Efficient softening and hardness removing process for high-hardness water body

Abstract

The invention provides an efficient softening and hardness-removing process for a high-hardness water body, which is applied to the technical field of water body purification. The efficient softening and hardness-removing process comprises a pretreatment mechanism, a softening reaction mechanism, a flocculent precipitation mechanism and a sludge closed-loop treatment mechanism which are sequentially connected along a water body treatment flow direction, the efficient softening and hardness-removing process for the high-hardness water body comprises the following raw water treatment steps: S1, treating raw water by virtue of the pretreatment mechanism, so as to obtain ultrafiltration effluent; and S2, the ultrafiltration effluent enters the softening reaction mechanism, and under the control of the electric cabinet control mechanism, chemicals are added for softening and flocculation reaction. The total hardness removal rate can reach more than 90% through accurate addition of the medicament, two-stage pH control and optimization of reaction conditions, which is far superior to that of a traditional resin ion exchange method, the influence of high-hardness water discharge on receiving water is reduced, ecological and health problems caused by excessive hardness of the water are avoided, and the harsh requirements of industrial production and environmental protection on soft water are met.

Description

Technical Field

[0001] This invention relates to the field of water purification technology, and specifically to a water softening process, that is, a highly efficient softening and hardening process for high-hardness water. Background Technology

[0002] In industrial production processes, hardness substances such as calcium and magnesium ions in water are key factors restricting production efficiency and increasing operating costs. Direct use or recycling of high-hardness water can cause a series of problems: First, it easily forms scale on equipment pipes and heat exchanger surfaces, leading to decreased heat transfer efficiency. Statistics show that scale caused by hard water results in more than one-third of fuel waste, while also increasing the risk of equipment corrosion and blockage, significantly raising maintenance costs. Second, calcium and magnesium ions in hard water react with active ingredients in detergents and production aids to form metal salts, reducing cleaning or auxiliary effects. Research by the American Detergent Association shows that hard water doubles detergent costs and laundry expenses compared to soft water. Third, direct discharge of high-hardness water increases the hardness of receiving water bodies. The calcium and magnesium ions in the water easily form precipitates in the human digestive system, causing bloating, diarrhea, and other discomfort, and in severe cases, inducing gastric stones. my country's drinking water hygiene standards clearly stipulate that the total hardness must not exceed 450 mg / L.

[0003] Existing water softening technologies mainly include the following three categories: Ion exchange method: softening is achieved by adsorbing calcium and magnesium ions in water with resin, but it has significant drawbacks: the resin needs to be regenerated frequently (once every 8 hours), each regeneration consumes a large amount of salt (830 kg per cycle), and the operating cost is high (average monthly salt consumption cost of 64,740 yuan); the regeneration process generates high-salt wastewater, which can easily cause secondary pollution; the hardness of the effluent is unstable, with an average hardness of about 300 mg / L, which is difficult to meet the requirements of high-precision production.

[0004] Electrodialysis: This method uses the selective permeability of ion exchange membranes to separate calcium and magnesium ions. However, the equipment is expensive, energy-intensive, and has strict requirements on the quality of the influent, making it unsuitable for treating raw water with high turbidity and high hardness.

[0005] Traditional lime softening method: This method involves adding lime, soda ash, and other reagents to precipitate calcium and magnesium ions. It has the advantages of low cost and mature technology, but it has core technical defects: the amount of reagent added depends on human experience and cannot be adjusted in real time according to water quality fluctuations, resulting in large fluctuations in treatment effect (the hardness of the effluent can deviate by ±50mg / L); the reaction time is not accurately controlled, and the calcium ion precipitation is insufficient; the sludge separation efficiency is low, which can easily cause secondary pollution, thus limiting its large-scale application in the treatment of high-hardness water.

[0006] To address the aforementioned shortcomings of existing technologies, this invention proposes a highly efficient softening and hardening process for high-hardness water. By optimizing reagent dosing control, innovating process flow, and co-designing equipment, it achieves efficient, stable, and low-cost softening and reuse of high-hardness water, filling the gap in the balance between treatment effect and operating cost in existing technologies. Summary of the Invention

[0007] The purpose of this invention is to provide an efficient softening and hardening process for high-hardness water, solving the technical problems of expensive ion exchange wastewater treatment, poor stability of effluent hardness, and difficulty in controlling the dosage of chemicals and low sludge treatment efficiency in lime softening methods.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A high-efficiency softening and hardening process for high-hardness water includes a pretreatment unit, a softening reaction unit, a flocculation and sedimentation unit, and a sludge closed-loop treatment unit connected sequentially along the water treatment flow direction. The high-hardness water softening and hardening removal process includes the following raw water treatment steps: S1: Raw water is treated by the pretreatment unit to obtain ultrafiltration effluent; S2: The ultrafiltration effluent enters the softening reaction mechanism, and under the control of the electrical control mechanism, chemicals are added to carry out softening and flocculation reactions; S3: After the reaction, the water enters the flocculation and sedimentation mechanism for solid-liquid separation, resulting in softened water supernatant and calcium carbonate sludge. S4: The supernatant of the softened water enters the softened water storage and reuse mechanism for storage and reuse.

[0009] The above technical solution further includes: The calcium carbonate sludge enters the sludge closed-loop treatment mechanism, and after being buffered and pneumatically stirred in the sludge buffer tank, it is dewatered by a plate and frame filter press. The filter water produced is returned to the flocculation and sedimentation mechanism along with the wastewater discharged from the reaction vessel. The supernatant after treatment in the settling tank is returned to the pretreatment mechanism.

[0010] The pretreatment unit is configured to remove impurities from the raw water to obtain ultrafiltration effluent; A softening reaction mechanism is connected to the outlet of the pretreatment mechanism. The softening reaction mechanism includes a reaction vessel, which is equipped with a dosing mechanism and a first pH probe for adding chemicals to the ultrafiltration effluent to carry out a softening reaction. The flocculation and sedimentation mechanism is connected to the outlet of the softening reaction mechanism. The flocculation and sedimentation mechanism includes a settling tank, which is equipped with a second pH probe and an inclined plate for solid-liquid separation of the water after the reaction. A closed-loop sludge treatment mechanism is connected to the sludge outlet of the flocculation and sedimentation mechanism. The closed-loop sludge treatment mechanism includes a sludge buffer tank and a plate and frame filter press connected in sequence. The sludge buffer tank is equipped with a pneumatic stirring device. The softened water storage and reuse mechanism is connected to the supernatant outlet of the flocculation and sedimentation mechanism, and the softened water storage and reuse mechanism includes a softened water tank. The filter water outlet of the plate and frame filter press and the sewage outlet of the reaction vessel are both connected to the flocculation and sedimentation mechanism so that the filter water and sewage from the reaction vessel are returned to the settling tank for treatment. The settling tank is also equipped with a circulation pipeline connected to the pretreatment mechanism for returning the supernatant of the settling tank to the pretreatment mechanism.

[0011] It also includes an electrical control cabinet, which is communicatively connected to the first pH probe and the dosing mechanism, and is used to control the dosage of the dosing mechanism in a closed loop based on the detection value of the first pH probe.

[0012] The reactor includes a primary rectangular reactor and a secondary rectangular reactor connected in series. The primary rectangular reactor is equipped with a dosing mechanism for adding sodium carbonate solution, and the secondary rectangular reactor is equipped with a dosing mechanism for adding flocculant.

[0013] The reactor is equipped with a flow guide channel. The inlet of the reactor is located at the top and the outlet is located at the bottom. The water flow is configured to be guided by the flow guide channel to rise slowly from the bottom.

[0014] The inclined plates in the settling tank are sloping plates with an angle of 60° to the horizontal plane and a plate spacing of 5cm; the upward flow velocity of the settling tank is configured to be 0.56mm / s.

[0015] The pneumatic stirring device in the sludge buffer tank includes a stirring pipe with air holes.

[0016] The softened water tank is equipped with a liquid level sensor and a water replenishment pipeline. The electrical control cabinet is communicatively connected to the liquid level sensor and the water replenishment valve on the water replenishment pipeline, and is used to automatically control water replenishment according to the liquid level.

[0017] The electrical control cabinet includes a PLC controller, and the outlet of the flocculation and sedimentation mechanism is also equipped with a second pH probe. The second pH probe is communicatively connected to the electrical control cabinet, and the electrical control cabinet is configured to adjust the dosage of the softening reaction mechanism according to the detection value of the second pH probe.

[0018] The beneficial effects of this invention are: 1. This invention combines traditional lime softening with chemical softening technology to remove hardness. Through precise dosing of reagents, dual-stage pH control, and optimized reaction conditions, the total hardness removal rate can reach over 90%, which is far superior to the traditional resin ion exchange method. This reduces the impact of high-hardness water discharge on receiving water bodies, avoids ecological and health problems caused by excessive water hardness, and meets the stringent requirements of industrial production and environmental protection for soft water.

[0019] 2. This invention achieves stable effluent turbidity below 1 NTU through PLC-linked two-stage pH closed-loop control, precise flow regulation, and flocculation sedimentation optimization. The effluent exhibits good stability, with a stable pH value between 7.0 and 7.5 and no hardness rebound. It can be directly connected to the production system, avoiding equipment scaling and clogging.

[0020] 3. Compared with the traditional resin ion exchange method, the method of combining lime softening and chemical softening provided by this invention has significant advantages in terms of economic operation, as lime and sodium carbonate are cheaper and the operating costs are significantly lower than those of resin ion exchange and electrodialysis.

[0021] 4. The entire process of this invention is controlled by a PLC control cabinet, which links pH probes, level sensors, metering pumps and other equipment to achieve fully automated control of water intake, chemical addition, reaction, sedimentation and water replenishment. No real-time manual operation is required, only regular monthly maintenance is needed, thus reducing labor intensity. Attached Figure Description

[0022] Figure 1 This is a flow chart of the hard water softening process of the present invention; Figure 2 This is a schematic diagram of the connection between the sand filter and the carbon filter in this invention. Detailed Implementation

[0023] 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.

[0024] A highly efficient softening and hardening process for high-hardness water includes a phased closed-loop process of "pretreatment - softening reaction - flocculation sedimentation - sludge closed-loop treatment - reuse and storage", as detailed below: The incoming water to the workshop passes through the following stages in sequence: air flotation (to remove suspended particulate matter) → biochemical equipment (to degrade organic matter) → inclined tube equipment (for preliminary sedimentation) → sand filtration equipment (to filter fine impurities) → carbon filtration equipment (to adsorb odors and residual organic matter) → ultrafiltration equipment (to retain colloidal and macromolecular impurities), resulting in ultrafiltration effluent. Softening reaction stage: The ultrafiltration effluent is pumped to the top of the rectangular reactor through a DN80 water supply pipe and mixed with the sodium carbonate solution added by the dosing tank. The water flows through the guide channel inside the reactor and rises from the bottom to achieve full gas-liquid contact reaction. Flocculation and sedimentation stage: After the reaction, the water enters the secondary reactor, where polyaluminum chloride flocculant is added. The water flows up again through the guide channel and enters the settling tank. The settling tank is equipped with inclined plates, and the calcium carbonate crystal particles settle rapidly under the action of the inclined plates. The supernatant is the softened water. Closed-loop treatment stage of sludge: ① The sludge (calcium carbonate suspension) at the bottom of the settling tank is transported to the sludge buffer tank by a lift pump; ② A pneumatic stirring device is installed in the sludge buffer tank to prevent sludge sedimentation and ensure uniform sludge transportation; ③ The sludge is transported from the buffer tank to the plate and frame sludge press for dewatering. After filtration, the sludge cake is bagged and recycled, and the sludge pressing water is returned to the sedimentation tank for recycling. ④ The calcium carbonate precipitated in the rectangular reactor is discharged into the sedimentation tank through the DN50 drain outlet to avoid sludge accumulation in the reactor; Reuse and storage stage: The supernatant (softened water) from the settling tank is transported to the softened water tank for storage.

[0025] This embodiment takes a wastewater treatment project with a daily processing capacity of 500 tons of high-hardness industrial wastewater as an example to illustrate the specific implementation process of the present invention.

[0026] 1. Raw water (referring to the high-hardness water to be treated) quality and treatment standards The raw water has a calcium hardness of 396 mg / L (calculated as CaCO3) and needs to be treated to meet the industrial reuse standards (total hardness ≤110 mg / L, turbidity ≤1 NTU).

[0027] 2. Equipment Configuration and Specifications Reactor: Length 4m × Width 2m × Height 2.5m, effective volume 20m³ 3 The reaction residence time is 16-17 minutes, and an internal guide channel (10cm wide × 5cm high) is provided. Settling tank: Dimensions are 8.6m × 7.5m, depth is 2.45m, effective water depth is 1.8m, and effective volume is 110m³. 3 The upward flow velocity is 0.56 mm / s, and it is equipped with a 60° inclined plate with a plate spacing of 5 cm. Sludge buffer tank: Plan dimensions 8m × 1m, effective water depth 0.6m, effective volume 5m³ 3 Built-in DN40 pneumatic stirring tube (3mm air holes, 10cm spacing). Dosing system: 3 dosing tanks (2×2m) 3 +1×1m 3), DN15 dosing pipeline, metering pump (flow rate 0~50L / h, accuracy ±1%); Softening water tanks: 2 in series (2m×2m×4.5m + 4m×2.5m×4.5m), total effective volume 56m³. 3 Electrical cabinet control mechanism: includes pH probe (measuring range 0~14pH, accuracy ±0.1pH), liquid level sensor (measuring range 0~5m, accuracy ±1cm), and PLC controller; Plate and frame sludge press: filtration area 50m² 2 The working pressure is 0.6 to 1.2 MPa, and the moisture content of the mud cake is ≤60%.

[0028] The system includes: a reaction vessel providing space for reagent reaction, with a guide channel structure to improve gas-liquid contact efficiency and ensure uniform reaction; a settling tank for calcium carbonate particle precipitation and separation, with an inclined plate optimizing the sedimentation path and improving separation efficiency; a sludge buffer tank using pneumatic stirring to prevent sludge deposition and ensure uniform delivery; a dosing mechanism using a metering pump linked to a pH probe to achieve closed-loop dosing; a softened water tank with a series design to ensure continuous water supply; an electrical control cabinet providing parameter monitoring and automatic control, achieving multi-parameter linkage through PLC programming without manual intervention; and a plate and frame sludge press for sludge dewatering.

[0029] 3. Implementation Process and Details Workshop incoming water → Pretreatment unit (air flotation → biochemical → inclined tube sedimentation → sand filtration → carbon filtration → ultrafiltration) → Softening reaction unit (first-stage rectangular reactor + second-stage rectangular reactor) → Flocculation sedimentation unit (settling tank) → Sludge closed-loop treatment unit (sludge buffer tank → plate and frame sludge press) → Softened water storage and reuse unit (softened water tank).

[0030] The entire process is equipped with an electrical control cabinet to achieve precise control of water intake, chemical dosing, reaction, sedimentation, and water replenishment. Key control indicators are: reactor pH 8.2-8.6, effluent pH 7.0-7.5, effluent hardness ≤110mg / L (actual average 50mg / L), and water resource reuse rate ≥95%.

[0031] In the pretreatment unit, the connection method of each device is as follows: The workshop's production wastewater is directly connected to the inlet of an air flotation device (e.g., an air flotation machine). The air flotation effluent is then connected to a biochemical treatment device (e.g., a biochemical reactor) via a DN100 pipe. The biochemical effluent is then connected to an inclined tube sedimentation tank via a DN100 pipe. The supernatant from the inclined tube sedimentation tank is then connected to a sand filter (e.g., a quartz sand filter) via an overflow trough. Figure 2As shown, the sand filtration effluent is connected to the carbon filtration equipment (e.g., activated carbon filter) through a DN80 pipe, the carbon filtration effluent is connected to the ultrafiltration equipment (e.g., ultrafiltration membrane module) through a DN80 pipe, and the ultrafiltration effluent is connected to the reactor of the softening reaction mechanism through a DN80 water supply pipe.

[0032] In the pretreatment unit, the functions of each piece of equipment are as follows: Air flotation equipment is used to remove suspended particulate matter (particle size ≥ 5 μm) and oily substances from raw water and reduce turbidity (raw water turbidity 5~8 NTU → treated water turbidity ≤ 3 NTU). Biochemical equipment is used to degrade organic pollutants in raw water (such as latex residue additives), reduce COD value (ensuring COD≤50mg / L), and avoid the reaction between organic matter and chemicals affecting the softening effect; Inclined tube equipment is used to further remove fine suspended particles (particle size ≥1μm) from water, achieving preliminary solid-liquid separation and reducing turbidity to ≤2NTU; Sand filtration equipment is used to filter and remove residual fine impurities and colloidal particles from water, reducing turbidity to ≤1 NTU; Carbon filtration equipment is used to adsorb odors, residual organic matter and some heavy metal ions in water, ensuring the stability of the subsequent ultrafiltration membrane operation. Ultrafiltration equipment is used to remove colloids, macromolecular organic matter and microorganisms from water to obtain high-purity ultrafiltration water (hardness of about 530 mg / L and turbidity ≤0.5 NTU), providing qualified raw water for softening reaction.

[0033] In the softening reaction mechanism, chemical agents are added to react with calcium ions in the water to induce precipitation. Combined with precise parameter control, this achieves efficient hardness removal. The core reaction principle is as follows: .

[0034] In the softening reaction unit, the primary rectangular reactor inside the reactor vessel is equipped with a dosing system (two 2-ton dosing tanks + one 1-ton dosing tank, with matching DN15 dosing pipes and metering pumps) and a first pH online monitoring probe (measurement range 0–14 pH, accuracy ±0.1 pH). The ultrafiltration effluent is pumped through a water pump (flow rate 40 m³ / h). 3 The water (with a flow rate of 30 m / h and a head of 30 m) is fed into the upper part of the primary rectangular reactor. The water flow is guided through the guide channel inside the primary rectangular reactor and rises slowly from the lower part of the primary rectangular reactor to ensure uniform water distribution and avoid flow interruption.

[0035] The dosing unit prepares a 1.5% (mass concentration) sodium carbonate solution in advance: it is prepared on a large scale according to the ratio of "0.25g Na2CO3 solid + 16.4ml tap water". For example, 30kg of industrial-grade sodium carbonate (purity ≥98%) is added to a 2-ton dosing tank, and tap water is added to bring the volume to 2ml. 3Mark the graduation mark, start the stirrer (100 r / min) and stir for 30 min until completely dissolved; the metering pump automatically adjusts the dosage based on the feedback signal from the first pH probe in the primary rectangular reactor: initial dosage flow rate 30 L / h, maintaining the pH value of the primary rectangular reactor at 8.2-8.6 in real time (optimized range, balancing reaction sufficiency and reagent conservation); control the reaction residence time to 16-17 min (in practice, the water flow path is extended through the design of the guide channel to ensure effective reaction time), so that calcium ions and sodium carbonate can fully react to form calcium carbonate precipitate.

[0036] In the softening reaction unit, the secondary rectangular reactor inside the reactor is equipped with a polyaluminum chloride (PAC) dosing system (integrated into a 1-ton dosing tank among three dosing tanks). Water from the primary rectangular reactor flows naturally into the secondary rectangular reactor through a guide channel, following the "top in, bottom up" flow pattern. A 5% concentration of PAC solution is added from the 1-ton dosing tank, with the dosage controlled at 5–10 mg / L (based on a treatment capacity of 500 m³). 3 The daily dosage of PAC is calculated as 2.5-5 kg, and it is precisely delivered through a metering pump. As a flocculant, polyaluminum chloride aggregates and enlarges the fine calcium carbonate crystals through adsorption and bridging, forming large-particle flocs (particle size ≥ 50 μm) that are easy to settle, laying the foundation for subsequent precipitation and separation.

[0037] In flocculation and sedimentation mechanisms, such as Figure 1 As shown, the settling tank is equipped with a second online pH monitoring probe for the effluent. Specific operational details are as follows: After the reaction in the secondary rectangular reactor, the floc-containing water flows into the settling tank through a DN100 pipe. The upward flow velocity is strictly controlled at 0.56 mm / s (matched by the influent flow rate and the effective cross-sectional area of ​​the settling tank). The water rises slowly in the settling tank, and the calcium carbonate flocs adhere to the surface of the inclined plate under gravity and gradually settle to the bottom of the tank, achieving solid-liquid separation. A second pH probe is installed at the outlet of the settling tank to monitor the pH value of the effluent in real time, ensuring that it is stable at 7.0-7.5 (meeting the pH requirements for industrial reclaimed water). If the pH exceeds the range, the sodium carbonate dosage in the primary rectangular reactor is finely adjusted through the control cabinet. The supernatant in the settling tank (i.e., softened water, hardness 40-50 mg / L, turbidity ≤1 NTU) flows into the softened water tank through the overflow channel. The calcium carbonate sludge (water content about 90%) deposited at the bottom of the tank is temporarily stored, and the subsequent sludge treatment process is started when the liquid level reaches 1.5m.

[0038] In a closed-loop sludge treatment facility, such as Figure 1 As shown, the sludge at the bottom of the settling tank is transported to a sludge buffer tank via a lift pump. The sludge buffer tank buffers the sludge and uses pneumatic agitation to prevent sludge deposition and caking. Then, a sludge pump (flow rate 5m³ / h) is used to transfer the sludge to the buffer tank. 3The plate and frame sludge press is connected to the sludge press. The sludge is dewatered by the plate and frame sludge press, and the sludge water and dry sludge cake are separated. The sludge water is returned to the sedimentation tank through the DN50 pipeline to form a closed loop, and the dry sludge cake is collected through the discharge port.

[0039] It is worth emphasizing that the small amount of calcium carbonate precipitate deposited inside the reactor is discharged into the sedimentation tank through the bottom drain outlet. The sedimentation tank is used to treat the sludge water and residual sludge in the reactor discharge. The supernatant is pumped back to the air flotation equipment to participate in the pretreatment again, forming a closed loop.

[0040] In the softened water storage and reuse system, the softened water tank is equipped with a tap water replenishment pump (flow rate 20m³ / h). 3 / h) and a liquid level sensor (measuring range 0~4.5m, accuracy ±1cm).

[0041] The qualified softened water output from the settling tank is stored in a softened water tank made of 304 stainless steel with anti-corrosion treatment on the inner wall to prevent secondary pollution of the water. A level sensor monitors the water level in real time: when the water level is 1m below the bottom (corresponding to a volume of 20m³), the water level will be lowered. 3 When the water level reaches 2m (corresponding to a volume of 30m³), the control unit of the electrical cabinet automatically starts the tap water replenishment pump to add tap water to the water tank until the water level reaches 2m (corresponding to a volume of 30m³). 3 The system stops when necessary to ensure continuous water supply for production reuse; the water from the softened water tank is connected to the workshop production system through a DN100 water supply pipeline for use in latex product production, equipment cleaning, and other scenarios, thus realizing the recycling of water resources.

[0042] 4. Treatment effect Cost Analysis of Traditional Resin Ion Exchange Method Operation frequency: Perform salt washing 3 times a day.

[0043] Salt usage per salt wash: 830 kg salt.

[0044] Total daily salt consumption: 3 times × 830kg / time = 2490kg.

[0045] Monthly salt consumption (calculated based on 26 working days): 2490kg / day × 26 days = 64740kg (equivalent to 64.74 tons).

[0046] The cost of salt: The unit price of salt is 1,000 yuan / ton, and the monthly cost is 64.74 tons × 1,000 yuan / ton = 64,740 yuan.

[0047] Cost Analysis of Chemical Softening Method (i.e., Lime Softening Method Provided in this Example) Equipment electricity costs: The average daily power consumption of equipment (such as agitators, water pumps, etc.) is 120 kWh.

[0048] Monthly electricity consumption (26 working days): 120kWh / day × 26 days = 3120kWh.

[0049] Electricity price per unit: 0.8 yuan / kWh, monthly electricity cost is 3120kWh × 0.8 yuan / kWh = 2496 yuan.

[0050] Cost of sodium carbonate: Average daily sodium carbonate usage: 3 bags, 50kg per bag, totaling 150kg.

[0051] Monthly usage (26 working days): 150kg / day × 26 days = 3900kg (equivalent to 3.9 tons).

[0052] Sodium carbonate unit price: 3000 yuan / ton, monthly cost is 3.9 tons × 3000 yuan / ton = 11700 yuan.

[0053] Other costs: including solid waste treatment, heat consumption, hydrochloric acid and maintenance costs, estimated at 10,000 yuan per month.

[0054] Total monthly cost of chemical softening method: 2496 yuan (electricity) + 11700 yuan (sodium carbonate) + 10000 yuan (other expenses) = 24196 yuan.

[0055] In summary, the method combining lime softening and chemical softening provided in this embodiment saves RMB 40,544 per month and RMB 225,612 per year compared to the traditional resin ion exchange method, demonstrating significant advantages in economic operation.

[0056] Table of water softening effects of traditional resin ion exchange method: Table of water softening effects of chemical softening method: As shown in the table above, the average hardness of the effluent from the resin ion exchange method is around 300 mg / L, while the average hardness of the effluent from the chemical softening method of this invention is around 50 mg / L. The comparison shows that the chemical softening method of this invention has a significantly better softening effect on the water.

[0057] Specifically, this invention combines the traditional lime softening method with chemical softening and hardening removal technology. First, a chemical reaction is carried out in a reaction vessel to soften the hard water and sodium carbonate solution, achieving the effect of hardening removal. Then, the calcium carbonate crystals produced by the softening reaction are precipitated through the inclined plate of the settling tank, further softening the water. Due to the crystallization of calcium carbonate, the particles gradually increase in size. The CaCO3 aqueous solution is pumped to the sludge buffer tank by the settling tank lift pump, and then pumped from the sludge buffer tank to the plate and frame sludge press. The plate and frame sludge press then returns the treated sludge water to the settling tank, forming a closed-loop treatment.

[0058] This invention achieves precise control of reagent dosing by using dual-point pH monitoring in the reaction vessel and settling tank, and linking a metering pump. This solves the technical problems of relying on experience for reagent dosing and fluctuating treatment effects in the traditional lime softening method, with pH control accuracy reaching ±0.1pH.

[0059] The present invention combines the flow channel structure of the rectangular reactor with the slope plate design of the settling tank to ensure that the reaction residence time is stable at 16-17 min, the sedimentation upward flow velocity is optimized to 0.56 mm / s, and the calcium ion precipitation efficiency is improved by about 30%.

[0060] This invention sets up a sludge buffer tank and a pneumatic stirring device to achieve a closed-loop treatment of sludge from sedimentation, buffering, transportation to filter press. The sludge water is recycled and retreated, resulting in no secondary pollution and a high sludge recovery rate.

[0061] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A highly efficient softening and hardening process for high-hardness water, characterized in that: The pre-treatment mechanism, the softening reaction mechanism, the flocculation and sedimentation mechanism, the sludge closed-loop treatment mechanism and the electric cabinet control mechanism are connected in sequence along the treatment flow direction of the water body; The high-hardness water body high-efficiency softening and hardness removal process comprises the following raw water treatment steps: S1: raw water is treated by the pre-treatment mechanism to obtain ultrafiltration effluent; S2: the ultrafiltration effluent enters the softening reaction mechanism, and a medicament is added under the control of the electric cabinet control mechanism to perform softening and flocculation reaction; S3: after reaction, the water body enters the flocculation and sedimentation mechanism to perform solid-liquid separation, to obtain softening water supernatant and calcium carbonate sludge; S4: the softening water supernatant enters the softening water storage and recycling mechanism for storage and recycling.

2. The process of claim 1, wherein the process is characterized by: The calcium carbonate sludge enters the sludge closed-loop treatment mechanism, is buffered and aerated by the sludge buffer tank, and is dewatered by the plate-and-frame filter press to produce filter water, which is returned to the flocculation and sedimentation mechanism together with the blowdown water of the reaction kettle, and the supernatant after treatment of the settling tank is returned to the pre-treatment mechanism.

3. The process of claim 2, wherein the process is characterized by: The pre-treatment mechanism is configured to remove impurities from raw water to obtain ultrafiltration effluent; The softening reaction mechanism is connected with the effluent outlet of the pre-treatment mechanism, and comprises a reaction kettle provided with a dosing mechanism and a first pH probe for adding a medicament to the ultrafiltration effluent to perform softening reaction; The flocculation and sedimentation mechanism is connected with the effluent outlet of the softening reaction mechanism, and comprises a settling tank provided with a second pH probe and an inclined plate for solid-liquid separation of the water body after reaction; The sludge closed-loop treatment mechanism is connected with the sludge outlet of the flocculation and sedimentation mechanism, and comprises a sludge buffer tank and a plate-and-frame filter press connected in sequence; The softening water storage and recycling mechanism is connected with the supernatant outlet of the flocculation and sedimentation mechanism, and comprises a softening water tank. The filter water outlet of the plate-and-frame filter press and the blowdown outlet of the reaction kettle are connected with the flocculation and sedimentation mechanism, so that the filter water and the blowdown water of the reaction kettle are returned to the settling tank for treatment, and the settling tank is further provided with a circulation pipeline connected with the pre-treatment mechanism for returning the supernatant of the settling tank to the pre-treatment mechanism.

4. The process of claim 3, wherein the process is characterized by: The electric cabinet control mechanism is in communication connection with the first pH probe and the dosing mechanism, and is used for closed-loop control of the medicament addition amount of the dosing mechanism according to the detection value of the first pH probe.

5. The process as claimed in claim 3, wherein the process is characterized by: The reaction kettle comprises a first-stage rectangular reactor and a second-stage rectangular reactor connected in series, the dosing mechanism of the first-stage rectangular reactor is used for adding sodium carbonate solution, and the dosing mechanism of the second-stage rectangular reactor is used for adding a flocculant.

6. The process as claimed in claim 5, wherein the process is characterized by: A flow guide groove is arranged in the reaction kettle, the water inlet of the reaction kettle is located at the upper portion, and the water outlet is located at the lower portion, and the water flow is guided to slowly rise from the lower portion through the flow guide groove.

7. The process as claimed in claim 3, wherein the process is characterized by: The inclined plate in the settling tank is a slope plate, the included angle between the slope plate and the horizontal plane is 60°, and the plate spacing is 5 cm; and the rising flow rate of the settling tank is configured as 0.56 mm / s.

8. The process as claimed in claim 3, wherein the process is characterized by: The aerated stirring device in the sludge buffer tank comprises a stirring pipe provided with air holes.

9. The process as claimed in claim 4, wherein the process is characterized by: The softened water tank is provided with a liquid level sensor and a water supplement pipeline, and the electric cabinet control mechanism is in communication connection with the liquid level sensor and a water supplement valve on the water supplement pipeline, so as to automatically control water supplement according to the liquid level.

10. The process as claimed in claim 4, wherein the process is characterized by: The electric cabinet control mechanism comprises a PLC controller, the water outlet of the flocculation and precipitation mechanism is further provided with a second pH probe, the second pH probe is in communication connection with the electric cabinet control mechanism, and the electric cabinet control mechanism is configured to adjust the medicament adding amount of the softening reaction mechanism according to the detection value of the second pH probe.

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