DE102007021887B3 - Procedure for biological treatment of wastewater with low temperature, comprises settling bio film consisting of sessile micro organisms, and flowing unheated, colder mixture containing waste water and mud to subsurface of the film - Google Patents

Abstract

The procedure for biological treatment of wastewater with low temperature, comprises settling a bio film (18) consisting of sessile micro organisms, flowing unheated, colder mixture containing the waste water and mud to a temperable subsurface of the film, and regulating heat supplied to the subsurface in such a manner that the subsurface is warmed up but not the mixtures, based on the proportions between a total reactor volume and a heated packed bed (2). An independent claim is included for a device for the biological treatment of wastewater with low temperature.

Description

The The invention relates to a method and a device for biological Treatment of wastewater with low temperatures.

Characteristic of the known technical solutions

All Biological wastewater treatment processes are based on food and reproductive strategy of self-developing bacteria on. Will they carrier material as nursery area offered, they settle on it as a so-called biofilm. There she firmly on the nursery surfaces are fixed, is spoken by sessile microorganisms on fixed beds.

process engineering can these fixed beds as independent technical structures are operated in a biological reactor. They take over the entire cleaning of the wastewater.

On the other hand is understood by combined methods the installation of firmly anchored Fixed beds in the activated sludge or a similar process. Take over here the fixed beds only a part of the cleaning services. For fixed beds have z. B. structured packages of corrugated, with each other connected plastics proved to be suitable. The fixed beds can be up, down or down sideways flows through become. The flow directions in particular in aerobic processes by the type of aeration devices certainly.

Such methods and systems are z. B. from the DE 19859 542 A1 or the DE 3916250 A1 known.

Of the current Knowledge is also in principle by H.-J. Pöpel in "fixed bed and fluidized bed reactors for nitrification and denitrification as an alternative to the activated sludge process "(Series WAR 91 - TH Darmstadt, pp. 101 to 128, ed.: Association for the Promotion of the Institute WAR - Darmstadt 1996) well described.

Thereon are related to one of the performance for aerobic and anoxic methods and devices.

So is after the DE 19807458 A1 a biological sewage treatment plant equipped with fixed beds, in which at least two electrodes for generating a current flow are installed in a clarification chamber equipped with a fixed bed. As a result, at wastewater-typical temperatures, an electrochemical precipitation with simultaneous increase in the oxygen supply can be initiated.

From the DE 3916250 A1 is a mixing chamber element, consisting of a plurality of mixing chamber elements mixing chamber unit and their use for biological wastewater treatment known.

there the mixing chamber elements are designed in their geometric shapes, that a complete Mixing of the flowing through Medium should be achieved. By this intended thorough mixing the contents of the mixing chamber elements or the mixing chamber units can always be the "mixing chamber unit when heating individual mixing chamber elements 28 "including her entire media contents are heated to a temperature of 37 ° C.

The required high energy consumption when heating the respective total volume of wastewater are regarded as uneconomical in the known from the prior art method. The size of the additional energy requirement becomes clear after knowledge volume and inhabitant-related reference values. For traditional methods of municipal wastewater treatment at waste water temperatures of 8 ° C to 14 ° C is approximately: • Wastewater Ponds (ATV-A 201) 10m ³ / EW ... 3m ³ / EW • aeration plants (nitri / denitri) (ATV-A 131) 0.2m ³ / EW ... 0.1m ³ / EW • aeration plants (aerobic stabilization) (ATV-A 131) 0.6m ³ / EW ... 0.3m ³ / EW • Fixed Bed Systems (KA 2002 [49], No. 12) ≤ 0.03m ³ / EW

temperature increases in reactors / fermenters with these volumes were and are energetically unacceptable. Furthermore would the heated ones purified wastewater from 30 ° C for environmental reasons again chilled become.

Object of the invention

In order to avoid these serious disadvantages, the basic idea of the claimed method according to the invention is then to heat only the surfaces of the fixed beds and not the spaces of the reactors / fermenters with the entire wastewater volume involved. If combined processes are preferably used, the ratio between the large reactor volumes (10 m ³ / rev. ... 0.1 m ³ / rev.) And the then installed heated fixed beds with a maximum of 0.03 m ³ / rev. that at the desired temperature differences of 2 ° C ... 4 ° C between the cold waste water and the warm fixed beds, no heating of the wastewater is felt. In other words, with still low wastewater sludge temperatures in the reactors / fermenters, the activity and amount of bacteria colonizing the heated fixed beds should be improved.

• • in belüfteten Oxidationsteichen mit eingebauten Festbetten bei Abwassertemperaturen < 3°C zur Aufrechterhaltung relevanter Reinigungsleistungen;
• • in Belebungsanlagen mit eingebauten Festbetten bei Abwassertemperaturen < 10°C zur Gewährleistung der Nitrifikation und Denitrifikation;

In order to obtain and increase the conversion rates of sessile heterotrophic and autotrophic bacteria for the treatment of waste water at low temperatures and be increased with minimal energy consumption, z. B.

• • in ventilated oxidation ponds with built-in fixed beds at wastewater temperatures <3 ° C to maintain relevant cleaning performance;
• • in activated sludge plants with built-in fixed beds at wastewater temperatures <10 ° C to ensure nitrification and denitrification;

These The object is achieved by the features of the method according to claim 1 and the features of the device according to claim 2 solved.

Explanation of the essence of the invention

The inventive solution applicable in the biological treatment of organically polluted and nitrogenous wastewater by means of aerobic and anoxic living microorganisms. At low Sewage and reactor temperatures, eg. B. <3 ° C for the organic carbon degradation and <10 ° C for nitrification and denitrification, should be the minimum conversion rates of microorganisms by the exclusive Heating the fixed beds maintained energetically optimized stay.

The essence of the invention is based on the knowledge that the biological processes of wastewater treatment are temperature-dependent. In particular, it is the applicable environmental conditions pH value, nutrient ratio, salt and O ₂ content, as well as explicitly the temperature, which determine the substrate degradation rates of dissolved wastewater constituents by means of aerobic, anoxic and anaerobic microorganisms. Increasing speeds can also lead to shortening of the required reaction spaces.

As part of the MONOD kinetics, the growth rates μ [h ^-1 ] of the microorganisms can be theoretically defined as a function of different influencing factors. However, the following related equation describes only one particular bacterium. Mixed populations, such as those used in municipal wastewater treatment in particular, can therefore only be characterized as such.

wobei unter

μ_max

= maximale Wachstumsrate [h^–1]

S

= Substratkonzentration [mg/l]

k_s

= Halbsättigungskonstante, abhängig u. a. von der Temperatur [mg/l]

t

= Zeit [h]

verstanden wird.After Monod is:

being under

μ _max

= maximum growth rate [h ^-1 ]

S

= Substrate concentration [mg / l]

k _s

= Half-saturation constant, depending among other things on the temperature [mg / l]

t

= Time [h]

is understood.

going it is believed that microbial growth is directly proportional the substrate degradation rate is the qualitatively definable Meaning of temperature for the degradation of wastewater constituents.

in the The focus of interest considerations are aerobic and anoxic processes to reduce organic carbon and nitrogen compounds using heterotrophic and autotrophic bacteria. This is primarily about maintaining the minimum substrate degradation rates low wastewater temperatures as a prerequisite for compliance the statutory monitoring values.

fixed beds are lapped by the wastewater in differently directed currents. she are characterized by large ones growth surfaces for the Biomass and high solids content. The temperature conditions for the settled biomasses on the fixed beds correspond to the supplied wastewater temperatures.

By the heating according to the invention the fixed beds can on these the settled microorganisms, regardless of the present sewage temperatures, idealized temperature conditions for disposal be put. In the targeted exclusive heating of the fixed beds The energy required to maintain and increase the conversion rates of the bacteria are reduced.

For heating The fixed beds are almost all heat sources applicable. Especially are within the anaerobic sludge treatment within the sewage treatment plants suitable alternative energy sources suitable.

The forming the fixed bed, the heating medium leading internals, e.g. Tube made of good thermal conductivity Materials, can with thermal insulation Wrapped in fabrics become. The latter substances should vary depending on their desired outside temperature in the flow direction Rejuvenate the heating medium. Thus, on the heat-insulating Substances settling bacteria guarantees a nearly constant temperature become.

When a particular problem with heated fixed beds is the rapid growth of sludge with rising temperatures and a sudden almost abrupt desludging on. The removal of this excess sludge from the biological reactor requires separate constructive solutions.

Around the efficiency to maintain the de-mudded fixed beds, can its surfaces coated with different materials (eg textiles) become. As a result, such. B. of "weakly loaded drip bodies" known, a short-term Total power reduction avoided.

embodiments

The Invention is based on two embodiments with associated Pictures closer explained. Showing:

1 : Scheme of a wastewater treatment plant according to a first embodiment

2 : Heatable carrier material as a single element according to the first embodiment

3 : Scheme of a wastewater treatment plant according to a second embodiment

The first embodiment shows accordingly 1 schematically the device with a flow-through fixed bed ( 2 ). This consists of heatable carrier material. The fixed bed ( 2 ) is in the biological reactor ( 1 ) on rigid supports ( 15 ) firmly anchored. Depending on the method, this fixed bed ( 2 ) are implemented in a separate or combined process.

The biological reactor ( 1 ) is via the supply line ( 7 ) supplied mechanically pre-treated wastewater. Its flow direction is determined by the baffle ( 8th ). This guarantees the flow of the fixed bed ( 2 ) from underneath. The effluent from the biological reactor ( 1 ) via the overflow threshold ( 10 ) in the process ( 9 ) for clarification.

On the heated substrate according to single element ( 17 ) to 2 colonize microorganisms. As a result of the optimal living conditions created by the heating, the microorganisms grow quickly and quickly slip out of the fixed bed after a short time ( 2 ) as excess sludge in the sludge collection room ( 14 ). In the sludge collection room, the excess sludge is stored intermediately and if necessary via a sludge line ( 11 ) forwarded for final treatment.

By a compressor ( 13 ) is by means of a pressure line ( 12 ) the fixed bed ( 2 ) fumigated. The heating of the carrier material according to single element ( 17 ) to 2 can take place via the media hot water, oil o. Ä. The required definable temperature guarantees a heat exchanger ( 3 ) from an external, higher temperature heating medium ( 16 ) is supplied as a heat source. The regulation of the required temperature constancy takes place via a control and regulating device ( 6 ). About the pipes ( 4 and 5 ) the heating circuit is closed.

This in 2 specified single element ( 17 ) consists of a welded together pipe system, preferably made of plastic material. The individual elements ( 17 ) can be bundled into tube packages. These are from above the pipeline ( 4 ) with the selected medium, e.g. As hot water, charged and warm. The cooled medium is taken below the pipe package and passed through the pipeline ( 5 ) to the heat exchanger ( 3 ) returned. On the surface of the individual elements ( 17 ), the microorganisms settle as biofilm or biomass ( 18 ) at. This biomass ( 18 ) dissolves abruptly after a short time from the surface of the individual elements ( 17 ) and slips into the mud stacking room ( 14 ).

The second embodiment according to 3 shows schematically a sideways flowed through and fixed bed ( 22 ). It consists of electrically heatable contact plates on which microorganisms as biomass ( 18 ) settle. The contact plates are bundled to form a heating package. The fixed bed ( 22 ) is by means of a metal frame ( 23 ) elevated. The supply of electric energy via solar panels (photovoltaic system 19 ). Via a control building ( 20 ), the electrical system can be controlled. In this case, the electrical energy by means of elevated E-cable ( 24 ) on the contact plates of the fixed bed ( 22 ) transfer. The energy supply results from the definable living conditions of the microorganisms.

The sideways flow of the fixed bed ( 22 ) guarantees a water-immersed spiral aerator ( 21 ), from which a water-air mixture is produced. The geometric distance of the spiral aerator ( 21 ) to the fixed bed ( 22 ) describes the essence of a combined process.

1

biological reactor

2

upward flowed through fixed bed

3

heat exchangers

4

pipeline

5

pipeline

6

Tax- and control organ

7

supply line

8th

baffle

9

procedure

10

Overflow threshold

11

sludge line

12

pressure line

13

compressor

14

Sludge storage space

15

Support

16

heating medium, heat source

17

Single element

18

biomass, biofilm

19

photovoltaic system

20

control building

21

Wend aerators

22

sideways flow through fixed bed

23

metal frame

24

E cable

Claims (5)

Method for maintaining and increasing performance biological sewage treatment plants, especially in the treatment of waste water with low temperatures, at the warranty ideal temperature conditions of heterotrophic and autotrophic Bacteria on consisting of sessile microorganisms biofilm a targeted temperable subsurface is settled by an unheated, colder one Sewage sludge mixtures flows around is, with the underground heating power supplied, so regulated that is due to the size ratios between the total reactor volume and the heated fixed bed, permanent only the substrate, but not the sewage sludge mixtures are heated. Device for carrying out the method according to claim 1, wherein in a biological reactor ( 1 ) a fixed bed ( 2 ; 22 ), the outer wall of which as a supporting structure and growth surface for an existing from sessile microorganisms biofilm ( 18 ), and the fixed bed ( 2 ; 22 ) through its interior through an outside of the biological reactor ( 1 ) arranged heat source ( 3 ; 16 ; 19 ) Is heated and wherein on the outer walls of the fixed bed materials additionally heat-insulating growth bodies are applied, which limit the removal of energy in the flow around sewage sludge mixtures and regulate in terms of a bacteria-friendly outdoor temperature. Device according to claim 2, characterized that on the outer walls of fixed bed material additional and different materials, e.g. As textiles, to increase and Creation of variable adhesion conditions for the microorganisms attached to prevent their simultaneous rinsing from the fixed bed surface. Device according to claim 2 or 3, characterized in that the heated fixed bed ( 2 . 22 ) in the biological reactor ( 1 ) is firmly anchored. Device according to one of claims 2 to 4, characterized in that the heat supply to the heated fixed bed ( 2 . 22 ) outside of the biological reactor ( 1 ) and control organs ( 6 . 20 ) is controlled.