DE19758486C2 - Method and device for the biological removal of nitrogen from waste water - Google Patents

Description

The invention relates to a method and a device for the biological removal of nitrogen from waste water with special attention to the biological phos phatelimination.

It is known to be purified by a water Reactor containing floating grain from top to bottom to flow to prepare a biological cleaning to take.

According to DE 33 38 170 C2, the cleaning of the Floating grain in a separate one, below the reactor located washing tank, which with the reactor in Connection is established. The floating grain is attached to the reactor taken from its conical tip and arrives at the best between the reactor and the wash tank pressure difference in the wash tank, is there with Rinsed pure water and comes back via buoyancy forces in the reactor.

DE 25 49 415 C2 discloses water to be purified through a reactor containing floating grain from below flow upward to a biological reini to perform. The cleaning of the floating grain he follows from a so-called heavy flush Reactor-mounted rinsing water tank in counterflow. Depending on the load on the reactor, backwashing takes place instead, the temporal, volume proportional or via difference pressure is triggered. For this flush is in opposition to DE 33 38 170 C2 a short business interruption conducive.

EP 0 389 958 B1 describes a device which the intervals between two backwashes at one of reactor flowed through from bottom to bottom clearly should reduce.

For this purpose, filter material loaded with biomass is used one through the raw water flow or through the Recirculation current driven water jet pump the filter bed continuously during the operation of a Withdrawn reactor. Shear forces make biomass and carrier material in the discharge line from one another Cut. The cleaned carrier material is stored again after entering the reactor below the filter material fill, while the separated biomass in the coni sedimented part of the reactor. Through this continuous Animal recirculation of filter material can take longer Run times of the reactors can be achieved.

All of the above methods are used for filtration or for biological processes like denitrification or wise nitrification used.

EP 0 504 065 A1 describes a method for biological Wastewater treatment described, being cleaned the waste water from bottom to top through a reactor or biological filter, which is used as a carrier material for bacteria contains polystyrene particles. The so-called Fixed bed is fi above by a restraint xiert. The wastewater to be cleaned is on its way enriched with oxygen-containing gas through the filter material chert. Part of the pure water is in the inlet area returned. The reactor is backwashed in the counter electricity. In contrast to the above methods fin an anaerobic or anoxic process (De nitrification) and an aerobic process (nitrification) in one Reactor instead. The individual reaction stages are spatial not separated from each other. A disadvantage of this method is that in principle only a certain carrier material Density can be used. For optimal cleaning must the entire water volume of the reactor out be exchanged. With the spatially separate system must only the heavily loaded zone (denitrification and filtrate onszone) are backwashed because the nitrification applied onszone does not come into contact with Suspensa etc. This has a significant reduction in the amount of flushing water Episode. Furthermore, the individual reaction step is difficult can be optimized individually, such as internal recir circulation cycles, rinsing etc.

The invention has for its object the disadvantages to avoid the above procedures. Invention Ge This task is moderated by the features of the claim 1 and 6 solved. Advantageous developments of the invention include the features of claims 2 to 5 and 7, 8.

The invention has compared to the above-mentioned method ren the advantage that the anaerobic and anoxic range through a separate nozzle floor is separated. Due to the strict spatial separation of the two Reaction zones can be made of support materials on polystyrene use a base with different density. That’s it for example, the anoxic zone in the lower reak Gate area with high density and finer substrates Grain and Trä in the aerobic area above low density, large grain materials clog. Only then is the process engineering approach of the individual reaction zones and the advantage of separating these two zones clearly.

The most important task of the anoxic zone is next to the biological denitrification the separation and retention treatment of wastewater suspension and excess sludge, fine carrier material is an advantage here.

For the aerobic reactor area (nitrification) is the Oxygen input and transfer (mass transfer) from ent outgoing meaning, so that here coarser filter material with higher gaps, better fluid dynamic egg properties and less tendency to form dead zones is cheaper. Because the majority of the Suspensa be was already held back in the anoxic zone the Randbe required for optimal nitrification conditions are optimally observed.

The reactor consisting of two chambers is operated by un The waste water to be cleaned is fed upwards. Foamed polystyrene is used as the carrier material, which functions both as a filter and as a bioma exercise carrier material. One chamber is used for denitrification cation and at the same time the suspension suspension, while the other chamber ventilated and used as nitrification zone becomes. By separating it into two reaction spaces biological phosphate removal also takes place. The doors The reaction spaces in the upper reactor make it possible area to use a filter material that is clogged has lower bulk density than that in the lower area put filter material. Without separation, it would be forced the materials are frequently mixed, d. H. the different density of the carrier materials would lead to a reversal of the filling the procedure would no longer be feasible.

A partial stream of the pure water is fed back to the raw water stream to adjust the C / N ratio. The backwash runs counter to the direction of loading ( Fig. 1).

The invention is based on an Ausfüh tion example are explained in more detail.

The reactor consisting of reaction zones 1 and 2 is fed with the wastewater to be purified from the bottom up. The reaction zones are separated from one another by a nozzle plate. Foamed polystyrene is used as the carrier material. The anoxic reaction zone 2 in the lower reactor area contains carrier materials with high density and fine grain and the aerobic reaction zone 1 above contains carrier materials with low density and coarse grain.

The wastewater is passed through an anoxic area in reaction zone 2 , Suspensa being retained, COD / BOD being broken down and nitrogen in the form of nitrate being reduced to elemental nitrogen. The water depleted in this way is then passed into a reaction zone 1 , an oxygen-rich environment being generated under air and / or oxygen gassing 8 a and the nitrogen compounds being oxidized to nitrate.

In the process flow of FIG. 1, the so-called bio-P plays only a subordinate role.

The backwashing takes place according to FIG. 1 from a rinsing water reservoir placed on the filter in the direction of the heavy force. Rinse water pumps are not required. It is triggered via time or differential pressure.

For this purpose, the supply 4 and return line 5 is interrupted and a valve in the rinse water drain 9 is opened. The backwash quantity depends on the loading of the carrier material. It can consist of a so-called heavy-duty flush at high speed or of multiple interval flushes. The backwashing speed can be freely selected via a throttle valve. The backwashing speed is set so that the carrier materials in reaction zones 1 , 2 expand completely and both Suspensa and the biomass formed are removed from the system.

An addition of air via an additional entry device ( 8 b) during the backwashing process can also be used for very heavy loads. After rinsing, the filter can be put back into operation immediately.

Reference list

1

,

2nd

Reaction zones with carrier material

3rd

Air line / oxygen supply

4th

Raw water supply

5

return

6

Pure water drain

7

Rinse / pure water tank

8th

a Air inlet device process and purge air upper zone

8th

b Air inlet device, purge air, lower zone

9

Rinsing sewer.

Claims (8)

1. Process for the biological purification of waste water, the waste water ( 4 ) being introduced into a reactor consisting of two zones and containing support materials and being passed through an anoxic region in the reaction zone ( 2 ), Sus pensa being retained, COD / BOD is broken down and nitrogen in the form of nitrate is reduced to elemental nitrogen, the depleted water is passed into a reaction zone ( 1 ), an oxygen-rich environment and the nitrogen compounds being generated with air and / or oxygen gassing ( 8 a) are oxidized to nitrate, characterized in that the reaction zones ( 1 , 2 ) are separated from one another by a nozzle plate, and contain floatable carrier materials of different density and grain size, the anoxic reaction zone ( 2 ) in the lower reactor region carrying materials with high density and fine grain and the overlying aerobic reaction zone ( 1 ) carrier materials with low density and coarse grain. 2. The method according to claim 1, characterized in net that the reactor supports on polystyrene base contains. 3. The method according to any one of the above claims, characterized in that from a flushing water reservoir ( 7 ) in the direction of gravity and against the loading direction backwashing of the carrier materials. 4. The method according to any one of the above claims, characterized in that the backwashing takes place with an additional air supply ( 8 b). 5. The method according to any one of the above claims characterized in that a partial stream of the torn off water to adjust the C / N ratio is supplied to the wastewater to be cleaned. 6. Device for the biological purification of water, consisting of a reactor with two stacked carrier materials with different density and grain size containing zones ( 1 , 2 ) which are separated from each other by a nozzle bottom, the reaction zone ( 2 ) with carrier material high density and fine grain and the reaction zone ( 1 ) has carrier material with low density and coarse grain. 7. The device according to claim 6, characterized in that a rinsing water serreservoir ( 7 ) is arranged above the reaction zone ( 1 ). 8. Device according to one of the above claims, characterized in that the reactor has a waste water supply line ( 4 ), a partial flow return line ( 5 ), an outlet line ( 6 ) for cleaned waste water, a rinse water discharge line ( 9 ) and an air line ( 3 ) has an air inlet device ( 8 a) for process and purge air for the upper zone and an air inlet device ( 8 b) for purge air for the lower zone.