MXPA98010556A - Reactor for wastewater treatment contamin - Google Patents

Abstract

The present invention relates to contaminated wastewater in a tank (1,100) in which a number of cavitation oxygenators (5,6,11) are installed near and parallel to the bottom of the tank and divided into three types, one (5) that ejects recirculated water and air, the second (6) that expels water, air and mud and suctioned foam from the upper region of the tank, both types located to cause turbulence (F1, F2, F3, F4) of the contaminated water inside the tank , and the third (11) located to cause an additional turbulent movement of water contaminates

Description

REACTOR FOR A WATER PURIFICATION ESIPT - * ^ < "^^^ AMINADAS DESCRIPTION OF THE INVENTION The present invention relates to a reactor for the purification of contaminated wastewater, more especially a physical-chemical-biological reactor with forced circulation to purify industrial and civil waste contaminated water. The prior art comprises the use of biological reactors of air and / or oxygen and is explained in detail below with an example and with reference to figure 1, in which: E = input of the water to be purified, N = neutralization tank, CH = dosage of neutralization products VI = homogenization tank, V2 = biological reaction tank, V3 = sludge settling tank, A = air inlet of 02 RF = mud recycling, and FS = residual sludge . The administration of air or oxygen takes place in one of the following ways: 1 - With compressed air or oxygen input through porous plates or tubes evenly distributed in the bottom of tanks VI and V2; 2 - With air or oxygen sucked by a Venturi tube effect by pumps placed with nozzles distributed in some points at the bottom of tanks VI and V2; 3 - With rotors placed on the free surface of tanks VI and V2 that lift the water and spray it on the surrounding air, air as it falls. The disadvantages of the prior art are shown below: at least three tanks are required in order to obtain neutralization also by means of chemical products, it is necessary to add compressed air or oxygen to the water by means of porous plates or tubes, with a variable porosity, for example, between 30 μ and 250 μ, which consequently generates microbubbles that expand, reducing the gas-water contact surface, which in itself is scarce with the previous porosity values, - administration by means of some venturi type nozzles, with larger diameter water taps, for example 40-80 mm, and with a water pressure of approximately 1.5-2 kg / cm2 does not improve the dimensions of the air-water contact surfaces, due to that the spigot itself is not in a condition of cavitation. air and oxygen, inside the ejector, are dragged and do not mix intimately within the water, as would be desirable, the water rises 1 or 2 meters with a centrifugal blade wheel and is thrown into the surrounding air; also in this case no relevant air-water contact surfaces are generated, given the low energy to break the surface tension (cavitation), in none of the three cases for administration described above there is a phenomenon of contemporary separation by mud flotation, but only pre-mixing appears, the roughness and limited dimensions of the air-water contact surfaces in the three methods described above do not generate any useful natural correction of the pH and an appreciable reduction in toxicity, due to the presence of reducing substances inorganic (chemical reactions due to sufficient molecular dissolution of oxygen), the treatment of water produces waste sludge (FS), the residence time in the homogenization and biological reaction tanks is practically limited to the value of the proportion between the volume of the two tanks and the supply per hour of water to be purified. The present invention eliminates the drawbacks mentioned above and, as characterized in the first claim, is a reactor comprising a tank for containing and purifying contaminated water in which the number of oxygenators, in accordance with Italian patent number 1 147 264 by Ambrogio AFFRI, or equivalents, here referred to as cavitation oxygenators or simply oxygenators, administer recirculating air and water to the contaminated water body and distribute it so that, in the entire mass of the contaminated water, a first turbulence arises. length of the perimeter of the tank; therefore, in a recapilar, square or polygon tank, the number of oxygenators can be all directed in the same way parallel to the bottom of the tank or, as it would be more advantageous, they can be divided into two groups separated by axes of symmetry parallel to the bottom of the tank, a group in which the oxygenators point in one direction, and the other in the opposite direction, always parallel to the bottom of the tank; in a circular tank the oxygenators are placed parallel to the lines tangent to the circle of the tank. In this context, cavitation -oxygenators- or more simply -oxygenators-, we refer to oxygenators built in order to operate in liquid effluent conditions in the area where water and air are mixed inside their bodies at pressures less than atmospheric pressure, in other words, under conditions such that the total energy of the effluent liquid is totally kinetic.

The invented reactor, with the previous arrangement of the oxygenators, in turn is divided into first oxygenators and second oxygenators (as explained in the present) is a reactor of forced circulation. In it, there is also a second turbulent movement that recirculates contaminated water from below to the top of the tank and vice versa. In this way, three layers are formed which, starting from the top, can be identified as the first zone or zone of sludge and foams, the second zone or zones of reaction and flotation, and the third zone or zone of purified water or primary water. The first oxygenators are distributed uniformly in one or more planes close to and parallel to the bottom of the tank, substantially in the region of the boundary between the second and third zones, while the second oxygenators are placed in one or more planes coinciding with the planes mentioned above , but only in a part of the bottom of the tank. The previous distribution of the oxygenators has the purpose of creating the global circulation in the second zone of the liquid present in the tank by means of the impulse of the air-water mixture of the effluent of the same oxygenators. The contaminated water that is going to be purified enters from one end of the tank and leaves the opposite side, purified. The recirculating liquid, that is, circulating in the second zone, is sucked by a pump and sent under pressure to the first oxygenators fed by a feeding tube and by a water distribution network. All the first oxygenators, thanks to the liquid under pressure that reaches them and that flows out of them through the nozzles, sucks in atmospheric air through a first tube that extends beyond the upper level of the first zone. . The number of second oxygenators sucks in a mixture of air plus sludge and foam through a pipe opening in the first zone. The highest horizontal plane in which all layers of oxygenators define the region of separation between the second and third zones. The distribution of the first oxygenators in their planes must have a density (number of oxygenators per square meter) so that it creates, through the air that flows outside them, a floating effect capable of separating and keeping suspended in the zone of reaction and flotation the active biological sludge that is generated by itself with the organic substances contaminants in the liquid. The distribution described before the oxygenators is such that the fluid that moves, which flows, starting at the upper level in the highest plane of the oxygenators, is continuously traversed by the air that flows out of the first oxygenators, which is throughout the second zone, although the oxygenators do not occupy all the points. This ensures the effectiveness of the flotation that separates and differentiates the quality of the liquid with the highest level of concentration of organic substances in such zone, of the liquid with low concentration of residual organic substances in the third underlying zone. The air plus the mud and the foam are formed in the first zone due to the flotation effect and are sucked through each of the second tubes; the additional passage through the second oxygenators represents a first part of recirculation of the mud and foam in the liquid biomass of the second zone, for reaction and flotation. Identically, a third tube opening at its upper end in the second zone and at its lower end in the first zone where the pump sucks into the purified water creating a flow of the biomass representing a second part of the recirculation in the reaction and flotation zone, the tube is placed along its length with a partialization valve to adjust the amount of liquid biomass that is going to recirculate. As an option, the reactor may comprise numerous auxiliary oxygenators, each surrounded by a cylindrical collar and associated with a fourth tube opening in the second zone in order to operate a third part of recirculation of the biomass attracted by the Venturi effect. As a further option, the reactor may comprise a surface scraping device when, due to the high pollution load of the waters undergoing treatment, the production of surface mud and foam is excessive and is out of control. The main advantages of the invention are: although with the current technique the different functions are physically separated and take place in more than one tank, with the invention, all of them take place in a single compact structure, therefore an availability of significantly more limited space, the recirculation of the entire liquid mass through the oxygenators, operated by a pump which recirculates every hour a volume of water multiple of the one introduced every hour in the tank based on the degree of evolution of the water under treatment , increases the air-water contact time, contact time which is expressed as a ratio between the volume of the tank and the supply per hour, in m3 / h of the wastewater that is treated, according to the following formula: t = (R / E). (V / E) + (V / E) in which: t is contact time in hours, R is the supply rate per hour of the pump E is the hourly supply of contaminated water, in m3 / h, and V is the volume of the tank, in m3. Example: with (R / E) = 2 and (V / E) = 24, we have that t = 48 + 24 = 72 hours; - fí in the case of a tank equipped with air compressors and porous plates, the value t is simply equal to V / E = 24 hours; that is to say that the invention, in the considered example, provides contact time values three times higher than the usual ones (24 hours) in the prior art. the distribution of the oxygenators, in opposition to its plane and the circulation of the residual water induced by its impulse, causes the microdiffusion of oxygen in the air to be uniform throughout the mass, as it is suctioned and in a state of liquid cavitation within the same oxygenators.

The microdiffusion not only supports the biological reactions in the reaction zone (stage V = of the prior art) but also activates the oxide-reduction and natural neutralization reactions both within the oxygenators and in the same reaction and flotation region (N and CH stages in the prior art); in addition, it improves flotation separation towards the reaction and flotation region as well as colloidal particles (slurry concentrator in zone H, aqueous ammonia extractant and volatile substances). The zone in which the clarification takes place replaces the step V3 in the prior art. The recirculation of sludge and sludge and foams is carried out inside, and not outside, the reactor, respectively, by means of the second pipe and the pump and by means of the third pipes. In both cases, the sludge passes through the oxygenators placed in the plane that separates the second and third zones. It obtains important degrees of purification, without producing mud. This results in the advantage not only that smaller dimensions are required for the performance of the various depuration stages, but also given the same final results, the production of a lower total amount of sludge. The compact and multi-function characteristics of the reactor allow to detect, during the test experimentation, an almost total detoxification of the waters, protecting and ensuring stability to an environment located for bacterial life; in addition, due to the flotation effect, the reactor also reveals its ability to reduce, by separation and degradation, the presence of dyes and surfactants that are also toxic components, in the treated waters that flow outwards. Known techniques do not offer this ability to any appreciable degree. The water treated with the present reactor offers an uncommon stability of quality and an ability to be treated in additional refining plants with high efficiency. The invention will be illustrated in further detail herein, with an example of one embodiment and with reference to the drawings, in which the first figure serves as a reference in order to appreciate the differences between the prior art and the invention; therefore, in the drawings: figure 1 is a block diagram, figure 2 is a first plan view, figure 3 is a longitudinal cross section, figure 4 is a second plan view, figure 5 is a view of a detail, figure 6 is a diagram, figure 7 is a third plan view, and figure 8 is a cross section. Figure 1 has already been discussed at the beginning of the present description. Figures 2 and 3, together, show a rectangular flat tank with a useful capacity of 2000 m3. The contaminated water to be treated enters the reactor from duct 2 and comes out purified along the vertical IT tube and duct 3; in a plane 4 near the bottom of tank 1, number 88 first oxygenators are installed with their axes parallel to the bottom of the tank and distributed evenly on two sides of the longitudinal axis of tank II, number 44, the oxygenators on one side are directed towards the right side of the figure, according to arrow Fl, and the other 44 are directed to the left, according to arrow F2; similarly, 12 oxygenators 6 are installed, 6 of which are oriented to the right and 6 to the left, the oxygenators 5 and G are fed with water under pressure through a duct and a distribution network 7 fed by a pump 8 with a supply of 100 m3 / h and a lifting height of 80 m and an absorption power of 28 kW; each of the first oxygenators 5 is also associated with a first vertical tube T2 with an opening above the upper level of the tank in order to suck atmospheric air, while each of the second oxygenators 6 is also associated with a second tube T3 with opening in the first zone in order to suck a mixture of air plus mud and foam so as to cause a partial recirculation of the mud and foam in the second zone of the tank (see arrows F3 and F4); at least a third tube T4 is positioned with the upper end opening in the upper part of the second zone and the lower end opening in the region of the third zone where the pump 8 sucks in the purified water of the DI pipe with in order to return it to the second zone through the oxygenators along the ducts D2 and 7, the third tube has a partializing valve 10, 4 auxiliary oxygenators 11, two oriented to the right and two to the left, respectively, on one side, and the other longitudinal axis of the tank that is installed near the left side of the tank, each of them is fed by the feed water and the distribution network 7, and is surrounded by a cylindrical collar and associated with a fourth tube T5 with opening in the upper region of the second zone in order to cause a second recirculation of the biomass by a Venturi effect (see detail in figure 5). Figure 4 shows the distribution of oxygenators 5, 6 and 11 in a tank with a circular plant 100; they are fed by a supply and distribution network 70 and are oriented in directions parallel and tangent to the tank circle; the reactor is also placed with the parts, 3, 8, DI, D2, TI, T2, T3, T4 and T5 already described with reference to figures 2 and 3; the mass of contaminated water acquires a circular movement, in accordance with the arrows F. Figure 5 shows an auxiliary oxygenator 11 comprising an oxygenator 5 in accordance with the annotated patent, but placed with the collar 40 conveniently extended past the oxygenator outlet . The collar generates the effect of extracting water and mud from the second zone through a fourth tube T5; upstream, the oxygenator 5 receives at A a through pipe 7 and from the nozzles 50, recirculates the water under pressure from the third zone and from the top, at B and from the tube T3, receives air, mud and foam from the first zone: Rl refers to a region of greater turbulence and a broad exchange surface, and R2 shows the region in which the primary mixture of air and water is formed. It can be seen that the collar 40 is closed in the section included between the connections of the tubes T3 and T5.

Figure 6 is an experimental oxygenation curve; shows that the amount of oxygen introduced into the tank every hour is equal to 0.324 x 100 oxygenators = 32.4 kg of oxygen / hour. The contaminated water that enters the tank through the pipeline 2, with an average supply of 35 m3 / h. The pollution parameters that characterize the water are as follows: Chemical demand of 02 (C.O.D.) = "1350 mg / 1 Total of surfactant (95%) nonionic + 5% anionic = 150 mg / 1 Sulphites + sulphites (toxic substances) = 100 mg / 1 pH = 4-4.5 After a real time of permanence or contact, t, with 02, equal to t = (R / E) x (V / E) + (V / E) = (100/35) x (2000/35) = 220 hours the water that leaves the duct 3 (figures 2 and 3) have the following characteristics: Residual chemical demand of 02 (COD) = 590 mg / 1 Total surfactants = 20 mg / 1 Sulphides + sulphites = trace pH = 6.6-6.8 The following efficiencies can be inferred: 1 - Suppression of the demand of 02 = (1350 - 590) / 1350) x 100 = 56.29% 2 - Suppression of surfactants = (150 - 20) / 150) x 100 = 86.66% 3 - Suppression of sulfides + sulphites (toxic substances) = 99.9% 4 - The efficiency in terms of 02 used compared to the quantity introduced = (0.76 x 35) /32.4) x 100 = 82%. 5 - Natural pH correction, that is, without requiring the addition of chemical products, values between 4 and 4.5 to values between 6.6 and 6.8. Figures 7 and 8 show a device for the removal of excess mud and foam; the arms 20 rotate according to F5 above the upper edge of the tank push this - mud and foam until it falls into the hopper 21 where a centrifugal sucker 22 sucks them upward, decomposes the surface tension and discharges them in liquid form into a discharge container 23. It is understood that this device can be carried out by replacing the rotating arms with other suitable means for "scraping" the mud and foam and pushing it into the hopper, for example, several blades conveniently placed on a wheel that turns tangent to the upper edge or in some other way a jet of compressed air parallel to the edge of the tank pointing towards the hopper. A pump 24 provides recirculation of the liquid sludge in the second zone of the reactor.

Claims (10)

1. A reactor for the purification of contaminated wastewater, characterized in that it comprises: (a) a tank into which contaminated wastewater is introduced and purified, inside the tank there are several cavitation oxygenators fed by pressurized recirculated water and placed horizontally on at least a plane close to the bottom of the tank, these oxygenators are constituted of first oxygenators that expel water and atmospheric air, and second oxygenators that expel water and air plus mud and suctioned foam in the upper region of the tank, the two types of oxygenators are placed so as to cause a first turbulent movement substantially parallel to the side walls of the tank, and a second turbulent movement along the vertical planes of the tank in such a way as to cause the overall circulation of the liquid in the tank and the formation of three zones, a first upper zone within which air is transferred to along the mud and foam, a second intermediate zone in which the reaction and flotation takes place, and a third, inferior to the plane in which the purified water accumulates; (b) a pump sucking purified water in a region in the third zone in order to return it to the second zone and at least one tube with the lower end opening within the same region and with the upper end opening within the second zone in a manner that causes a first part of circulation of the biomass within the second zone.

2. The reactor according to claim 1, characterized in that the pump 8 has a supply per hour which is multiple of the amount of contaminated water per hour introduced in the tank.

3. The reactor according to claim 1, characterized in that in the tank with a rectangular, square or polygonal plant, all the oxygenators are placed pointing in the same direction.

4. The reactor according to claim 1, characterized in that within the tank of rectangular, square or polygonal plant, the number of oxygenators is divided into two groups separated by a symmetrical axis parallel to the axis of the tank, a group with the oxygenators pointing in a direction and another in which the oxygenators point in the opposite direction.

5. The reactor according to claim 1, characterized in that inside the circular tank the oxygenators are oriented in a direction parallel to various tangents to the tank circle.

6. The reactor according to claim 1, characterized in that it comprises several auxiliary oxygenators, each surrounded by a collar and associated to the second tube and the fourth tube in order to obtain a third part of recirculation of the biomass in the second zone, the collar recovers due to the Venturi effect.

7. The reactor according to claims 1 and 6, characterized in that the distribution of the first oxygenators on their planes generates a density such that it produces a flotation effect that separates and keeps in the second zone suspended self-generated biologically active sludge from the contamination of substances organic and where the distribution of the auxiliary oxygenators defines a density located to recirculate the liquid biomass in quantities proportional to the supply of the treated water.

8. The reactor according to claim 1, characterized in that all the first oxygenators, thanks to the pressurized liquid they receive and that flow out of them through the nozzles, sucks in atmospheric air through a first tube that extends passing the upper level of the first zone and where all of the second oxygenators suck into the air mixture with mud and foam through a second tube opening within the first zone.

9. The reactor according to claim 1, characterized in that it comprises a means located to scrape the excess of mud and foam from the surface of the first zone and transfer them to a hopper from which a centrifugal suction machine sucks them, decomposing their surface tension and unloading them. in liquid form inside a recovery container.

10. The reactor according to claim 9, characterized in that the pump transfers the sludge and the foam from the container to the second zone of the reactor.