DE102019131391A1 - Process for sewage sludge treatment and sewage sludge plant - Google Patents

Abstract

The invention relates to a method for sewage sludge treatment and a sewage sludge plant. It is therefore the object of the invention to eliminate the disadvantages of the prior art and to provide a sewage sludge treatment method which dispenses with the use of flocculants, which contain pollutants, in particular heavy metals, pharmaceutical compounds and microplastics, extracted from raw sludge, which reduces transport and disposal costs and effectively transforms existing goods, in particular a residual fraction containing carbon, low in nutrients and pollutants, phosphorus, methane, etc. into economically relevant goods and thus reveals a value creation process. It is also an object to provide a sewage sludge plant that can be retrofitted in existing sewage sludge plants. This problem is solved by the features listed in the claims.

Description

The invention relates to a method for sewage sludge treatment and a sewage sludge plant.

A sewage treatment plant, also known as a wastewater treatment plant, is a technical system for cleaning wastewater. Mechanical (also called physical), biological and chemical processes are used to purify the water-polluting components of the wastewater. Excess sewage sludge is produced during the wastewater treatment process and has to be treated. This treatment takes place in two steps: stabilization and volume reduction. Stabilization means the extensive breakdown of the organic substances contained in the sewage sludge (mineralization) and takes place aerobically directly in the activation process on small sewage treatment plants and anaerobically in digestion towers on large sewage treatment plants. The stabilization thus already includes a certain reduction in the amount of sewage sludge. The aim of stabilization is to ensure that subsequent biological or chemical conversion processes only take place to a limited extent or very slowly, so that sewage sludge can be recycled. The actual quantity reduction is achieved, however, by separating water from the sewage sludge. The usual methods here are sludge thickening or dewatering with appropriate machines and chemical aids, such as flocculants. The use of flocculants for solid / liquid separation increases the efficiency of the separation of the liquid from the sludge.

By adding flocculants, the very fine particles in the sewage sludge in the micrometer to nanometer range are combined into large-volume, rapidly sedimenting flakes and thus the effectiveness of mechanical solid / liquid separations is considerably increased. Inorganic compounds such as iron or aluminum salts are used as flocculants. The disadvantage here, however, are the large amounts of flocculation used, which cause the sludge to thicken. Most flocculation processes therefore use water-soluble, organic polymers as flocculants.

Both synthetic and natural polymers are used as polymeric flocculants. Flocculants based on synthetic polymers have the advantage that they can be produced very specifically with regard to chemical structure and molecular parameters for the respective application. This has resulted in a greater number of flocculants being commercially available but very expensive to purchase.

The use of polymeric flocculants in wastewater treatment has been discussed controversially for a long time. Depending on their composition, they are classified in different water hazard classes. In view of the increasing contamination of the earth with microplastics, the use of synthetic polymers in water treatment, especially in drinking water treatment, is to be regarded as problematic.

Alternatively, biodegradable flocculants based on renewable raw materials are used. When they are used as flocculants, however, the formation of less stable flocs, as required for mechanical dewatering processes, can occur.

Presentation of the invention

It is therefore the object of the invention to eliminate the disadvantages of the prior art and to provide a sewage sludge treatment process which dispenses with the use of flocculants, which extracts pollutants, in particular heavy metals, pharmaceutical compounds and microplastics, from raw sludge, which reduces transport and disposal costs and reduces existing ones Goods, in particular a residual fraction containing carbon, low in nutrients and pollutants, phosphorus, methane, etc., are effectively transformed into economically relevant goods and thus enable a value creation process.

It is also an object to provide a sewage sludge plant that dispenses with the use of flocculants, which extracts pollutants, in particular heavy metals, pharmaceutical compounds and microplastics, from raw sludge, which reduces transport and disposal costs, and existing goods, in particular a residual fraction containing carbon, low in nutrients and pollutants , Phosphorus, methane etc. are effectively transformed into economically relevant goods, thus enabling a value-added process and which can be retrofitted in existing sewage sludge plants

This problem is solved by the features listed in the claims.

1. a. pH-Wert-Absenkung des Klärschlamms auf einen Wert von 1-3,5 mittels Zugabe von Phosphorsäure. Mittels der Zugabe von Phosphorsäure in den Klärschlamm erfolgt eine Ionisation der Atome und Moleküle in dem Klärschlamm, was zu einer Lösung der Schwermetalle und des Phosphors in die flüssige Phase führt.
2. b. Ferner erfolgt eine Zerstörung der Zellstrukturen im Klärschlamm. Dies erfolgt mittels einer Ultraschalldesintegrationsbehandlung des Klärschlamms zur Aufspaltung fast aller pharmazeutischen Verbindungen und zur Übertragung der restlichen Schadstoffe in die flüssige Phase. Mittels der Cavitationsblasen, welche sich durch die Ultraschallbehandlung bilden und implodieren, erfolgt die Zerstörung der Zellstrukturen und der Schadstoffe, welche in den Zellstrukturen eingebunden sind. Die in der Zellstruktur gebundenen Phosphate werden ebenfalls freigesetzt, was zu einer höheren Effektivität bei der Phosphorrückgewinnung führt. Gemäß verschiedenen Ausführungsformen können bei der Ultraschalldesintegration verschiedene physikalische und chemische Wirkungsmechanismen zum Tragen kommen:
   1. i. Microjets: Flüssigkeitsstrahlen bis 100 m/s
   2. ii. Shockwaves: Druckwellen (bis 103 MPa) mit enormen Scherkräften
   3. iii. Hotspots: Kurzfristige Temperaturen bis 5000° C und oder Drücken bis zu 500 bar
   4. iv. Sonochemie: Radikalbildung von *OH und *H
   5. v. Hydrolysevorgänge
3. c. Ferner erfolgt eine Fest-Flüssigtrennung mittels Zentrifugierens des Klärschlamms, sowie Nachfiltrieren des Klärschlamms mittels Anschwemmfiltern. Mittels des Zentrifugierens und des Filterns des Klärschlamms wird ein kohlenstoffhaltiger, nährstoff- und schadstoffarmer Feststoff und eine nähr- und schadstoffreiche Flüssigkeit gebildet. Dieser Schritt bewirkt eine gute Abtrennung der Feststoffe von der Flüssigkeit und macht eine Verwendung von Flockungsmitteln unnötig. Zur Verbesserung kann der Schritt der Fest-Flüssigtrennung beliebig oft wiederholt werden. Die entstandene kohlenstoffhaltige, nährstoff- und schadstoffarme Restfraktion kann zur Wertschöpfung einem nährstoffreichen Produkt in Form von Düngemitteln oder Pflanzenkohle hinzugefügt wird. Beispielsweise kann mittels des entstandenen Feststoffes in Verbindung mit Pflanzenkohle ein guter Bodenverbesserer hergestellt werden, welcher damit vergleichbar ist mit Terra preta. Terra preta ist die Bezeichnung für einen fruchtbaren, im Amazonasbecken anzutreffenden anthropogenen Boden. Der Boden besteht aus einer Mischung von Holz- und Pflanzenkohle, menschlichen Fäkalien, Dung und Kompost, durchsetzt mit Tonscherben und gelegentlich auch Knochen sowie Fischgräten. Pflanzenkohle kombiniert mit dem entstandenen Feststoff ist einsatzbar in der Landwirtschaft als Bodenverbesserer und Trägerstoff für Düngemittel sowie als Hilfsstoff für die Kompostierung und Nährstofffixierung von Gülle zugelassen. Fernern kann der entstandene Feststoff einer landwirtschaftlichen Verbringung unterzogen werden.
4. d. Ferner erfolgt ein Entfrachten bzw. Entfernen der Schadstoffe aus der nähr- und schadstoffreichen Flüssigkeit mittels Hybridkieselgelfiltration, Fällung und/oder Ionisation. Bei den Schadstoffen handelt es sich hauptsächlich um Schwermetalle.
5. e. Ferner erfolgt eine Phosphorrückgewinnung aus der nährstoffreichen und schadstoffarmen Flüssigkeit mittels eines chemischen Verfahrens. Dieser Schritt setzt eine Magnesium-Ammonium-Phosphat-Fällung (MAP-Fällung), welche einen Aufschluss einer phosphor- und stickstoffhaltigen Verbindung in Form von Struvit beinhaltet, voraus. Gemäß verschiedenen Ausführungsformen kann zur Aufbereitung des Klärschlamms vor dem Verfahrensschritt a) eine Vorbehandlung des Klärschlamms erfolgen, wobei die Vorbehandlung eine biologische Vorreinigung sein kann.

According to various embodiments, a method for processing sewage sludge to obtain phosphorus, a soil conditioner and purified water and other products that are low in pollutants and nutrients is disclosed, the sewage sludge having a solid and a liquid phase. The method has the following method steps for this, it being conceivable to carry out the method in a sequence other than that described below:

1. a. Lowering the pH of the sewage sludge to a value of 1-3.5 by adding phosphoric acid. By adding phosphoric acid to the sewage sludge, the atoms and molecules in the sewage sludge are ionized, which leads to a solution of the heavy metals and phosphorus in the liquid phase.
2. b. Furthermore, the cell structures in the sewage sludge are destroyed. This is done by means of an ultrasonic disintegration treatment of the sewage sludge to break down almost all pharmaceutical compounds and to transfer the remaining pollutants into the liquid phase. By means of the cavitation bubbles, which form and implode as a result of the ultrasound treatment, the cell structures and the pollutants that are integrated in the cell structures are destroyed. The phosphates bound in the cell structure are also released, which leads to a higher efficiency in phosphorus recovery. According to various embodiments, various physical and chemical mechanisms of action can come into play during ultrasonic disintegration:
   1. i. Microjets: liquid jets up to 100 m / s
   2. ii. Shockwaves: Pressure waves (up to 103 MPa) with enormous shear forces
   3. iii. Hotspots: Short-term temperatures up to 5000 ° C and / or pressures up to 500 bar
   4. iv. Sonochemistry: radical formation of * OH and * H
   5. v. Hydrolysis processes
3. c. Furthermore, there is a solid-liquid separation by centrifuging the sewage sludge, as well as post-filtering the sewage sludge by means of precoat filters. By centrifuging and filtering the sewage sludge, a carbon-containing, nutrient and pollutant-poor solid and a nutrient and pollutant-rich liquid are formed. This step provides good separation of the solids from the liquid and makes the use of flocculants unnecessary. To improve this, the solid-liquid separation step can be repeated as often as required. The resulting carbon-containing, nutrient- and pollutant-poor residual fraction can be added to a nutrient-rich product in the form of fertilizers or biochar to create value. For example, a good soil improver can be produced using the resulting solid in combination with biochar, which is comparable to terra preta. Terra preta is the name for a fertile anthropogenic soil found in the Amazon basin. The soil consists of a mixture of charcoal and biochar, human feces, manure and compost, interspersed with potsherds and occasionally bones and fish bones. Biochar combined with the resulting solid can be used in agriculture as a soil conditioner and carrier for fertilizers as well as approved as an additive for composting and nutrient fixation of manure. Furthermore, the resulting solid can be subjected to an agricultural shipment.
4. d. Furthermore, the pollutants are released or removed from the nutrient and pollutant-rich liquid by means of hybrid silica gel filtration, precipitation and / or ionization. The pollutants are mainly heavy metals.
5. e. Furthermore, phosphorus is recovered from the nutrient-rich and low-pollutant liquid by means of a chemical process. This step requires a magnesium-ammonium-phosphate precipitation (MAP precipitation), which includes a breakdown of a phosphorus and nitrogen-containing compound in the form of struvite. According to various embodiments, a pretreatment of the sewage sludge can take place for the preparation of the sewage sludge before method step a), wherein the pretreatment can be a biological pre-cleaning.

According to various embodiments, a pretreatment of the sewage sludge can take place for the treatment of the sewage sludge before method step a), wherein the pre-treatment can be a biological pre-cleaning.

• PARFORCE-Verfahren (Phosphoric Acid Recovery From Organic Residues and Chemicals by Electrochemistry). Die PARFORCE-Technologie ist ein flexibles, umweltfreundliches chemisches Verfahren zur Gewinnung von universell einsetzbarer Phosphorsäure durch Verwertung von phosphathaltigen Abfällen. Das PARFORCE-Verfahren ist ein nasschemisches Verfahren, in dem im ersten Prozessschritt mittels Salz- oder Salpetersäure der zu verarbeitende phosphathaltige Primär- oder Sekundärrohstoff in einem Aufschlussreaktor chemisch aufgeschlossen wird. Die Aufschlusssuspension wird in einem zweiten Schritt filtriert und die Phosphorsäure in einem dritten Prozessschritt durch einen Membranprozess abgetrennt. Bei der Veredelung von Magnesiumammoniumphosphat (MAP)- auch Struvit genannt (Rückstand der Schlammbehandlung in Kläranlagen) - entsteht als Nebenprodukt Magnesiumchlorid, das als Magnesiumquelle für die Struvit-Kristallisation im Klärwerk wiederverwendet werden kann und somit den Stoffkreislauf im Klärwerk wieder zugeführt werden kann. Ferner kann mittels des PARFORCE-Verfahrens die im Verfahren eingesetzte Phosphorsäure zurückgewonnen werden.

According to various embodiments, the following chemical process is used for phosphate recovery:

• PARFORCE process (Phosphoric Acid Recovery From Organic Residues and Chemicals by Electrochemistry). The PARFORCE technology is a flexible, environmentally friendly chemical process for the production of universally applicable phosphoric acid by recycling phosphate-containing waste. The PARFORCE process is a wet chemical process in which, in the first process step, the primary or secondary raw material containing phosphate is chemically digested in a digestion reactor using hydrochloric or nitric acid. The digestion suspension is filtered in a second step and the phosphoric acid is separated off in a third process step using a membrane process. The refinement of magnesium ammonium phosphate (MAP) - also known as struvite (residue from sludge treatment in sewage treatment plants) - is a by-product Magnesium chloride, which can be reused as a magnesium source for struvite crystallization in the sewage treatment plant and can thus be fed back into the material cycle in the sewage treatment plant. Furthermore, the phosphoric acid used in the process can be recovered by means of the PARFORCE process.

The use of alternative methods for phosphate recovery is conceivable.

According to various embodiments of the method according to the invention, the MAP product can be used as a fertilizer.

According to various embodiments, phosphoric acid can also be recovered directly from the sewage sludge fraction. However, the formation of MAP crystals (MAP product) is preferred. In this way, the MAP products formed can advantageously be collected in the local sewage sludge plants and transported to a central phosphate recovery plant in order to then recover phosphoric acid therefrom. However, the recovery from the MAP products can also take place directly in the local sewage sludge plant. It is also conceivable that the MAP products will continue to be used for the production of fertilizers.

According to various embodiments, various energy generation methods can be used with regard to the generation of self-generated energy. For example, energy generation by means of photovoltaic systems and / or by means of methane combustion, with methane production being achieved through additional digestion. The digestion has the advantage that further pharmaceutical compounds can be broken down.

• • einen ersten Behälter zur Aufnahme des Klärschlamms und zur Senkung des pH-Wertes des Klärschlamms,
• • einen Ultraschalldesintegrationsreaktor zur Zerstörung der Zellstrukturen im Klärschlamm,
• • eine Zentrifuge und/oder einen Anschwemmfilter zur Fest-Flüssig-Trennung,
• • einen Fällungsreaktor, einen Ionenaustauscher und/oder einen Filterreaktor zur Schadstoffentfernung, wobei der Filterreaktor derart ausgestaltet ist, eine Hybridkieselgelfiltration durchzuführen,
• • einen MAP-Reaktor zur Phosphorrückgewinnung.

To solve the problem, a sewage sludge plant for processing sewage sludge to obtain phosphorus, a soil improver and purified water that is low in nutrients and pollutants and other products is proposed. The sewage sludge plant has the following for this:

• • a first container to hold the sewage sludge and to lower the pH value of the sewage sludge,
• • an ultrasonic disintegration reactor to destroy the cell structures in the sewage sludge,
• • a centrifuge and / or a precoat filter for solid-liquid separation,
• • a precipitation reactor, an ion exchanger and / or a filter reactor for removing pollutants, the filter reactor being designed to perform a hybrid silica gel filtration,
• • a MAP reactor for phosphorus recovery.

According to various embodiments, the proposed sewage sludge plant uses the method according to claim 1.

According to various embodiments, the ultrasonic disintegrator is designed in the form of a loop reactor.

According to various embodiments, a further container for pretreating the sewage sludge can be provided for processing the sewage sludge, wherein the pretreatment can be a biological pre-cleaning.

• Parforce-Verfahren. Die Verwendung alternativer Verfahren zur Phosphatrückgewinnung sind denkbar.

According to various embodiments, the following chemical process is used for phosphate recovery:

• Parforce procedure. The use of alternative methods for phosphate recovery is conceivable.

According to various embodiments, various energy generation methods can be used with regard to the generation of self-generated energy. For example, energy generation by means of photovoltaic systems and / or by means of methane combustion, with methane production being achieved through additional digestion. The digestion has the advantage that further pharmaceutical compounds are broken down. For this purpose, the sewage sludge system according to the invention has corresponding energy generation systems. An additional container for receiving the sewage sludge, in which digestion for methane production is carried out, can be arranged according to various embodiments.

According to various embodiments, filter aids used are regenerated and / or recovered after the pollutant removal in process step d) so that, for example, hybrid silica gel, ion exchangers and / or resins can be recovered and returned to the sewage sludge cleaning process.

• • eines ersten Behälters zur Aufnahme des Klärschlamms und zur Senkung des pH-Wertes des Klärschlamms,
• • eines Ultraschalldesintegrationsreaktor zur Zerstörung der Zellstrukturen im Klärschlamm,
• • einer Zentrifuge und/oder eines Anschwemmfilters zur Fest-Flüssig-Trennung,
• • eines Fällungsreaktors, eines Ionenaustauschers und/oder eines Filterreaktors zur Schadstoffentfernung, wobei der Filterreaktor derart ausgestaltet ist, eine Hybridkieselgelfiltration durchzuführen,
• • eines MAP-Reaktors zur Phosphorrückgewinnung.

To solve the problem, a retrofit concept for existing sewage sludge treatment plants is also proposed, whereby the retrofit concept includes the installation of the following components:

• • a first container to hold the sewage sludge and to lower the pH value of the sewage sludge,
• • an ultrasonic disintegration reactor to destroy the cell structures in the sewage sludge,
• • a centrifuge and / or a precoat filter for solid-liquid separation,
• • a precipitation reactor, an ion exchanger and / or a filter reactor for removing pollutants, the filter reactor being designed to perform a hybrid silica gel filtration,
• • a MAP reactor for phosphorus recovery.

According to various embodiments, the ultrasonic disintegrator is designed in the form of a loop reactor.

According to various embodiments, a further container can be installed for the treatment of the sewage sludge for the treatment of the sewage sludge, wherein the pre-treatment can be a biological pre-cleaning.

• Parforce-Verfahren. Die Verwendung alternativer Verfahren zur Phosphatrückgewinnung sind denkbar.

According to various embodiments, the following chemical process is used for phosphate recovery:

• Parforce procedure. The use of alternative methods for phosphate recovery is conceivable.

According to various embodiments of the method according to the invention, the MAP product can be used as a fertilizer.

According to various embodiments, different energy generation methods can be used with regard to the generation of self-generated energy, with the installation of required components for the respective type of generation being necessary. For example, the use of a photovoltaic system requires the installation of appropriate solar cells and transformers. The use of methane incineration requires the installation of an appropriate incineration system and possibly an additional container in which methane can be generated and collected by digesting the sewage sludge.

The advantage of the method according to the invention, the sewage sludge plant according to the invention and the retrofitting concept according to the invention is the cost savings on the disposal side. Sewage sludge fractions do not have to be laboriously and expensively dewatered, transported and disposed of (incinerated). There is a gain in added value by transforming existing goods into goods with a higher monetary value. By removing pollutants, sewage sludge fractions can be returned to agriculture in a legally compliant manner. No expensive and polluting polymers are used for this. Phosphorus is also recovered legally. The requirements of the Sewage Sludge Ordinance 2017 that the sewage sludge producer has to utilize the sewage sludge arising in his wastewater treatment plant as high quality as possible, as well as that a recovery of phosphorus and a return of the recovered phosphorus to the economic cycle are to be aimed for, are fully met by means of the method according to the invention. There are a variety of approaches to recover phosphorus from sewage sludge. The vast majority of these approaches, however, are mainly aimed at the production of fertilizer. On the one hand, these must be approved as such and, above all, accepted by the market. This problem does not exist with the recovery of phosphoric acid. In addition, phosphoric acid is a valuable raw material, the market value of which exceeds the cost of extraction.

In the sewage sludge treatment according to the invention, heavy metals, other pollutants, resistant germs and pharmaceutical residues (for example antibiotic residues) are separated from the sewage sludge beforehand by ultrasonic disintegration, solid-liquid separation and filtration. There is also a targeted recovery of nutrients in the form of nitrogen and phosphorus recycling, so that in the end a nutrient-poor, purified water and a pollutant-free solid are created, which can be made into a soil improver through nutrient processing.

By using an ecotoxicologically harmless hybrid silica gel, particle assemblies (agglomerates) the size of a table tennis ball are produced, which float on the surface of the liquid and can be easily removed from there. Through the use of adaptive technology paired with a tailor-made material solution, the polluted water is cleaned of unwanted organic-chemical micropollutants.

Figure list

• 1 ein Ablaufdiagramm zum erfindungsgemäßen Verfahren

The invention is explained in more detail using an exemplary embodiment. This shows

• 1 a flow chart for the method according to the invention

In the description, reference is made to the accompanying drawings, in which there is shown, by way of illustration, specific embodiments in which the inventive arrangement may be practiced. In this regard, will uses directional terminology such as "up,""down," etc. to refer to the orientation of the drawings being described. The directional terminology is used for purposes of illustration and is in no way limiting.

It goes without saying that other embodiments can be used and structural or logical changes can be made without departing from the scope of protection of the present invention. It goes without saying that the features of the various exemplary embodiments described herein can be combined with one another, unless specifically stated otherwise. The following detailed description is therefore not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

1. a. pH-Wert-Absenkung des Klärschlamms auf einen Wert von 1-3,5 mittels Zugabe von Phosphorsäure
2. b. Ultraschalldesintegrationsbehandlung des Klärschlamms zur Übertragung der Nährstoffe und Schadstoffe in die flüssige Phase, sowie Aufbruch pharmazeutischer Verbindungen,
3. c. Fest-Flüssigtrennung mittels Zentrifugierens des Klärschlamms, sowie Nachfiltrieren des Klärschlamms mittels Anschwemmfilter, wobei ein Feststoff gebildet wird, womit eine stoffliche Verwertung erfolgt. Ferner wird in der Fest-Flüssigtrennung eine nähr- und schadstoffreiche Flüssigkeit gebildet.
4. d. Entfernen von Schadstoffen aus der nähr- und schadstoffreichen Flüssigkeit mittels Hybridkieselgelfiltration, einem lonentauscher und/oder einer Fällung, wobei eine nährstoffreiche Flüssigkeit gebildet wird.
5. e. Phosphorrückgewinnung mittels chemischer Verfahren aus der nährstoffreichen- und schadstoffarmen Flüssigkeit mittels einer Magnesium-Ammonium-Phosphat-Fällung (MAP-Fällung), wobei ein MAP-Produkt, sowie nährstoffarmes gereinigtes Wasser gebildet wird.

In 1 a flowchart for the method according to the invention for processing sewage sludge is shown. The method according to the invention uses sewage sludge which, for example, arises as a waste product after the treatment of waste water in a sewage treatment plant. This usually has a solid and a liquid phase. The process is used to obtain phosphorus / phosphoric acid, a soil conditioner and nutrient-poor purified water. It has the following procedural steps:

1. a. Lowering the pH of the sewage sludge to a value of 1-3.5 by adding phosphoric acid
2. b. Ultrasonic disintegration treatment of the sewage sludge to transfer the nutrients and pollutants into the liquid phase, as well as breaking up pharmaceutical compounds,
3. c. Solid-liquid separation by centrifuging the sewage sludge, as well as post-filtering the sewage sludge by means of a precoat filter, whereby a solid is formed, whereby a material recycling takes place. Furthermore, a liquid rich in nutrients and pollutants is formed in the solid-liquid separation.
4. d. Removal of pollutants from the nutrient and pollutant-rich liquid by means of hybrid silica gel filtration, an ion exchanger and / or a precipitation, whereby a nutrient-rich liquid is formed.
5. e. Phosphorus recovery using chemical processes from the nutrient-rich and low-pollutant liquid by means of magnesium-ammonium-phosphate precipitation (MAP precipitation), whereby a MAP product and nutrient-poor purified water are formed.

According to various exemplary embodiments, partial pressures of up to 500 bar and partial temperatures of 5000 ° C. are used during the ultrasonic disintegration treatment.

It is conceivable that a pretreatment of the sewage sludge takes place before process step a), wherein the pretreatment can in particular be a biological pre-cleaning. Further treatment techniques, also between the process steps, are conceivable.

According to various exemplary embodiments, the solid formed in method step c) is processed further, in particular into a soil improver.

The chemical process for phosphorus recovery is preferably a PARFORCE process. The use of other chemical processes for the recovery of phosphorus and / or phosphoric acid is conceivable. The MAP product resulting from phosphorus recovery is preferably used as a fertilizer and / or for further processing of phosphoric acid.

According to various exemplary embodiments, the centrifugation in method step c) is repeated at least once. A multiple repetition is conceivable, however, and can have a positive effect on the end result of the sewage sludge fraction.

According to various exemplary embodiments, the method has its own energy generation. In particular, the methane produced during the process can be used to generate its own energy.

According to various embodiments, filter aids used are regenerated and / or recovered after the pollutant removal in process step d) so that, for example, hybrid silica gel, ion exchangers and / or resins can be recovered and returned to the sewage sludge cleaning process.

• • einen ersten Behälter zur Aufnahme des Klärschlamms und zur Senkung des pH-Wertes des Klärschlamms,
• • einen Ultraschalldesintegrationsreaktor zur Zerstörung der Zellstrukturen im Klärschlamm,
• • eine Zentrifuge zur Fest-Flüssig-Trennung,
• • einen Fällungsreaktor, einen lonentauscher und/oder einen Reaktor, welcher derart ausgestaltet ist eine Hybridkieselgelfiltration durchzuführen,
• • einen MAP-Reaktor zur Phosphorrückgewinnung.

A sewage sludge plant according to the invention for processing sewage sludge for the production of phosphorus, a soil improver and purified water that is low in pollutants and nutrients (not shown here) has the following components according to various exemplary embodiments:

• • a first container to hold the sewage sludge and to lower the pH value of the sewage sludge,
• • an ultrasonic disintegration reactor to destroy the cell structures in the sewage sludge,
• • a centrifuge for solid-liquid separation,
• • a precipitation reactor, an ion exchanger and / or a reactor which is designed in such a way to carry out a hybrid silica gel filtration,
• • a MAP reactor for phosphorus recovery.

The ultrasonic disintegration reactor can be designed in the form of a loop reactor, but other embodiments which are suitable for carrying out the ultrasonic disintegration are conceivable.

According to various embodiments, there is at least one further container which is designed for pretreatment and / or intermediate treatment of the sewage sludge.

The sewage sludge plant according to the invention preferably has an own energy generation plant which, according to various exemplary embodiments, is a photovoltaic plant and / or a gas combustion plant.

The sewage sludge plant can have a digester which is designed to carry out digestion of the sewage sludge. Methane can be produced during digestion. The digester is preferably designed in such a way that the digester gases produced therein are collected and fed to the gas incineration plant.

In particular, the sewage sludge plant according to the invention is designed in such a way that it can be installed in the retrofitting process for existing sewage sludge treatment plants. It is conceivable that individual components, for example the MAP reactor or the internal energy generation system, are arranged in individual containers.

Claims (20)

Process for the treatment of sewage sludge comprising a solid and a liquid phase for the production of phosphorus, a soil improver and nutrient-poor purified water, comprising the following process steps: a. Lowering the pH of the sewage sludge to a value of 1-3.5 by adding phosphoric acid b. Ultrasonic disintegration treatment of the sewage sludge to transfer the nutrients and pollutants into the liquid phase, as well as breaking up pharmaceutical compounds, c. Solid-liquid separation by centrifuging the sewage sludge, as well as post-filtering the sewage sludge by means of a precoat filter, whereby a solid is formed and a liquid rich in nutrients and pollutants is formed, d. Removal of pollutants from the nutrient and pollutant-rich liquid by means of hybrid silica gel filtration, an ion exchanger and / or a precipitation, whereby a nutrient-rich and pollutant-poor liquid is formed, e. Phosphorus recovery using chemical processes from the nutrient-rich and low-pollutant liquid by means of magnesium ammonium phosphate precipitation (MAP precipitation), whereby magnesium ammonium phosphate (MAP) and / or phosphoric acid is formed. Process for the treatment of sewage sludge according to Claim 1 , characterized in that the ultrasonic treatment uses partial pressures of up to 500 bar. Method for processing sewage sludge according to one of the preceding claims, characterized in that the ultrasonic treatment is used at partial temperatures of 5000 ° C. Method for processing sewage sludge according to one of the preceding claims, characterized in that the sewage sludge is pretreated before method step a). Process for the treatment of sewage sludge according to Claim 4 , characterized in that the pre-treatment is a biological pre-cleaning. Method for processing sewage sludge according to one of the preceding claims, characterized in that the solid formed in method step c) is further processed to form a soil improver. Process for processing sewage sludge according to one of the preceding claims, characterized in that the chemical process for phosphorus recovery is a Parforce process. Method for processing sewage sludge according to one of the preceding claims, characterized in that the MAP product is further used as a fertilizer and / or for further processing of phosphoric acid. Method for processing sewage sludge according to one of the preceding claims, characterized in that the centrifugation in method step c) is repeated at least once. Method according to one of the preceding claims, characterized in that the method has its own energy generation. Process for the treatment of sewage sludge according to Claim 10 , characterized in that methane produced during the process is used to generate the process’s own energy. Method according to one of the preceding claims, characterized in that filter aids are regenerated and / or recovered after the pollutant removal in method step d). Sewage sludge plant for the treatment of sewage sludge for the production of phosphorus, a soil improver and low-pollutant and low-nutrient purified water, the sewage sludge having a solid and a liquid phase, having a sewage sludge plant • a first container to hold the sewage sludge and to lower the pH value of the sewage sludge, • an ultrasonic disintegration reactor to destroy the cell structures in the sewage sludge, • a centrifuge for solid-liquid separation, • A precipitation reactor, an ion exchanger and / or a reactor which is designed in such a way to carry out a hybrid silica gel filtration, • A MAP reactor for phosphorus recovery. Sewage sludge plant according to Claim 13 , characterized in that the ultrasonic disintegrator is designed in the form of a loop reactor. Sewage sludge plant according to Claim 13 or 14th , further comprising a further container for the pretreatment of the sewage sludge. Sewage sludge plant according to Claim 13 , 14th or 15th furthermore having an own energy generation system. Sewage sludge plant according to Claim 16 , characterized in that the own energy generation system is a photovoltaic system and / or gas combustion system. Sewage sludge plant according to one of the Claims 13 to 17th , further comprising a digester, which is designed to carry out digestion of the sewage sludge. Sewage sludge plant according to Claim 18 , characterized in that the digester is designed in such a way as to collect the digestion gases produced therein and to feed them to the gas incineration plant. Sewage sludge plant according to one of the preceding Claims 13 - 19th , characterized in that the sewage sludge plant is designed in such a way that it can be installed in the retrofitting process for existing sewage sludge treatment plants.

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