JP813H - How to biologically purify wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for the aeration of waste water with air and / or pure oxygen in the presence of biomass immobilized in a reactor on a carrier material, which is a granulate of flexible polyurethane foam, and the Containing organic impurities by separating wastewater into purified water and sludge in the post-sedimentation section and introducing porous granules in the form of debris and / or granules as carrier material for microorganisms in the reactor Method for biologically purifying waste water to be treated. In the case of conventional activated sludge processes, the wastewater to be treated is mixed with activated sludge in a reactor formed as an activation tank with simultaneous oxygen supply. Due to the action of aerobic microorganisms contained in the activated sludge, the organic waste of the wastewater, which exists in a dissolved state or in a colloidal state, is partially converted into a bacterial substance, and part of the organic waste is mainly CO ₂ and water. Is made to react to. The settling section after the activation tank largely separates the activated sludge from the purified water by the settling. At least a portion of the sludge that settles in the post-sedimentation section is returned to the activation tank as return sludge in order to maintain the desired sludge concentration in the activation tank. In this case, in order to obtain sufficient purification of the wastewater, it is necessary to maintain the sludge concentration as high as possible in the activation tank. Due to the completely limited concentration of activated sludge, it is still up to 3 ~
A sludge concentration of 8 g / l can only be obtained. This represents a correspondingly large amount of return sludge that needs to be returned to the activation tank, which requires large pump energy. If the sludge concentration in the activation tank is high, the load in the post-sedimentation tank is also correspondingly large, so that the post-sedimentation tank needs to be relatively large. The problem underlying the present invention is to form a method of the type mentioned above and a device for implementing the method in a simple and economical way, above all in such a way that a large purification rate of high-load wastewater can be obtained. Is. According to the invention, this problem is addressed by a small specific gravity, 5-50 mm
Particles having a particle size of 0.1 to 3 mm and open cells of 0.1 to 3 mm are loaded in an amount corresponding to a volume of 5 to 70% of the reactor volume, in which individual particles are suspended so that they can move freely in the waste water. In the case of 5 to 40% by volume of granules, the reactor is operated as a complete mixing type activation tank, and at least temporarily the activated sludge is returned from the post-sedimentation section into the reactor, and the carrier substance is moved in the reactor. The solution is to maintain free activated sludge with the biomass fixed on top. The use of porous granules with a low specific gravity provides the microorganism with a large active surface area for propagation. In this case, the porous granules force bacterial dispersal growth, which results in a significantly larger mass exchange area than in conventional activated sludge flakes. Furthermore, since the microorganisms that grow due to the contents of the wastewater strongly propagate inside the granules in the pores and the granules are easily retained in the reactor, the dry matter concentration in the conventional activated sludge method is Far surpassing 15g
A very high dry matter concentration with a value of / l or more can be maintained, which on the one hand requires a correspondingly small excess sludge removal rate and on the other hand a very large wastewater loading volume or Conversely, there is a slight residence time in the reactor of the wastewater associated with a reduction in reactor volume. In this case, due to the possible retention of the main amount of biomass synthesized in the reactor, a larger post-sedimentation tank than in conventional activated sludge processes is unnecessary, despite the large dry matter concentration. Furthermore, the small sludge volume due to the unfixed biomass allows the post-sedimentation tank volume to be reduced compared to the volume required in conventional activated sludge processes. In the extreme case where the return sludge is no longer pumped back into the reactor, only a very small post-sedimentation tank is needed to further separate excess sludge. Nevertheless, the high dry matter concentration allows a reduction in the sludge return ratio, which results in a reduction in pump energy when transporting the return sludge. A large mass exchange is ensured by the method in which the respective material particles are floated freely in the wastewater. In this case, the free distribution of the granulate is preferably 20-80 kg / m.
Its slight specific gravity of ³ , as well as gas- or liquid flow in the direction opposite to the downward movement is promoted. This requires that the oxygen-containing gas, in the form of air and / or industrial oxygen, required for microbial supplementation is introduced from the bottom of the reactor vessel, for example via conventional fine-, intermediate- or coarse bubble aeration. , Or just introducing the wastewater to be treated from the bottom of the reactor. Related to it,
An increase in the reaction rate is obtained by the turning up of the respective granulate, which may optionally be further enhanced by the turning device. In this case, the loss of biomass should not be a concern, because the microorganisms that grow due to the wastewater content propagate strongly inside the granules in the pores,
It is therefore protected from wear during mechanical action. Since it does not excessively prevent the floating motion of each particulate matter,
The granulate used as carrier material is introduced into the reactor in an amount corresponding to 5 to 70% of the reactor volume. Thus, depending on the packing density and properties of the granulate, a particular type of reactor can be manufactured in relation to the load volume of the wastewater to be treated. The reactor is therefore preferably a fully mixed activation tank in the case of 5-40% by volume of granules and a floating-bed and / or fluidized bed reactor in the case of 40-70% by volume of particles. Be driven. As carrier material, particles having a particle size of 5 to 50 mm and open cells of 0.1 to 3 mm are used. Granules of each of these sizes give rise to stable bacterial condensates and ensure oxygen supply and mass transport into all individual granules. On the other hand, if this is desired, an additional anoxic region inside the carrier material can be obtained by limiting the concentration of dissolved oxygen or by choosing the diameter of the respective granules in the upper range of a given value. Can be created. As a result, the denitrification step can be allowed to proceed in the reactor in some cases. The macropores of each of the above dimensions in the granulate prevent clogging of the pores by impurities and allow microorganisms to use a large surface area for breeding. It is likewise possible to use particulate particles as carrier material, especially if the reactor is formed as a floating-bed or fluidized-bed reactor. As carrier material, granules of organic polymer compounds are used. Above all, granules of polyurethane flexible foam or similar materials with open pores, such as those obtained in the plastics processing industry, fulfill all of the abovementioned properties required for a suitable carrier substance, in which case there remains a residual- And scraps of scrap can be used. As is apparent, just 1 m ³ of such polyurethane flexible foam particles absorb and bind more than 30 kg of biological dry matter, resulting in a sludge dry matter in the reactor at a foam volume ratio of up to 50% of the reactor volume. Is 15 g /
Values above l can be obtained. The process according to the invention is particularly advantageous if the carrier material is applied with powdered activated carbon before the wastewater is led through the reactor. Thus, with constant energy consumption for oxygen transfer, a doubling of the oxygen transfer efficiency can advantageously be obtained. Furthermore, the method according to the present invention can be applied to such a wastewater purification device, which has only allowed an imperfect purification efficiency as compared with the conventional case, as well as economical purification of high-load wastewater. In this case, it is particularly advantageous if the effluent of the biological filter and / or the chemical and / or physical purification process is introduced into the reactor as wastewater to be purified. A short aeration time is sufficient to treat this effluent, since the biomass concentration can be largely maintained in the reactor due to the presence of carrier particles. Furthermore, only a very slight load on the post-sedimentation tank occurs,
And from the outset, the formation of aerated sludge, which can occur during aeration, especially in biological filter effluents, is prevented. An apparatus for carrying out the method includes a reactor and a post-sedimentation section that is post-attached to the reactor via a drain. According to the invention, as a carrier material for the microorganisms in the reactor,
Porous particles with a small specific gravity in the form of fragments and / or particles are present so that they can move freely. Advantageously, a separation device, for example a simple wire mesh, is arranged in the drain of the reactor in order to retain the particles in the reactor. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the drawings, 1 represents a reactor which is closed to the atmosphere and which is formed as a complete mixing type activation tank. In the activation tank 1, as represented by parallel lines, as a carrier substance for microorganisms, the diameter is 5 to 50 mm and the specific gravity is 20 to 8
Porous granules 13 of 0 kg / m ³ and open cells 0.1-3 mm, of polyurethane flexible foam, among others, are free to move in an amount corresponding to a volume of 5-70% of the activation tank volume. It is located in. The wastewater to be treated is introduced into the activation tank 1 via the supply pipe 2 and the treated wastewater is removed via the drainage pipe 3 connected to the upper part of the activation tank 1, in which case The drainage pipe is provided with a separating device 4 for holding each particulate matter, which may be a simple wire mesh, for example.
A drainage pipe 3 of the activation tank 1 is connected to a post-sedimentation section 5 formed as a sedimentation tank, and the sedimentation section 5 is a water discharge pipe 6 for purification, and a pump for returning sludge into the activation tank 1. And a sludge return pipe 8 for excess sludge. In order to supply oxygen to the microorganisms, a gas containing industrial pure oxygen or at least a larger amount of oxygen than air is introduced into the air chamber formed under the lid of the activation tank 1, and the air is introduced into the air chamber. It is arranged to supply the gas present via a conduit to a gas distribution device 10 arranged near the bottom of the activation tank 1.
Waste air is removed via a valve-controlled exhaust pipe 11. In this case, the rising gas bubbles of the aeration gas provide a sufficient levitation force to keep the biomass-loaded granules 13 in suspension, the specific gravity of which is very slightly above that of water. In order to obtain as good a mixing and a good reaction rate as possible, a swirler 12, for example a simple stirrer with a motor drive, is arranged directly above the gas distributor 10. With the arrangement of the processing gas supply pipe 9 shown in the drawing, the gas supply pipe is directly connected to the activation tank 1 through a large number of connecting pipes.
It is possible to connect to the bottom of the tank and obtain an additional upward air stream in this way. Similarly, the wastewater supply pipe 2 maintains a liquid flow directed upward in the activation tank,
It is possible to have a number of connecting pipes which can be distributed on the bottom of the tank. Further, when treating high-load wastewater, since the foam 1m ³ can absorb and bind 30 kg or more of biological dry matter, the volume of the activation tank 1 and the post-precipitation part 5 is required by the conventional activation method. It can be reduced compared to the tank volume. In this case, the amount of activated sludge to be returned from the post-sedimentation section 5 into the activation tank can be maintained extremely small. It is even possible to prevent the sludge return flow at least once by switching off the pump in the sludge return pipe 7. Table 1 below lists the numerical values of one example of an activator operated according to the method according to the invention in comparison with a conventional activator:

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a schematic diagram showing an embodiment of the device according to the invention. 1 ... Reactor, 2 ... Waste water supply pipe, 3 ... Drainage pipe, 4 ... Separator, 5 ... Post-sedimentation section, 6 ... Purified water outlet pipe, 7 ... Sludge return pipe, 8 ... Sludge outlet pipe, 9 ... Gas Supply pipe, 10 ... Gas distribution device, 11 ... Exhaust pipe, 12 ... Rotating device, 13 ... Granular material.

Claims (1)

Claims: Claims: 1. Wastewater is supplied with air and / or pure oxygen in a reactor in the presence of biomass immobilized in a reactor on a carrier material which is a granulate of flexible polyurethane foam. By venting and subsequently separating the wastewater into clarified water and sludge in the post-sedimentation section and introducing porous granules in the form of debris and / or granules as carrier material for the microorganisms in the reactor. , In a method for biologically purifying wastewater containing organic impurities, a small specific gravity of 5 to 50
particles having a particle size of mm and open cells of 0.1 to 3 mm, in an amount corresponding to a volume of 5 to 70% of the reactor volume, in which the individual particles are suspended so that they can move freely in the waste water. In the case of charging and when the volume fraction of the particulate matter is 5 to 40%, the reactor is operated as a complete mixing type activation tank, and at least temporarily, the activated sludge is returned from the post-sedimentation section into the reactor, and the carrier is carried in the reactor. A method for biologically purifying wastewater, characterized in that it maintains free activated sludge as well as biomass fixed on the material. 2. A biological filter and / or a chemical purification process and / or wastewater to be purified into the reactor.
Alternatively, the method for biologically purifying the wastewater according to claim 1, which comprises introducing the effluent of the chemical-physical purification step.