A method for combined purification of mine wastewater and excess sludge

Abstract

The present application relates to the technical field of combined purification of pollutants, and in particular to a method for combined purification of mine wastewater and residual sludge, taking into account both economic and environmental benefits, combining the technical idea of ​​"treating waste with waste", linking the coordinated treatment of acid mine wastewater and residual sludge, not only improving the biodegradability of acid mine wastewater, but also achieving the stabilization, reduction and harmlessness of sludge; at the same time, from simple standard discharge, to the recovery of metals, phosphorus and sulfur, reuse of digestate and methane cogeneration and other resource regeneration directions, to achieve "waste" resource utilization; in addition, the acid mine wastewater treatment and residual sludge disposal processes are optimized, and heavy metals and phosphorus are removed in the pre-process of anaerobic ammonia oxidation and the pH of the wastewater is adjusted to weak alkalinity, thereby overcoming the problem that traditional microbial treatment technology has poor treatment effect on acid mine wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of combined purification of pollutants, in particular to a method for combined purification of mine wastewater and surplus sludge. Background Art

[0002] Acid mine drainage treatment technologies include physical and chemical methods and microbial methods. Among them, the physical and chemical methods mainly include ion exchange, membrane separation, adsorption, neutralization precipitation, etc. Their disadvantages are lengthy processes, high economic costs, poor treatment efficiency, and secondary pollution. The microbial methods mainly include microbial methods and artificial wetland methods, which are mainly limited by slow microbial growth, poor tolerance to metal ions, and unstable treatment effects. At the same time, urban sewage treatment plants produce a large amount of residual sludge, and the sludge treatment process is cumbersome and incurs additional costs.

[0003] In the prior art, acid mine drainage and excess sludge are treated relatively independently, resulting in high purification costs for acid mine drainage and excess sludge. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for jointly purifying mine wastewater and excess sludge.

[0005] In a first aspect, an embodiment of the present invention provides a method for jointly purifying mine wastewater and excess sludge, the method comprising:

[0006] The acid mine wastewater and the residual sludge in the urban sewage treatment system are passed into the acidification tank for acidification treatment to obtain acidified sludge, and further dehydrated to obtain acidified dehydrated sludge;

[0007] The acidified sludge dewatering liquid is transported to a sedimentation tank, and the acidified dewatered sludge is transported to a thermal hydrolyzer for thermal hydrolysis treatment;

[0008] The thermal hydrolysis liquid is transported to a sedimentation tank, and the sludge after the thermal hydrolysis treatment is transported to a digestion tank for anaerobic digestion treatment to obtain digested sludge and digestion gas;

[0009] The digested sludge dehydrated liquid is transported to the sedimentation tank, and the digestion gas is transported to the energy conversion unit to provide energy for the urban sewage treatment system and the thermal hydrolyzer after energy conversion;

[0010] The sediment in the sedimentation tank is dried and stored, and the tail water of the sedimentation tank is transported to the anaerobic ammonium oxidation reactor in the urban sewage treatment system to undergo sulfate-type anaerobic ammonium oxidation reaction to deeply treat the tail water and recover sulfur.

[0011] In combination with the first aspect, the steps of passing the acid mine wastewater and the residual sludge in the urban sewage treatment system into an acidification tank for acidification treatment to obtain acidified sludge, and further dehydrating to obtain acidified dehydrated sludge include:

[0012] The acid mine wastewater and the residual sludge in the urban sewage treatment system are introduced into the acidification tank for mixed acidification;

[0013] Determine whether the phosphorus release rate in the acidification pond has reached an inflection point;

[0014] If so, the mixture of acid mine wastewater and excess sludge in the municipal sewage treatment system is dehydrated to 80%-85% moisture content to obtain acidified dehydrated sludge.

[0015] In combination with the first aspect, the step of conveying the acidified dewatered sludge to a thermal hydrolyzer for thermal hydrolysis treatment comprises:

[0016] The acidified dewatered sludge is subjected to high temperature thermal hydrolysis treatment at a temperature of 150-170°C and a pressure of 0.5-0.8MPa to obtain thermal hydrolysis liquid and thermal hydrolysis sludge;

[0017] The thermal hydrolysis liquid is transported to a sedimentation tank, and the thermal hydrolysis sludge is diluted and cooled to obtain thermal hydrolysis treated sludge having a moisture content of 90%-95% and a temperature of 50°C-55°C.

[0018] In combination with the first aspect, the step of transporting the sludge after the thermal hydrolysis treatment to a digestion tank for anaerobic digestion treatment to obtain digested sludge and digestion gas includes:

[0019] The digestion treatment lasts for 15-18 days at a temperature of 35℃-40℃, a pH of 6.8-7.5 and a sludge dosing rate of 5%-12%.

[0020] In combination with the first aspect, the step of transporting the digestion gas to the energy conversion unit for energy conversion to provide energy for the urban sewage treatment system and the thermal hydrolyzer includes:

[0021] The digestion gas is transported to an activated carbon purification unit to obtain methane gas with a content of 60%-70%;

[0022] transporting methane gas to a methane storage tank;

[0023] The methane gas in the methane storage tank is transported to the cogeneration device to convert it into electrical energy and thermal energy;

[0024] The electrical and thermal energy is delivered to the mainstream and sidestream sewage treatment units and thermal hydrolyzers in the municipal sewage treatment system.

[0025] In combination with the first aspect, the tail water of the sedimentation tank is transported to the anaerobic ammonium oxidation reactor in the urban sewage treatment system to undergo a sulfate-type anaerobic ammonium oxidation reaction to deeply treat the tail water and recover sulfur, including:

[0026] The tail water is transported to the anaerobic ammonium oxidation reactor to undergo a sulfate-type anaerobic ammonium oxidation reaction, thereby obtaining a qualified effluent and a mixture of anaerobic ammonium oxidation sludge and elemental sulfur;

[0027] The mixture of anaerobic ammonium oxidation sludge and elemental sulfur is separated by a cyclone separator to obtain elemental sulfur;

[0028] The sulfur element is transported to the dryer for drying and then stored.

[0029] In combination with the first aspect, the step of conveying the tail water to the anaerobic ammonium oxidation reactor to undergo a sulfate-type anaerobic ammonium oxidation reaction further includes:

[0030] The simultaneous removal of ammonia nitrogen and sulfate is carried out under the conditions of pH range of 7.0-8.5, temperature of 25℃-37℃, molar ratio of ammonia nitrogen and sulfate of 1:1 - 3:1, and ORP of -300mV to -150mV.

[0031] In combination with the first aspect, the sedimentation tank is also connected to a sodium sulfide storage tank, and the sodium sulfide storage tank and the digestion tank are respectively connected to the control mechanism; the method further comprises:

[0032] The sodium sulfide in the sodium sulfide storage tank and the dehydrated liquid of the digester tank are added to the sedimentation tank in sequence to gradually remove the target metal ions and phosphorus to obtain a precipitate.

[0033] In combination with the first aspect, the step of successively adding the sodium sulfide in the sodium sulfide storage tank and the digested sludge dehydrated liquid in the digestion tank to the sedimentation tank comprises:

[0034] Sodium sulfide is added to the sedimentation tank until the precipitation of the precipitate does not increase, and the precipitate is transported to the dryer for drying and storage;

[0035] Add digested sludge dehydrated liquid to the sedimentation tank until the pH is 3, add sodium sulfide until the precipitation of precipitate does not increase, and transport the precipitate to the dryer for drying and storage;

[0036] Add digested sludge dehydrated liquid to the sedimentation tank again to pH=5-5.5, continue to add sodium sulfide until the precipitation of precipitate does not increase, and transport the precipitate to the dryer for drying and storage;

[0037] Add digested sludge dehydrated liquid to the sedimentation tank again to pH = 6-8, until the precipitation of precipitate stops increasing, and transport the precipitate to the dryer for drying and storage.

[0038] In combination with the first aspect, after the step of adding digested sludge dehydrated liquid to the sedimentation tank again to a pH of 6-8 until the precipitation of precipitate does not increase, and transporting the precipitate to the dryer for drying and storage, the method further includes:

[0039] Add digested sludge dehydrated liquid to the sedimentation tank again to pH = 8.5-10, until the precipitation of precipitate does not increase, and transport the precipitate to the dryer for drying and storage.

[0040] The embodiments of the present invention bring the following beneficial effects: the method for jointly purifying mine wastewater and excess sludge provided in the present application comprises: passing acid mine wastewater and excess sludge in a municipal sewage treatment system into an acidification tank for acidification treatment to obtain acidified sludge, and further dehydrating to obtain acidified dehydrated sludge; conveying the acidified sludge dehydrated liquid to a sedimentation tank, and conveying the acidified dehydrated sludge to a thermal hydrolyzer for thermal hydrolysis treatment; conveying the thermal hydrolysis liquid to a sedimentation tank, and conveying the thermally hydrolyzed sludge to a digestion tank for anaerobic digestion treatment to obtain digested sludge and digestion gas; conveying the digested sludge dehydrated liquid to a sedimentation tank, and conveying the digestion gas to an energy conversion unit to provide energy for the municipal sewage treatment system and the thermal hydrolyzer after energy conversion; drying and storing the precipitate in the sedimentation tank, and conveying the tail water of the sedimentation tank to an anaerobic ammonia oxidation reactor in the municipal sewage treatment system to cause a sulfate-type anaerobic ammonia oxidation reaction to deeply treat the tail water and recover elemental sulfur.

[0041] The present invention takes into account both economic and environmental benefits, combines the technical idea of ​​"treating waste with waste", and links the coordinated treatment of acid mine wastewater and residual sludge, which not only improves the biodegradability of acid mine wastewater, but also realizes the stabilization, reduction and harmlessness of sludge; at the same time, it develops from simple standard discharge to resource regeneration such as metal, phosphorus and sulfur recovery, digested sludge dehydration liquid reuse and methane cogeneration, so as to realize the resource utilization of "waste"; in addition, it optimizes the acid mine wastewater treatment and residual sludge disposal processes, removes heavy metals and phosphorus in the pre-process of anaerobic ammonia oxidation and adjusts the pH of wastewater to weak alkalinity, thereby overcoming the problem that traditional microbial treatment technology has poor treatment effect on acid mine wastewater.

[0042] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 A flow chart of a method for jointly purifying mine wastewater and excess sludge provided in an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of the principle of combined purification of mine wastewater and excess sludge provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0048] To facilitate understanding of this embodiment, the application scenarios and design concepts of the embodiments of the present application are briefly introduced below.

[0049] Acid mine drainage treatment technologies include physical and chemical methods and microbial methods, both of which have poor treatment effects. Urban sewage treatment systems produce a large amount of excess sludge, and the sludge treatment process is cumbersome and incurs additional costs. In the existing technology, excess sludge treatment and acid mine drainage treatment are relatively independent, resulting in high actual purification treatment costs.

[0050] Based on this, an embodiment of the present application provides a method for jointly purifying mine wastewater and residual sludge.

[0051] Example 1

[0052] The present application provides a method for jointly purifying mine wastewater and excess sludge, combining Figure 1 As shown, the method includes:

[0053] S110, acid mine wastewater and residual sludge in the urban sewage treatment system are introduced into an acidification tank for acidification treatment to obtain acidified sludge, and further dehydrated to obtain acidified dehydrated sludge.

[0054] S120, the acidified sludge dewatering liquid is transported to a sedimentation tank, and the acidified dewatered sludge is transported to a thermal hydrolyzer for thermal hydrolysis treatment.

[0055] S130, the thermal hydrolysis liquid is transported to a sedimentation tank, and the sludge after the thermal hydrolysis treatment is transported to a digestion tank for anaerobic digestion treatment to obtain digested sludge and digestion gas.

[0056] S140, the digested sludge dehydrated liquid is transported to the sedimentation tank, and the digestion gas is transported to the energy conversion unit to provide energy for the urban sewage treatment system and the thermal hydrolyzer after energy conversion.

[0057] S150, the sediment in the sedimentation tank is dried and stored, and the tail water of the sedimentation tank is transported to the anaerobic ammonium oxidation reactor in the urban sewage treatment system to undergo a sulfate-type anaerobic ammonium oxidation reaction, so as to deeply treat the tail water and recover sulfur.

[0058] In this embodiment, combined with Figure 1 , Figure 2 As shown, the acid mine drainage and the residual sludge are jointly purified, and the waste acid mine drainage is used to acidify the residual sludge, and then the digestion gas is produced after hydrolysis and digestion, and the digestion gas is converted and processed again to provide energy for the urban sewage treatment system. In this way, the combined treatment of acid mine drainage and urban sludge can be achieved, and the technical idea of ​​"using waste to treat waste" can be implemented, which effectively reduces the treatment cost and improves the biodegradability of acid mine drainage. At the same time, the sludge is stabilized, reduced and harmless, and the generated methane gas resources are used for regeneration to realize the resource utilization of "waste".

[0059] In combination with the first aspect, step S110 includes:

[0060] S111, acid mine wastewater and residual sludge in the urban sewage treatment system are introduced into the acidification tank for mixed acidification.

[0061] S112, determining whether the phosphorus release rate in the acidification tank has reached an inflection point.

[0062] If so, execute step S113.

[0063] S113, dehydrating the mixture of acid mine wastewater and excess sludge in the urban sewage treatment system to a moisture content of 80%-85% to obtain acidified dehydrated sludge.

[0064] In this embodiment, the acid mine wastewater and the excess sludge are introduced into the acidification tank, and the excess sludge is acidified by the acid mine wastewater to release the heavy metals and phosphorus in the excess sludge. Therefore, the phosphorus release rate gradually increases during the acidification of the excess sludge, and when the inflection point is reached, the acidified sludge is dehydrated to achieve mud-water separation.

[0065] In combination with the first aspect, in step S120, the acidified dewatered sludge is transported to the thermal hydrolyzer for thermal hydrolysis treatment, specifically including:

[0066] The acidified dewatered sludge is subjected to high-temperature thermal hydrolysis treatment at a temperature of 150-170° C. and a pressure of 0.5-0.8 MPa to obtain thermal hydrolysis liquid and thermal hydrolysis sludge.

[0067] The thermal hydrolysis liquid is transported to a sedimentation tank, and the thermal hydrolysis sludge is diluted and cooled to obtain thermal hydrolysis treated sludge having a moisture content of 90%-95% and a temperature of 50°C-55°C.

[0068] The special environment of high temperature and high pressure is used to break the organic molecules in the sludge, further release organic phosphorus, and improve the volume utilization rate of the anaerobic digester, the degradation rate of organic matter in anaerobic digestion, and the gas production. The thermal hydrolysis process can also remove harmful substances in the sludge and recycle the nutrients in the sludge.

[0069] In combination with the first aspect, in step S130, the sludge after the thermal hydrolysis treatment is transported to the digestion tank for anaerobic digestion treatment to obtain the digested sludge and digestion gas, which specifically includes:

[0070] The digestion treatment lasts for 15-18 days at a temperature of 35℃-40℃, a pH of 6.8-7.5 and a sludge dosing rate of 5%-12%.

[0071] In this embodiment, the main functions of anaerobic digestion are: converting organic matter in sludge into biogas, improving the dewatering performance of sludge, reducing the volume of sludge, and methanogenic bacteria deoxygenating acetic acid and acetate to produce methane, and also converting CO 2 and H 2 Converted into methane.

[0072] In combination with the first aspect, in step S140, the digestion gas is transported to the energy conversion unit to provide energy for the urban sewage treatment system and the thermal hydrolyzer after energy conversion, which specifically includes:

[0073] The digestion gas is transported to an activated carbon purification unit to obtain methane gas with a content of 60%-70%.

[0074] The methane gas is transported to the methane storage tank.

[0075] The methane gas in the methane storage tank is transported to the cogeneration device and converted into electrical energy and thermal energy.

[0076] The electrical and thermal energy is delivered to the mainstream and sidestream sewage treatment units in the municipal sewage treatment system; it is also delivered to the thermal hydrolyzer.

[0077] After methane gas is obtained through digestion in step S130, the methane gas (i.e., biogas) is first purified and stored, and then energy conversion is performed using methane as a raw material to generate electricity and heat. 2 The S content is high, and the subsequent biogas desulfurization operation cost is high. However, due to the acidification of acid mine wastewater, iron ions will be mixed into the sludge, and iron ions can effectively inhibit H 2 Therefore, the present invention can reduce H in biogas without setting up an iron salt dosing system in the heat exchange workshop. 2 S content, with significant advantages.

[0078] In combination with the first aspect, S150 includes:

[0079] S151, the tail water is transported to the anaerobic ammonium oxidation reactor to undergo a sulfate-type anaerobic ammonium oxidation reaction to obtain qualified effluent and a mixture of anaerobic ammonium oxidation sludge and elemental sulfur.

[0080] S152, separating the mixture of anaerobic ammonium oxidation sludge and elemental sulfur through a cyclone separator to obtain elemental sulfur.

[0081] S153, transporting the sulfur element to a dryer for drying and then storing.

[0082] Traditional anaerobic ammonium oxidation refers to a biological reaction that generates nitrogen and nitrate under anoxic conditions with ammonia as an electron donor and nitrite as an electron acceptor. This process is catalyzed by a unique type of obligate anaerobic autotrophic bacteria called "anaerobic ammonium oxidizing bacteria". It does not require an external organic carbon source as an electron donor, nor does it require aeration. It can efficiently denitrify sewage with low operating costs. It is currently the most economical and sustainable biological denitrification process. The research team found that anaerobic ammonium oxidizing bacteria have diverse metabolic pathways. Among them, the sulfate-type anaerobic ammonium oxidation reaction is a biological reaction in which anaerobic ammonium oxidizing bacteria use ammonia as an electron donor and sulfate as an electron acceptor, and its reaction products are nitrogen and sulfur. After the tail water of the sedimentation tank is transported to the anaerobic ammonium oxidation reactor, the sulfate-type anaerobic ammonium oxidation reaction occurs. After the mixture is separated by a cyclone separator, the anaerobic ammonium oxidation granular sludge returns to the anaerobic ammonium oxidation reactor, and the sulfur is dried in the dryer and sent to the storage room for storage.

[0083] In combination with the first aspect, ammonia nitrogen and sulfate are removed simultaneously under the conditions of a pH range of 7.0-8.5, a temperature of 25°C-37°C, a molar ratio of ammonia nitrogen to sulfate of 1:1 - 3:1, and an ORP of -300mV to -150mV.

[0084] Under the above conditions, anaerobic ammonium oxidizing bacteria can undergo sulfate-type anaerobic ammonium oxidation reactions, converting sulfate into elemental sulfur, achieving sulfur recovery and avoiding harmful sulfide emissions.

[0085] In combination with the first aspect, the sedimentation tank is also connected to a sodium sulfide storage tank, and the sodium sulfide storage tank and the digestion tank are respectively connected to the control mechanism; the method further comprises:

[0086] The sodium sulfide storage tank and the digestion tank are controlled to add sodium sulfide and digested sludge dewatering liquid in succession, so as to gradually remove the target metal ions and phosphorus to obtain precipitate.

[0087] After the acidified sludge dehydrated liquid is transported to the sedimentation tank or the thermal hydrolysis liquid is transported to the sedimentation tank, the digested sludge dehydrated liquid and sodium sulfide are added in batches to gradually precipitate the target pollutants.

[0088] The specific method of controlling the sodium sulfide storage tank and the digestion tank to add sodium sulfide and digested sludge dehydrated liquid successively includes:

[0089] First, add sodium sulfide to the sedimentation tank until the precipitation does not increase, discharge the sediment to the dryer for drying and storage; add digested sludge dehydrated liquid to the sedimentation tank to pH = 3, then add sodium sulfide until the precipitation does not increase, discharge the sediment to the dryer for drying and storage; add digested sludge dehydrated liquid to the sedimentation tank to pH = 5-5.5, then add sodium sulfide until the precipitation does not increase, discharge the sediment to the dryer for drying and storage (so far, heavy metals are basically precipitated in the form of sulfides); add digested sludge dehydrated liquid to the sedimentation tank to pH = 6-8, until the precipitation does not increase, discharge the sediment to the dryer for drying and storage (so far, FeP is basically precipitated, and the recovery rate can reach 95%). Add digested sludge dehydrated liquid to the sedimentation tank to pH = 8.5-10, until the precipitation does not increase, and discharge the sediment (at this time, ferrous hydroxide is basically precipitated).

[0090] Obviously, by optimizing the acid mine drainage treatment and residual sludge disposal process, removing heavy metals and phosphorus and adjusting the wastewater pH to weak alkalinity in the precursor process of anaerobic ammonia oxidation reaction, the problem of poor treatment effect of traditional microbial treatment technology on acid mine drainage can be overcome.

[0091] In combination with the first aspect, digested sludge dehydrated liquid is added to the sedimentation tank again to a pH of 6-8, until the precipitation of precipitate does not increase, FeP can be precipitated, and the precipitate is transported to the dryer for drying and then stored, and the stored precipitate (i.e., FeP) is also placed in the surrounding farmland.

[0092] FeP powder is soluble in water and can slowly release elements such as phosphorus and iron in the soil, which is beneficial to plant growth. It is widely used in agricultural production and can improve the yield and quality of crops.

[0093] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0094] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0095] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0096] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0097] Finally, it should be noted that the above embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for combined purification of mine wastewater and excess sludge, characterized in that: The method comprises: The acid mine wastewater and the residual sludge in the urban sewage treatment system are passed into the acidification tank for acidification treatment to obtain acidified sludge, and further dehydrated to obtain acidified dehydrated sludge; The acidified sludge dewatering liquid is transported to a sedimentation tank, and the acidified dewatered sludge is transported to a thermal hydrolyzer for thermal hydrolysis treatment; The thermal hydrolysis liquid is transported to the sedimentation tank, and the sludge after the thermal hydrolysis treatment is transported to the digestion tank for anaerobic digestion treatment to obtain digested sludge and digestion gas; The digested sludge dehydrated liquid is transported to the sedimentation tank, which is also connected to a sodium sulfide storage tank, and the sodium sulfide storage tank and the digestion tank are respectively connected to a control mechanism; the sodium sulfide in the sodium sulfide storage tank and the digested sludge dehydrated liquid in the digestion tank are successively added to the sedimentation tank to gradually remove target metal ions and phosphorus to obtain a precipitate, and the digestion gas is transported to an energy conversion unit to perform energy conversion to provide energy for the urban sewage treatment system and the thermal hydrolyzer; The sediment in the sedimentation tank is dried and stored, and the tail water in the sedimentation tank is transported to the anaerobic ammonium oxidation reactor in the urban sewage treatment system to undergo a sulfate-type anaerobic ammonium oxidation reaction, so as to deeply treat the tail water and recover sulfur.

2. The method according to claim 1, characterized in that: The steps of introducing the acid mine wastewater and the residual sludge in the urban sewage treatment system into an acidification tank for acidification treatment to obtain acidified sludge, and further dehydrating to obtain acidified dehydrated sludge include: Passing the acid mine wastewater and the residual sludge in the urban sewage treatment system into the acidification tank for mixed acidification; Determining whether the phosphorus release rate in the acidification pool has reached an inflection point; If so, the mixture of the acid mine wastewater and the excess sludge in the urban sewage treatment system is dehydrated to a moisture content of 80%-85% to obtain acidified dehydrated sludge.

3. The method according to claim 1, characterized in that: The step of conveying the acidified dewatered sludge to a thermal hydrolyzer for thermal hydrolysis treatment comprises: The acidified dehydrated sludge is subjected to high temperature thermal hydrolysis treatment at a temperature of 150-170° C. and a pressure of 0.5-0.8 MPa to obtain thermal hydrolysis liquid and thermal hydrolysis sludge; The thermal hydrolysis liquid is transported to the sedimentation tank, and the thermal hydrolysis sludge is diluted and cooled to obtain thermal hydrolysis treated sludge with a moisture content of 90%-95% and a temperature of 50°C-55°C.

4. The method according to claim 1, characterized in that: The step of transporting the sludge after the thermal hydrolysis treatment to a digestion tank for anaerobic digestion treatment to obtain digested sludge and digestion gas includes: The digestion treatment lasts for 15-18 days at a temperature of 35℃-40℃, a pH of 6.8-7.5 and a sludge dosing rate of 5%-12%.

5. The method according to claim 1, characterized in that The step of delivering the digestion gas to an energy conversion unit for energy conversion to provide energy for the urban sewage treatment system and the thermal hydrolyzer comprises: The digestion gas is transported to an activated carbon purification device to obtain a methane gas with a content of 60%-70%; transporting the methane gas to a methane storage tank; The methane gas in the methane storage tank is transported to a cogeneration device to convert it into electrical energy and thermal energy; The electrical energy and thermal energy are transmitted to the mainstream sewage treatment unit and the side stream sewage treatment unit in the urban sewage treatment system and the thermal hydrolyzer.

6. The method according to claim 1, characterized in that The tail water of the sedimentation tank is transported to the anaerobic ammonium oxidation reactor in the urban sewage treatment system to undergo a sulfate-type anaerobic ammonium oxidation reaction, so as to deeply treat the tail water and recover sulfur, comprising: The tail water is transported to the anaerobic ammonium oxidation reactor to undergo a sulfate-type anaerobic ammonium oxidation reaction to obtain qualified effluent and a mixture of anaerobic ammonium oxidation sludge and elemental sulfur; Separating the mixture of the anaerobic ammonium oxidation sludge and elemental sulfur through a cyclone separator to obtain elemental sulfur; The sulfur element is transported to a dryer for drying and then stored.

7. The method according to claim 6, characterized in that The step of conveying the tail water to the anaerobic ammonium oxidation reactor to undergo sulfate-type anaerobic ammonium oxidation reaction also includes: The simultaneous removal of ammonia nitrogen and sulfate is carried out under the conditions of pH range of 7.0-8.5, temperature of 25℃-37℃, molar ratio of ammonia nitrogen and sulfate of 1:1 - 3:1, and ORP of -300mV to -150mV.

8. The method according to claim 1, characterized in that The step of successively adding the sodium sulfide in the sodium sulfide storage tank and the digested sludge dehydrated liquid in the digestion tank to the sedimentation tank comprises: Adding the sodium sulfide into the sedimentation tank until the precipitation of the precipitate does not increase, and conveying the precipitate to a dryer for drying and then storing; Adding the digested sludge dehydrated liquid to the sedimentation tank until the pH is 3, adding the sodium sulfide until the precipitation of the precipitate does not increase, and conveying the precipitate to the dryer for drying and storage; Adding the digested sludge dehydrated liquid to the sedimentation tank again until the pH value is 5-5.5, continuing to add the sodium sulfide until the precipitation of the precipitate does not increase, and conveying the precipitate to the dryer for drying and storage; The digested sludge dehydrated liquid is added to the sedimentation tank again to a pH of 6-8 until the precipitation of precipitates does not increase, and the precipitates are transported to the dryer for drying and storage.

9. The method according to claim 8, characterized in that The digested sludge dehydrated liquid is added to the sedimentation tank again to a pH of 6-8 until the precipitation of the precipitate does not increase, and the precipitate is transported to the dryer for drying and storage, and the step further includes: The digested sludge dehydrated liquid is added to the sedimentation tank again to a pH of 8.5-10 until the precipitation of precipitate does not increase, and the precipitate is transported to the dryer for drying and then stored.

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