CS275735B6 - Method of mesophilic or thermophilic anaerobic enzymatic conditioning of liquid organic substances and biological materials - Google Patents

Abstract

The invention relates to the conditioning of liquid organic substances and biomass, in particular of domestic sewage sludge with the aid of chelating agents and enzymes. According to the invention the process of breaking down the organic substance in the aerobic conditioning reactor with the addition of chelating agents and enzymes is stopped, before the complete dissolution thereof, after a time of 0.5 to 20 hours. The mixture of substances is then subjected to a non-aerated, open after-reaction phase of 5 to 15 hours, when biogenic flocculation occurs. A solid/liquid separation is then carried out. Conditioning agents can be added to increase the rate of the after-reactions. The biogenic flocculation and the degassing in the after-reaction container can be improved by agitation or raising the temperature. The dried sludge has a high heating value. Its agricultural utility is high.

Description

The invention relates to a method of mesophilic or thermophilic aerobic enzymatic conditioning of liquid organic substances and bio-matter, in particular municipal sludge from municipal sewage treatment plants using complexing agents and enzymes.

The processes known for several years for the treatment of sludge using enzymes allow a significant reduction of the stabilization time compared to conventional processes. The patent literature includes a number of methods that describe the decomposition of organic matter using enzymes in a certain dry matter-related amount. The object of the known enzymatic processes is to decompose the treated activated sludge as quickly as possible into a stabilized form. High levels of decomposition are to be achieved with a small amount of foreign enzymes, with a positive effect on the drainage properties of the enzymatically treated sludge.

In the process of GB 1563335, 0.001 to 15% finely divided dry matter and up to 5% dry matter of the prepared enzyme and thermophilic microorganisms are introduced into the reaction vessel and vented, maintaining the sludge continuously at 50 to 70 ° C.

DE 2633514 relates to a method for increasing filterability and a tendency to sediment a suspension, wherein an enzyme or enzyme group is added to the suspension with stirring.

US 4267049 describes the conversion of treated sludge to useful substances by hydrolyzing the organic material present in the sludge by adding at least one hydrolytic enzyme and hydrolytic enzyme producing microorganisms to the sludge, leaving the sludge with enzymes or microorganisms, and then separating the slurry into waste and wet product.

According to DO WP 234 571, a process is known in which enzymatically treated organic substances and bio-matter are fed to a reaction medium containing 0.01 to 1% by weight, depending on the type and composition of the enzymatically treated organic substances and the bio-matter. % of hydrolytic enzymes introduced and 0.005 wt. % of the complexing agent, based on the weight of organic solids, and the temperature is 30 to 60 ° C.

The reaction medium is an aqueous solution of enzymatically treated organic substances, such as clarified slurry or slurry, or bio-matter, such as activated sludge or microorganism cultures.

When organic substances and bio-mass are added to this reaction medium, the hydrolysis enzymes present rapidly hydrolyze the organic macromolecules contained in the organic substances and bio-mass (carbohydrates, proteins, fats) to microbially utilizable low-molecular compounds (sugar, organic acids). These are available to utilize microorganisms introduced into the reaction medium with organic substances and as bio-matter, thus stimulating their biochemical activity. The complexing agent contained in the reaction medium affects the metabolism of microorganisms so far that a highly unilateral preference for breathing is achieved by the permeable effect and the metabolism by the cell walls is accelerated.

The sudden introduction of organic substances having at least 10 ° C lower temperature range and bio-masses into the reaction medium of 30 to 60 ° C results in an increased surrender of exoenzymes by microorganisms to the reaction medium and self-disintegration of microorganisms (autolysis). The additive effect of hydrolytic enzymes, complexing agent and temperature difference results in rapid decomposition of biodegradable substances and biohistures, eventually increased metabolism by the cell wall of microorganisms and increased production of metabolic metabolites (enzymes, vitamins, organic acids, antibiotics and others).

In addition to natural dewatering, centrifuges are also used to dewater the sludge from the clarification plant as a method of machine sludge dewatering. It is necessary to add larger amounts of polymeric flocculant to obtain a relatively high solids concentration in the centrifuge yield and preferably a low central concentration.

So far, the technical regulations for drainage have only been obtained by costly large-scale drainage experiments. The so far determined parameters, on a laboratory scale (filtration resistance, CST value, etc.) only provide an evaluation of the drainage performed.

CS 275 735 B6

By means of granulomatic measurement and determination of the surface tension, an evaluation of the condition is obtained, which allows evaluation of the drainage result.

Despite the use of expensive flocculants, no dry matter content is often achieved in the centrifuge yield, which allows subsequent sludge incineration without fuel addition.

When sludge is burned, the sludge volume is reduced to a minimum. The remaining ash is sterile and can be easily removed. In the known sludge incineration processes, both fresh activated sludge is fed to the combustion, requiring considerable additional fuel and digested sludge.

Incineration of digested sludge requires additional energy when the water content of the sludge cake is too high. In any case, additional fuel is needed. The considerable fuel and energy costs make the known sludge incineration methods too expensive, and this has to be solved now and in the future in the case of territorial deposition problems.

According to 0E-3429055, a method for removing sludge, especially clarified sludge, is known, wherein a part of the thick sludge is pre-dried in a dryer to a certain dry matter content and the remaining thick sludge is burned with a dry material feed.

DE 2916216 discloses a process for utilizing sludge in which the sludge is thickened, conditioned with the addition of a certain amount of fine coal, then fed to a filter press and finally incinerated.

These disadvantages in the treatment of sludges with regard to their pretreatment for combustion are only positively influenced in the latter manner.

It is an object of the invention to reduce the sludge removal costs in a short reaction time and using a small amount of chemicals. The finished products resulting from the treatment can be used economically well or their calorific value can be high.

SUMMARY OF THE INVENTION The object of the present invention is to provide a process by which liquid organic substances, preferably sewage sludge, are treated at extremely short reaction times using complexing agents and enzymes so that their particle size and surface activity allow biogenic flocculation and solids in the attached dewatering stage they could easily be separated from the liquid phase. The end products may be well composted or combustible at high calorific values.

A method of mesophilic or thermophilic aerobic enzymatic conditioning of liquid organic substances and bio-matter, in particular sludge from municipal sewage treatment plants, wherein 0.001 to 0.1% of a complexing agent, preferably nitrilotriacetic acid salt, relative to the organic substance, is added to the treated liquids in the aerobic conditioning reactor. and 0.001 to 1.5% of an enzyme that breaks down the organic constituents of the solids or enzyme mixture, based on the organic portion of the dry matter, and is intensively aerated, characterized in that the treated liquid organic matter and bio-mass are fed as main stream or in partial streams to the aerobic conditioning reactor, the aerobic reaction process of breaking the organic substance into a smaller particle size is interrupted after 0.5 to 20 hours of reaction time, i.e. before completely dissolving, the treated substance mixture is subjected to a non-aerated further reaction phase for 5 to 15 hours, at the same time allowing degassing and then solid-liquid separation. ,

In the phase of addition of the complexing agent, the organic matter is split into smaller sludge particles with a higher specific surface area while increasing the surface activity. According to the invention, the process of breaking the substance is interrupted when about 30 to 50% of the particles are (about 40 to 70% of the particles are 5 µm) and the surface saturation value of the sludge particles is about 15 to 30% higher than the raw sludge. This is observed after a reaction time of 0.5 to 20 hours, and the mixture is then fed to the connected reactor for a non-aerated further reaction phase for a period of 5 to 15 hours. In this phase, biogenic flocculation of the surfactant particles takes place while at the same time breaking the stabilization of the dispersion.

To optimize the subsequent performance of the machine dewatering, the further reaction is interrupted when

Only 15 to 20% of the particles are < 1 µm and 30 to 40% of the particles are 5 µm, while at the same time the surface saturation is minimal. The remaining residual saturation of the surface to adjust the isoelectric point can be compensated in order to further reduce the dose of polymeric flocculants relative to conventional practice by adding suitable inorganic substances.

A conditioning agent such as a polymeric flocculant and / or a precipitant is added to the fabric mixture before or during the next reaction phase.

The solid-liquid separation is then carried out by known means, for example a decanter centrifuge or gravity thickeners.

To accelerate aggregation and shorten the next reaction time, the subsequent reaction phase may take place at an elevated temperature range of 20 to 38 ° C or 45 to 75 ° C. The temperature increase affects the reduction of surface tension, which also accelerates degassing. At the same time, the stability of flocculation is increased. Further, the partial stream of the treated mixture of substances can be withdrawn and aerated prior to aeration to treat the enzymes contained therein, for example by means of a ball mill. Thereafter, this partial stream is also fed to the aerobic reaction process. This reduces the addition of the foreign enzyme.

The conditioning process is strongly accelerated by the addition of active substances (enzyme, complexing agents). During the enzymatic transformation process, biodegradable substances are only partially eliminated (about 8% vs. about 30% for digested sludge and about 15 to 20% for enzymatically stabilized sludge).

The temperature range required for conditioning in the aerobic reactor (25-38 ° C) is preferably achieved using an exothermic metabolism process of the microorganisms contained in the sludge.

To this end, it is necessary to introduce air oxygen into the reactor by means of suitable aeration devices and to keep the reactor contents circulated by means of suitable devices such as a rotary pump. Alternatively, said temperature range can be realized by supplying external energy to the aerobic reactor.

The following examples illustrate the invention:

Example 1

The municipal sewage sludge with a solids content of 4% is homogenized in a bulk sludge tank. Thereafter, the raw sludge is fed quasi-continuously through a flexible pipe with inductive flow measurement and a raw sludge pump to the aerobic conditioning reactor. 60 g of the triammonium salt of nitrilotriacetic acid previously dissolved in about 30 l of tap water are added. 60 g of complex enzyme preparation previously dissolved in about 100 times the amount of tap water containing Q-glucanase, amylase, protease and lipase are then continuously added to πΡ of the crude sludge containing the complexing agent. About one tenth of the crude sludge is treated in a ball mill before being added to the aerobic reactor. Here, the release of the enzyme itself takes place, thereby reducing the added amount of foreign enzymes.

For intensive aeration the sludge circulates continuously in the conditioning reactor and is supplied with oxygen.

In the case of intermittent aeration, the circulation is carried out by means of a rotary pump.

The temperature of the raw sludge is increased by the exothermic metabolism of the microorganisms contained in the sludge from 20 ° C to about 30 ° C and remains approximately constant. Biological metabolism and intensive aeration lead to the cleavage of organic matter into small sludge particles with a higher specific particle surface area.

The digestion of the organic substance in the conditioning reactor does not proceed as in the case of enzymatic stabilization of the sludge, except for its complete dissolution. The process is interrupted after 4 hours. At this point, the comminuted sludge particles have a high surface activity.

The treated sludge is transferred to an open additional reaction tank after addition of cationic polymeric flocculants (Zetag 92, ACM / BRD). Here, intensive aggregation of sludge particles takes place. Out of circulation, degassing is accelerated by elevated temperature to 38 ° C by further heating. At the same time, this accelerates aggregation.

in

CS 275 735 B6 4

After a further reaction time of 10 hours, the treated sludge is fed into a mobile decanter centrifuge and drained.

The degree of solids separation is 97 to 99%. The resulting sludge water with less than 0.1 wt. the dry matter is fed to the inflow of the water treatment plant. The dewatered sludge has a dry matter content of about 32% by weight. and thus a high calorific value, a finely crumbly structure and a low water-absorption capacity. It is almost completely odorless. High calorific value allows combustion without (self-energy) or with greatly reduced additional energy consumption.

Due to the limit concentration of heavy metals, dewatered sludge with a high phosphorus and nitrogen content can be directly recovered, composted or deposited economically.

Example 2

The raw sludge from the municipal sewage treatment plant with a solids content of 4% is homogenized in a bulk tank. Then, the raw sludge is fed quasi-continuously through a flexible pipe with inductive flow measurement and a raw sludge pump to the aerobic conditioning reactor. 60 g of the triammonium salt of nitrilotriacetic acid previously dissolved in about 30 l of tap water are added. Subsequently, 60 g of complex enzyme preparation previously dissolved in about 100-fold tap water containing Q-glucanase, amylase, protease and lipase are continuously metered onto the raw sludge containing complexing agent. About one tenth of the crude sludge is treated in a ball mill before being added to the aerobic reactor. Here, the release of the enzyme itself occurs, thereby reducing the amount of foreign enzymes added. For intensive aeration, the sludge recirculates continuously in the conditioning reactor and supplies it with oxygen.

In the case of continuous aeration, another circulation is carried out by means of a rotary pump.

The temperature of the raw sludge is increased by the exothermic metabolism of the microorganisms contained in the sludge from 20 ° C to about 30 ° C and remains almost constant. Biological metabolism and intensive aeration will lead to the cleavage of organic matter into smaller sludge particles with a higher specific particle surface area.

The cleavage of the organic substance in the conditioning reactor proceeds not as in the enzymatic stabilization of the sludge until complete dissolution. The process is interrupted after 4 hours. At this point, the comminuted sludge particles have a high surface activity.

The sludge thus treated is transferred to an open further reaction vessel. Due to the high surface activity of the sludge particles, the sludge particles are agglomerated back. Such shear-stable agglomerates can be formed on the basis of the fine primary particles formed during the reaction phase. Degassing is accelerated at an elevated temperature of about 38 ° C by further heating. At the same time, aggregation is faster. After an additional 10 hours of reaction time, cationic polymeric flocculating agents (Zetag 92, Fa. ACM / BRO) are added to the sludge after the charge of the primary flocculating agent (FeCl-j) and dewatered by machine (e.g. decanter).

The degree of solids separation is 97-99%. The resulting sludge water has a dry matter content of less than 0.1% by weight. is fed to the inflow of the waste water treatment plant. The dewatered sludge has a dry matter content of about 32% by weight. and thus a high calorific value, a finely crumbly structure and a low water-absorption capacity. It is almost completely odorless. High calorific value allows combustion without (self-energy) or with greatly reduced additional energy consumption.

Due to the limit concentration of heavy metals, dewatered sludge with a high phosphorus and nitrogen content can be directly recovered, composted or deposited economically.

Example 3

Raw sludge from municipal sewage treatment plant with hardly degradable components with a solids content of 3% is homogenized in a bulk tank. Then the raw sludge is fed through a quasi-continuously flexible pipe with inductive flow measurement and a suro5 pump.

CS 275 735 B6 sludge into the aerobic conditioning reactor. 60 g of the triammonium salt of nitrilotriacetic acid previously dissolved in about 30 l of tap water are added. Further, 60 g of complex enzyme preparation previously dissolved in about 100-fold tap water containing B-glucanase, amylase, protease and lipase are still added to the nP of the crude sludge containing the complexing agent. About one tenth of the crude sludge is treated in a ball mill before being added to the aerobic reactor. Here, the release of the enzymes itself takes place, thereby reducing the amount of foreign enzymes added. For intensive aeration, the sludge is continuously recirculated through the conditioning reactor and supplied with oxygen.

In the case of intermittent aeration, the circulation is carried out by means of a rotary pump.

The temperature of the sludge is increased by the exothermic metabolism of the microorganisms contained in the sludge from 20 ° C to 50 ° C within 20 hours. Biological metabolism and intense aeration cause the organic matter to be split into smaller particles with a higher genetic particle surface.

The pre-treated sludge is transferred to an open further reaction vessel. Due to the high surface activity of the sludge particles, re-aggregation of the sludge particles takes place. Based on the fine primary particles formed during the reaction phase, shear-stable agglomerates can be formed. By applying external energy, the sludge temperature is maintained at a constant value of 50 ° C so that aggregation takes place faster. At the same time, degassing is accelerated.

After a further reaction time of 15 hours, a cationic polymeric flocculating agent (Zetag 92, Fa. ACM / BRD) is added to the sludge and dewatered by machine (e.g. decanter).

The degree of solids separation is 97 to 99. The resulting sludge water with a dry matter content of less than 0.1% by weight. is fed to the inflow of the waste water treatment plant. The dewatered sludge has a dry matter content of about 32% by weight. and thus a high calorific value, a finely crumbly structure and a low water-absorption capacity. It is almost completely odorless. High calorific value enables combustion without (self-energy) or with greatly reduced additional energy consumption.

Due to the limit concentration of heavy metals, dewatered sludge with a high phosphorus and nitrogen content can be directly recovered, composted or deposited economically.

Example 4

The lentil from a pig mill with a solids content of 6% is homogenized in a tank. The slurry is then fed quasi-continuously through a flexible pipe with inductive flow measurement and a pump to the aerobic conditioning reactor. 60 g of the triammonium salt of nitrilotriacetic acid previously dissolved in about 30 liters of tap water are added. Subsequently, 60 g of complex enzyme preparation previously dissolved in about 100 times the amount of tap water containing β-glucanase, amylase, protease and lipase are continuously dosed per mole containing complexing agent. About one tenth of the slurry is treated in a ball mill before being added to the aerobic reactor. Here, the release of the enzyme itself takes place, thereby reducing the added amount of foreign enzymes. For intensive aeration, the slurry is continuously recirculated in the conditioning reactor for half an hour and supplied with oxygen.

In the case of continuous aeration, the circulation is carried out by means of a rotary pump. The temperature is increased by exothermic metabolism of the microorganisms contained in the slurry from 20 ° C to about 30 ° C and remains almost constant. Biological metabolism and intensive aeration will cause the organic material to break down into smaller particle sizes, increasing the specific surface area of the particles.

The pretreated liquid manure is transferred to an open further reaction vessel. Due to the high surface activity of the sludge particles, the sludge particles are agglomerated back. Such shear-stable agglomerates can be formed on the basis of the fine primary particles formed during the reaction phase. The sludge temperature is on average 25 ° C. After an additional reaction time of five hours, cationic polymeric flocculating agent (Zetag 92, Fa. ACM / BRD) is added to the slurry and mechanically dewatered (e.g., decanter).

CS 275 735 B6

The degree of solids separation is 97 to 99%. The resulting sludge water has a dry matter content of less than 0.1% by weight. is supplied to the inflow of the waste water treatment plant. The dewatered sludge has a dry matter content of about 32% by weight. and thus a high calorific value, a finely crumbly structure and a low water absorption capacity. It is almost completely odorless. High calorific value allows combustion without (self-energy) or with greatly reduced additional energy consumption.

Due to the limit concentration of heavy metals, dewatered sludge with a high phosphorus and nitrogen content can be directly recovered, composted or deposited directly.

Claims (4)

PATENT CLAIMS A method of mesophilic or thermophilic aerobic enzymatic conditioning of liquid organic substances and bio-matter, in particular sludges from municipal sewage treatment plants, wherein 0.001 to 0.1% of a complexing agent, preferably nitrilotriacetic acid salt, is added to the treated liquid substances in an aerobic conditioning reactor. to the organic part of the dry matter, and from 0.001 to 1.5% of an enzyme digesting the organic component of the solids or enzyme mixture contained in the organic part of the dry matter and intensively aerated, characterized in that the treated liquid organic matter and bio-matter are fed as main stream or partial streams to the aerobic conditioning reactor, the aerobic reaction process of splitting the organic substance to a smaller particle size is interrupted after 0.5 to 20 hours, i.e. before completely dissolving, the thus treated substance mixture is exposed to the non-aerated reaction phase for 5 to 15 hours, at the same time allowing degassing and then solid-liquid separation. 2. A process according to claim 1, characterized in that the partial stream of the liquid substance mixture to be treated is treated so that the enzymes are released and then the partial stream is introduced into the aerobic reaction process. 3. The process according to claim 1, wherein a conditioning agent, such as a polymeric flocculant and / or a precipitant, is added to the fabric mixture before or during the next reaction phase. 4. A process according to any one of claims 1 to 3, wherein the further reaction phase takes place in an elevated temperature range of 20 to 38 ° C or 45 to 75 ° C.