Method for safely treating medical sludge in situ and converting carbon source

Abstract

The invention relates to a method for safely treating medical sludge in situ and converting a carbon source, which comprises the following steps: controlling the pH range and hydrolysis time of the medical sludge, so that sludge extracellular polymers are subjected to directional alkaline hydrolysis to expose cell outer walls; the method comprises the following steps: starting hydrodynamic cavitation, introducing ozone, adding sodium hypochlorite, stirring and reacting, and oxidizing medical sludge cell wall breaking and cell dissolving to release soluble organic matters in cells by utilizing strong oxidation capacity HO released by hydrodynamic cavitation ozone; ammonia nitrogen and organic amine nitrogen in dissolved organic matters released by the sludge are oxidized into nitrogen by using ClO generated by the reaction of the HO and the sodium hypochlorite; after the reaction is finished, solid-liquid separation is performed, a liquid phase serves as a carbon source for medical sewage treatment, a solid phase flows back to the biochemical pool, and in-situ safe treatment and complete resource utilization of the medical sludge are achieved. Dissolved organic matters released by the medical sludge can be converted into a carbon source required by hospital sewage treatment, and safe treatment and recovery of the sludge are realized.

Description

Technical Field

[0001] The present invention relates to a technology in the field of medical care, specifically a method for in-situ safe disposal of medical sludge and conversion into a carbon source. Background Art

[0002] Biochemical treatment of medical wastewater generates large amounts of "excess sludge" containing viruses, bacteria, and pharmaceuticals. This sludge, enriched with bacteria, viruses, insect eggs, pathogens, and residual pharmaceuticals, is complex and classified as "hazardous waste" by the government, requiring safe disposal. Existing medical sludge treatment primarily utilizes a "concentration + dehydration + external transportation + third-party disposal" approach, involving the disposal and management of the hospital, transportation, and third-party disposal. To address this issue, various third-party disposal technologies have been developed in recent years, including lime disinfection and low-temperature drying, lime disinfection and low-temperature heat treatment, high-temperature hydrothermal treatment, and high-temperature combustion in incinerators. However, these processes are complex, costly, and result in significant secondary pollution, making them inefficient and inefficient for resource utilization. Furthermore, the transportation process poses significant safety risks and can easily lead to viral transmission, endangering human health and the ecological environment. Furthermore, existing technologies have been developed to prevent viral transmission during medical wastewater treatment and sludge transportation. However, these disinfection technologies suffer from low efficiency, cannot completely eliminate viral transmission, and cannot fully utilize the sludge as a resource. Therefore, the current disposal of "residual sludge" lacks in-situ, real-time, safe, efficient and resource-based disposal methods. Summary of the Invention

[0003] In response to the above-mentioned deficiencies in the prior art, the present invention proposes a method for the in-situ safe disposal and conversion of medical sludge into a carbon source. By performing directional alkaline hydrolysis of extracellular polymers, cavitation ozone oxidation to break down cell walls and lyse cells to release organic matter, and utilizing ClO• to oxidize ammonia / amine nitrogen in organic matter for denitrification, the soluble organic matter released from the medical sludge is converted into the carbon source required for hospital wastewater treatment, thereby achieving safe disposal and resource utilization of the sludge.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to a method for in-situ safe disposal and carbon source conversion of medical sludge. The method comprises the following steps: controlling the pH range and hydrolysis time of the medical sludge so that extracellular polymers in the sludge undergo directional alkaline hydrolysis to expose the outer cell walls; starting hydraulic cavitation, introducing ozone, adding sodium hypochlorite and stirring for reaction; utilizing the strong oxidizing capacity HO• released by the hydrodynamic cavitation ozone to oxidize the medical sludge cell walls, break the walls and lyse the cells to release dissolved organic matter in the cells; utilizing ClO• generated by the reaction of HO• with sodium hypochlorite to oxidize ammonia nitrogen and organic amine nitrogen in the dissolved organic matter released by the sludge to convert them into nitrogen gas; after the reaction is completed, solid-liquid separation is performed, the liquid phase is used as a carbon source for medical wastewater treatment, and the solid phase is returned to a biochemical tank, thereby achieving in-situ safe disposal and complete resource utilization of the medical sludge.

[0006] The control of the pH range and hydrolysis time of the medical sludge refers to: adjusting the pH value to 9.0-10.0 by adding alkali and stirring, the hydrolysis time is 1-3 minutes, and the stirring speed is 3000 revolutions / min.

[0007] The hydraulic cavitation is started at a cavitation speed of 2800-3500 rpm.

[0008] The stirring reaction has a reaction time of 15 to 25 minutes.

[0009] The ozone is introduced at a flow rate of 1-3 mgO3 / min per liter of wet sludge.

[0010] The dosage of the sodium hypochlorite is 100-1000 mg / L.

[0011] Technical Effects

[0012] The present invention controls the hydrolysis of medical sludge under weak alkaline conditions of pH 9.0-10.0 and a very short time of 1-3 minutes, thereby achieving the goal of both targeted cleaning of extracellular polymers outside the sludge cell walls and preventing excessive hydrolysis and emulsification of polymers and cell walls, thereby avoiding the formation of a large amount of foam in the subsequent ventilation process, which ultimately makes solid-liquid separation difficult; the present invention utilizes the highly oxidizing HO• formed by hydrodynamic cavitation ozone to oxidize the cell walls to break the cells and lyse the cells to release organic matter; by controlling the short cell breaking and lysing reaction time of 15-25 minutes, the system is prevented from being over-oxidized to form an emulsion, which leads to the problem of difficult solid-liquid separation, and reduces energy consumption; the formed ClO• / Cl• is used to oxidize the ammonia nitrogen and organic amine nitrogen in the organic matter released from the sludge, thereby achieving ammonia / amine nitrogen denitrification and improving the quality of the liquid carbon source; the formed HO• / ClO• and the like are used to disinfect viral microorganisms in the medical sludge; thereby achieving in-situ safe disposal of medical sludge and high-quality conversion to a carbon source. Compared with the existing technology: after the medical sludge is broken and lysed, the solid and liquid are easy to separate, the carbon source conversion efficiency is high, the liquid phase has a high concentration as a carbon source and a low nitrogen content, and bacteria and viral microorganisms are completely disinfected, realizing the complete resource utilization of medical sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The EPR test results of free radicals during the cavitation ozone process in Example 1;

[0014] In the picture: Indicates the DMPO-HO• signal peak formed by DMPO capturing HO•, Indicates the DMPO-ClO• signal peak formed by DMPO capturing ClO•;

[0015] Figure 2 This is a schematic diagram of Control Example 1;

[0016] In the figure: A live picture showing that the early hydrolysis under relatively high alkaline conditions (pH 10.5) and for a long time (5 min) caused emulsification, which led to severe foaming in the later stage and difficulty in solid-liquid separation. DETAILED DESCRIPTION

[0017] Example 1

[0018] This embodiment includes the following steps: placing medical wet sludge in a reaction vessel, adjusting the pH value of the medical sludge to 9.5 with NaOH, stirring at a speed of 3000 rpm, and hydrolysis stirring for 2 minutes to allow alkaline hydrolysis of the sludge extracellular polymers and expose the sludge cell wall, then starting hydrodynamic cavitation at a speed of 3000 rpm, and introducing ozone at an ozone flow rate of 2 mgO3L -1 Wet sludge / min, and sodium hypochlorite 700mg / L, reaction time 20min. After the reaction is completed, solid-liquid separation is carried out, and the liquid phase is used as a carbon source for wastewater treatment, with dissolved chemical oxygen demand >45% and ammonia nitrogen concentration <5mg / L. The solid phase is returned to the biochemical tank, achieving safe in-situ disposal and efficient resource utilization of medical sludge.

[0019] like Figure 1 As shown in the figure, the HO• and ClO• results observed by EPR during the hydrodynamic cavitation-ozone-sodium hypochlorite reaction process are shown in the figure. Indicates the DMPO-HO• signal peak formed by DMPO capturing HO•, The DMPO-ClO• signal peak is formed by DMPO capturing ClO•, indicating that HO• with strong oxidizing ability is released under the conditions of the present invention, oxidizing the cell walls of medical sludge to break and lyse the cells; it indicates that ClO• is formed under the conditions of the present invention, which can realize the conversion of ammonia nitrogen and organic amine nitrogen in the dissolved organic matter released by the sludge into nitrogen gas.

[0020] The effects of Example 1 are illustrated below using five comparative examples.

[0021] Comparative Example 1

[0022] As a control, under the condition that other conditions in Example 1 remain unchanged, the pH value of medical sludge was adjusted to 10.5 with NaOH, and the hydrolysis stirring time was 5 minutes. Due to the high alkaline reaction conditions and the long initial hydrolysis time, the extracellular polymers and the subsequent broken cell wall and lysed organic matter were overly hydrolyzed and emulsified, resulting in severe foaming after ozone injection, and ultimately difficult solid-liquid separation. Figure 2 shown.

[0023] Comparative Example 2

[0024] As a control, with other conditions in Example 1 unchanged, only the stirring speed of 3000 rpm was used instead of the hydraulic cavitation operation. After the reaction was completed, the solid-liquid separation was carried out, and the soluble chemical oxygen demand released by the sludge in the liquid phase was less than 10%.

[0025] Comparative Example 3

[0026] As a control, when other conditions in Example 1 remained unchanged, sodium hypochlorite was not added. After the reaction was completed, solid-liquid separation was performed, and the ammonia nitrogen concentration in the separated liquid carbon source was >150 mg / L.

[0027] Comparative Example 4

[0028] As a control, when other conditions in Example 1 remained unchanged, the reaction time of hydrodynamic cavitation-ozone-sodium hypochlorite was 40 min. Excessive reaction time resulted in excessive oxidation of the cell wall-broken and lysed organic matter, causing severe emulsification and foaming, and ultimately making it impossible to perform solid-liquid separation.

[0029] Comparative Example 5

[0030] As a control, under the condition that other conditions in Example 1 remain unchanged, the reaction time of hydrodynamic cavitation-ozone-sodium hypochlorite is 10 minutes. After the reaction is completed, the solid-liquid separation is performed, and the soluble chemical oxygen demand released by the sludge in the liquid phase is less than 25%.

[0031] Example 2

[0032] This embodiment includes the following steps: placing medical wet sludge in a reaction vessel, adjusting the pH value of the medical sludge to 9 with NaOH, stirring at a speed of 3000 rpm for 3 minutes, allowing alkaline hydrolysis of the sludge extracellular polymers and exposing the cell walls of the sludge, then starting hydrodynamic cavitation at a speed of 2800 rpm, and introducing ozone at an ozone flow rate of 1 mgO3L -1 Wet sludge / min, and sodium hypochlorite 100mg / L, reaction time 25min. After the reaction is completed, solid-liquid separation is carried out, and the liquid phase is used as a carbon source for wastewater treatment, with dissolved chemical oxygen demand >40% and ammonia nitrogen concentration <10mg / L. The solid phase is returned to the biochemical tank, achieving safe in-situ disposal and efficient resource utilization of medical sludge.

[0033] Example 3

[0034] This embodiment includes the following steps: placing medical wet sludge in a reaction vessel, adjusting the pH value of the medical sludge to 10 with NaOH, stirring at a speed of 3000 rpm for 1 minute, allowing alkaline hydrolysis of the sludge extracellular polymers and exposing the cell walls of the sludge, then starting hydrodynamic cavitation at a speed of 3500 rpm, and introducing ozone at an ozone flow rate of 3 mgO3L -1 Wet sludge / min, and sodium hypochlorite 1000mg / L, reaction time 15min. After the reaction is completed, solid-liquid separation is carried out, and the liquid phase is used as a carbon source for wastewater treatment, with dissolved chemical oxygen demand >42% and ammonia nitrogen concentration <3mg / L. The solid phase is returned to the biochemical tank, achieving safe in-situ disposal and efficient resource utilization of medical sludge.

[0035] Although existing ozone oxidation technology can utilize HO• formed by ozone to oxidize medical sludge, causing it to release organic matter and kill bacteria and viral microorganisms, the HO• concentration formed by existing technology is low, resulting in low efficiency in the safe disposal of medical sludge and low efficiency in the release of dissolved organic matter. On the other hand, the released dissolved organic matter contains a large amount of ammonia nitrogen and organic amine nitrogen compounds. If these ammonia / amine nitrogen-containing organic substances are directly used as carbon sources for sewage treatment, the ammonia nitrogen and organic amine nitrogen compounds mixed therein will also consume a large amount of carbon source, resulting in a significant reduction in its carbon source efficiency. The present invention first adopts weak alkaline conditions with a pH value of 9.0-10.0 and performs short-term hydrolysis for 1-3 minutes to directionally control and clean extracellular polymers outside the cell wall without causing excessive hydrolysis and emulsification. Then, hydrodynamic cavitation technology is used to break the cell wall and lyse the cells. The hydrodynamic cavitation action includes the collapse of cavitation bubbles, high temperature and high pressure supercritical action and advanced oxidation, which can enhance ozone to form high-concentration HO·, thereby promoting cell wall breakdown and releasing organic matter in the cell fluid, which is beneficial to killing bacteria and viral microorganisms in medical sludge. The released organic matter can be used as a carbon source for sewage treatment. On this basis, the present invention cleverly utilizes the high concentration of HO• generated by system enhancement, which then reacts with hypochlorite ions with high selectivity and rapidity to generate ClO•. ClO• selectively oxidizes ammonia nitrogen and organic amine nitrogen in organic matter into nitrogen gas, converting the released organic matter into a high-efficiency carbon source with low nitrogen content. Compared with other denitrification methods, the denitrification of ammonia nitrogen and organic amine nitrogen by ClO• has good selectivity, fast denitrification rate, is not interfered by strong oxidizing species such as HO• (which can effectively avoid the formation of nitrate nitrogen), and has low toxic by-products, thereby obtaining a high-quality low-nitrogen carbon source for medical wastewater treatment. In addition, the local high temperature and high pressure generated when the cavitation bubbles collapse, as well as the strong oxidizing effect of HO•, can also cleverly convert the Cl• already existing in the system into nitrogen. -Oxidized to Cl·, Cl· can also participate in the cyclic denitrification of ammonia nitrogen and organic amine nitrogen, achieving efficient denitrification and thus reducing the amount of sodium hypochlorite added. By controlling weakly alkaline conditions and employing a short initial hydrolysis process, the present invention not only removes polymers from the cell wall surface, but also prevents the emulsification of extracellular polymers and the subsequent broken cell walls and cell fluid to form an emulsion. Furthermore, the reaction time of the hydrodynamic cavitation-ozone-sodium hypochlorite reaction is strictly controlled to avoid severe emulsification under weakly alkaline conditions. These measures avoid the problem of large amounts of foam generated during the aeration process, and thus avoid the difficulty of subsequent solid-liquid separation.

[0036] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.

Claims

1. A method for in-situ safe disposal of medical sludge and conversion into carbon sources, characterized in that: By controlling the pH range and hydrolysis time of medical sludge, the extracellular polymers of the sludge undergo directional alkaline hydrolysis to expose the outer cell wall; then, hydraulic cavitation is started, ozone is introduced, sodium hypochlorite is added and the reaction is stirred. The strong oxidizing capacity HO• released by the hydrodynamic cavitation ozone is used to oxidize the medical sludge cell wall, break the cell wall and lyse the cells to release the dissolved organic matter in the cells. The ClO• generated by the reaction of HO• and sodium hypochlorite is used to oxidize the ammonia nitrogen and organic amine nitrogen in the dissolved organic matter released by the sludge into nitrogen gas; after the reaction is completed, the solid and liquid are separated, the liquid phase is used as the carbon source for medical wastewater treatment, and the solid phase is returned to the biochemical pool to achieve the safe in-situ disposal and complete resource utilization of the medical sludge.

2. The method for in-situ safe disposal of medical sludge and conversion into carbon sources according to claim 1, characterized in that: The controlling of the pH range and the hydrolysis time of the medical sludge refers to: adding alkali and stirring to adjust the pH value to 9.0-10.

0.

3. The method for in-situ safe disposal of medical sludge and conversion into carbon source according to claim 1 or 2, characterized in that: The hydrolysis time is 1 to 3 minutes, and the stirring speed is 3000 revolutions per minute.

4. The method for in-situ safe disposal of medical sludge and conversion into carbon sources according to claim 1, characterized in that: The hydraulic cavitation is started at a cavitation speed of 2800-3500 rpm.

5. The method for in-situ safe disposal of medical sludge and conversion into carbon source according to claim 1, characterized in that: The ozone is introduced at a flow rate of 1-3 mgO3 / min per liter of wet sludge.

6. The method for in-situ safe disposal of medical sludge and conversion into carbon sources according to claim 1, characterized in that: The dosage of the sodium hypochlorite is 100-1000 mg / L.

7. The method for in-situ safe disposal of medical sludge and conversion into carbon source according to any one of claims 1, 4-6, characterized in that: The stirring reaction has a reaction time of 15 to 25 minutes.

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