DE19614306A1 - Treating highly polluted industrial waste water, especially waste tips water - Google Patents

Abstract

In a system for treating highly polluted industrial waste water especially water escaping from waste tips, by chemical ozone treatment and biological treatment, the water is first de-nitrified in a pretreatment reactor (1) with vigorous agitation. Ozone (12) is then dosed and injected (5) into the water and the water and ozone are pumped through a reaction vessel (6). The water then enters a post-reaction vessel (7) followed by a post-treatment reactor where it is vigorously agitated and subjected to nitrification. The vigorous agitation is effected by a fluid bed reactor. Apparatus for carrying out the above process is also claimed. Gas containing oxygen is drawn from the post-treatment vessel, expanded to 1-1.5 bar and totally freed of ozone using a catalytic process 100-200 deg C, and used for nitrification in the post-treatment reactor. The pressure of the water discharged from the post-reaction vessel is reduced to > 1 to 1.6 bar, any residual ozone being destroyed by exposure to UV light. Prior to water treatment, adsorption agents are dosed to absorb impurities and produce sediment which is removed (3, 4) before the water is introduced to the pretreatment reactor (1).

Description

The present invention relates to a method and a plant for the treatment of high polluted industrial wastewater according to the preamble of claim 1 or claim 13.

For cleaning highly polluted industrial waste water, especially landfill leachate, it is known to waste water with ozone in combination with UV radiation and in bioreak biological treatment of gates.

DE 39 19 835 C2 uses one for cleaning highly polluted industrial waste water a biological stage combinable ozone-UV treatment of the wastewater gene, in which the wastewater in a first process variant initially uses ozone as an oxidant onsmittel is fed via an injector before it is connected in two in series Reaction and degassing container is promoted. Before the wastewater from the first in the second reaction and degassing container or a partial flow from which it Most reaction and degassing containers get into a return line, it passes through because a UV radiation unit. According to a second proposed process variant ante, the wastewater to be cleaned is split into two sub-streams, one Partial stream is first supplied to ozone before this first reaction and Entga solution tank passes through and is merged with the other partial flow. The merged partial streams are then in a second reaction and degassing conveyed container, with a return having a UV radiation unit Is provided. The wastewater containing ozone is recycled several times in this way Pumped circuit and repeated the UV radiation through the radiation unit exposed. This method does indeed allow oxidation of poorly degradable damage substances and in the intended combination with a biological level, compliance of single-conductor limit values, however, those for the UV radiation units and the multiple fa che circulation of the wastewater required for repeated irradiation cost relatively high due to the high energy consumption.

For the biological treatment of waste water, the bioreactors are generally used as Fixed bed reactors formed by the waste water to be treated from the top flowed through below. Admittedly, the fixed bed reactor filled with adsorbent  Ren - a commonly used adsorbent is expanded clay, for example - at the same time realize biological and adsorptive treatment of the wastewater, but here it is a relatively long residence time in the reactor is required, which is usually only appropriate large and cost-intensive reactors can be achieved. Fixed bed reactors also tend to Constipation, the trouble-free continuous operation of a wastewater treatment endanger the system.

The object of the present invention is a method and a system according to the Ober to specify the concept of claim 1 or claim 13, which is a continuous, largely trouble-free and economical cleaning of heavily loaded industries allows watering.

This object is according to the characterizing part of claim 1 and Claim 13 solved.

In this way, a continuous, largely trouble-free and economical journey of highly polluted industrial wastewater. With the intended procedure In addition, easily degradable pollutants can be broken down in denitrification the COD be reduced so that the ozone consumption in the downstream ozone action and thus the operating costs can be reduced. By a between deni Trification and nitrification switched ozone treatment can biological treatment Otherwise, inaccessible pollutants such as humic and inert substances are oxidized and the subsequent metabolization in the nitrification stage the. Depending on the composition of the wastewater, Achieve elimination rates of 60-95%.

Oxygen-containing gas drawn off from the after-reaction container is advantageously used Nitrification passed into the aftertreatment reactor and essentially the nitrification operated pure oxygen, which comes from the ozone generation.

In order to have a largely homogeneously distributed oxygen concentration over the aftertreatment reactor To ensure concentration, the gas withdrawn from the after-reaction tank is on a pressure of <1 to 1.5 bar relaxed and via a bottom in the aftertreatment reactor arranged oxygen distributor entered. To damage the bacteria To avoid strains in the aftertreatment reactor, this becomes from the postreaction ons container extracted, oxygen-containing gas before entry catalytically at a tem temperature of 100 to 200 ° C completely free of ozone.  

The wastewater emerging from the after-reaction tank is preferred before entering throttled the aftertreatment reactor to the system pressure there and by a UV reactor directed to residual ozone destruction.

If the wastewater is metered into the biological treatment reactor - reactor 1 and / or reactor 2 as an example in the figure - and loaded adsorbent is at least partially returned to the treatment reactor via a sedimentation sludge separation downstream of the respective treatment reactor, the biological degradation of pollutants can also continued outside of the treatment reactor on or in the adsorbent particles and pollutants that are difficult to decompose are removed from the waste water. In this way it is possible to biologically treat the biodegradable pollutants beyond the hydraulic residence time in the respective treatment reactor. A preferred treatment reactor is a stirred loop reactor. Reactors which work like a fluidized bed are also well suited according to the invention.

The wastewater in the treatment reactors is formed like a loop with the formation of Circulated vortices rotating about essentially horizontal axes can be advantageously used an intensive mixing of adsorbent and waste water as well as a Mass transfer favoring thin boundary layer formation at the adsorption Ensure adsorbent particles.

The wastewater to be treated is advantageously through before entering the denitrification stage one connected to the cooling unit of a cooling circuit for an ozone generator Heat exchanger heated, preferably to an inlet temperature of 20 to 25 °.

The waste water is used to absorb the ozone via the injector before it enters the injector advantageously brought to a pressure of 3 to 6 bar, preferably 4 to 5.5 bar.

The hydraulic residence time in the pretreatment reactor for denitrification is dependent of the pollution and is preferably 10 to 30 hours, especially be preferably 15 to 25 hours.

The residence time in the aftertreatment reactor for nitrification is also dependent on the pollution and is preferably 40 to 80 hours, particularly preferably 50 up to 70 hours.  

For sedimentative separation of excess sludge and loaded adsorbent a lamella clarifier or an inclined clarifier is preferred after a treatment reactor intended.

Further embodiments of the invention are the following description of the figure and the subclaims.

The invention is illustrated below with reference to one in the accompanying figure Embodiment of a plant for cleaning landfill leachate explained in more detail.

The figure shows a schematic representation of a plant for cleaning landfills kerwasser.

The plant shown schematically in the figure comprises a pretreatment reactor designed as a stirring loop reactor 1 for denitrification and a post-treatment reactor designed as a stirring loop reactor 2 for nitrification.

The stirring loop reactors 1 , 2 are each followed by two diagonal clarifiers 3 , 4 , which are arranged with feedback lines.

Between the stirred loop reactor 1 and the stirred loop reactor 2 , an injector 5 for metering in ozone, a reaction vessel 6 and a secondary reaction vessel 7 arranged after it, and a UV reactor 8 for residual ozone destruction.

The post-reaction tank 7 is arranged downstream of a residual ozone destroyer 10 with an upstream throttle 9 . A line leads from the throttle 10 to an oxygen distributor 11 provided in the bottom of the stirring loop reactor 2 .

To generate ozone from technical oxygen, an ozone generator 12 connected to the injector 5 is provided, which is cooled via a cooling circuit 13 with a cooling unit 14 .

For preheating the wastewater entering the system, a heat exchanger 15 is seen before, which transfers heat to be dissipated from the cooling unit 14 to the wastewater via a water circuit.

Waste water entering the system is preheated via the heat exchanger 15 and mixed with a recirculated partial flow of the discharge. Before entering the Rührschlau fenreaktor 1 activated carbon is added to the waste water as an adsorbent to a concentration of about 20 g / l.

The waste water is then circulated several times in a stirring loop reactor 1 during a residence time of approximately 7 hours. From the wastewater withdrawn from the stirring loop reactor 1 , the sludge is separated off via the inclined clarifier 3 and returned to, excess sludge which arises can be discharged into a sludge, not shown, thicker. The largely sludge-free wastewater is then mixed with a recirculated partial flow from the reaction vessel 6 and brought to a pressure of approximately 4 to 5.5 bar before the generator 12 produced in the ozonator gas is metered in via the injector 5 .

To oxidize the pollutants, the wastewater containing ozone and oxygen is then pumped into the reaction vessel 6 and subsequently into the after-reaction vessel 7 , a partial stream of the wastewater emerging from the reaction vessel 6 before the injector 5 with a reflux ratio of about 0.5 to 0.7 is returned.

The oxygen / residual ozone mixture collecting at the top in the after-reaction container 7 is catalytically freed of ozone by the residual ozone destroyer 9 at a temperature of approximately 100 to 200 ° C., throttled to a pressure of approximately <1 to 1.5 bar by the throttle 10 and passed to the oxygen distributor 11 in the stirring loop actuator 2 .

Waste water emerging from the after-reaction tank 7 is pumped through the UV reactor 8 and then into the stirring loop reactor 2 for the destruction of residual ozone. The sludge is separated from the wastewater emerging from the stirring loop reactor 2 in the inclined clarifier 4 and returned to the stirring loop reactor 2 . Here again excess sludge can be removed to the sludge thickener, not shown. The wastewater escaping from the inclined clarifier 4 , largely freed of solids, is partly recycled in front of the stirring loop reactor 1 in order to reduce the nitrate load.

Claims (20)

1. Process for the purification of highly polluted industrial wastewater, in particular deoxygenated water, in which the wastewater is treated chemically with ozone and biologically, characterized in that the wastewater is first pretreated by denitrification in a vortex generated in a pretreatment reactor, then the wastewater contains ozone-containing gas metered in by means of an injector and the wastewater containing ozone is pumped through a reaction vessel and an after-reaction vessel connected downstream thereof, and then after-treated by nitrification in a vortex generated in an after-treatment reactor. 2. The method according to claim 1, characterized in that the vortexing in a fluidized bed. 3. The method according to claim 1, characterized in that from the post-reaction withdrawn oxygen-containing gas for nitrification in the aftertreatment reactor is directed. 4. The method according to claim 3, characterized in that from the post-reaction withdrawn gas from the container before entering the aftertreatment reactor on egg a pressure of 1 to 1.5 bar is released. 5. The method according to claim 3 or 4, characterized in that from the post-reaction withdrawn gas from the container before entering the aftertreatment reactor catalyzed table is completely freed of ozone at a temperature of 100 to 200 ° C. 6. The method according to claim 1 to 5, characterized in that from the Nachreak wastewater escaping before entering the aftertreatment reactor throttled a pressure of <1 to 1.6 bar and for the destruction of residual ozone by a UV reactor is passed. 7. The method according to any one of claims 1 to 6, characterized in that the Ab water is metered into the pretreatment reactor and adsorbent loaded denes adsorbent via a se after the pretreatment reactor dimentative sludge separation is returned in this.   8. The method according to any one of claims 1 to 7, characterized in that the Ab water is metered into the aftertreatment reactor adsorbent and be loaded adsorbent via a downstream of the aftertreatment reactor sedimentative sludge separation is returned in this. 9. The method according to claim 7 or 8, characterized in that the waste water in the pre-treatment reactor and / or the post-treatment reactor with the formation of vortices rotating around essentially horizontal axes is rolled. 10. The method according to any one of claims 1 to 9, characterized in that for cooling tion of the ozone generator, a cooling circuit is provided and by the cooling circuit heat to be dissipated via a heat exchanger to the waste water to be treated water is released before its entry into the pretreatment reactor. 11. The method according to any one of claims 1 to 10, characterized in that a part stream of the wastewater emerging from the reaction vessel and returned with wastewater originating from the pretreatment reactor is mixed. 12. The method according to any one of claims 1 to 11, characterized in that a part stream of the emerging from the aftertreatment reactor, largely from solids freed wastewater is returned to the pretreatment reactor. 13. The method according to any one of claims 1 to 12, characterized in that the Ab water before entering the injector to a pressure of 3-6 bar, preferably 4-5.5 bar, brought. 14. Plant for the treatment of highly polluted industrial wastewater, in particular landfill leachate, with an ozone generator ( 12 ), an injector ( 5 ) for metering the ozone generated into the wastewater, a reaction tank ( 6 ) and a post-reaction tank ( 7 ) for the oxidation of the pollutants , characterized in that the reaction vessel ( 6 ) precedes a pre-treatment reactor ( 1 ) for denitrification and the post-reaction vessel ( 2 ) is followed by a post-treatment reactor for nitrification and the pre-treatment reactor ( 1 ) and the post-treatment reactor ( 2 ) enable fluidization. 15. Plant according to claim 14, characterized in that the post-treatment reactor ( 2 ) for gassing with oxygen via a supply line with the post-reaction container ( 7 ) is in communication. 16. Plant according to claim 14 or 15, characterized in that the pretreatment reactor ( 1 ) and / or post-treatment reactor ( 2 ) is designed as a stirred loop reactor. 17. Plant according to one of claims 14 to 16, characterized in that the pre-treatment reactor ( 1 ) and / or the post-treatment reactor ( 2 ) is followed by a sedimentation device ( 3 , 4 ) for sludge separation. 18. Plant according to claim 17, characterized in that the Sedimentationsvorrich device ( 3 , 4 ) is designed as a lamella clarifier. 19. Plant according to claim 17, characterized in that the Sedimentationsvorrich device ( 3 , 4 ) is designed as an inclined clarifier. 20. Plant according to claim 14, characterized in that the pretreatment and Post-treatment reactor are designed as fluidized bed reactors.