RU2556655C1 - Method of eliminating pathogenic microorganisms and device for its realisation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to thermochemical processing of sewage water sediment (SWS) and can be used at treatment plants, stages of biological purification of household and industrial sewages. Reagents from bunker for reagents 1 are preliminarily diluted with water in reservoir for suspension preparation 5, mixed with further addition of suspension into sediment with humidity higher than 92%, in amount, sufficient for obtaining pH value 12, but with quantity of reagent in mixture being, by weight, at least less than quantity of solid substance in sediment. After that, obtained mixture is mixed in chamber 10 and subjected to dehydration and heating in accumulating tanks 14 for time period, sufficient for reduction of quantity of pathogenic microorganisms to the level 1000 colonies per gram of dry substance.

EFFECT: reduced consumption of reagents, improved quantity of obtained product, application of dehydrated sediment as fertiliser, reduced volume of capital and current expenditures.

15 cl, 3 dwg

Description

The invention relates to methods for thermochemical treatment of sewage sludge (hereinafter - WWS) and can be used in workshops at treatment plants, at biological treatment plants for domestic and industrial wastewater.

The effectiveness of the use of WWS as fertilizer is currently well known. See, for example, the document at the link: http://rudocs.exdat.com/docs/index-398936.html?page=3.

The obstacle is pathogenic microorganisms and heavy metals contained in the WWS. Currently, various methods for the disposal of WWS are known.

Most often composting is used for this purpose, see, for example, patent RU 2212391 C2, IPC ⁷ C05F 3/00, 11/00, C02F 11/14, publ. September 20, 2003

The cost of composting is several times less than when using other methods. However, the composting method has a number of significant drawbacks.

1. In the composting process, which can last for months or even years, compost spreads pathogenic microorganisms with the help of insects, rodents of wind and water into the air, into the ground and underground waters. If composting sites are isolated from the environment, the cost of disposal of WWS increases several times.

2. Composting requires significant areas that completely disappear for use.

To neutralize WWS, drying is also used, followed by burning. With this method, the cost of drying is many times higher than the cost of composting.

From the description of patent RU 2159745 C2, IPC ⁷ C02F 11/14, publ. November 27, 2000, there is a known method of processing WWS, including heating to 70 ° C and holding for 20 minutes. This method is ineffective for removing pathogenic microorganisms. The experiments performed by us showed that with this treatment it is not possible to reduce the number of pathogenic microorganisms.

From patent RU 2113417 C1, IPC ⁶ C02F 11/14, publ. 06/20/1998, there is a known method of destroying pathogens in waste, including heating to 70 ° C with exposure in time and adding lime to WWS two or more times the amount of dry matter in WWS. The disadvantage of this method is increased by several times (compared with composting) cost.

From the source http://npckvadra.ru/wp-content/uploads/2013/10/il.pdf there are known examples of the processing of WWS by various physical methods, including radiation, electromagnetic, ultrasonic, etc. The cost of such methods is many times more expensive than composting.

These methods are described, for example, in patents RU 2057725 C1, IPC ⁶ C02F 11/10, C02F 11/14, publ. 04/10/1996, RU 2109696 C1, IPC ⁶ C02F 11/14, publ. 04/27/1998, RU 2116267 C1, IPC ⁶ C02F 11/14, publ. 07/27/1998, and in the document at the link http://dulvictor.narod.ru/8-4osv.htm.

All of the above methods are significantly more expensive than composting and therefore do not find practical application. However, with composting, environmental contamination occurs.

For the closest analogue of the proposed method is taken the method known from patent RU 2159745 C2, IPC ⁷ C02F 11/14, publ. 11/27/2000, In the analogue method, lime is added to the dehydrated sludge containing approximately 10-60% dry matter, which, according to the authors, “behaves more like a solid than a liquid”. The resulting mixture is placed in a pasteurization chamber, in which a conveyor belt moves the mixture from the inlet to the outlet “without significant shaking” at a predetermined temperature. The speed of the conveyor ensures that the mixture stays in the pasteurizer for a predetermined time. The amount of added lime, the temperature in the pasteurizer and the residence time of the mixture in the pasteurizer should ensure the disinfection of the product.

The analogue method has a number of significant disadvantages.

The addition of lime without significant shaking in a dehydrated sludge, which contains 10-60% solids, complicates the interaction of lime with the entire volume of sludge. Therefore, to increase the reliability of the widespread reaction of sludge with lime, it is necessary to increase the amount of lime. As a result:

1. The amount of lime to be added to the mixture is increasing. The authors recommend adding “2–25 pounds of lime per pound of dry matter”. Under such conditions, the finished product becomes lime with a small addition of sludge. The effectiveness of the resulting product as a fertilizer sharply decreases.

2. The addition of a large amount of lime and its transportation significantly increase the cost of the product.

3. Lime contains heavy metals and other harmful impurities. A large amount of lime per unit of nutrient significantly increases the amount of heavy metals and harmful substances per unit of nutrient and makes the resulting product unsuitable for further use, at least as a fertilizer.

4. A large amount of lime will sharply reduce the acidity of the soil, which may not be acceptable in specific conditions. In addition, in regions with a high content of calcium in the soil, the introduction of additional calcium with fertilizers is undesirable.

For the closest analogue of the device for implementing the method adopted device, also known from patent RU 2159745 C2, IPC ⁷ C02F 11/14, publ. November 27, 2000, containing bins for storing reagents, a chamber for mixing reagents and sludge and a heating system.

The disadvantages of the analog device are the high consumption of reagents and the low quality of the resulting product.

The task that is solved by the claimed method and device is the creation of technology for thermochemical treatment of WWS, which provides:

- effective treatment of effluents from pathogenic microorganisms and heavy metals at low cost of the final product;

- increased quality of the final product, due to the possibility of its long-term storage and use as fertilizer.

The technical result, to which the claimed invention is directed, is to reduce the consumption of reagents and improve the quality of the resulting product.

The specified technical result is achieved in a method of treating sewage sludge with reagents, for example, lime, which is added in an amount by weight of less dry matter to reduce the acidity of sludge to the desired pH value, for example 12, and holding in this state at an elevated temperature of 80 ° C for a period of time sufficient to reduce pathogenic microorganisms in sediment.

The technical result is achieved in the proposed method in that the reagents are pre-diluted with water in a proportion (for example, 1 part lime to 10 parts water), which gives the resulting suspension fluidity sufficient for use in the process, mix and add the suspension to the sludge with moisture more than 92%, in an amount sufficient to obtain the desired pH, but so that the reagent in the mixture is by weight at least less than the amount of solids in the sediment; then the resulting mixture is mixed and subjected to dehydration and heating for a time sufficient to reduce the number of pathogenic microorganisms to a level below that specified in the regulatory documentation. Moreover, in cases where the humidity of the mixture before and after dehydration differs slightly, the mixture is heated to dehydration, using the heat that the sludge received in the meta-stove. In cases where the humidity of the mixture before and after dehydration differs significantly, the mixture is heated after dehydration. Suspension and sludge can be fed into the chamber for mixing by pumps under pressure and at an angle to each other, which ensures the best mixing of the mixture. The mixture, if necessary, is further forcedly mixed in the mixing chamber. The mixture can withstand over time and at a temperature sufficient to reduce the number of pathogenic microorganisms to an amount significantly lower than permitted in regulatory documents.

The above technical result is also achieved in the device for implementing the method, including hoppers for storing reagents, a chamber for mixing reagents and sludge and a heating system.

The technical result is achieved in the device by the fact that it is equipped with dispensers for the dosed automatic supply of reagents and water into a container for the manufacture of a suspension, a container for the formation of a suspension, containing, if necessary, an automated heating system for the suspension, a mixer and a pump for feeding the suspension into a storage tank, storage a tank equipped with an automatic heating system, as well as a pipeline and, if necessary, a pump for feeding the suspension into the mixing chamber of the suspension and sludge, the camera mixing slurry and sludge, containing pumps for feeding and mixing the slurry with sludge in the mixing chamber, an automatic mixture heating system, if necessary, devices for mixing sludge and slurry, sensors for determining the pH value and controlling the pump supplying the slurry to this tank for feeding in a tank of such an amount of suspension that will ensure a given pH value, as well as a pump and pipeline for pumping the mixture into storage tanks, a pipeline for pumping the mixture into storage tanks a ki containing a switchgear for loading tanks according to a given program, a software system for tasking and controlling the temperature in all units of the device, determining and controlling the amount of reagents supplied to form a suspension, setting the amount of suspension supplied to the mixing chamber of the suspension and sludge, and controlling the distribution a device loading the mixture into storage tanks. Moreover, at stations where the humidity of the mixture before and after dehydration is much different in magnitude, the device can be equipped with a chamber for heating the dehydrated mixture installed after the device for dehydration, and the camera is made of three compartments, the first of which serves to load and heat the mixture, the second for holding the mixture for a given time at a given temperature, and the third for unloading the mixture. Pumps for feeding and mixing the suspension and sludge in the mixing chamber can be installed opposite to each other, at an angle between their nozzles with the possibility of adjusting their relative position and changing the angle between the direction of their jets. Dosers for the dosed automatic supply of reagents and water to the slurry container can be controlled from a computer, which is designed to automatically adjust the doses of water and reagent, depending on the cost of the coolant, reagent, pH of the supplied water, sludge and mixture. The device may include an electric heating system for the suspension, sludge and mixture, in which the heaters are connected to an electric generator operating on gas from the reactors of the treatment station. The device may include a heating system for slurry, sludge and mixture using pipelines filled with running water, in which the cooling system of an internal combustion engine or turbine is used to heat the water. The device may include a heating system for slurry, sludge and mixture using pipelines filled with running water, in which a boiler is used to heat the water, working on the exhaust gases of an internal combustion engine or turbine. The device may include a heating system for slurry, sludge and mixture using pipelines filled with running water, in which solar panels are used to heat the water. The device may have at least three tanks for storing the finished product, which are used sequentially and alternately - the first for receiving and heating the mixture of sludge and suspension, the second for guaranteed storage of the mixture for a predetermined time at a given temperature, and the third for dispensing the finished product.

The invention is illustrated by the following drawings.

In FIG. 1, 2 show variants of a circuit device for implementing the method;

In FIG. 3 shows part A of the circuit of the device shown in FIG. one.

With reference to FIG. 1-3 are indicated;

1 - hopper for reagents;

2 - dispenser for loading reagents;

3 - capacity for the preparation of the suspension;

4 - heater;

5 - dispenser for loading water into the tank for preparing the suspension.

6 - pump for mixing the suspension and pumping it into the storage tank 7;

7 - storage capacity;

8 - high pressure pump for feeding the suspension into the chamber 10 for mixing the suspension with sludge;

9 - high pressure pump for feeding sludge into the chamber 10 for mixing the suspension and sludge in the chamber 10;

10 - a chamber for mixing the suspension and slurry, equipped with pumps for feeding the suspension and sludge, devices for mixing the suspension with sludge, sensors for determining the pH value and controlling the pump supplying the suspension to this tank in order to supply such a quantity of suspension to the tank that will provide a given pH value;

11 - pump for supplying the mixture to the drives 14;

12 - pipelines for supplying the mixture to the drives 14;

13 - distribution device for feeding the mixture into the drives 14;

14 - drives;

15 - pipelines for pumping the finished product into the installation for dehydration;

16 - automatic valves that allow access to the finished product in pipelines;

17 - pump for supplying the finished product to the installation for dehydration;

18 - metatank; a device for dehydrating the mixture;

19 - aerotank;

20 - mixer;

21 - a chamber for heating the dehydrated mixture with three compartments: for loading and heating the dehydrated mixture; for exposure at a given temperature and a given time; for unloading in a vehicle;

22 - a device for dewatering the mixture;

23 - pump nozzle for feeding sludge;

24, 25 - ball bearings;

26 - nozzle pump for supplying a suspension.

The proposed method is implemented as follows. The reagent, for example, lime, is added to a fluid sludge in which the solids content is preferably substantially less than 8% (e.g. 3%). Lime is pre-diluted with water in a ratio of, for example, 9 parts water to 1 part lime. The water used is preferably water obtained by dehydration of a fluid sludge from sludge after its neutralization. The resulting suspension is poured into a container simultaneously with sludge and mixed thoroughly. The ratio of the amount of sludge and suspension is set depending on the pH in the sludge and the desired pH in the mixture, for example 12. The resulting mixture is heated to a predetermined temperature, for example, to 80C, and kept for a time sufficient to reduce the number of pathogenic organisms to the level below the normative documents. Heating sludge allows you to use the heat that sludge has when exiting the metatank.

If the volume of sludge is many times greater than the volume of sludge that is obtained after dehydration of the pulp, it is more advantageous to heat the sludge.

To increase the efficiency of the process:

1. The suspension is preheated.

2. The suspension and sludge are mixed in a special container or pipeline, in which the direction of the streams of milk of lime and sludge are provided. And one or several mixers of a mechanical, vibrational, thermal, air, hydraulic or any other type and sensors are built into the walls of the tank to determine the pH value and control the pump supplying the suspension to the tank for mixing the suspension and sludge in order to obtain a given pH value.

3. The resulting mixture is heated to a predetermined temperature, for example 80 ° C, with the help of biogas released during the treatment of effluents in meta tanks, electric heaters, solar energy, exhaust gases of internal combustion engines or turbines, water from cooling systems of other units or in any other way.

4. From a special container, the mixture is transported to storage tanks in which it is stored for a predetermined time until dehydration. Storage tanks are equipped with a mixture heating system and temperature sensors that control heating elements and maintain the required temperature.

5. In some cases, the sludge formed as a result of dehydration of the mixture is heated to a predetermined temperature.

The proposed method provides for the treatment of effluents from pathogenic microorganisms and heavy metals. Moreover, its cost is much lower than the cost of composting and other methods of cleaning sludge. This makes it possible to replace composting everywhere and protect the environment from pathogenic microorganisms, from which composting cannot protect.

A device for implementing the proposed method is shown schematically in FIG. 1-3. Moreover, in FIG. Figure 3 shows a large part of the chamber for mixing suspension and sludge with nozzles of pumps for feeding sludge 23 and slurry 26, which are located on ball bearings 24 and 25, respectively, which make it possible to adjust the angle between the axes of the nozzles for better mixing of sludge and suspension.

A device for implementing the described method comprises:

- bins for receiving and storing reagents, for example quicklime, with a device for the normalized delivery of reagent to a container for preparing a suspension;

- a dispenser for the normalized delivery of water into a container for preparing a suspension;

- a tank for preparing a suspension with a mechanical or other type mixing system, a pH measurement and adjustment system by changing the amount of reagent, and a pump for pumping the suspension into a storage tank; this tank can also be equipped with a suspension heating system, including temperature control and adjustment;

- a storage tank with a heating system, with a temperature control and regulation system and a pipeline for supplying the suspension to the tank for mixing the suspension with sludge;

- a tank for mixing suspension with sludge, equipped with two pumps, mainly high pressure, for feeding and mixing the suspension and sludge in this tank; the container can also be equipped with a system for constant mixing of the mixture, using a mechanical or some other mixer, or using thresholds inside the container, providing turbulent movement and mixing of the mixture inside the container; this tank is also equipped with a mixture heating system with measuring and adjusting its temperature, as well as sensors for determining the pH value and controlling the pump supplying the suspension to this tank in order to supply such a quantity of suspension in the tank that will provide a given pH value;

- a pipeline for supplying the mixture from the mixing tank to one or more storage tanks with a pump for pumping the mixture into the storage tanks and a system of controlled valves that distribute the mixture among the storage tanks;

- one or more storage tanks equipped with a mixture heating system, a temperature measuring and adjustment system and one or more pumps for supplying the mixture to a device for its dehydration;

- a computer system that is designed to determine the amount of ingredient supplied per unit mass of dry matter and the temperature at which the cost of the final product will be minimal depending on the cost of the ingredient and the coolant;

In the case when the volume of the mixture before dehydration is many times greater than the volume of the mixture after dehydration, the heating elements are installed only in the heating chamber of the dehydrated mixture.

Consider a specific example of the invention (see Fig. 1). Dispensers 2 are loaded from hoppers 1 into a container 3 of size 5 cubic meters. m. 400 kg. quicklime. At the same time, dispenser 5 is poured into a container of 3 4000 kg of water. A stirrer 20 mix the mixture thoroughly until a homogeneous suspension is formed. After readiness, the pump 6 pumps the suspension into the accumulator 7 with a volume of 10 cubic meters, in which the suspension is heated to 80 ° C. From the reservoir 7, the suspension is pumped under pressure by the pump 8 into the mixing chamber 10. At the same time, the pump 9 is fed into the chamber 10 20 liters of sludge for each liter of suspension. At the same time, for each liter of sludge there is only 5 grams. lime. In order to ensure the PH12 value everywhere with such a small amount of lime per kg of sludge, thorough mixing of the mixture of sludge and suspension in the chamber 10 is necessary. Therefore, in the chamber 10 the mixture is continued to be mixed and heated to a temperature of 80 ° C. The pump 8 can increase or decrease the amount of suspension supplied to the chamber 10, at the command of sensors that determine the pH in the chamber 10. The pump 11 using the distribution device 13 injects the mixture through pipelines 12 into the accumulators 14, in which the mixture is heated and stored at the same temperature for 3-12 hours. The resulting mixture (fertilizer) using valves 16 and pump 17 is pumped through pipelines 15 into a device for dehydration.

As a result of processing sludge using the proposed technology, the colic content decreased from 15,000 colonies per gram of dry matter to zero. Permissible colic content in fertilizers according to Israeli law and the American standard is 1000 colonies per gram of dry matter.

At the same time, the cost of fertilizer obtained is half the cost of composting. This allows replacing composting with the proposed technology everywhere and eliminating composting sites that occupy agricultural land and infect the surrounding air, land and water with microorganisms dangerous to nature and humans.

In a device whose circuit is shown in FIG. 2, unlike the device shown in FIG. 1, all the heaters are removed from the accumulator 7, the mixing chamber 10 and the accumulators 14. The mixture from the accumulators 14 is pumped into the dewatering device 22. The dehydrated mixture is supplied to the chamber 21, in which it is heated to a temperature set by the computer, for example 80 ° C, and stand for a period of time also set by the computer, for example 6 hours. Chamber 21 has three compartments. The dehydrated mixture is poured into the first compartment and heated, in the second compartment the mixture is heated and maintained at the set temperature for the required time, and it is unloaded from the third compartment into the vehicle, with which the fertilizer is delivered to the consumer.

Claims (15)

1. A method of destroying pathogenic microorganisms in sewage sludge comprising adding to the sludge lime sludge to reduce the acidity to pH values of 12 and holding at ⁸⁰ ° C, characterized in that the lime is previously diluted with water in a ratio of 1 part lime to 10 parts water, mixed until a homogeneous suspension is formed, the suspension is added to the sewage sludge with a moisture content of more than 92% in an amount sufficient to obtain a pH of 12, while the amount of lime in the mixture should be less by weight than honors the solids in the sludge, then the resulting mixture was stirred and lime sludge, dewatered, heated to ⁸⁰ ° C and held for a time sufficient to reduce the amount of pathogenic microorganisms to a level of up to 1000 colonies per gram of dry matter. 2. The method according to p. 1, characterized in that in cases where the humidity of the mixture before and after dehydration differs slightly, the mixture is heated to dehydration, using the heat that sludge was received in the metatank. 3. The method according to p. 1, characterized in that in cases where the humidity of the mixture before and after dehydration differs significantly, the mixture is heated after dehydration, using, but not only, the heat of the exhaust gases from a turbine operating on biogas metatenki, or products combustion of this gas. 4. The method according to p. 1, characterized in that the suspension and sludge are fed into the chamber for mixing by pumps under pressure and at an angle to each other, which ensures the best mixing of the mixture. 5. The method according to p. 1, characterized in that the mixture, if necessary, is additionally forced to mix in the mixing chamber. 6. The method according to p. 1, characterized in that the mixture is incubated for a time and at a temperature sufficient to reduce the number of pathogenic microorganisms to an amount significantly lower than permitted in regulatory documents. 7. A device for implementing the method according to claim 1, containing hoppers for storing reagents, a chamber for mixing reagents and sludge and a heating system, characterized in that it is equipped with dispensers for dosed automatic supply of reagents and water into a container for preparing a suspension, a container for preparing suspension, optionally containing an automated suspension heating system, a mixer and a pump for feeding the suspension into a storage tank, a storage tank equipped with an automatic heating system, as well as a pipeline and, if necessary, a pump for supplying the suspension to the suspension and sludge mixing chamber, a suspension and sludge mixing chamber, containing pumps for feeding and mixing the suspension with sludge in the mixing chamber, an automatic heating system of the mixture, and if necessary devices for mixing sludge and suspension, sensors for determining the pH value and controlling the pump supplying the suspension to the suspension and sludge mixing chamber in order to supply the suspension and sludge to such a quantity of suspension that This will provide a given pH value, as well as a pump and pipeline for pumping the mixture to the tank, a pipeline for pumping the mixture into the tank, containing a switchgear for loading tanks according to a given program, a software system for task and temperature control in all units of the device, determination and control the amount of reagents supplied to form the suspension, set the amount of suspension supplied to the mixing chamber of the suspension and sludge, and control the switchgear, loading yuschim mixture into storage tanks. 8. The device according to claim 7, characterized in that if the humidity of the mixture before and after dehydration is much different in magnitude, the device is equipped with a chamber for heating the dehydrated mixture installed after the dehydration device, and the camera is made of three compartments, the first of which serves to load and heat the mixture, the second for holding the mixture for a given time at a given temperature, and the third for unloading the mixture. 9. The device according to claim 7, characterized in that the pumps for feeding and mixing the suspension and pulp in the mixing chamber are mounted opposite to each other at an angle between their nozzles with the possibility of adjusting their relative position and changing the angle between the direction of their jets. 10. The device according to p. 7, characterized in that the dispensers for the dosed automatic supply of reagents and water into the container for the manufacture of suspensions are made controlled by a computer, which is designed to automatically adjust the doses of water and reagent depending on the cost of the coolant, reagent, pH supplied water, sludge and mixtures. 11. The device according to claim 7, characterized in that it contains an electric heating system for the suspension, sludge and mixture, in which the heaters are connected to an electric generator operating on a gas that is released in digesters. 12. The device according to p. 7, characterized in that it contains a heating system for the suspension, sludge and mixture using pipelines filled with running water, in which the cooling system of an internal combustion engine or turbine is used to heat the water. 13. The device according to p. 7, characterized in that it contains a system for heating the suspension, sludge and mixture using pipelines filled with running water, in which a boiler is used to heat the water, working on the exhaust gases of an internal combustion engine or turbine. 14. The device according to p. 7, characterized in that it contains a heating system for the suspension, sludge and mixture using pipelines filled with running water, in which solar panels are used to heat the water. 15. The device according to p. 7, characterized in that it has at least three tanks for storing the finished product, which are used sequentially and alternately:
1st - for receiving and heating a mixture of pulp and suspension,
2nd - for guaranteed storage of the mixture for a given time at a given temperature, and
3rd - for the delivery of the finished product for dehydration.

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