DE102005025508A1 - Continuous-biotechnological sludge disintegration of suspended solid in liquid sludge, comprises pre-fermentation; splitting organic macro-molecule; obtaining liquid sludge; transferring split product; aerobic post-treating and recycling - Google Patents

Abstract

Continuous-biotechnological sludge disintegration, for the disintegration of suspended solids in liquid sludge from unavoidable waste, remainders and raw materials, comprises pre-fermentation; splitting of the organic macro-molecules present in the liquid sludge; obtaining the liquid sludge as pre-fermentation broth into methane fermenting stage; transferring the split products present in the pre-fermentation broth; obtaining the liquid sludge as a foul fermentation broth; post-treating under aerobic condition and recycling as further less volume-occupying residue. Continuous-biotechnological sludge disintegration, for the disintegration of all suspended solids in liquid sludge from unavoidable waste, remainders and raw materials, which result due to production and services of the communal economy, industries, food processing industry and agricultural industry, with the goal, to reduce the volume and the continuous-biotechnological sludge value of the liquid sludge to a very large extent through the holistic use of the metabolic activities of anaerobic and/or aerobic consortia of bacteria and/or the techniques of process engineering, which also results in energy-laden biogas, comprises pre-fermentation; splitting of the organic macro-molecules present in the liquid sludge, under defined process and environment conditions, by a consortia of hydrolytic bacteria fixed on a static substrate bio-film system and then through consortia of fermentative bacteria fixed on the same substrate bio-film system that are fermented to carbonic acid, gas and alcohol in the pre-fermentation reactor; obtaining the liquid sludge as pre-fermentation broth into the second process step, that is the methane fermenting stage; transferring the split products present in the pre-fermentation broth, under defined process and environment conditions, to methanogenic substrate through a consortia of acetogenic bacteria fixed on the substrate bio-film system and then with the help of consortia of methanogenic bacteria fixed on the same substrate bio-film system energy-laden biogas that is formed in the methane reactor; obtaining the liquid sludge as a foul fermentation broth in the third process step; post-treating under aerobic condition, in which the foul fermentation broth, under defined process and environment conditions is aerated and after the aeration of the remaining total solid mass content, results in a less volume-occupying sediment at the bottom of the airlift reactor and as liquid sludge sediment is transferred to the fourth process step, where it is concentrated and separated by the technique of filtration and/or gravity-separation, and recycling as further less volume-occupying residue, during which the permeate whose chemical oxygen requirement is reduced to more than 90%, with the clear phase of the third process step, directed to a reservoir or into one of the upstream process step and/or to an available clarifier.

Description

field of use the invention

The "Advanced biotechnology liquid sludge disintegration process according to the invention (WBFD method) " both as an autonomous procedural move and as complementary to existing ones conventional and / or biological treatment plants for targeted Biotechnological treatment of sewage sludge can be used.

in the The WBFD process is based on bioprocess engineering Ways to intensify the anaerobic and aerobic metabolic process of indigenous bacterial consortia with the aim of a more extensive Reduction of the volume, the COD value and the absolute TS content of liquid sludge with coupled recycling. All solid mass shares in liquid sludge fall in connection with the production of assets and Services in the field of communal services, industry, the Food industry and agriculture as solids suspended in water unavoidable Waste, residual and raw materials.

Information about State of the art

With known conventional methods and technologies such as e.g. thermal Processes, mechanical processes, chemical processes and / or enzymatic / biochemical Procedures can a whole range of primary requirements that to be provided to methods for the disintegration of sewage sludge, are met. These include u. a. as the first phase of microbial degradation of biomass known hydrolysis phase such. B. the enzymatic cleavage of Proteins, carbohydrates and fats in amino acids, sugars, glycerol and fatty acids, the transfer of organic cellular and extracellular Ingredients of the sludge in the aqueous supernatant, breaking up Cell envelopes, the killing / inactivation undesirable living germs, improving the drainage behavior of sludge, the Reduction of foaming, acceleration of the reaction rate the sludge digestion, the shortening the hydraulic residence time of the sludge in the sewage treatment plant, the increase of the Degree of degradation of organic matter contained in the sludge, the improvement of the specific biogas yield during sludge digestion and the reduction in the amount of microbial activity in the aeration tank / secondary clarifier biological sewage treatment plants resulting secondary sludge.

further Requirements that are especially for the ecology, economy and dissemination of sewage sludge disintegration processes for the most part in rural Space located smaller wastewater treatment plants are important, such. B. a targeted drainage Bioprocessing treatment of approximately up to 5% dry matter containing liquid sludge (thin sludge) for reduction of the CSB to over 98%, a significant reduction of liquid sludge volume by more than 95 vol. %, the targeted use and coupling of anaerobic and aerobic Metabolic processes for the bioprocessing treatment of Liquid sludge, the realization of the separate but coupled process steps expiring processes of the pre-fermentation and methane fermentation in high-pressure reactors operated under atmospheric pressure, the setting moderate process and environmental conditions, the extraction of the required process energy by the thermal utilization of the accumulating biogas, a significant shortening the hydraulic residence time of the liquid sludge in the high-performance reactors, the increase the digester load, the production of high-energy biogas can from all the above conventional sewage sludge disintegration processes not fulfilled anymore become.

Under Disintegration of liquid sewage sludge here is the drainage-free Reduction of all organic and / or inorganic solids content proportions through the microbial destruction of mud flakes and the microbial digestion of bacterial cells up to the mechanical separation and removal of all solid mass fractions from the liquid sludge Understood.

To be agreed here under septic tank load the ratio of the concentration of organic Solid mass fractions to the mean hydraulic residence time of the liquid sludge in each bioreactor, under Vorgär- or methane reactor respectively a temperable for The normal pressure designed container with integrated and fully in fermentation broth submerged static support biofilm system (s-T-B-S), as a pre-fermentation the microbial decomposition (hydrolysis) of organic macromolecules and as Fermentation of Cleavage products by on carrier material fixed hydrolytic and fermentative bacterial consortia, as methane fermentation the microbial formation of methanogenic substrates and the formation of Biogas through on support material fixed acetogenic and methanogenic bacterial consortia, under im Suspended liquid sludge organic solid matter fractions both organic mud flakes as well as contained therein or separately in the liquid sludge aerobic bacterial cells Understood.

In the case of thermal sewage sludge disintegration, the choice of the reaction temperature and the duration of the treatment are above all an improvement the subsequent microbial degradation process sought. The disadvantage here is that a maximum of externally generated energy is needed for the thermal disintegration of sewage sludge. At treatment temperatures above 100 ° C, pressure vessels must also be used. Costly are also required for increasing the temperature of sewage sludge heat transfer apparatuses.

at mechanical sludge disintegration Does it come to the digestion of the mud flakes or microorganism cells, if the necessary mechanical energy in the form of pressure, translation or rotation energy to disposal stands. The disadvantage here is that essentially from the precious energy form electric power in costly process engineering apparatus such as z. B. agitator ball mills, high-pressure homogenizers, Centrifugal techniques, impact blasting techniques, ultrasonic techniques etc. under high energy losses for the digestion of biomass needed mechanical energy must be generated.

at chemical sludge disintegration have to when using oxygen as an oxidant for fast Oxidation of the sewage sludge contained organic components either similarly high treatment temperatures and pressures as in the case of thermal disintegration or if strong oxidizing agents such. As ozone or hydrogen peroxide are used, can oxidation under normal pressure and at ambient temperatures expire. The disadvantage here is that the generation and handling the for needed the oxidation Oxidizing agent is very expensive and technically complex. The same applies to the acids used for alkaline or acidic hydrolysis and Bases.

at enzymatic / biochemical sewage sludge disintegration by acting as biocatalysts autolytic or external enzymes produced the rate of reaction of the microbial Diminishing evidence demonstrably raised. The disadvantage here is that in the stages of biological sewage treatment plants working with aerobic microbial consortia the thus developed internal carbon sources only in biomass and carbon dioxide are converted. There are no high-energy recyclables educated. Another disadvantage is that in the context of disintegration desired reduction of inevitably forming secondary sludges not in the desired Scope takes place.

Task of invention

task The invention is based on a holistic use the natural one Metabolic processes of anaerobic and / or aerobic bacterial consortia a simple, economical, ecological, innovative and practice-relevant method for "advanced biotechnological liquid sludge disintegration" (WBFD method) to develop.

Farther It is the object of the invention while avoiding significant disadvantages the listed known conventional sewage sludge disintegration process, such as B. the use of externally generated thermal, electrical and / or high energy density mechanical energy or use costly aggregates such as e.g. externally produced enzymes, acids, Bases, additives and / or oxidants, based on bioprocess engineering Paths in moderate process and environmental conditions, in normal pressure operation designed bioreactors, the liquid sludge of the subjugate further disintegration as well as one against the classical anaerobic treatment of liquid sludge a significant reduction of COD value over 95% and liquid sludge volume from above To reach 90 vol.% And thereby as valuable high-energy biogas to win.

Solution of task

The Task the WBFD procedure for further biotechnological Disintegration of liquid sludges too will develop according to the invention solved, that in a first process stage the liquid sludge, at defined Process and environmental conditions in defined quantities, one in the frame of the start-up regime in the high-performance bioreactor or microorganism suspension is added continuously and with Help adapted facultative anaerobic bacterial consortia, the active part of a static carrier biofilm system (s-T-B-S) are the pre-fermentation is subjected.

It was found that the pre-fermentation process in a temperature range of + 0 ° C up to + 35 ° C and at hydraulic residence times of the liquid sludge between 1 and 4 days cheap expires.

surprisingly Way, it was found that at the end of the pre-fermentation process as opposed to other known anaerobic technologies contained in the Vorgärbrühe on the organic dry matter content of the liquid sludge related specific Amounts of methanogenic substances in the form of free organic Acids or pure carbon-hydrogen-oxygen compounds significantly elevated are and both the speed and the intensity of the digestion in the liquid sludge suspended organic solids mass portions have been intensified is.

Farther was noticed that the Vorgärprozess always stable, if in the exhaust of the Vorgärstufe more than 90% carbon dioxide is contained.

The resulting Vorgärbrühe is subjected in a second stage of the actual methane fermentation. For this, the Vorgärbrühe in defined Quantities continuously or quasi-continuously from the first stage of the process deducted and in the second stage in the context of the start-up regime submitted starter or microbial suspension added. In the second stage of the procedure then under defined process and environmental conditions with help adapted strictly anaerobic bacterial consortia, the active part a static support biofilm system (s-T-B-S) are the methane fermentation from.

It turned out that the process of methane fermentation in a temperature range of + 30 ° C up to + 55 ° C and at hydraulic residence times of Vorgärbrühe between 2 and 20 days runs optimally.

surprisingly Way was found that, in contrast to the known biogas process even with larger Faulraumbelastungen the methane production process is stable and does not lead to hyperacidity or the so-called "tipping over" of the process comes. It was also found that the methane content in the exhaust gas (biogas) the second process stage by about 10 to 20 vol.% Above the usual Way to expected values. Furthermore, it was found that the COD value in the digested fermentation broth compared to the initial value in the liquid sludge about 84% and the TS content was lowered by about 82%.

In a third stage of the process is then carried out under defined process and environmental conditions the aerobic aftertreatment of the still in the digested fermentation broth existing residues of organic solid mass fractions. For this purpose will be a defined amount of the digested fermentation broth from the second process step continuously or quasi-continuously in an airlift reactor spent and fumigated there after a certain regime with air.

It it was found that the aerobic aftertreatment in a temperature range from + 3 ° C to about 35 ° C and at hydraulic residence times of the digested fermentation broth of 3 Hours up to more than 20 hours stable. Surprisingly, it was found that it, in relation to those determined in the digested fermentation broth Parameters for COD and liquid sludge volume, to a further significant reduction of the liquid sludge volume and further serious lowering of the COD value.

It it was found that after switching off the ventilation still remaining in the liquid phase Remainder of suspended organic and inorganic solid mass fractions very good and fast sedimented and thereby the volume of liquid sludge in the sediment phase by 78% by vol the initial liquid sludge volume is lowered. Furthermore was found to be up at a further concentration the initial DM content of the liquid sludge the remaining in the sediment phase solid mass fractions by means of a normal filter unit in a fourth process stage, the Liquid sludge volume the sediment phase is reduced by a further 77% by volume.

It was also found that the COD value in the liquid supernatant (clear phase) of the airlift reactor across from the COD value determined in the digested fermentation broth by further 93% was lowered.

Surprised is, although in the digested fermentation broth the COD and liquid sludge volume have been largely lowered and only relatively small Mud volumes and COD values existed that with the on going biotechnological liquid sludge Disintegration of the remaining COD residue and the liquid sludge volume across from the cited known agents, methods and methods even more essential continue - almost completely - reduced could be.

Advantages of invention

• 1. die gezielte Desintegration von Flüssig- bzw. Dünnschlämmen mit Feststoffmasseanteilen bis etwa 5 % auf natürliche Art und Weise sowohl mit Hilfe mikrobieller Prozesse, die durch die metabolischen Aktivitäten fakultativ anaerober bzw. strikt anaerober und aerober Bakterienkonsortien bewirkt werden und sich zur Realisierung und Aufrechterhaltung der jeweils notwendigen optimalen Prozess- und Milieubedingungen die jeweiligen Bakterienkonsortien in separaten aber stofflich gekoppelten Verfahrensstufen befinden, als auch durch energiearme die Schwerkraft nutzende verfahrenstechnische Wirkungen erreicht wird.
• 2. gegenüber den bekannten Anaerobtechnologien sowie konventionellen Klärschlammdesintegrationsverfahren mit Hilfe des MBFD-Verfahrens ohne die Nutzung bekannter klassischer Entwässerungsmaßnahmen sowie unter Berücksichtigung der Tatsache, dass nach der zweiten Verfahrenstufe die Triebkräfte für die Klärschlammdesintegration sich signifikant abgeschwächt haben, in der dritten und vierten Verfahrenstufe das Volumen des zu entsorgenden/zu verwertenden Flüssigschlammes über das bisher bekannte Maß hinaus und der CSB in der Klarphase des Flüssigschlammes fast vollständig abgesenkt worden sind.
• 3. zur Realisierung der im WBFD-Verfahren durchzuführenden mikrobiellen Prozesse Bioreaktoren (Vorgär- bzw. Methanreaktor) eingesetzt werden in denen es durch die Zurückhaltung der aktiven Bakterienkonsortien durch Fixierung auf geeigneten Trägermaterialien und das jeweils gewählte Betriebs- bzw. Belüftungsregime zu einer signifikanten Verbesserung der Raum-Zeit-Ausbeute kommt.
• 4. wegen der moderaten Prozess- und Milieubedingungen (Prozesstemperaturen von +3°C bis +55°C, pH-Werte zwischen 5,5 und 7,5 und Betrieb bei Normaldruck) für die Bioreaktoren keine Sonderkonstruktionen benötigt werden und diese Bioreaktoren wegen 1. und 2. kompakt gebaut werden können und dadurch wesentlich kostengünstiger sind.
• 5. wegen der kompakten Bioreaktorbauweise der gesamte Verfahrenszug modular gestaltet und in Containern untergebracht sowohl als stationäre als auch mobile Anlage eingesetzt werden kann.
• 6. die Volumenreduktion des Flüssigschlammes im Rahmen des WBFD-Verfahrens ohne konventionelle Entwässerung und/oder Trocknung sowie ohne den Einsatz zusätzlicher Energie bis auf etwa 5 Vol. % des Anfangsvolumens auf natürliche Art und Weise realisiert wird.
• 7. der CSB-Wert im klaren Überlauf der dritten und vierten Verfahrensstufe um etwa 99 % gegenüber dem Anfangswert gesenkt werden kann.
• 8. wegen 1. bis 7. die zu entsorgende noch nicht konventionell entwässerte Menge Flüssigschlamm unabhängig von der Kapazitätsausnutzung u. a. von im ländlichen Bereich liegenden kommunalen Kläranlagen um 95 % gesenkt werden kann und sich dadurch die Ökonomie der Verwertung des Flüssigschlammes signifikant verbessert.

The developed WBFD process for the further biotechnological disintegration of liquid sludges is advantageous over the known conventional sewage sludge disintegration processes because, inter alia,

• 1. the targeted disintegration of liquid or thin sludges with a solids content of up to about 5% in the natural way, both with the aid of microbial processes, which are caused by the metabolic activities of facultatively anaerobic and / or aerobic bacterial consortia, and for realization and maintenance the respective optimal process and environment conditions the respective bacterial consortia are in separate but materially coupled process stages, as well as by low-energy using the gravity procedural effects is achieved.
• 2. compared to the known anaerobic technologies and conventional sludge disintegration processes using the MBFD process without the use of known classical Entwäs in the third and fourth stages of the process, the volume of liquid sludge to be disposed of / recovered exceeds the previously known level and the CSB in the clear phase of the sludge Liquid sludge almost completely lowered.
• 3. to implement the WBFD process to be performed microbial processes bioreactors (pre-fermentation or methane reactor) are used in which it by the retention of the active bacterial consortia by fixing on suitable substrates and the selected operating or ventilation regime to a significant improvement of Space-time yield comes.
• 4. Because of the moderate process and environmental conditions (process temperatures of + 3 ° C to + 55 ° C, pH values between 5.5 and 7.5 and operation at atmospheric pressure) for the bioreactors no special constructions are needed and these bioreactors because of 1 and 2. can be made compact and thus are much cheaper.
• 5. Modular design due to the compact bioreactor design of the entire process train and housed in containers can be used both as a stationary and mobile plant.
• 6. the volume reduction of the liquid sludge is realized in a natural way within the WBFD process without conventional dewatering and / or drying and without the use of additional energy up to about 5 vol.% Of the initial volume.
• 7. the CSB value in the clear overflow of the third and fourth stage of the procedure can be reduced by about 99% compared to the initial value.
• 8. due to 1 to 7, the amount of liquid sludge to be disposed of, not yet conventionally dewatered, can be reduced by 95% irrespective of the capacity utilization, inter alia, of municipal sewage treatment plants located in rural areas, thereby significantly improving the economics of liquid sludge utilization.

description an embodiment

The "advanced biotechnological liquid sludge disintegration process (WBFD process)" according to the invention for the further biotechnological disintegration of liquid sludge will be explained in more detail below using an exemplary embodiment. 1 shows a representation of the WBFD process according to the invention for the biotechnological disintegration of liquid sludge, which comes from a lying in rural municipal sewage treatment plant with a wastewater treatment capacity of about 10,000 population equivalents (EWG), with the aim of the volume of liquid sludge and the content of organic matter ( chemical oxygen demand / COD) in the liquid sludge continue to reduce.

1 shows here the basic structure of the apparatus for performing the WBFD method.

Of the liquid sludge (COD at the inlet = 38400mg / l; liquid sludge volume at the entrance 1000 l; based on the volume of liquid sludge at the entrance Solids content TS = 2.68% TS) is continuously in the Vorgärreaktor 1, the first stage of the process. The pre-fermentation takes place at 24 ° C. In the first stage of the process are suspended in liquid sludge organic macromolecules (Carbohydrates, fats, proteins) first by hydrolysis in sugars, fatty acids, amino acids and bases split. Then the actual fermentation of the Fission products to carboxylic acids, Gases and alcohols. In the escaping from the Vorgärreaktor gas were over 90 vol.% Determined carbon dioxide. After about 4 days, the Vorgärbrühe is continuous the pre-fermentation reactor 1 and into the methane reactor 2, the second stage of the process, spent. In methane reactor 2, the actual methane fermentation takes place at 35 ° C. In the second stage of the process are suspended in the Vorgärbrühe Cleavage products by acetogenesis in acetic acid, hydrogen and carbon dioxide transformed. This is followed by methanogenesis the formation of Biogas (methane and carbon dioxide). In the emerging from the methane reactor Biogas was measured between 60 vol.% And 72 vol.% Methane. After about 14 days leaves then the digested fermentation broth methane reactor 2. In the digested fermentation broth a COD of 6000 mg / l and a TS content of 0.5% were determined.

When passing through the first and second process stages, the COD of the liquid sludge has been reduced by about 85% and the DM content by about 81%. The digested fermentation broth is then introduced quasi-continuously into the airlift reactor 3, the third process stage. In the airlift reactor 3, the aerobic aftertreatment of the digested fermentation broth is carried out. For this purpose, air is blown into the digested fermentation broth at about 25 ° C. After about 15 hours of aerobic treatment of the digested fermentation broth in the airlift reactor and a settling phase of about 1 hour, the volume fraction in the clear phase (supernatant in the airlift reactor) is about 78 Vol.% And the volume fraction of the sediment phase (disintegrated liquid sludge or disperse phase at the bottom of the Airlift reactor) about 22 vol.%. In the clear phase, a COD of 400 mg / l was determined. In the sediment phase, a TS content of 0.5% was determined. Subsequently, the sediment phase is withdrawn from the airlift reactor 3 quasi-continuously and fed to the concentration of the TS content to about 2.5% of a normal filtration unit or gravity separator 4, the fourth stage of the process. In the normal filtration unit 4, all solid mass fractions suspended in the sediment phase are continuously separated from the liquid phase, concentrated, discharged as retentate and utilized. The clear phase (permeate) from the fourth process stage then passes together with the supernatant of the third process stage in the receiving water. With the passage of the digested fermentation broth through the third and fourth process stages, the COD in the clear phase coming from the airlift reactor 3 and the normal filter unit 4 was lowered by a further 14% by approximately 99% to just under 1% of the initial value. The volume of liquid sludge is reduced by about 78% by volume to just under 22% by volume and then further by 17.6% by volume to about 4.4% by volume of the initial sludge volume without conventional dewatering or drying after passing through the third and fourth process stages Service.

Claims (9)

Secondary Biotechnological Liquid Sludge Disintegration Process (WBFD Process) for the disintegration of all suspended in liquid sludge Solid mass fractions from unavoidable waste, residual and Commodities related to the production of assets and commodities Services in the field of communal services, industry, of the food industry as well Agriculture, with the aim of obtaining the volume and the COD value of the liquid sludge the holistic use of metabolic processes anaerobic and / or aerobic Bacterial consortia and / or procedural effects, very largely to reduce and gain high-energy biogas, characterized in that in the first process stage, the Pre-fermentation stage, under defines the given process and environment conditions in liquid sludge existing organic macromolecules by on a static Substrate biofilm system (s-T-B-S) Fixed hydrolytic bacterial consortia are split and then by fermentative bacterial consortia fixed on the same s-T-B-S to carboxylic acids, Gases and alcohols fermented in Vorgärreaktor be, the liquid sludge then passes as Vorgärbrühe in the second stage of the process, the Methangärstufe, in the defined under Process and environmental conditions contained in the Vorgärbrühe cleavage products by the acetogenic bacterial consortia fixed on an s-T-B-S converted into methanogenic substrates and then from these with the help of methanogenic bacterial consortia fixed on the same s-T-B-S in the methane reactor high-energy biogas is formed, the liquid sludge then passes as fermented fermentation broth in the third stage of the process, the aerobic post-treatment stage, in which under defined process and environmental conditions, the fermented fermentation broth is aerated and after ventilation the remaining total solid mass fraction than in volume requirement significantly reduced sediment in the bottom area of the airlift reactor accumulates and as liquid sludge sediment into the fourth process stage, the filtration stage or gravitational separator stage, is withdrawn, there by normal filtration or gravity separation concentrated, separated and as further reduced in volume Retentate is recycled during that over 90% COD reduced permeate with the clear phase of the third process stage in the receiving water or in one of the upstream process stages or existing sewage sludge tanks is derived. WBFD process according to claim 1, characterized in that in the reactors of the first and second process stage of the WBFD process there is a static carrier material biofilm system (sTBS) completely submerged in fermentation broth, which consists of randomly constructed waste and / or aggregates. or residual materials or from new artificial and / or natural substances that arise in the production and consumption of assets on the surface adapted biofilms form in which defined bacterial consortia / starter cultures are fixed, the targeted mineralization of organic and / or cause inorganic solids mass fractions loaded liquid and / or gaseous pure substances or mixtures, which can be used carrier materials of different and / or same size, configuration, structure, surface finish, specific surface and material composition, as disordered and / or ordered aggregate of identical and / or different discrete carrier element moduli of variable ratio of equivalent diameter to height (dglTr / HTr) of 0.1 to 0.6 and variable ratio of equivalent diameter of the carrier material element to the inner diameter of the reaction vessel (the like). d reactor) of 0.1 to 0.3 so in one or more closed and / or open with each other materially and energetically coupled reaction vessels are arranged, the defined static Trägermaterialschüttungen with a void degree of 0.4 to 0.8 for fluids and 0, 6 to 0.95 at Gases and a specific surface area (A spec.) Of less than or equal to 500 m ² / m ³ reactor volume arise on parts or the whole true or exposed surface of the support material by the use of starter or microorganism suspensions (defined microorganism suspension such as a Mixture of solids-relieved pork and / or cattle liquid manure, which after about 20 to 40 days on the substrates stable substrate biofilm systems with a biofilm height of 0.8 to 1.8 mm arise) active biofilms are formed, which are independent in short Adapt adaptation phases of 3 to 10 days to changing process and environmental conditions as well as mixed substrate systems and remain active over a period of 2 to 3 years and remain unblocked while maintaining the same process and environmental conditions. WBFD method according to claim 1 and 2, characterized in that the optimal process and environment conditions for the pre-fermentation of the liquid sludge at temperatures of + 0 ° C to + 55 ° C and at medium hydraulic residence times of more than 20 hours consist. WBFD method according to claim 1, 2 and 3, characterized in that during the pre-fermentation a waste gas enriched with more than 90% by volume of carbon dioxide is produced and in the Vorgärbrühe only a rest in height of more than 5% by volume dissolved Carbon dioxide remains and thus the methane fermentation process in the second Process stage without "overturning" runs very stable. WBFD method according to claim 1, 2, 3 and 4, characterized in that the process of methane fermentation at pH values greater than 6.5, at temperatures in both the mesophilic and the thermophilic range, at mean hydraulic residence times of the digested fermentation broth of more than 2 days optimally and in the digested fermentation broth both the COD value as also the TS content in a range up to <85% compared to the initial values in the liquid sludge were lowered. WBFD method according to claim 1, 2, 3, 4 and 5, characterized in that the process of aerobic aftertreatment of the rotted fermentation broth at temperatures of + 0 ° C up to + 55 ° C, a more than 3 hours lasting excess fumigation with air, at medium hydraulic residence times of the digested fermentation broth in the airlift reactor of more than 3 hours and runs optimally after a rest period of more than 1 hour which is still in the rotted Fermentation broth remained Solid mass shares quickly by the action of gravity sediment, the volume the dispersed sediment phase compared to the initial volume in the liquid sludge reduced to less than 25 vol.% and the COD in the clear phase by more than 90% is reduced. WBFD method according to claim 1, 2, 3, 4, 5 and 6, characterized in that the TS content of the sediment phase with Help of a suitable normal filter unit or gravitational separator except for the initial content of the liquid sludge can be concentrated, thereby increasing the volume of the sediment phase (Retentate) further to less than 5 vol.% Of the initial value in the liquid sludge reduced and the COD in the clear phase (permeate) is less than 10%. WBFD method according to claim 1, 2, 3, 4, 5, 6 and 7, characterized in that the method with its four process steps separately or parallel in stationary mobile or existing wastewater treatment plants, the individual process stages are coupled materially and energetically are that the main stream (pre-fermentation broth, fermented fermentation broth and clear phase) discontinuous, continuous and / or quasi-continuous all and returned to all stages of the process or respectively in the Guided and for disposal / recycling can be removed. WBFD method according to claim 1, 2, 3, 4, 5, 6, 7 and 8, characterized in that the liquid sludge or other suitable aqueous substrates, which strongly promote the growth of anaerobic bacterial consortia and a high solubility potential for carbon dioxide in an amount of 0.1 to 24% by weight of Biogenic Co substrates, the methanogenic substances in the form of free organic acids or contain pure carbon-hydrogen-oxygen compounds, be added and so a strong enriched with methanogenic substances Mixture fermentation broth arises, the good and stable with high Faulraumbelastung of the anaerobic bacterial consortia are metabolized and used as a valuable substance methane-rich biogas is formed.