Biochemical treatment optimization process suitable for high-calcium and high-concentration wastewater

Abstract

The invention discloses a biochemical treatment optimization process suitable for high-calcium and high-concentration wastewater. The process comprises the following steps: S1, mixing high-calcium wastewater with return sludge, and adding chemicals for coagulation; s2, carrying out solid-liquid separation to remove suspended particles; s3, mixing and tempering primary precipitation effluent and part of secondary precipitation effluent; s4, the diluted sludge enters an IC reactor, organic matter is degraded, and calcified sludge is settled; s5, carrying out cyclone separation on heavy calcified sludge at the bottom of the IC anaerobic reactor, and refluxing activated sludge; s6, carrying out aerobic treatment on effluent of the IC anaerobic reactor, and carrying out desanding and refluxing on returned sludge; and S7, performing mud-water separation, partially refluxing the sludge, and discharging residual sludge and standard water. According to the method, two-stage rotational flow physical calcium removal is adopted, and light sludge is refluxed and kept alive; secondary precipitation effluent and IC external circulation double dilution are performed, and concentration reduction and toxicity inhibition are performed instantaneously; the sludge quickly flows back to supplement the quantity and is self-recovered under the impact load. The whole process is free of softening agents, chemical sludge and unpicking and washing, and high-calcium and high-concentration wastewater runs efficiently, low in consumption and stable for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial wastewater treatment, and in particular to an optimized process for biochemical treatment of high-calcium and high-concentration wastewater. Background Art

[0002] In the treatment of high calcium and high concentration wastewater discharged from chemical, pharmaceutical, printing and dyeing, papermaking and other industries, Ca 2+ The concentration is usually over 500 mg / L, and COD (chemical oxygen demand) is often higher than 5000 mg / L. In existing technologies, if this type of wastewater is directly treated with conventional "anaerobic-aerobic" biochemical processes, it will face the following technical bottlenecks: Anaerobic sludge calcification: high concentration of Ca 2+ With CO3 2- 、SO4 2- PO4 3- The reaction generates precipitates such as CaCO3, CaSO4, and Ca3(PO4)2, which coat and block the surface and pores of the granular sludge, resulting in a sudden drop in VSS / TSS, obstructed mass transfer, and exhaustion of methanogenesis activity. At the same time, the sludge density increases and fluidization becomes difficult, eventually forming dead zones and sedimentation, requiring frequent sludge replenishment.

[0003] Low aerobic sludge activity: Calcified particles also wrap aerobic activated sludge, and VSS / TSS can drop to about 20%. Even if high TSS operation is maintained, the COD removal rate is still limited; sludge renewal is accelerated, sludge age is shortened, and system stability and denitrification efficiency decrease simultaneously.

[0004] Weak shock resistance: When the influent COD suddenly changes or toxic substances impact instantly, the traditional process lacks effective buffering, which can easily induce anaerobic sludge running, aerobic sludge expansion, large amounts of foam and effluent exceeding the standard. The recovery cycle is long and production continuity is threatened.

[0005] Severe scaling of equipment pipelines: Calcium salts continuously deposit in two-phase or three-phase separators, aeration heads, and pipelines, causing blockages. In actual cases, anaerobic effluent pipelines need to be dismantled and cleaned every 2-3 years, and aerators require dedicated cycle descaling, resulting in frequent maintenance shutdowns and significantly increased operating costs.

[0006] Chemical softening pretreatment is costly: lime, soda ash and other chemicals can be used to temporarily remove calcium, but the cost of chemicals per ton of water is high, making it difficult to sustain long-term use for industrial wastewater of 10,000 m³ / d. Economic feasibility has become a bottleneck for its promotion.

[0007] Based on the fact that traditional biochemical treatment of high-calcium and high-concentration wastewater faces three major problems: sludge calcification and inactivation, equipment scaling and clogging, and weak impact resistance, the cost of chemical softening is high, and an optimized process with no or little drug and continuous operation is urgently needed, an optimized process suitable for the biochemical treatment of high-calcium and high-concentration wastewater is proposed. Summary of the Invention

[0008] The purpose of the present invention is to solve the above problems and to propose an optimized process for biochemical treatment of high-calcium and high-concentration wastewater.

[0009] In order to achieve the above object, the present invention adopts the following technical solution: a process for optimizing the biochemical treatment of high-calcium and high-concentration wastewater, comprising the following steps: S1. High-calcium and high-concentration wastewater and return sludge from the secondary sedimentation tank are introduced into the coagulation reaction tank for mixing, and coagulant is added for coagulation reaction; S2, introducing the mixed liquid obtained in step S1 into a primary sedimentation tank for solid-liquid separation; S3, the effluent from the primary sedimentation tank and part of the effluent from the secondary sedimentation tank are introduced into the regulating tank for mixing to adjust the water quality and quantity; S4, mixing and diluting the effluent from the regulating tank and the effluent from the external circulation of the IC anaerobic reactor, and introducing the mixture into the IC anaerobic reactor for anaerobic treatment; S5. The heavy calcified granular sludge discharged from the bottom of the IC anaerobic reactor is discharged into the anaerobic sludge storage tank, and then transported to the anaerobic sludge decalcifier through the anaerobic sludge pump for cyclone classification, and the light activated sludge is returned to the IC anaerobic reactor; S6. The effluent from the IC anaerobic reactor is introduced into the biochemical reaction tank for aerobic treatment. The sludge returned from the secondary sedimentation tank is separated by cyclone flow in the aerobic sludge desander for calcification and then returned to the biochemical reaction tank. S7. The effluent from the biochemical reaction tank is introduced into the secondary sedimentation tank for mud-water separation. Part of the resulting sludge is returned to the coagulation reaction tank and the biochemical reaction tank, and part of the effluent is returned to the regulating tank. The remaining sludge and qualified effluent are discharged from the system separately.

[0010] Preferably, NaOH is added to the regulating tank to adjust the pH, and urea and phosphate solution are added to supplement the N and P nutrients; when the inlet water temperature is higher than the set value, the inlet water is cooled by a cooling tower installed on the regulating tank. Preferably, an inverted cone hopper cyclone water distribution system is provided at the bottom of the IC anaerobic reactor, and the inverted cone hopper cyclone water distribution system includes an inverted cone sludge collecting hopper and a cyclone water distribution pipeline. The cyclone water distribution pipeline is provided with multiple layers of straight water distribution pipelines at different heights along the inverted cone sludge collecting hopper. Each of the straight water distribution pipelines forms a certain angle with the radial direction of the IC anaerobic reactor and is inclined in the same direction. A flushing valve is provided at the outer end of the straight water distribution pipeline.

[0011] Preferably, a forced external circulation system is provided outside the IC anaerobic reactor, the forced external circulation system comprises an external circulation riser and an external circulation water pump, and an antiscalant dosing system is provided at the inlet pipe of the external circulation water pump.

[0012] Preferably, the anaerobic sludge decalcifier includes a straight cylinder section 1, a cone bucket section 1 and a washing and water distribution pipe distributed from top to bottom. The cone bucket section is provided with a mud inlet in a tangential direction, and a slag discharge port is provided at the bottom of the cone bucket section 1. The separation of heavy calcified granular sludge and light activated sludge is achieved through cyclone classification.

[0013] Preferably, a cyclone aerator is provided in the biochemical reaction tank for aeration and oxygen supply, and an aerobic sludge desander is provided on the return sludge pipeline of the biochemical reaction tank. The aerobic sludge desander comprises a second straight cylinder section, a second cone bucket section and a sand collecting tank, and separates calcifications by cyclone.

[0014] Preferably, part of the effluent from the secondary sedimentation tank is returned to the equalization tank through the secondary sedimentation effluent return pump to dilute the inlet water, part of the sludge is returned to the coagulation reaction tank through the secondary sedimentation sludge return pump 2 to enhance flocculation, and another part of the sludge is returned to the biochemical reaction tank through the secondary sedimentation sludge return pump 1, and the remaining sludge and qualified effluent are discharged by the remaining secondary sedimentation sludge discharge pump.

[0015] Preferably, the coagulant includes polyaluminium chloride and polyacrylamide, and the scale inhibitor is an organic phosphonate scale inhibitor.

[0016] Preferably, the biochemical reaction tank is composed of an anaerobic tank, an anoxic tank and an aerobic tank. A stirrer is provided in the anaerobic tank and the anoxic tank, and oxygen in the aerobic tank is supplied by an aeration fan of the aerobic tank.

[0017] Preferably, the aerobic tank returns the nitrified liquid to the anoxic tank through a mixed liquid reflux pump for denitrification.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In this application, a cyclone classifier is set at the anaerobic end to immediately peel off and discharge the calcified and dense granular sludge, and the light activated sludge is returned to continue working; the light sludge whose surface is not covered by sediment has continuously open pores, and the mass transfer and methane production activities can be maintained for a long time, and the system biomass can be maintained without frequent sludge replenishment.

[0019] 2. In this application, the cyclone aerator has a shear cleaning function, which can slow down the calcification and blockage of the aerator during operation; the inorganic components such as calcium slag in the sludge are discharged through the desander, the sludge VSS / TSS no longer drops sharply, the sludge age is stable, and the COD removal, denitrification and phosphorus removal efficiencies are simultaneously restored and maintained at a high level.

[0020] 3. In this application, the regulating tank is first diluted with the effluent from the secondary sedimentation tank, and the IC reactor is then diluted for the second time with a high-multiple external circulation to instantaneously reduce the calcium concentration and toxicity peak. At the same time, the activated sludge from the secondary sedimentation tank can be quickly returned to the coagulation tank and the aerobic tank. When the influent COD or toxic substances suddenly increase, the dilution and sludge feeding are started simultaneously to buffer the shock load, avoid sludge leakage, sludge expansion or effluent exceeding the standard after the deterioration of the traditional system operation, and achieve short-term self-recovery and continuous stable operation.

[0021] 4. In this application, the self-cleaning design of the inverted cone bucket swirl water distribution at the bottom of the IC reactor prevents calcium crystals from depositing in dead corners or on the surface of the aeration head; the flow channel always maintains high-speed shear, and the anaerobic effluent pipe and aerator free pipe removal cycle is greatly extended, reducing the number of maintenance shutdowns.

[0022] 5. In this application, the entire process relies on the physical means of coagulation-cyclone separation-internal reflux for targeted calcium removal, without the need to add softening agents such as lime and soda ash, which not only saves the cost of agents, but also eliminates the burden of secondary disposal of chemical sludge, thereby reducing the economic cost of high-calcium wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the wastewater biochemical treatment optimization process according to the first embodiment of the present invention is shown; Figure 2 It shows a schematic diagram of the wastewater biochemical treatment optimization process according to the second embodiment of the present invention; Figure 3 It shows a schematic elevation view of a water distribution and mud collection system provided according to an embodiment of the present invention; Figure 4 A schematic plan view of a water distribution and sludge collection system according to an embodiment of the present invention is shown; Figure 5 shows a schematic elevation view of an anaerobic sludge storage tank according to an embodiment of the present invention; Figure 6 A schematic elevation view of an anaerobic sludge decalcifier provided in an embodiment of the present invention is shown; Figure 7 A schematic elevation view of an aerobic sludge desander provided according to an embodiment of the present invention is shown.

[0024] Legend: 1. Coagulation tank; 2. Primary sedimentation tank; 3. Equalization tank; 31. Cooling tower; 4. IC anaerobic reactor; 41. Inverted cone bucket swirl water distribution system; 411. Inverted cone sludge collection hopper; 412. Swirl water distribution pipeline; 42. Three-phase separator; 43. Downcomer; 441. External circulation riser; 442. External circulation water pump; 451. Gas-liquid separation tank; 452. Water seal defoamer tank; 521. Straight cylinder section 1; 522. Cone bucket section 1; 523. Washing and selection water distribution pipe; 46. Antiscalant dosing system System; 5. Anaerobic sludge storage tank; 51. Anaerobic sludge pump; 52. Anaerobic sludge decalcifier; 6. Biochemical reaction tank; 61. Mixer; 62. Cyclone aerator; 63. Mixed liquor return pump; 64. Aerobic tank aeration fan; 65. Aerobic sludge desander; 651. Straight cylinder section 2; 652. Cone bucket section 2; 653. Sand collecting trough; 7. Secondary sedimentation tank; 71. Secondary sedimentation sludge discharge pump; 72. Secondary sedimentation sludge return pump 1; 73. Secondary sedimentation sludge return pump 2; 74. Secondary sedimentation effluent return pump. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] Example 1: Please refer to Figure 1-Figure 7 The present invention provides a technical solution: a process for optimizing the biochemical treatment of high-calcium and high-concentration wastewater, comprising the following steps: S1, high calcium and high concentration wastewater and return sludge from secondary sedimentation tank 7 are introduced into coagulation reaction tank 1 for mixing, and coagulant is added for coagulation reaction; S2, introducing the mixed liquid obtained in step S1 into the primary sedimentation tank 2 for solid-liquid separation; S3, the effluent from the primary sedimentation tank 2 and part of the effluent from the secondary sedimentation tank 7 are introduced into the regulating tank 3 for mixing and regulating the water quality and quantity; S4, mixing and diluting the effluent from the regulating tank 3 and the effluent from the external circulation of the IC anaerobic reactor 4, and introducing the mixture into the IC anaerobic reactor 4 for anaerobic treatment; S5. The heavy calcified granular sludge discharged from the bottom of the IC anaerobic reactor 4 is discharged into the anaerobic sludge storage tank 5, and then transported to the anaerobic sludge decalcifier 52 through the anaerobic sludge pump 51 for cyclone classification, and the light activated sludge is returned to the IC anaerobic reactor 4; The effluent from the S6 and IC anaerobic reactors 4 is introduced into the biochemical reaction tank 6 for aerobic treatment. The sludge returned from the secondary sedimentation tank 7 is subjected to cyclone separation of calcified matter in the aerobic sludge desander 65 and then returned to the biochemical reaction tank 6. S7, the effluent from the biochemical reaction tank 6 is introduced into the secondary sedimentation tank 7 for mud-water separation, and part of the resulting sludge is returned to the coagulation reaction tank 1 and the biochemical reaction tank 6, and part of the effluent is returned to the regulating tank 3, and the remaining sludge and qualified effluent are discharged from the system respectively.

[0027] First, a coagulant and returned sludge form flocs in the coagulation tank to capture suspended particles. After initial separation in the primary sedimentation tank 2, the effluent is mixed with the diluted effluent from the secondary sedimentation tank 7 to adjust the water quality. Subsequently, the effluent is diluted through the external circulation of the IC anaerobic reactor 4 to reduce the instantaneous COD and the concentrations of toxic and biochemically sensitive substances. The heavily calcified sludge at the bottom is separated by a cyclone decalcifier and then returned to the light activated sludge to prevent calcification and inactivation. The aerobic tank is equipped with a cyclone aerator 62 and a desander to continuously remove calcified materials. The sludge and water from the secondary sedimentation tank 7 are recycled through multiple paths to separate the calcium salts within the system. Ultimately, chemical softening is not required to maintain sludge activity, prevent equipment scaling, and improve shock resistance.

[0028] The second embodiment is basically the same as the first embodiment, except that: like Figure 1 and Figure 2 As shown, NaOH is added to the regulating tank 3 to adjust the pH, and urea and phosphate solution are added to supplement the N and P nutrients; when the inlet water temperature is higher than the set value, the inlet water is cooled by the cooling tower 31 provided on the regulating tank 3.

[0029] NaOH rapidly raises the acidic pH often associated with high-calcium and high-concentration wastewater, preventing low pH from inhibiting microbial activity. By quantitatively adding urea and phosphate, it provides absorbable nitrogen and phosphorus sources for the subsequent IC anaerobic reactor 4 and aerobic tank, preventing nutritional imbalance caused by high COD. The cooling tower 31 uses water-air heat exchange to cool the inlet water above the set value, maintaining the optimal temperature window for anaerobic and aerobic bacteria.

[0030] The third embodiment is basically the same as the first embodiment, except that: like Figure 1-Figure 4 As shown, an inverted cone hopper swirl water distribution system 41 is provided at the bottom of the IC anaerobic reactor 4. The inverted cone hopper swirl water distribution system 41 includes an inverted cone sludge collecting hopper 411 and a swirl water distribution pipeline 412. The swirl water distribution pipeline 412 is provided with multiple layers of straight water distribution pipelines at different heights along the inverted cone sludge collecting hopper 411. Each straight water distribution pipeline forms a certain angle with the radial direction of the IC anaerobic reactor 4 and is inclined in the same direction. A flushing valve is provided at the outer end of the straight water distribution pipeline.

[0031] Since high-calcium wastewater easily forms a CaCO3 scale layer on the inner wall of the water distribution pipe, the flushing valve is connected to the factory's recycled water or IC outlet water. Timed short flushing can instantly generate a pulsed water flow, peeling off and removing the scale, keeping the water distribution pipe unobstructed.

[0032] The inverted cone angle of the inverted cone bucket swirl water distribution system 41 is about 60 degrees, with three to four layers of water distribution pipes, four to eight DN80 branch pipes on each layer, and a tangential inclination angle of about 30 degrees to 60 degrees.

[0033] Wastewater is injected at high speed through tangential distribution pipes into the inverted cone hopper cyclonic distribution system 41, forming a three-dimensional cyclonic field within the hopper. Heavy calcified particles are thrown toward the walls by centrifugal force and slide along the cone to the bottom for centralized discharge. Light, active particles rise with the central flow back to the reaction zone, achieving immediate separation. All distribution pipes are tilted at the same angle and in the same direction as the reactor's radial direction, generating a spiral upward flow. This not only prolongs the contact time between sludge and water, but also creates a continuous thrust, preventing localized sedimentation and ensuring uniform fluidization of the granular sludge.

[0034] Three to four layers of water distribution outlets are arranged along the height of the inverted cone, simultaneously diluting toxicity, maintaining suspension, and performing cyclonic separation, while achieving three-dimensional water distribution. A flushing valve at the outer end of the water distribution pipe regularly receives recycled water. This pulsed water flow rapidly strips CaCO3 scale from the inner wall, allowing the scale to fall directly into the cone along the cyclonic flow for discharge, achieving online blockage prevention without interrupting production.

[0035] A forced external circulation system is provided outside the IC anaerobic reactor 4 , and the forced external circulation system includes an external circulation riser 441 and an external circulation water pump 442 . An antiscalant dosing system 46 is provided on the inlet pipe of the external circulation water pump 442 .

[0036] The IC anaerobic reactor 4 is an internal circulation anaerobic reactor, comprising a three-phase separator 42 for separating biogas, wastewater, and granular sludge; a gas-liquid separator 451 for further separating wastewater and granular sludge carried by the biogas; a downcomer 43 for returning the wastewater and granular sludge separated in the gas-liquid separator 451 to the reaction zone, forming an internal circulation system; and a water-sealed defoamer 452 for removing foam from the biogas before outputting it to the subsequent biogas treatment system. Coagulants include polyaluminum chloride and polyacrylamide, and the scale inhibitor is an organic phosphonate.

[0037] External circulation pump 442 continuously pumps clarified water from the top of IC anaerobic reactor 4 through external circulation riser 441, where it mixes with water from equalization tank 3 before returning to the reactor bottom. This process instantly reduces the influent COD concentration and peak toxicity, creating "internal dilution" that not only buffers against high-concentration or toxic shocks but also maintains the upward flow velocity, ensuring that the granular sludge remains fluidized and enhances mass transfer.

[0038] An antiscalant dosing system 46 is set at the inlet pipe of the external circulation water pump 442 to continuously inject organic phosphonate antiscalant (such as PBTCA or HEDP). The antiscalant returns to the reactor at high speed along with the circulating water, first reacting with Ca 2+ 、CO3 2- 、SO4 2-The plasma is fully mixed, and the growth of CaCO3 and CaSO4 crystal nuclei is suppressed through lattice distortion and complex solubilization, thereby slowing down the scaling rate of the three-phase separator 42, the downcomer 43 and the inverted cone bucket swirl water distribution system 41, and the reagent utilization rate is high.

[0039] The front-end coagulant is a combination of polyaluminium chloride (PAC) and polyacrylamide (PAM), which can quickly capture SS, part of COD and phosphate in the coagulation reaction tank 1, and reduce the formation of calcium salt matrix (such as PO4 3- ), indirectly reducing the amount of chemical precipitation in the anaerobic zone and reducing the load on the scale inhibitor.

[0040] The circulation volume is regulated by the frequency conversion of the external circulation water pump 442, and is linked to the online monitoring of the inlet COD; the scale inhibitor dosage is controlled by real-time feedback of the circulating water flow and calcium hardness, forming a "load-scaling" double closed loop to ensure long-term stable operation of the process.

[0041] The fourth embodiment is basically the same as the first embodiment, except that: like Figure 1 、 Figure 2 、 Figure 5 、 Figure 6 and Figure 7 As shown, the anaerobic sludge decalcifier 52 includes a straight cylinder section 521, a cone bucket section 522 and a washing and water distribution pipe 523 distributed from top to bottom. The cone bucket section 522 is tangentially provided with a mud inlet, and the bottom of the cone bucket section 522 is provided with a slag discharge port. The separation of heavy calcified granular sludge and light activated sludge is achieved through cyclone classification.

[0042] The sludge that enters the cone bucket section 522 tangentially rotates at high speed in the straight cylinder section 521. The centrifugal force throws the heavy calcified particles with higher density toward the wall of the device and slides down along the cone wall, and is continuously discharged from the bottom slag discharge port; while the light activated sludge with lower density is carried upward to the center by the internal vortex, washed by the upward water flow of the washing and distribution water pipe 523, and then returned to the IC anaerobic reactor 4, realizing the online separation of calcified particles and activated sludge.

[0043] A cyclone aerator 62 is provided in the biochemical reaction tank 6 for aeration and oxygen supply to alleviate calcification and blockage of the aeration system. An aerobic sludge desander 65 is provided on the return sludge pipeline of the biochemical reaction tank 6. The aerobic sludge desander 65 includes a second straight cylinder section 651, a second cone bucket section 652 and a sand collecting trough 653, which separates calcifications through cyclone flow.

[0044] The spirally rising gas-liquid two-phase flow generates a faster shear rate on the surface of the aeration head, which promptly strips off the initial CaCO3 crystal nuclei; the aerator can be lifted out of the water surface as a whole and pulse-flushed with recycled water, which can restore the oxygen mass transfer efficiency without stopping the pool, thus achieving online descaling without stopping production.

[0045] The secondary sedimentation return sludge enters the straight section 651 tangentially, forming a secondary vortex. Calcified matter and gravel, due to their high density, slide along the conical bucket section 652 into the sand collection trough 653 and are discharged regularly. The decalcified activated sludge returns to the aerobic tank.

[0046] The fifth embodiment is basically the same as the first embodiment, except that: like Figure 1 and Figure 2 As shown, part of the effluent from the secondary sedimentation tank 7 is returned to the regulating tank 3 through the secondary sedimentation effluent return pump 74 to dilute the influent, part of the sludge is returned to the coagulation reaction tank 1 through the secondary sedimentation sludge return pump 2 73 to strengthen flocculation, and another part of the sludge is returned to the biochemical reaction tank 6 through the secondary sedimentation sludge return pump 1 72, and the remaining sludge and qualified effluent are discharged by the remaining secondary sedimentation sludge discharge pump 71.

[0047] Secondary sedimentation effluent return pump 74 returns a portion of the effluent to regulating tank 3, instantly reducing raw water COD, toxic concentrations, and temperature fluctuations. This creates a primary buffer, mitigating the load impact on the subsequent IC anaerobic reactor 4 and biochemical reactor 6. Secondary sludge return pump 2 73 returns sludge rich in microflocs and active substances to the coagulation reactor 1. The return sludge utilizes the sludge residue for contact flocculation, improving PAC / PAM utilization. The sludge also adsorbs some toxic organic matter, further reducing the risk of bioinhibition. Secondary sludge return pump 1 72 returns a portion of the activated sludge to the front end of the biochemical reactor 6 to replenish the MLSS and maintain the microbial biomass required for the biochemical reaction. The residual secondary sludge discharge pump 71 continuously discharges excess sludge at a set sludge age, preventing the accumulation of calcified particles and maintaining a constant sludge age in the system, ensuring long-term stable effluent compliance with standards.

[0048] The sixth embodiment is basically the same as the first embodiment, except that: like Figure 1 and Figure 2 As shown, the biochemical reaction tank 6 is composed of an anaerobic tank, an anoxic tank and an aerobic tank. A stirrer 61 is provided in the anaerobic tank and the anoxic tank. Oxygen in the aerobic tank is supplied by an aeration fan 64 of the aerobic tank. The aerobic tank returns the nitrified liquid to the anoxic tank through a mixed liquid reflux pump 63 for denitrification and denitrification.

[0049] Mixer 61 keeps the sludge suspended, allowing the phosphate-accumulating bacteria in the returned sludge to absorb and release phosphorus. It also hydrolyzes recalcitrant organic matter, providing a readily degradable carbon source for subsequent denitrification. In a high-calcium environment, the anaerobic section maintains a low ORP to prevent chemical precipitation of calcium salts from interfering with the phosphate-accumulating bacteria. Mixer 61 ensures thorough mixing of the sludge and water. The mixed liquid return pump 63 introduces the nitrified liquid produced in the aerobic tank into the anoxic tank. Denitrifying bacteria utilize the raw water and carbon source provided by the anaerobic tank to reduce nitrates to nitrogen, achieving denitrification and further reducing COD. Aeration fan 64 in the aerobic tank supplies oxygen through cyclone aerator 62.

[0050] The above description of the embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A biochemical treatment optimization process for high-calcium and high-concentration wastewater, characterized in that: The following steps are involved: S1, introducing high-calcium and high-concentration wastewater and return sludge from the secondary sedimentation tank (7) into the coagulation reaction tank (1) for mixing, and adding coagulant to carry out coagulation reaction; S2, introducing the mixed liquid obtained in step S1 into the primary sedimentation tank (2) for solid-liquid separation; S3, introducing the effluent from the primary sedimentation tank (2) and part of the effluent from the secondary sedimentation tank (7) into the regulating tank (3) for mixing and regulating the water quality and quantity; S4, mixing and diluting the effluent from the regulating tank (3) and the external circulation effluent from the IC anaerobic reactor (4), and introducing the mixed effluent into the IC anaerobic reactor (4) for anaerobic treatment; The heavy calcified granular sludge discharged from the bottom of the S5 and IC anaerobic reactors (4) is discharged into the anaerobic sludge storage tank (5), and then transported to the anaerobic sludge decalcifier (52) through the anaerobic sludge pump (51) for cyclone classification, and the light activated sludge is returned to the IC anaerobic reactor (4); The effluent from the S6 and IC anaerobic reactors (4) is introduced into the biochemical reaction tank (6) for aerobic treatment, and the sludge returned from the secondary sedimentation tank (7) is subjected to cyclone separation of calcified matter in the aerobic sludge desander (65) and then returned to the biochemical reaction tank (6); S7, the effluent from the biochemical reaction tank (6) is introduced into the secondary sedimentation tank (7) for mud-water separation. Part of the sludge is returned to the coagulation reaction tank (1) and the biochemical reaction tank (6), and part of the effluent is returned to the regulating tank (3). The remaining sludge and the effluent that meets the standards are discharged from the system respectively.

2. The process for biochemical treatment of high-calcium and high-concentration wastewater according to claim 1, characterized in that: Adding NaOH into the regulating tank (3) to adjust the pH, and adding urea and phosphate solution to supplement the N and P nutrient elements; When the inlet water temperature is higher than the set value, the inlet water is cooled by a cooling tower (31) provided on the regulating tank (3).

3. The process for biochemical treatment of high-calcium and high-concentration wastewater according to claim 1, characterized in that: An inverted cone hopper cyclone water distribution system (41) is provided at the bottom of the IC anaerobic reactor (4). The inverted cone hopper cyclone water distribution system (41) comprises an inverted cone shaped mud collecting hopper (411) and a cyclone water distribution pipeline (412). The cyclone water distribution pipeline (412) is provided with multiple layers of straight water distribution pipelines at different heights along the inverted cone shaped mud collecting hopper (411). Each straight water distribution pipeline forms a certain angle with the radial direction of the IC anaerobic reactor (4) and is inclined in the same direction. A flushing valve is provided at the outer end of the straight water distribution pipeline.

4. The process for optimizing biochemical treatment of high-calcium and high-concentration wastewater according to claim 3, characterized in that: A forced external circulation system is provided outside the IC anaerobic reactor (4), and the forced external circulation system comprises an external circulation riser (441) and an external circulation water pump (442). An antiscalant dosing system (46) is provided at the inlet pipe of the external circulation water pump (442).

5. The process for biochemical treatment optimization of high-calcium and high-concentration wastewater according to claim 1, characterized in that: The anaerobic sludge decalcifier (52) includes a straight cylinder section (521), a cone bucket section (522) and a washing and water distribution pipe (523) distributed from top to bottom. The cone bucket section (522) is tangentially provided with a mud inlet, and the bottom of the cone bucket section (522) is provided with a slag discharge port, so that the heavy calcified granular sludge and the light activated sludge are separated by cyclone classification.

6. The process for biochemical treatment optimization of high-calcium and high-concentration wastewater according to claim 1, characterized in that: A cyclone aerator (62) is provided in the biochemical reaction tank (6) for aeration and oxygen supply. An aerobic sludge desander (65) is provided on the return sludge pipeline of the biochemical reaction tank (6). The aerobic sludge desander (65) comprises a second straight cylinder section (651), a second cone bucket section (652) and a sand collecting trough (653), and separates calcified matter through cyclone flow.

7. The process for biochemical treatment optimization of high-calcium and high-concentration wastewater according to claim 1, characterized in that: Part of the effluent from the secondary sedimentation tank (7) is returned to the regulating tank (3) through the secondary sedimentation effluent return pump (74) to dilute the influent, part of the sludge is returned to the coagulation reaction tank (1) through the secondary sedimentation sludge return pump 2 (73) to enhance flocculation, and another part of the sludge is returned to the biochemical reaction tank (6) through the secondary sedimentation sludge return pump 1 (72), and the remaining sludge and qualified effluent are discharged by the remaining secondary sedimentation sludge discharge pump (71).

8. The process for biochemical treatment optimization of high-calcium and high-concentration wastewater according to claim 4, characterized in that: The coagulant includes polyaluminium chloride and polyacrylamide, and the scale inhibitor is an organic phosphonate scale inhibitor.

9. The process for biochemical treatment optimization of high-calcium and high-concentration wastewater according to claim 1, characterized in that: The biochemical reaction tank (6) is composed of an anaerobic tank, an anoxic tank, and an aerobic tank. A stirrer (61) is provided in the anaerobic tank and the anoxic tank. Oxygen in the aerobic tank is supplied by an aeration fan (64) of the aerobic tank.

10. The optimized process for biochemical treatment of high-calcium and high-concentration wastewater according to claim 9, characterized in that: The aerobic tank returns the nitrified liquid to the anoxic tank via the mixed liquid return pump (63) for denitrification and denitrification.

Images