or gasoline stations and with which the method can be carried out beforehand. described. Said wastewater treatment plant has a mechanical and biological purification stage or, a sedimentation chamber, a tank, an aerosol filter, a bioreactor and a clean water tank being connected in series and interconnected through pipes, and the clean water tank being connected to the tank through a return pipe to maintain a water cycle through the tank, aerosol filter and bioreactor to the clean water tank after an interruption in the waste water supply. Obviously, the wastewater treatment plant has the necessary inputs and outputs for the wastewater, clean water and optionally potable water and the pumping devices needed to operate the plant, as well as a control system. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained more closely through the following figures, wherein: Figure 1 shows schematically a first embodiment of a wastewater treatment plant of the invention, and Figure 2 shows a variant of additional execution Figure 1 shows the procedure diagram of the waste water treatment plant. The wastewater that comes out of the car wash is collected in a waste water channel below the car wash and passes through the flow inlet 1 to the sedimentation chamber 2. Here, the sedimentation matter that arises is retained, such as sand, sediment and the like. The water released from the sedimentation material passes to the tank 3. Controlled by the level 4 control, the waste water is pumped through the feed pump 6 to the aerosol filter 7, a sand filter. Here, any suspended matter still present is removed. From the aerosol filter 7, the prepurified wastewater passes to a fixed bed reactor 8. The fluid phase of the fixed bed reactor 8 constantly circulates through a circulation pump 9 via the injector 10. In the injector 10, the phase of fluid is enriched with oxygen, preferably atmospheric oxygen from the ambient atmosphere. The fixed bed reactor 8 contains a porous support material with a high specific surface that serves as a colonization surface for the microorganisms. In particular, the formation of biofilm in the depressions of the support material is protected from mechanical shear forces.

The support material is able to absorb dissolved organic contaminants and thus provide food deposits for the microorganisms.

The presence of said deposits near microorganisms clearly accelerates bioderjradation. From the fixed shaft reactor circuit, the purified water passes to the clean water tank 11, from the clean water tank 11, the car wash is supplied through the outlet flow 13, the water runs through a installation of UV germination. In times of low wash activity, water is pumped from the clean water tank 13 through the pump 15 back to the settling chamber 2 and the circuit is maintained by the level 4 control. The pressure difference between the inlet and the outlet are measured both in the aerosol filter 7 and in the fixed bed reactor 8. When an empirically determined limiting value is reached, the degree of enrichment with suspended matter or biomass in the particular unit is so great that the unit must be regenerated by washing countercurrent to the sedimentation chamber. This is done by passing water from the clean water tank 11 through the pump 15 back through the fixed bed reactor 8 or aerosol filter 7 to the settling chamber 2. The two units are conveniently washed independently one of the other in the period of low wash activity. It is convenient for the operation of the plant, if the preservatives used in car washing support the biodegradation process. For example, conservative agents with article numbers 181000 to 185000 from Wolfgang Schenk GmbH satisfy this requirement. Obviously, first the wastewater treatment plant is activated and conditioned by inoculating the fixed bed reactor with an initiating culture and circulating the liquid phase before connecting the car wash. In the clean water tank 11 only potable water is supplied through the potable water connection 12 as it is removed from the water cycle by introduction or evaporation. Figure 2 shows a further variant of the control of the method of the invention. The same numbers designate the same positions. The dotted lines designate the control lines for the operation of the plant. The wastewater from the car wash, a store or the water running on the surface of a gas station area passes through the feed pipe 1 into the settling chamber 2, where the thicker dust is deposited. The pipe 21 continues to the tank 3, which serves as a buffer for the wastewater released from the coarse powder. Tank 3 contains a level 4 control with a higher and a lower switching point. The water in the reservoir 3 passes through a suction body 5 and supply pump 6, which form a unit in the present embodiment, through the line 22 to the aerosol filter 7. The line 23 is protected through a valve that allows sampling of dirty water from pipe 22. Water passes from tank 3 to aerosol filter 7 through manifold 24. The filter is filled with alternating layers of coarser and finer sand through the filter. which waste water runs from the top to the bottom. Through the manifold 26, the filtered waste water is carried using the pump 9 through the pipes 27. The level control 25 prevents the filter device from running in dry form but also has an internal switching point to empty the device of filter more or less completely. The overflow 28 recirculates through the pipe 14 to the settling chamber 2 and is required when the filter 7 is washed. The water removed from the filter through the manifold 26 passes through the pipe 27 and the pump 9, as well as the pipe 29 to the bioreactor 8. There it is distributed through the manifold 24 on the surface of the porous support material located at the same, conveniently active carbon pellets with a large pore volume and sufficient empty space between the individual particles. The porous support material is colonized by microorganisms conditioned to load organic dirt from the residual water. The wastewater runs through the fixed bed of the bioreactor from the top down and is fed to the clean water tank 11 through the manifold 26 of the bioreactor 8 through the pipe 30 using the pump 31. The control of level 25 ensures sufficient filling of the bioreactor 8, as with the aerosol filter 7. An injector inserted into the pipe 30 injects air taken via the pipe 32 to the water removed from the bioreactor 8. The water saturated with air is fed through the the pipe 30, first to the clean water tank 11 but partially also recirculated through the pipe 33 to the bioreactor, where it ensures a sufficient supply of oxygen for the reactor and the microorganisms. The solenoid valves 34 and 35 ensure the correct distribution ratio of saturated water with air between the bioreactor 8 and the clean water tank 11. The intermittent operation of the bioreactor 8 is likewise possible, however, where a circuit through a pipe 33 performs the air supply. Only fully rinsed water is fed to tank 11.

The clean water tank 11 receives the biologically clarified water from the bioreactor 8. The level control 36 ensures that the clean water tank is filled with a sufficient amount of water to allow the maintenance of both the washing operation and the operation of the night circuit. If the amount of water in circulation is too low, drinking water can be supplied through the pipe 12. The water is removed from the clean water tank 11 through the pipe 37 using the pump 15 and fed into the pipeline. I return 13 to the car wash. The disinfection facility 18, preferably based on UV radiation to prevent the addition of bactericidal degermination agents, optionally ensures the sterility of the wash water. The air-cushion container 19 ensures, together with the pump 15, a uniform water flow to the next car wash. A pressure gauge 39 is used to check and control the pressure. The outward flow 38 leads to the sewer and serves to remove surplus water in times of water accumulation above average. It is particularly convenient when the treatment plant also treats surface water from a gas station area and is subjected to large amounts of water from heavy precipitation.

In addition, the pressure measuring points are located in the pipes 27 to the bioreactor and 30 to a tank of clean water and bear the reference numbers 40.

They are used to verify the working pressure of pumps 9 and 10. In the event that one of these containers becomes heavily clogged with dust particles or biomass, a washing process is initiated from the clean water tank 11 through from piping 37, pump 15 and piping 16 and 17 to the aerosol filter 7 and bioreactor 8. Water enters the reactors through a lower manifold 26 and washes the dust or biomass particles through the overflow 28 and the pipe 14 towards the sedimentation chamber 2. In this way, the microorganisms also pass into the sedimentation chamber 2, colonize there and provide the biological treatment of the sedimented powder. In times of low wash activity, i.e., particularly during the night, weekends and holidays, a water cycle is preferably maintained in order to keep the filter in spray and the bioreactor in service. This circuit starts in the clean water tank 11 and runs through the pipe 37, pump 15 and pipe 43 back to the tank 3. The solenoid valve 44 is thus opened through the central control device. The stopping valves 41 and 42 of the car wash and towards the washing lines are simultaneously blocked. Then, the circuit is extended, as in the normal treatment operation, from the tank 3 via the aerosol filter 7 and the bioreactor 8 to the clean water tank. After a certain period of circulation, the quality of the circulating water and the connected tanks gradually approach the quality of the water in the clean water tank 11.

Claims (22)

1. CLAIMS 1. A method for the treatment of car wash wastewater in a stage of mechanical and biological treatment, where the waste water after running through a sedimentation chamber is collected in a tank, then passes through an aerosol filter towards a bioreactor and is collected for reuse after biological clarification in a tank of clean water, characterized in that after the interruption of the flow of residual water to the reservoir, a water cycle is maintained from the water tank clean through the tank, the aerosol filter and the bioreactor.
2. 2. The method of compliance with the claim 1, characterized in that the waste water is passed into the bioreactor 8 through a fixed bed consisting of an absorbent of porous support material for the organic ingredients of the waste water and colonized by microorganism known in the art to degrade such ingredients.
3. 3. The method of compliance with the claim 2, characterized in that the porous support material emerges as a bulky material.
4. 4. The method according to claim 2 or 3, characterized in that the porous support material consists of carbon, clay, silica gel, or zeolites in pellet form or plastic foam flakes.
5. 5. The method according to any of the preceding claims, characterized in that the aerosol filter is freely washed by being backwashed discontinuously with water from the clean water tank.
6. 6. The method according to any of the preceding claims, characterized in that the bioreactor is freely washed by being backwashed batchwise with water from the clean water tank.
7. The method according to claim 5 or 6, characterized in that the countercurrent water is passed to the sedimentation chamber.
8. 8. The method according to any of the preceding claims, characterized in that the bioreactor is fed with water saturated with air.
9. The method according to claim 8, characterized in that clean water saturated with air is recirculated to the bioreactor from the clean water tank or the feed pipe from the bioreactor to the clean water tank.
10. The method according to any of the preceding claims, characterized in that the clean water is recirculated to the car wash from the clean water tank.
11. 11. The method according to claim 10, characterized in that the recirculated clean water is degerminized with UV light.
12. 12. A wastewater treatment plant, in particular for treating and recirculating car wash wastewater, having a mechanical and a biological purification stage, characterized in that it has a sedimentation chamber, a tank, an aerosol filter, a bioreactor and a clean water tank, which are connected in series and interconnected through pipes, the clean water tank being connected through a pipe back to the tank to maintain the water cycle through the tank, the aerosol filter and the bioreactor to the clean water tank after an interruption in the waste water supply.
13. The plant according to claim 12, characterized in that the bioreactor has a fixed bed consisting of an absorbent of porous support material for the organic ingredients of the wastewater and colonized with microorganisms known in the art to degrade the organic ingredients of the bioreactor. residual water.
14. 14. The plant according to claim 13, characterized in that the porous support material emerges as a bulky material.
15. The plant according to claim 13 or 14, characterized in that the porous support material consists of coal, clay, silica gel or zeolites in the form of pellets or plastic foam flakes.
16. 16. The plant according to any of claims 12 to 15, characterized by a countercurrent pipe from the clean water tank to the aerosol filter.
17. The plant according to any of claims 12 to 16, characterized by a countercurrent pipe from the clean water tank to the bioreactor.
18. 18. The plant according to claim 16 or 17, characterized by a pipe returning from the aerosol filter or bioreactor to the settling chamber for the countercurrent material.
19. The plant according to any of claims 12 to 18, characterized by a pipe with an air injector inserted to return clean water saturated with air to the bioreactor.
20. 20. The plant according to any of claims 12 to 19, characterized by a dry operation protection in the tank, aerosol filter, bioreactor and / or clean water tank.
21. The plant according to any of claims 12 to 20, characterized in that the clean water pipe of the clean water tank has a degermination stage.
22. 22. The plant according to any of claims 12 to 21, characterized by pressure measuring devices following the aerosol filter and / or the bioreactor.