Optimization process for biochemical treatment of high-calcium and high-concentration wastewater

Abstract

The application discloses a kind of suitable for high calcium high concentration wastewater biochemical treatment optimization process, comprising the following steps: S1, high calcium wastewater is mixed with reflux sludge, and dosing coagulation is carried out;S2, solid-liquid separation is carried out to remove suspended particles;S3, primary sedimentation effluent is mixed with part of secondary sedimentation effluent to adjust quality;S4, after dilution, into IC reactor, organic matter is degraded, and calcified sludge is settled;S5, heavy calcified sludge at the bottom of IC anaerobic reactor is separated by cyclone, and active sludge is refluxed;S6, IC anaerobic reactor effluent is subjected to aerobic treatment, and sand is removed from reflux sludge before reflux;S7, sludge-water separation is carried out, sludge is partially refluxed, and remaining sludge and standard water are discharged.In the application, two-stage cyclone physical calcium removal is carried out, and light sludge is refluxed to keep active;Secondary sedimentation effluent and IC external circulation are doubly diluted, instantaneous concentration reduction is carried out to inhibit toxicity;Sludge is rapidly refluxed to supplement amount, and self-recovery is carried out under impact load.The whole process does not use softening agent, and is free of chemical sludge, free of disassembly and washing, and high calcium high concentration wastewater is long-term, efficient, low-consumption and stable operation.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to an optimized process for the biochemical treatment of high-calcium, high-concentration wastewater. Background Technology

[0002] In the treatment of high-calcium, high-concentration wastewater discharged from industries such as chemical, pharmaceutical, printing and dyeing, and papermaking, Ca... 2+ The concentration typically exceeds 500 mg / L, and the COD (chemical oxygen demand) often surpasses 5000 mg / L. In existing technologies, directly applying conventional anaerobic-aerobic biological treatment processes to this type of wastewater presents the following technical bottlenecks:

[0003] Anaerobic sludge calcification: high concentration of Ca 2+ With CO3 2- SO4 2- PO4 3- The reaction produces precipitates such as CaCO3, CaSO4, and Ca3(PO4)2, which coat and block the surface and pores of granular sludge, leading to a sharp drop in VSS / TSS, impaired mass transfer, and depletion of methanogenic activity. At the same time, the sludge density increases and fluidization becomes difficult, eventually forming dead zones and sedimentation, requiring frequent sludge replenishment.

[0004] Low aerobic sludge activity: Calcified particles also coat aerobic activated sludge, and VSS / TSS can drop to about 20%. Even if high TSS is maintained, COD removal rate is still limited. Sludge turnover is accelerated and sludge age is shortened, and system stability and denitrification efficiency decrease simultaneously.

[0005] Weak resistance to shocks: When the COD of the influent changes suddenly or is subjected to instantaneous shocks from toxic substances, traditional processes lack effective buffering, which can easily induce anaerobic sludge runoff, aerobic sludge bulking, excessive foaming, and excessive effluent standards. The recovery period is long and the continuity of production is threatened.

[0006] Severe scaling in equipment and 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 disassembled and cleaned every 2-3 years, aerators require dedicated personnel for circulating descaling, maintenance shutdowns are frequent, and operating costs are greatly increased.

[0007] Chemical softening pretreatment is costly: While softening with agents such as lime and soda ash can temporarily remove calcium, the cost per ton of water is high, making it difficult to sustain for industrial wastewater of 10,000 m³ / d in the long term, thus economic efficiency becomes a bottleneck for its promotion.

[0008] Based on the three major challenges of traditional biochemical treatment of high-calcium and high-concentration wastewater, namely sludge calcification and deactivation, equipment scaling and clogging, and weak shock resistance, and the high cost of chemical softening, there is an urgent need for an optimized process that is chemical-free or low-drug and can be operated continuously. Therefore, an optimized process suitable for the biochemical treatment of high-calcium and high-concentration wastewater is proposed. Summary of the Invention

[0009] The purpose of this invention is to provide an optimized process for the biochemical treatment of high-calcium, high-concentration wastewater in order to solve the above-mentioned problems.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: an optimized process for the biochemical treatment of high-calcium, high-concentration wastewater, comprising the following steps:

[0011] S1. High-calcium, high-concentration wastewater and secondary sedimentation tank return sludge are introduced into the coagulation reaction tank for mixing, and coagulant is added to carry out coagulation reaction.

[0012] S2. Introduce the mixture obtained in step S1 into the primary sedimentation tank for solid-liquid separation.

[0013] S3. The effluent from the primary sedimentation tank and part of the effluent from the secondary sedimentation tank are introduced into the equalization tank for mixing to adjust the water quality and quantity.

[0014] S4. After mixing and diluting the effluent from the equalization tank with the external circulating effluent from the IC anaerobic reactor, the mixture is introduced into the IC anaerobic reactor for anaerobic treatment.

[0015] The heavy calcified granular sludge discharged from the bottom of the S5 and IC anaerobic reactors is discharged into the anaerobic sludge storage tank, and then transported to the anaerobic sludge decalcifier for cyclone classification by the anaerobic sludge pump. The light activated sludge is returned to the IC anaerobic reactor.

[0016] The effluent from the S6 and IC anaerobic reactors is introduced into the biological reaction tank for aerobic treatment. The sludge returned from the secondary sedimentation tank is returned to the biological reaction tank after being separated from calcium by the aerobic sludge desander.

[0017] S7. The effluent from the biochemical reaction tank is introduced into the secondary sedimentation tank for sludge-water separation. Part of the sludge is returned to the coagulation reaction tank and the biochemical reaction tank, and part of the effluent is returned to the equalization tank. The remaining sludge and the qualified effluent are discharged from the system respectively.

[0018] Preferably, NaOH is added to the equalization tank to adjust the pH, and urea and phosphate solutions are added to supplement N and P nutrients; when the influent temperature is higher than the set value, the influent is cooled by a cooling tower installed on the equalization tank.

[0019] Preferably, the bottom of the IC anaerobic reactor is provided with an inverted cone swirl water distribution system, which includes an inverted cone-shaped sludge collection hopper and swirl water distribution pipes. The swirl water distribution pipes are provided with multiple layers of straight water distribution pipes at different heights along the inverted cone-shaped sludge collection hopper. Each of the straight water distribution pipes 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 each straight water distribution pipe.

[0020] Preferably, a forced external circulation system is provided outside the IC anaerobic reactor. The forced external circulation system includes an external circulation riser and an external circulation water pump. The inlet pipe of the external circulation water pump is equipped with a scale inhibitor dosing system.

[0021] Preferably, the anaerobic sludge decalcifier includes a straight cylindrical section, a conical section, and a washing and distributing water pipe distributed from top to bottom. The conical section is provided with a sludge inlet in a tangential direction, and the bottom of the conical section is provided with a sludge discharge outlet. The separation of heavy calcified granular sludge and light activated sludge is achieved through cyclone grading.

[0022] Preferably, the biochemical reaction tank is equipped with a cyclone aerator for aeration and oxygen supply, and an aerobic sludge desander is installed on the return sludge pipeline of the biochemical reaction tank. The aerobic sludge desander includes a straight section, a cone section, and a sand collection trough, and separates calcium deposits through cyclone separation.

[0023] Preferably, part of the effluent from the secondary sedimentation tank is returned to the equalization tank to dilute the influent via a secondary sedimentation effluent return pump, part of the sludge is returned to the coagulation reaction tank to enhance flocculation via a secondary sedimentation sludge return pump, another part of the sludge is returned to the biochemical reaction tank via a secondary sedimentation sludge return pump, and the remaining sludge and qualified effluent are discharged by the remaining secondary sedimentation sludge discharge pump.

[0024] Preferably, the coagulant includes polyaluminum chloride and polyacrylamide, and the scale inhibitor is an organophosphonate scale inhibitor.

[0025] Preferably, the biochemical reaction tank consists of an anaerobic tank, an anoxic tank, and an aerobic tank. Agitators are installed in the anaerobic tank and the anoxic tank, and oxygen in the aerobic tank is supplied by an aerobic tank aeration blower.

[0026] Preferably, the aerobic tank uses a mixed liquor return pump to return the nitrified liquor to the anoxic tank for denitrification.

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. In this application, a cyclone classifier is installed at the anaerobic end to immediately peel off and discharge the calcified, high-density granular sludge, while the light activated sludge is returned to continue working; the light sludge, whose surface is not covered by sediment, has continuously open pores, and its mass transfer and methanogenic activity can be maintained for a long time, so that the system biomass can be maintained without frequent sludge replenishment.

[0029] 2. In this application, the cyclone aerator has a built-in shearing and cleaning function, which can reduce the calcification and blockage of the aerator during operation; inorganic components such as calcium slag in the sludge are discharged through the sand remover, the sludge VSS / TSS no longer drops sharply, the sludge age is stable, and the COD removal, nitrogen removal and phosphorus removal efficiency are restored and maintained at a high level.

[0030] 3. In this application, the equalization tank is first diluted with the effluent from the secondary sedimentation tank, and then the IC reactor is diluted again with a high-multiplier external circulation, which instantly reduces 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 COD or toxic substances in the influent suddenly increase, the dilution and sludge replenishment are started simultaneously to buffer the shock load and avoid sludge runoff, sludge expansion or effluent exceeding the standard after the traditional system deteriorates. This achieves short-term self-recovery and continuous stable operation.

[0031] 4. In this application, the self-cleaning design of the inverted conical bucket swirling 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 shearing, which greatly extends the cycle of anaerobic effluent pipes and aerators without disassembly, reducing the number of maintenance shutdowns.

[0032] 5. In this application, the entire process relies on physical means of coagulation-cyclone separation-internal reflux for directional calcium removal, without the need to add softening agents such as lime and soda ash, which saves on agent costs and eliminates the burden of secondary treatment of chemical sludge, thereby reducing the economic cost of high-calcium wastewater treatment. Attached Figure Description

[0033] Figure 1 A schematic diagram of the optimized process flow for wastewater biochemical treatment provided in Embodiment 1 of the present invention is shown.

[0034] Figure 2 A schematic diagram of the optimized process flow for wastewater biochemical treatment provided in Embodiment 2 of the present invention is shown.

[0035] Figure 3 A schematic elevation view of a water distribution and sludge collection system provided according to an embodiment of the present invention is shown;

[0036] Figure 4 A schematic plan view of a water distribution and sludge collection system provided according to an embodiment of the present invention is shown;

[0037] Figure 5 A schematic elevation view of an anaerobic sludge storage tank provided according to an embodiment of the present invention is shown;

[0038] Figure 6 A schematic elevation view of an anaerobic sludge calcium removal device provided according to an embodiment of the present invention is shown;

[0039] Figure 7 A schematic elevation view of an aerobic sludge desander provided according to an embodiment of the present invention is shown.

[0040] Legend:

[0041] 1. Coagulation reactor; 2. Primary sedimentation tank; 3. Equalization tank; 31. Cooling tower; 4. IC anaerobic reactor; 41. Inverted cone vortex water distribution system; 411. Inverted cone sludge hopper; 412. Swirl water distribution pipeline; 42. Three-phase separator; 43. Downcomer; 441. External circulation riser; 442. External circulation water pump; 451. Gas-liquid separator; 452. Water seal demister; 521. Straight section one; 522. Conical section one; 523. Washing and sorting water distribution pipe; 46. Scale inhibitor dosing 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 blower; 65. Aerobic sludge sand remover; 651. Straight section II; 652. Conical section II; 653. Sand collection trough; 7. Secondary sedimentation tank; 71. Secondary sedimentation sludge discharge pump; 72. Secondary sedimentation sludge return pump I; 73. Secondary sedimentation sludge return pump II; 74. Secondary sedimentation effluent return pump. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1: Please refer to Figures 1-7 This invention provides a technical solution: an optimized process for the biochemical treatment of high-calcium, high-concentration wastewater, comprising the following steps:

[0044] S1. High-calcium, high-concentration wastewater and return sludge from secondary sedimentation tank 7 are introduced into coagulation reaction tank 1 for mixing, and coagulant is added to carry out coagulation reaction.

[0045] S2. Introduce the mixture obtained in step S1 into the primary sedimentation tank 2 for solid-liquid separation.

[0046] S3. The effluent from the primary sedimentation tank 2 and part of the effluent from the secondary sedimentation tank 7 are introduced into the equalization tank 3 for mixing and water quality and quantity adjustment.

[0047] S4. After mixing and diluting the effluent from the equalization tank 3 with the external circulating effluent from the IC anaerobic reactor 4, the mixture is introduced into the IC anaerobic reactor 4 for anaerobic treatment.

[0048] 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 calcium remover 52 for cyclone classification by the anaerobic sludge pump 51. The light activated sludge is returned to the IC anaerobic reactor 4.

[0049] The effluent from S6 and IC anaerobic reactor 4 is introduced into biological reaction tank 6 for aerobic treatment. The sludge returned from secondary sedimentation tank 7 is returned to biological reaction tank 6 after being separated from calcium by aerobic sludge sand remover 65.

[0050] S7. The effluent from the biochemical reaction tank 6 is introduced into the secondary sedimentation tank 7 for sludge-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 equalization tank 3. The remaining sludge and the qualified effluent are discharged from the system respectively.

[0051] First, coagulants and returned sludge are used to 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 water 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 concentration of toxic and biosensitive substances. The heavy calcified sludge at the bottom is separated by a cyclone decalcifier and returned to the light activated sludge to prevent calcification and deactivation. The aerobic tank is equipped with a cyclone aerator 62 and a sand remover to continuously remove calcifications. The sludge and water in the secondary sedimentation tank 7 achieve the circulation and separation of calcium salts within the system through multi-path return. Ultimately, sludge activity can be maintained without chemical softening, equipment scaling can be prevented, and shock resistance can be improved.

[0052] Example 2 is basically the same as Example 1, except that:

[0053] like Figure 1 and Figure 2 As shown, NaOH is added to the equalization tank 3 to adjust the pH, and urea and phosphate solution are added to supplement 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 installed on the equalization tank 3.

[0054] NaOH rapidly raises the acidic pH often associated with high-calcium, high-concentration wastewater, preventing low pH from inhibiting microbial activity. By quantitatively adding urea and phosphate, absorbable nitrogen and phosphorus sources are provided for the subsequent IC anaerobic reactor 4 and aerobic tank, preventing nutrient imbalance caused by high COD. Cooling tower 31 uses water-air heat exchange to cool the influent above the set value, maintaining the optimal temperature window for anaerobic and aerobic bacteria.

[0055] Example 3 is basically the same as Example 1, except that:

[0056] like Figures 1-4 As shown, the bottom of the IC anaerobic reactor 4 is equipped with an inverted cone swirl water distribution system 41. The inverted cone swirl water distribution system 41 includes an inverted cone-shaped sludge collection hopper 411 and a swirl water distribution pipe 412. The swirl water distribution pipe 412 is provided with multiple layers of straight water distribution pipes at different heights along the inverted cone-shaped sludge collection hopper 411. Each straight water distribution pipe 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 pipe.

[0057] Because 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 plant's recycled water or IC outlet water. Timed short flushes can instantly generate a pulse water flow to peel off and carry away the scale, keeping the water distribution pipe unobstructed.

[0058] The inverted cone angle of the inverted cone vortex water distribution system 41 is about 60°, with three to four layers of water distribution pipes, each layer having four to eight DN80 branch pipes, and a tangential inclination angle of about 30°~60°.

[0059] Wastewater is injected at high speed into the inverted cone vortex distribution system 41 through tangential distribution pipes, forming a three-dimensional vortex field within the cone. Heavy calcified particles are thrown against the wall by centrifugal force and slide along the cone wall to the bottom for discharge, while light active particles rise with the central flow and return to the reaction zone, achieving immediate separation. All distribution pipes are inclined at the same angle and in the same direction to the reactor radially, generating a spiral upward flow, which prolongs the sludge-water contact time and forms a continuous thrust, preventing local deposition and ensuring uniform fluidization of granular sludge.

[0060] Three to four layers of water distribution outlets are arranged along the height of the inverted cone, which serve to dilute toxicity, maintain suspension, and perform swirling separation, while also achieving three-dimensional water distribution. The flushing valve at the outer end of the water distribution pipe is connected to recycled water at regular intervals. Through pulsed water flow, the CaCO3 scale on the inner wall is quickly stripped off, and the stripped material falls directly into the cone and is discharged along the swirling flow, achieving online anti-clogging without interrupting production.

[0061] An external forced circulation system is provided on the outside of the IC anaerobic reactor 4. The external forced circulation system includes an external circulation riser 441 and an external circulation water pump 442. A scale inhibitor dosing system 46 is provided on the inlet pipe of the external circulation water pump 442.

[0062] 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 by the gas-liquid separator 451 to the reaction zone to form an internal circulation; and a water-sealed demister 452 for removing foam from the biogas before outputting it to the subsequent biogas treatment system. The coagulants include polyaluminum chloride and polyacrylamide, and the scale inhibitor is an organophosphonate scale inhibitor.

[0063] The external circulation pump 442 continuously draws the clarified water from the top of the IC anaerobic reactor 4 through the external circulation riser 441, mixes it with the influent from the equalization tank 3, and then returns it to the bottom of the reactor. This process instantly reduces the influent COD concentration and peak levels of toxic substances, forming an "internal dilution" that buffers high concentrations or toxic shocks and ensures that the granular sludge remains in a fluidized state by maintaining the upward flow velocity, thus enhancing mass transfer.

[0064] A scale inhibitor dosing system 46 is installed at the inlet pipe of the external circulating water pump 442 to continuously inject an organophosphonate scale inhibitor (such as PBTCA or HEDP). The agent is returned to the reactor at high speed with the circulating water, and first reacts with Ca... 2+ CO3 2- SO4 2- The plasma is fully mixed, and the growth of CaCO3 and CaSO4 crystal nuclei is inhibited through lattice distortion and complexation solubilization, thereby slowing down the scaling rate of the three-phase separator 42, downcomer 43 and inverted conical vortex water distribution system 41, resulting in high chemical utilization.

[0065] The front-end coagulant uses a combination of polyaluminum chloride (PAC) and polyacrylamide (PAM) to rapidly capture suspended solids (SS), some COD, and phosphates in coagulation reaction tank 1, reducing the formation of calcium salt matrix (such as PO4) before entering the IC reactor. 3- This indirectly reduces the amount of chemical precipitation in the anaerobic zone, thus reducing the load on the scale inhibitor.

[0066] The circulation volume is adjusted by the frequency converter of the external circulating water pump 442, and the COD of the influent is monitored online. The dosage of scale inhibitor is controlled by real-time feedback of circulating water flow and calcium hardness, forming a "load-scale" dual closed loop to ensure long-term stable operation of the process.

[0067] Example 4 is basically the same as Example 1, except that:

[0068] like Figure 1 , Figure 2 , Figure 5 , Figure 6 and Figure 7 As shown, the anaerobic sludge calcium removal device 52 includes a straight cylindrical section 521, a conical section 522, and a washing and distributing water pipe 523 distributed from top to bottom. The conical section 522 is tangentially provided with a sludge inlet and a sludge discharge outlet is provided at the bottom of the conical section 522. The separation of heavy calcified granular sludge and light activated sludge is achieved through cyclone classification.

[0069] The sludge tangentially enters the cone section 522 and rotates at high speed in the straight section 521. Centrifugal force throws the denser, heavy calcified particles against the wall of the reactor and slides down the cone wall, and is continuously discharged from the bottom sludge discharge port. Meanwhile, the less dense, light activated sludge is carried upward to the center by the internal swirling flow. After being washed by the upward water flow through the washing and screening distribution pipe 523, it is returned to the IC anaerobic reactor 4, realizing the online separation of calcified particles and activated sludge.

[0070] A cyclone aerator 62 is installed in the biochemical reaction tank 6 to provide aeration and oxygen supply, thereby reducing calcification and blockage of the aeration system. An aerobic sludge desander 65 is installed on the return sludge pipeline of the biochemical reaction tank 6. The aerobic sludge desander 65 includes a straight section 651, a cone section 652, and a sand collection trough 653, which separates calcifications through cyclone separation.

[0071] The spiral-rising gas-liquid two-phase flow generates a rapid shear velocity on the surface of the aeration head, which promptly strips away the initial CaCO3 crystal nuclei; the aerator can be raised as a whole to the water surface and rinsed with recycled water pulses, restoring oxygen mass transfer efficiency without stopping the tank, thus achieving online descaling without interrupting production.

[0072] The secondary sedimentation return sludge enters tangentially into the straight section 651, forming a secondary vortex. Due to their high density, calcium deposits and gravel slide down the conical section 652 into the sand collection trough 653 and are periodically discharged. The calcium-removed activated sludge is returned to the aerobic tank.

[0073] Example 5 is basically the same as Example 1, except that:

[0074] like Figure 1 and Figure 2 As shown, part of the effluent from the secondary sedimentation tank 7 is returned to the equalization tank 3 to dilute the influent via the secondary sedimentation effluent return pump 74, part of the sludge is returned to the coagulation reaction tank 1 to enhance flocculation via the secondary sedimentation sludge return pump 73, and another part of the sludge is returned to the biochemical reaction tank 6 via the secondary sedimentation sludge return pump 72. The remaining sludge and qualified effluent are discharged by the remaining secondary sedimentation sludge discharge pump 71.

[0075] Secondary sedimentation effluent return pump 74 returns a portion of the effluent to equalization tank 3, instantly reducing raw water COD, toxic substance concentration, and temperature fluctuations, forming the first buffer barrier and reducing the load impact on subsequent IC anaerobic reactor 4 and biological reaction tank 6. Secondary sedimentation sludge return pump 73 sends sludge rich in microflocs and active substances back to coagulation reaction tank 1, utilizing the sludge residue for contact flocculation, improving PAC / PAM utilization rate, while the sludge adsorbs some toxic organic matter, further reducing the risk of bioinhibition. Secondary sedimentation sludge return pump 72 returns a portion of activated sludge to the front end of biological reaction tank 6, supplementing MLSS and maintaining the microbial biomass required for biological reactions. The remaining secondary sedimentation sludge discharge pump 71 continuously discharges remaining sludge according to the set sludge age, preventing the accumulation of calcified particles and maintaining a constant system sludge age, ensuring long-term stable effluent compliance.

[0076] Example 6 is basically the same as Example 1, except that:

[0077] like Figure 1 and Figure 2 As shown, the biochemical reaction tank 6 consists of an anaerobic tank, an anoxic tank, and an aerobic tank. A mixer 61 is installed in the anaerobic tank and the anoxic tank. Oxygen in the aerobic tank is supplied by the aerobic tank aeration blower 64. The aerobic tank returns the nitrified liquid to the anoxic tank for denitrification and nitrogen removal through the mixed liquor return pump 63.

[0078] The mixer 61 keeps the sludge suspended, utilizing polyphosphate-accumulating bacteria in the returned sludge to absorb and release phosphorus, while simultaneously hydrolyzing recalcitrant organic matter to provide a readily degradable carbon source for subsequent denitrification. In a high-calcium environment, the anaerobic section maintains low ORP, inhibiting the interference of calcium salt chemical precipitation on polyphosphate-accumulating bacteria. The mixer 61 ensures complete mixing of the sludge and water. The mixed liquor return pump 63 introduces the nitrified liquid produced in the aerobic tank into the anoxic tank. Denitrifying bacteria utilize the carbon source provided by the raw water and the anaerobic tank to reduce nitrates to nitrogen, achieving denitrification and further reducing COD. The aeration blower 64 in the aerobic tank supplies oxygen through the cyclone aerator 62.

[0079] The above description of the embodiments enables those skilled in the art to make or use the 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optimized process for the biochemical treatment of high-calcium, high-concentration wastewater, characterized in that, Includes the following steps: S1. High-calcium and high-concentration wastewater and sludge returned from the secondary sedimentation tank (7) are introduced into the coagulation reaction tank (1) for mixing, and coagulant is added for coagulation reaction. S2. Introduce the mixture 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 equalization tank (3) for mixing and water quality and quantity adjustment. S4. After mixing and diluting the effluent from the equalization tank (3) with the external circulating effluent from the IC anaerobic reactor (4), the mixture is introduced 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) by the anaerobic sludge pump (51) for cyclone classification. 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 cyclone-separated from calcium deposits by 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 sludge-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 equalization tank (3). The remaining sludge and the qualified effluent are discharged from the system respectively. The IC anaerobic reactor (4) is equipped with an inverted cone swirl water distribution system (41) at the bottom. The inverted cone swirl water distribution system (41) includes an inverted cone sludge collection 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 collection hopper (411). Each of the straight water distribution pipelines 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. The inverted cone vortex water distribution system (41) has an inverted cone angle of 60°, three to four layers of water distribution pipes, four to eight DN80 branch pipes in each layer, and a tangential inclination angle of 30°~60°.

2. The optimized process for biochemical treatment of high-calcium, high-concentration wastewater according to claim 1, characterized in that, NaOH was added to the conditioning tank (3) to adjust the pH, and urea and phosphate solution were added to supplement 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) installed on the regulating tank (3).

3. The optimized process for biochemical treatment of high-calcium, high-concentration wastewater according to claim 1, characterized in that, The IC anaerobic reactor (4) is provided with a forced external circulation system, which includes an external circulation riser (441) and an external circulation pump (442). The inlet pipe of the external circulation pump (442) is provided with a scale inhibitor dosing system (46).

4. The optimized process for biochemical treatment of high-calcium, high-concentration wastewater according to claim 1, characterized in that, The anaerobic sludge decalcifier (52) includes a straight cylindrical section (521), a conical section (522), and a washing and distributing water pipe (523) distributed from top to bottom. The conical section (522) has a tangential sludge inlet and a sludge discharge outlet at the bottom. The separation of heavy calcified granular sludge and light activated sludge is achieved through cyclone grading.

5. The optimized process for biochemical treatment of high-calcium, high-concentration wastewater according to claim 1, characterized in that, The biochemical reaction tank (6) is equipped with a cyclone aerator (62) for aeration and oxygen supply. An aerobic sludge desander (65) is installed on the return sludge pipeline of the biochemical reaction tank (6). The aerobic sludge desander (65) includes a straight section two (651), a cone section two (652) and a sand collection tank (653), which separates calcium deposits through cyclone separation.

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

7. The optimized process for biochemical treatment of high-calcium, high-concentration wastewater according to claim 3, characterized in that, The coagulant includes polyaluminum chloride and polyacrylamide, and the scale inhibitor is an organophosphonate scale inhibitor.

Images