Acid wastewater treatment method and device

Abstract

The invention discloses an acid wastewater treatment method and device, and belongs to the technical field of water pollution treatment. Enabling the wastewater in the physicochemical treatment tank to flow into a buffer tank; a physicochemical pH meter detects the pH value of the physicochemical treatment pool in real time to obtain the pH value of the physicochemical pool; adjusting an alkali dosing assembly or an acid dosing assembly in real time according to the pH value of the physicochemical pool to add alkali or acid to the buffer pool for pH adjustment; pumping the wastewater subjected to pH regulation in the buffer pool into a biochemical treatment pool, and detecting the pH value of a nitration section in the biochemical treatment pool in real time through a biochemical pH meter to obtain a biochemical pH value; an alkali dosing pump of an alkali dosing assembly is controlled according to the biochemical pH value and different intervals, and the pH of the wastewater in the biochemical treatment pond is adjusted; the biochemical treatment pond is used for carrying out biochemical treatment on the wastewater subjected to pH regulation in the step 4, and the treated wastewater is discharged through a drainage pipe. Through the scheme of pre-adjusting and fine adjusting the pH, the dosing cost can be greatly reduced, and a biochemical system is more controllable and more stable.

Description

Technical Field

[0001] The invention relates to a method and a device for treating acidic wastewater, belonging to the technical field of water pollution treatment. Background Art

[0002] Industrial acidic wastewater mainly comes from production wastewater from the chemical, metal surface treatment, photovoltaic cells, semiconductor electronics and other industries. For example, low pH wastewater such as sulfuric acid, hydrochloric acid, HF, HNO3 will be produced during the synthesis, etching, pickling, desulfurization and other production processes. The wastewater often contains heavy metal pollutants and medium organic pollutants such as cleaning agents. The wastewater composition is relatively complex and the process treatment process is relatively long.

[0003] The typical treatment method involves removing pollutants through neutralization, coagulation, sedimentation, and biochemical methods. However, the discharge cycle of acidic wastewater is unstable, and the discharged water quality and quantity fluctuate greatly, often making it difficult to continuously treat the wastewater in multiple stages. If the coagulation dosage is insufficient or excessive, the treatment effect will not be achieved, and instead secondary pollution of the sludge and treatment costs will increase. This is especially true when mixed acidic wastewater, containing organic matter, total nitrogen, fluorine, and suspended solids, must be treated simultaneously. For physicochemical and biochemical treatment processes, whether operated in batch or continuous mode, ensuring the continuity of the front-end and back-end process systems and controlling the optimal reaction environment for physicochemical and biochemical treatment to achieve stable treatment results are challenges faced by this type of industrial wastewater.

[0004] Irregular fluctuations in the neutralization and coagulation treatment phase, coupled with improper operation or control, can easily lead to overdosing and excessive sludge production. Insufficient dosing, on the other hand, can hinder sludge settling and incomplete removal of fluoride, silicon, and metal ions, complicating subsequent microbial treatment of organic and nitrogen pollutants. Precise pH control, in particular, is a key factor in both coagulation and sedimentation and biological sludge growth, and a limiting factor in achieving intelligent, low-energy, and stable acid wastewater treatment. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the problem that excessive dosage of chemicals easily produces excessive sludge, while insufficient dosage makes it difficult for sludge to settle, and fluorine, silicon and metal ions are not completely removed, which increases the difficulty of microbial treatment of organic matter and nitrogen pollutants in the later stage, the present invention provides a method for treating acidic wastewater.

[0006] Technical solution: To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A method for treating acidic wastewater comprises the following steps:

[0008] Step 1: The wastewater in the physicochemical treatment pool flows into the buffer pool through the physicochemical outlet pipe; the physicochemical pH meter detects the pH value of the physicochemical treatment pool in real time to obtain the pH value of the physicochemical pool;

[0009] Step 2: According to the pH value of the physicochemical pool, the alkali dosing component or the acid dosing component is adjusted in real time to add alkali or acid to the buffer pool to adjust the pH;

[0010] Step 3: Pump the wastewater after pH adjustment in the buffer tank into the biochemical treatment tank, and use a biochemical pH meter to detect the pH value of the nitrification section in the biochemical treatment tank in real time to obtain the biochemical pH value;

[0011] Step 4, controlling the alkali dosing pump of the alkali dosing component in different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment pool;

[0012] Step 5: The biochemical treatment tank performs biochemical treatment on the wastewater after pH adjustment in step 4, and discharges the treated wastewater through a drain pipe.

[0013] Preferably, in step 2, the calculation method for adjusting the amount of alkali or acid added to the buffer tank by the alkali dosing component or the acid dosing component in real time according to the pH value of the physicochemical tank is as follows:

[0014] When the pH value of the physicochemical pool is ≥7, the following formula is used to obtain the pre-acidification dosage:

[0015]

[0016] Wherein, J1 represents the pre-adjusted acid dosage, β represents the dosage safety factor, Q represents the influent flow rate of the buffer tank, N represents the neutralization coefficient of the acid reagent H2SO4, X″0 represents the pH value of the physicochemical treatment tank when the pH is greater than 7, ρ1 represents the density of the acid reagent, y1 represents the mass concentration ratio of the acid reagent, and X0 represents the pre-adjusted target pH value of the buffer tank;

[0017] When the pH value of the physicochemical pool is less than 7, the following formula is used to obtain the pre-adjusted alkali dosage:

[0018]

[0019] Wherein, J2 represents the pre-adjusted alkali dosage, β represents the dosage safety factor, Q represents the inlet flow rate of the buffer tank, M represents the neutralization coefficient of the alkali agent NaOH, X0′ represents the pH value of the physicochemical treatment tank when the pH is less than 7, ρ2 represents the density of the alkali agent, y2 represents the mass concentration ratio of the alkali agent, and X0 represents the pre-adjusted target pH value of the buffer tank.

[0020] Preferably, the pH value of the buffer tank is detected in real time by a pre-adjusted pH meter to obtain a pre-adjusted pH value, and the safety factor β of the dosage is adjusted according to the pre-adjusted pH value.

[0021] Preferably: In step 4, the method for controlling the alkali dosing pump of the alkali dosing component according to different intervals of biochemical pH value is as follows:

[0022] Step 41: When the biochemical pH value x is within the first threshold range: x<7.2; in this range, the first opening is adjusted to increase the value as follows:

[0023]

[0024] The first real-time adjustment of the opening ratio is as follows:

[0025]

[0026] Among them, Δt1 is the first opening adjustment amplitude, k is the amplitude modulation ratio time, x is the biochemical pH value, i is the i-th cycle number of interval dosing, T1 is the first dosing cycle, v is the pH change rate, p1 is the first real-time adjustment opening ratio, p0 is the initial opening ratio of the dosing pump, when x increases with time, the formula is "-", when x decreases with time, the formula is "+";

[0027] Step 42: When the biochemical pH value x is within the second threshold range: 7.2≤x<7.5, in this range, the second opening time is adjusted as follows:

[0028]

[0029] The second real-time adjustment ratio is as follows:

[0030]

[0031] Among them, Δt2 is the second opening adjustment increase, T2 is the second dosing cycle, and p2 is the second real-time adjustment opening ratio;

[0032] Step 43: When the biochemical pH value x is within the third threshold range: 7.5≤x<7.8; in this range, the third opening time is adjusted as follows:

[0033]

[0034] The third real-time adjustment ratio is as follows:

[0035]

[0036] Among them, Δt3 is the third opening adjustment increase, T3 is the third dosing cycle, and p3 is the third real-time adjustment opening ratio;

[0037] Step 44 : When the biochemical pH value x is within the fourth threshold range: x≥7.8, the alkali dosing pump stops, ie, p4=0, and dosing stops.

[0038] Another object of the present invention is to provide an acidic wastewater treatment device, comprising a control unit, and a physicochemical treatment tank, a buffer tank, and a biochemical treatment tank connected in sequence;

[0039] The physicochemical treatment pool is provided with a physicochemical pH meter;

[0040] The buffer tank is provided with an alkali dosing component and an acid dosing component;

[0041] The alkali dosing component is in communication with the biochemical treatment tank;

[0042] The biochemical treatment pool is provided with a biochemical pH meter;

[0043] The physicochemical pH meter, the alkali dosing component, and the acid dosing component are respectively connected to the control unit.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 2. The present invention designs a buffer tank to pre-adjust the pH. After the effluent after physicochemical treatment is adjusted to a pH range more suitable for biochemical treatment, the effluent is automatically controlled by a multi-threshold pH control program for physicochemical treatment. The pre-adjustment + fine-tuning pH scheme can greatly reduce the cost of dosing, and the biochemical system is more controllable and stable.

[0046] 3. The present invention adopts a multi-threshold pH automatic control system, which eliminates the need for a frequency converter to drive the dosing pump, avoiding frequent manual adjustment of the dosing pump stroke. The pH changes in the wastewater are monitored in real time by an instrument. The system can automatically adjust the dosage time and total amount of the agent within different pH threshold ranges. The multi-threshold adjustment mechanism ensures that the pH value of the system fluctuates within a smaller range, reduces the use of drugs, and achieves precise control of water quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of the acidic wastewater treatment method.

[0048] In the figure, 1 is the collection tank, 12 is the aeration hole, 13 is the collection tank level gauge, 21 is the physical and chemical pump,

[0049] 22 is the physicochemical water inlet pipe, 3 is the physicochemical treatment tank, 31 is the mixing area, 32 is the flocculation area, 33 is the mixer, 34 is the sedimentation area, 35 is the inclined tube packing assembly, 36 is the physicochemical water outlet pipe,

[0050] 37 is a physicochemical pH meter, 4 is a buffer tank, 42 is a buffer tank level gauge, 43 is a pre-adjusted pH meter, 44 is an alkali dosing component, 45 is an acid dosing component, 51 is a biochemical pump, 52 is a biochemical water inlet pipe,

[0051] 6 is the biochemical treatment tank, 62 is the nitrification section, 63 is the denitrification section, 64 is the biochemical sedimentation section, 641 is the sludge discharge pipe, 65 is the ORP meter, 66 is the biochemical pH meter, 67 is the drainage return pump,

[0052] 671 is the drainage return pipe, 68 is the return sludge pump, 681 is the sludge return pipe, and 69 is the drainage pipe. DETAILED DESCRIPTION

[0053] The present invention is further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, modifications of various equivalent forms of the present invention made by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0054] Example 1

[0055] In the process of acidic wastewater treatment, due to the irregular fluctuation of the neutralization and coagulation treatment in the front stage, improper operation or control, it is easy to over-dosage and produce too much sludge. Insufficient dosage will make the sludge difficult to settle, and the removal of fluorine, silicon and metal ions will not be complete, which increases the difficulty of microbial treatment of organic matter and nitrogen pollutants in the back stage. In view of this, this embodiment provides a method for treating acidic wastewater, such as Figure 1 As shown, the following steps are included:

[0056] Step 1: The wastewater in the physicochemical treatment tank 3 flows into the buffer tank 4 through the physicochemical outlet pipe 36; the physicochemical pH meter 37 detects the pH value of the physicochemical treatment tank 3 in real time to obtain the pH value of the physicochemical tank;

[0057] Step 2: adjust the pH value of the buffer tank 4 by adding alkali or acid by adjusting the alkali dosing component 44 or the acid dosing component 45 in real time according to the pH value of the physicochemical tank;

[0058] Step 3: Pump the wastewater after pH adjustment in the buffer tank 4 into the biochemical treatment tank 6, and use the biochemical pH meter 66 to detect the pH value of the nitrification section 62 in the biochemical treatment tank 6 in real time to obtain the biochemical pH value;

[0059] Step 4, controlling the alkali dosing pump of the alkali dosing component 44 in different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment tank 6;

[0060] In step 5, the biochemical treatment tank 6 performs biochemical treatment on the wastewater after pH adjustment in step 4, and discharges the treated wastewater through the drain pipe 69.

[0061] The present invention designs a buffer tank to pre-adjust the pH. After adjusting the effluent after physicochemical treatment to a pH range more suitable for biochemical treatment, the effluent is automatically controlled by a multi-threshold pH control program for physicochemical treatment. The pre-adjustment + fine-tuning pH scheme can greatly reduce the dosing cost and make the biochemical system more controllable and stable.

[0062] The present invention uses a multi-threshold pH automatic control system, which eliminates the need for a frequency converter to drive the dosing pump, avoiding frequent manual adjustment of the dosing pump stroke. The pH changes in the wastewater are monitored in real time by an instrument. The system can automatically adjust the dosage time and total amount of the agent within different pH threshold ranges. The multi-threshold adjustment mechanism ensures that the pH value of the system fluctuates within a smaller range, reduces the use of drugs, and achieves precise control of water quality.

[0063] Example 2

[0064] This embodiment provides a method for treating acidic wastewater. Figure 1 As shown, the following steps are included:

[0065] Step 1: The wastewater in the physicochemical treatment tank 3 flows into the buffer tank 4 through the physicochemical outlet pipe 36; the physicochemical pH meter 37 detects the pH value of the physicochemical treatment tank 3 in real time to obtain the pH value of the physicochemical tank;

[0066] Step 2: adjust the pH value of the buffer tank 4 by adding alkali or acid by adjusting the alkali dosing component 44 or the acid dosing component 45 in real time according to the pH value of the physicochemical tank;

[0067] Industrial acidic wastewater often contains pollutants such as ammonia nitrogen, organic matter, and suspended solids. In the conventional nitrification and denitrification process for treating such wastewater, the nitrification process converts NH3-N into NO3-N, which will produce a certain acidity. + The denitrification process converts NO3-N into N2, which will replenish some alkalinity. In order to ensure the concentration of sludge and NO3-N treated by the system, the biochemical precipitation will return the muddy water to the nitrification process.

[0068] The nitrification process itself increases acidity, and at the same time, due to the fluctuation of the influent pH, the pH of the nitrification section often continues to drop, resulting in the inhibition of the growth of nitrifying bacteria and difficulty in normal operation of the system. The pH of the front-end nitrification section is the key to the stable pH conditions of the entire biochemical system.

[0069] The pH value of the buffer tank generally fluctuates between 5 and 10, depending on the pollutants being treated. Large pH fluctuations are extremely harmful to subsequent biochemical microorganisms. This solution automatically controls the pH of the buffer tank and the pH value downstream of the nitrification section of the biochemical treatment tank, adjusting the pH value to the range of 7-8 required for biological reactions. This pre-adjustment allows the dosage to be controlled within a controllable range in real time based on the changing influent water quality, which is also conducive to precise pH control in the subsequent biochemical process. Precision dosing is automatically controlled through a multi-threshold program based on the pH value downstream of the nitrification section of the biochemical treatment tank.

[0070] The pH of raw water is generally 1-2, and the pH of effluent after physical and chemical treatment is 5-10. Different pollutants such as fluorine, silicon, calcium, and iron have different pH requirements for precipitation removal. The pH conditions of the nitrification section of the biochemical treatment tank are stabilized by pre-adjustment in the buffer tank.

[0071] The target control range of pH value in nitrification section is 7.5-7.8, and the pH in denitrification section will generally increase slightly by 0.2-0.5 pH values. By controlling the pH of nitrification section at the water inlet end, the pH conditions for the growth of microorganisms in different units of the biochemical treatment pool can be guaranteed.

[0072] The key to this solution is to intelligently maintain a constant alkalinity for nitrification, ensuring a stable environment for the entire removal system. At the same time, it can precisely control and adjust the dosage of the drug to avoid excessive waste of the drug.

[0073] The inlet flow rate is Q (L / h), the buffer tank pre-adjustment target pH value x0x0 is a preset value of 7-8, the physicochemical treatment tank pH value <7 is recorded as x0' (5-7), the physicochemical treatment tank pH value ≥7 is recorded as x0" (7-10), and the physicochemical treatment tank pH value is obtained online by a 37 physicochemical pH meter. According to the value x0' or x0" obtained by the physicochemical pH meter, the pH value is pre-adjusted by adding acid or alkali.

[0074] The neutralization coefficient of the acid agent H2SO4 is Ng / mol, the mass concentration ratio y1 of the acid agent is 0.1-0.2, the density of the acid agent is ρ1kg / L, and the pre-adjusted acid agent dosage J1L / h is obtained by inputting the following formula into the PLC automatic control program.

[0075] When the pH value of the physicochemical pool is ≥7, the following formula is used to obtain the pre-acidification dosage:

[0076]

[0077] Wherein, J1 represents the pre-adjusted acid dosage, β represents the dosage safety factor, Q represents the inlet flow rate of the buffer tank, N represents the neutralization coefficient of the acid agent H2SO4, X″0 represents the pH value of the physicochemical treatment tank when the pH is greater than 7, ρ1 represents the density of the acid agent, y1 represents the mass concentration ratio of the acid agent, and X0 represents the pre-adjusted target pH value of the buffer tank; the neutralization coefficient of the alkali agent NaOH is Mg / mol, the mass concentration ratio of the alkali agent y2 is 0.1-0.2, and the density of the alkali agent is ρ2kg / L.

[0078] The initial alkali agent dosage J2L / h is input into the PLC automatic control program according to the following formula and obtained in real time.

[0079] When the pH value of the physicochemical pool is less than 7, the following formula is used to obtain the pre-adjusted alkali dosage:

[0080]

[0081] Wherein, J2 represents the pre-adjusted alkali dosage, β represents the dosage safety factor, Q represents the inlet flow rate of the buffer tank, M represents the neutralization coefficient of the alkali agent NaOH, X0′ represents the pH value of the physicochemical treatment tank when the pH is less than 7, ρ2 represents the density of the alkali agent, y2 represents the mass concentration ratio of the alkali agent, and X0 represents the pre-adjusted target pH value of the buffer tank.

[0082] Refer to J1L / h and J2L / h for the outflow rate and pump type of the alkali dosing assembly 44 and the acid dosing assembly 45. The online feedback value of the pre-adjusted pH meter 43 is used to verify the automatic dosing program. If there is any deviation, the dosing safety factor β is appropriately adjusted to 0.9-1.2.

[0083] x0 is a preset value with a certain range. It can be manually adjusted according to the changing factors of the actual wastewater, such as the influence of buffer ions, changes in reaction conditions, instrument detection feedback time, etc. The ultimate goal is to control the pH of the acidic wastewater after physical and chemical treatment to the target range of 7-8 that is suitable for biochemistry.

[0084] Step 3: Pump the wastewater after pH adjustment in the buffer tank 4 into the biochemical treatment tank 6, and use the biochemical pH meter 66 to detect the pH value of the nitrification section 62 in the biochemical treatment tank 6 in real time to obtain the biochemical pH value;

[0085] Step 4, controlling the alkali dosing pump of the alkali dosing component 44 in different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment tank 6;

[0086] In step 5, the biochemical treatment tank 6 performs biochemical treatment on the wastewater after pH adjustment in step 4, and discharges the treated wastewater through the drain pipe 69.

[0087] Example 3

[0088] This embodiment provides a method for treating acidic wastewater. Figure 1 As shown, the following steps are included:

[0089] Step 1: The wastewater in the physicochemical treatment tank 3 flows into the buffer tank 4 through the physicochemical outlet pipe 36; the physicochemical pH meter 37 detects the pH value of the physicochemical treatment tank 3 in real time to obtain the pH value of the physicochemical tank;

[0090] Step 2: adjust the pH value of the buffer tank 4 by adding alkali or acid by adjusting the alkali dosing component 44 or the acid dosing component 45 in real time according to the pH value of the physicochemical tank;

[0091] Step 3: Pump the wastewater after pH adjustment in the buffer tank 4 into the biochemical treatment tank 6, and use the biochemical pH meter 66 to detect the pH value of the nitrification section 62 in the biochemical treatment tank 6 in real time to obtain the biochemical pH value;

[0092] Step 4, controlling the alkali dosing pump of the alkali dosing component 44 in different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment tank 6;

[0093] After pre-adjustment, the pH value of the buffer tank is close to the target pH range of the biological treatment tank. However, due to the influence of microbial growth, dosing reaction time, instrument feedback time, etc., the pH value curve with running time often fluctuates greatly when the dosing rate is constant or changed. Controlling this fluctuation can ensure accurate dosing, save alkali, and maintain the biochemical stability of the system.

[0094] The alkali dosing pump is controlled according to different intervals. Different dosing cycles are set for each interval. The proportion of the dosing pump opening time in each cycle is different. The automatic control system reads the real-time changing pH value online. The pH value is linked to the interval dosing pump for linkage control. Finally, the pH value change curve over time fluctuates slightly within the target value range and tends to be flat.

[0095] Method for controlling the alkali dosing pump of the alkali dosing component 44 in different intervals according to the biochemical pH value:

[0096] Step 41: When the biochemical pH value x is within the first threshold range: x < 7.2. In this range, the dosing cycle is set to T1min. The pump is initially set to be on for 0.5T1 and off for 0.5T1, i.e., the dosing pump on-time ratio p0 = 50%. Based on the online pH value x, where x is the pH value obtained by monitoring at the i-th cycle, the pH change rate vpH / min, where i is the i-th cycle of the interval dosing (increasing with time, taking an integer, i in the first step starts at 3 and ends at 6), the on-time adjustment increase Δt(s) is designed based on the pH change rate. The design is based on the difference between the pH value at the i-th cycle within the i-th cycle and the target interval threshold, as well as the proportional relationship between the difference and the pH change rate. ks is the amplitude modulation ratio time, with k ranging from 1.0 to 1.1. The first on-time adjustment increase is as follows:

[0097]

[0098] The first real-time adjustment of the opening ratio is as follows:

[0099]

[0100] Where Δt1 is the first adjustment ramp, k is the modulation ratio time, x is the biochemical pH value, i is the i-th interval dosing cycle, T1 is the first dosing cycle, v is the pH change rate, p1 is the first real-time adjustment on-time percentage, and p0 is the initial on-time percentage of the dosing pump. p0 = 50%. If x increases over time, the formula uses "-"; if x decreases over time, the formula uses "+". The p1 value has an open control limit of 52% to 42%. The v value can be set between 0.005 and 0.015. This value is an empirical value for stable operation of water with different pH levels. T1 can also be manually set. To avoid overdosing, T1 is set between 1 and 2 minutes. The number of i cycles is generally 3, 4, 5, or 6 in the first sequence.

[0101] Step 42: When the biochemical pH value x is within the second threshold range: 7.2 ≤ x < 7.5. In this range, the pH value after dosing adjustment reaches the second threshold range. The closer it gets to the target range, the smaller the number of adjustment cycles becomes, and the dosing ratio is lowered to accurately reduce the dosage. Because a small amount of dosing can cause significant pH changes in the high pH range of around 8, considering the impact of reaction time and lag adjustment, the second threshold range is initially set to 60% of the first threshold range to reduce fluctuations. The second opening adjustment increment is as follows:

[0102]

[0103] The second real-time adjustment ratio is as follows:

[0104]

[0105] Where Δt2 is the second opening adjustment increment, T2 is the second dosing period, and p2 is the second real-time adjustment opening ratio. The p2 value open setting control limit is 29% to 42%, T2 is set between 0.6 and 1 minute, and i is set to 2 or 3 in the second sequence.

[0106] Step 43: When the biochemical pH value x is within the third threshold range: 7.5≤x<7.8. In this range, the pH value x of the nitrification section is adjusted to the target range by controlling the dosing pump opening ratio in the previous dosing range. The third opening adjustment increment is as follows:

[0107]

[0108] The third real-time adjustment ratio is as follows:

[0109]

[0110] Where Δt3 is the third opening adjustment increment, T3 is the third dosing period, and p3 is the third real-time adjustment opening ratio. The p3 value open setting control limit is 9% to 26%, T3 is set at 0.5-0.6 minutes, and i in the third sequence is set at 1,2.

[0111] Step 44: When the biochemical pH value x is within the fourth threshold range: x≥7.8, the alkali dosing pump stops, ie, p4=0, and dosing stops.

[0112] After stopping the dosing, the pH value will fluctuate due to the water quality fluctuations of continuous water inflow and muddy water return. The system monitors the pH value online. Once it falls back to the control range corresponding to the above four steps, the corresponding opening and closing ratio of the alkali dosing pump will be adjusted according to the algorithm program set by the system.

[0113] In step 5, the biochemical treatment tank 6 performs biochemical treatment on the wastewater after pH adjustment in step 4, and discharges the treated wastewater through the drain pipe 69.

[0114] Example 4

[0115] This embodiment provides a method for treating acidic wastewater. Figure 1 As shown, the following steps are included:

[0116] Step 1: The wastewater in the physicochemical treatment tank 3 flows into the buffer tank 4 through the physicochemical outlet pipe 36; the physicochemical pH meter 37 detects the pH value of the physicochemical treatment tank 3 in real time to obtain the pH value of the physicochemical tank;

[0117] Step 2: adjust the pH value of the buffer tank 4 by adding alkali or acid by adjusting the alkali dosing component 44 or the acid dosing component 45 in real time according to the pH value of the physicochemical tank;

[0118] Step 3: Pump the wastewater after pH adjustment in the buffer tank 4 into the biochemical treatment tank 6, and use the biochemical pH meter 66 to detect the pH value of the nitrification section 62 in the biochemical treatment tank 6 in real time to obtain the biochemical pH value;

[0119] The pH value of the buffer tank generally fluctuates between 5 and 10, depending on the pollutants being treated. Large pH fluctuations are extremely harmful to subsequent biochemical microorganisms. This solution automatically controls the pH of the buffer tank and the pH value downstream of the nitrification section of the biochemical treatment tank, adjusting the pH value to the range of 7-8 required for biological reactions. This pre-adjustment allows the dosage to be controlled within a controllable range in real time based on the changing influent water quality, which is also conducive to precise pH control in the subsequent biochemical process. Precision dosing is automatically controlled through a multi-threshold program based on the pH value downstream of the nitrification section of the biochemical treatment tank.

[0120] The pH of raw water is generally 1-2, and the pH of effluent after physical and chemical treatment is 5-10. Different pollutants such as fluorine, silicon, calcium, and iron have different pH requirements for precipitation removal. The pH conditions of the nitrification section of the biochemical treatment tank are stabilized by pre-adjustment in the buffer tank.

[0121] The target control range of pH value in nitrification section is 7.5-7.8, and the pH in denitrification section will generally increase slightly by 0.2-0.5 pH values. By controlling the pH of nitrification section at the water inlet end, the pH conditions for the growth of microorganisms in different units of the biochemical treatment pool can be guaranteed.

[0122] The key to this solution is to intelligently maintain a constant alkalinity for nitrification, ensuring a stable environment for the entire removal system. At the same time, it can precisely control and adjust the dosage of the drug to avoid excessive waste of the drug.

[0123] The inlet flow rate is Q (L / h), the buffer tank pre-adjustment target pH value x0x0 is a preset value of 7-8, the physicochemical treatment tank pH value <7 is recorded as x0'(5-7), the physicochemical treatment tank pH value ≥7 is recorded as x0"7-10, and the physicochemical treatment tank pH value is obtained online by a 37 physicochemical pH meter. According to the value of x0' or x0" obtained by the physicochemical pH meter, the pH value is pre-adjusted by adding acid or alkali.

[0124] The neutralization coefficient of the acid agent H2SO4 is Ng / mol, the mass concentration ratio y1 of the acid agent is 0.1-0.2, the density of the acid agent is ρ1kg / L, and the pre-adjusted acid agent dosage J1L / h is obtained by inputting the following formula into the PLC automatic control program.

[0125] When the pH value of the physicochemical pool is ≥7, the following formula is used to obtain the pre-acidification dosage:

[0126]

[0127] Wherein, J1 represents the pre-adjusted acid dosage, β represents the dosage safety factor, Q represents the inlet flow rate of the buffer tank, N represents the neutralization coefficient of the acid agent H2SO4, X″0 represents the pH value of the physicochemical treatment tank when the pH is greater than 7, ρ1 represents the density of the acid agent, y1 represents the mass concentration ratio of the acid agent, and X0 represents the pre-adjusted target pH value of the buffer tank; the neutralization coefficient of the alkali agent NaOH is Mg / mol, the mass concentration ratio of the alkali agent y2 is 0.1-0.2, and the density of the alkali agent is ρ2kg / L.

[0128] The initial alkali agent dosage J2L / h is input into the PLC automatic control program according to the following formula and obtained in real time.

[0129] When the pH value of the physicochemical pool is less than 7, the following formula is used to obtain the pre-adjusted alkali dosage:

[0130]

[0131] Where J2 represents the pre-adjusted alkali dosage, β represents the dosage safety factor. The pre-adjusted pH value is obtained by real-time monitoring of the pH value of the buffer tank 4 using the pre-adjusted pH meter 43, and the dosage safety factor β is adjusted based on the pre-adjusted pH value. Q represents the influent flow rate of the buffer tank, M represents the neutralization coefficient of the alkali agent NaOH, X0′ represents the pH value of the physicochemical treatment tank when the pH is less than 7, ρ2 represents the density of the alkali agent, y2 represents the mass concentration ratio of the alkali agent, and X0 represents the pre-adjusted target pH value of the buffer tank.

[0132] Refer to J1L / h and J2L / h for the outflow rate and pump type of the alkali dosing assembly 44 and the acid dosing assembly 45. The online feedback value of the pre-adjusted pH meter 43 is used to verify the automatic dosing program. If there is any deviation, the dosing safety factor β is appropriately adjusted to 0.9-1.2.

[0133] x0 is a preset value with a certain range. It can be manually adjusted according to the changing factors of the actual wastewater, such as the influence of buffer ions, changes in reaction conditions, instrument detection feedback time, etc. The ultimate goal is to control the pH of the acidic wastewater after physical and chemical treatment to the target range of 7-8 that is suitable for biochemistry.

[0134] Step 4, controlling the alkali dosing pump of the alkali dosing component 44 in different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment tank 6;

[0135] After pre-adjustment, the pH value of the buffer tank is close to the target pH range of the biological treatment tank. However, due to the influence of microbial growth, dosing reaction time, instrument feedback time, etc., the pH value curve with running time often fluctuates greatly when the dosing rate is constant or changed. Controlling this fluctuation can ensure accurate dosing, save alkali, and maintain the biochemical stability of the system.

[0136] The alkali dosing pump is controlled according to different intervals. Different dosing cycles are set for each interval. The proportion of the dosing pump opening time in each cycle is different. The automatic control system reads the real-time changing pH value online. The pH value is linked to the interval dosing pump for linkage control. Finally, the pH value change curve over time fluctuates slightly within the target value range and tends to be flat.

[0137] Method for controlling the alkali dosing pump of the alkali dosing component 44 in different intervals according to the biochemical pH value:

[0138] Step 41: When the biochemical pH value x is within the first threshold range: x < 7.2. In this range, the dosing cycle is set to T1min. The pump is initially set to be on for 0.5T1 and off for 0.5T1, i.e., the dosing pump on-time ratio p0 = 50%. Based on the online pH value x, where x is the pH value obtained by monitoring at the i-th cycle, the pH change rate vpH / min, where i is the i-th cycle of the interval dosing (increasing with time, taking an integer, i in the first step starts at 3 and ends at 6), the on-time adjustment increase Δt(s) is designed based on the pH change rate. The design is based on the difference between the pH value at the i-th cycle within the i-th cycle and the target interval threshold, as well as the proportional relationship between the difference and the pH change rate. ks is the amplitude modulation ratio time, with k ranging from 1.0 to 1.1. The first on-time adjustment increase is as follows:

[0139]

[0140] The first real-time adjustment of the opening ratio is as follows:

[0141]

[0142] Where Δt1 is the first adjustment ramp, k is the modulation ratio time, x is the biochemical pH value, i is the i-th interval dosing cycle, T1 is the first dosing cycle, v is the pH change rate, p1 is the first real-time adjustment on-time percentage, and p0 is the initial on-time percentage of the dosing pump. p0 = 50%. If x increases over time, the formula uses "-"; if x decreases over time, the formula uses "+". The p1 value has an open control limit of 52% to 42%. The v value can be set between 0.005 and 0.015. This value is an empirical value for stable operation of water with different pH levels. T1 can also be manually set. To avoid overdosing, T1 is set between 1 and 2 minutes. The number of i cycles is generally 3, 4, 5, or 6 in the first sequence.

[0143] Step 42: When the biochemical pH value x is within the second threshold range: 7.2 ≤ x < 7.5. In this range, the pH value after dosing adjustment reaches the second threshold range. The closer it gets to the target range, the smaller the number of adjustment cycles becomes, and the dosing ratio is lowered to accurately reduce the dosage. Because a small amount of dosing can cause significant pH changes in the high pH range of around 8, considering the impact of reaction time and lag adjustment, the second threshold range is initially set to 60% of the first threshold range to reduce fluctuations. The second opening adjustment increment is as follows:

[0144]

[0145] The second real-time adjustment ratio is as follows:

[0146]

[0147] Where Δt2 is the second opening adjustment increment, T1 is the second dosing period, and p2 is the second real-time adjustment opening ratio. The p2 value open setting control limit is 29% to 42%, T2 is set between 0.6 and 1 minute, and i in the second sequence is set to 2 or 3.

[0148] Step 43: When the biochemical pH value x is within the third threshold range: 7.5≤x<7.8. In this range, the pH value x of the nitrification section is adjusted to the target range by controlling the dosing pump opening ratio in the previous dosing range. The third opening adjustment increment is as follows:

[0149]

[0150] The third real-time adjustment ratio is as follows:

[0151]

[0152] Where Δt3 is the third opening adjustment increment, T3 is the third dosing period, and p3 is the third real-time adjustment opening ratio. The p3 value open setting control limit is 9% to 26%, T3 is set at 0.5-0.6 minutes, and i in the third sequence is set at 1,2.

[0153] Step 44: When the biochemical pH value x is within the fourth threshold range: x≥7.8, the alkali dosing pump stops, ie, p4=0, and dosing stops.

[0154] After stopping the dosing, the pH value will fluctuate due to the water quality fluctuations of continuous water inflow and muddy water return. The system monitors the pH value online. Once it falls back to the control range corresponding to the above four steps, the corresponding opening and closing ratio of the alkali dosing pump will be adjusted according to the algorithm program set by the system.

[0155] In step 5, the biochemical treatment tank 6 performs biochemical treatment on the wastewater after pH adjustment in step 4, and discharges the treated wastewater through the drain pipe 69.

[0156] Example 5

[0157] In the process of acidic wastewater treatment, due to the irregular fluctuation of the neutralization and coagulation treatment in the front stage, improper operation or control, it is easy to over-dosage and produce too much sludge. Insufficient dosage will make the sludge difficult to settle, and the removal of fluorine, silicon and metal ions will not be complete, which increases the difficulty of microbial treatment of organic matter and nitrogen pollutants in the back stage. In view of this, this embodiment provides an acidic wastewater treatment device, such as Figure 1 As shown, it includes a control unit, and a physicochemical treatment pool 3, a buffer pool 4, and a biochemical treatment pool 6 that are connected in sequence;

[0158] The physicochemical treatment tank 3 is provided with a physicochemical pH meter 37;

[0159] The buffer tank 4 is provided with an alkali dosing component 44 and an acid dosing component 45;

[0160] The alkali dosing component 44 is in communication with the biochemical treatment tank 6;

[0161] The biochemical treatment pool 6 is provided with a biochemical pH meter 66;

[0162] The physicochemical pH meter 37 , the alkali dosing component 44 , and the acid dosing component 45 are respectively connected to the control unit.

[0163] The control unit is used to adjust the alkali dosing component 44 or the acid dosing component 45 in real time according to the pH value of the physicochemical pool to add alkali or acid to the buffer pool 4 to adjust the pH, and is used to control the alkali dosing pump of the alkali dosing component 44 according to different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment pool 6;

[0164] Example 6

[0165] This embodiment provides an acidic wastewater treatment device, such as Figure 1 As shown, it includes a control unit, and a physicochemical treatment pool 3, a buffer pool 4, and a biochemical treatment pool 6 connected in sequence; the physicochemical treatment pool 3 and the buffer pool 4 are connected via a physicochemical outlet pipe 36; the buffer pool 4 and the biochemical treatment pool 6 are connected via a biochemical inlet pipe 52, and a biochemical pump 51 is provided on the biochemical inlet pipe 52.

[0166] The physicochemical treatment pool 3 is provided with a physicochemical pH meter 37; the physicochemical treatment pool 3 includes a mixing zone 31, a flocculation zone 32, and a sedimentation zone 34 connected in sequence, the physicochemical pH meter 37 is provided in the flocculation zone 32, the flocculation zone 32 is provided with a stirrer 33, and the sedimentation zone 34 is provided with an inclined tube packing assembly 35.

[0167] The buffer tank 4 is provided with an alkali dosing component 44 and an acid dosing component 45;

[0168] The alkali dosing component 44 is connected to the biochemical treatment tank 6; the buffer tank 4 is provided with a pre-adjusted pH meter 43, and the pre-adjusted pH meter 43 is connected to the control unit.

[0169] The biochemical treatment pool 6 is provided with a biochemical pH meter 66 ; the biochemical treatment pool 6 includes a nitrification section 62 , a denitrification section 63 and a biochemical precipitation section 64 connected in sequence, the nitrification section 62 is connected to the alkali dosing component 44 , and the biochemical pH meter 66 is provided in the nitrification section 62 ; the denitrification section 63 is provided with an ORP meter 65 .

[0170] The physicochemical pH meter 37 , the alkali dosing component 44 , and the acid dosing component 45 are respectively connected to the control unit.

[0171] The control unit is used to adjust the alkali dosing component 44 or the acid dosing component 45 in real time according to the pH value of the physicochemical pool to add alkali or acid to the buffer pool 4 to adjust the pH, and is used to control the alkali dosing pump of the alkali dosing component 44 according to different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment pool 6;

[0172] The biochemical treatment pool 6 includes a drainage return pipe 671 and a sludge return pipe 681; the water outlet of the biochemical precipitation section 64 is connected to the drainage pipe 69, the water inlet end of the drainage return pipe 671 is connected to the drainage pipe 69, the water outlet end of the drainage return pipe 671 is connected to the nitrification section 62, and the drainage return pipe 671 is provided with a drainage return pump 67; the sludge outlet of the biochemical precipitation section 64 is connected to the sludge discharge pipe 641, the sludge inlet end of the sludge return pipe 681 is connected to the sludge discharge pipe 641, the sludge outlet end of the sludge return pipe 681 is connected to the sludge discharge pipe 641, and the sludge return pipe 681 is connected to the nitrification section 62, and the sludge return pipe 681 is provided with a return sludge pump 68.

[0173] Example 7

[0174] This embodiment provides an acidic wastewater treatment device, such as Figure 1 As shown, it includes a control unit, and a collection tank 1, a physicochemical treatment tank 3, a buffer tank 4, and a biochemical treatment tank 6 that are connected in sequence.

[0175] Aeration holes 12 are provided at the bottom of the collection tank 1 , and the aeration holes 12 are evenly distributed at the bottom of the collection tank 1 . The aeration holes 12 are connected to the aerator, and the aerator aerates through the aeration holes 12 to mix the wastewater in the collection tank 1 to achieve preliminary homogenization and uniformity.

[0176] The collecting tank 1 is provided with a collecting tank level gauge 13. The collecting tank level gauge 13 monitors the liquid level of the collecting tank 1 in real time to obtain the collecting tank liquid level.

[0177] The collection tank 1 is connected to the physicochemical treatment tank 3 via a physicochemical water inlet pipe 22, which is provided with a physicochemical pump 21. By controlling the operating frequency of the physicochemical pump 21, the wastewater in the collection tank 1 is pumped into the physicochemical treatment tank 3 through the physicochemical water inlet pipe 22.

[0178] The physicochemical treatment tank 3 includes a mixing zone 31, a flocculation zone 32, and a sedimentation zone 34, which are interconnected in sequence. The flocculation zone 32 is equipped with a stirrer 33 and a physicochemical pH meter 37. The physicochemical pH meter 37 monitors the pH of the flocculation zone 32 in real time to obtain the physicochemical pH. Stirring is performed by the stirrer 33 to provide a hydraulic mixing environment for microorganisms and prevent sludge deposition. The sedimentation zone 34 is equipped with an inclined tube packing assembly 35 to increase sedimentation load and efficiency.

[0179] The physicochemical treatment tank 3 and the buffer tank 4 are connected via a physicochemical water outlet pipe 36 .

[0180] The buffer tank 4 is equipped with a buffer tank level gauge 42, a pre-adjusted pH meter 43, an alkali dosing assembly 44, and an acid dosing assembly 45. The buffer tank level gauge 42 monitors the buffer tank 4's liquid level in real time. The pre-adjusted pH meter 43 monitors the pre-adjusted pH of the buffer tank 4 in real time. Alkali is added to the buffer tank 4 by controlling the alkali dosing assembly 44, while acid is added to the buffer tank 4 by controlling the acid dosing assembly 45.

[0181] The buffer tank 4 is connected to the biochemical treatment tank 6 via a biochemical water inlet pipe 52, which is provided with a biochemical pump 51. By controlling the operating frequency of the biochemical pump 51, the wastewater in the buffer tank 4 is pumped into the biochemical treatment tank 6 through the biochemical water inlet pipe 52.

[0182] The biochemical treatment tank 6 includes a drainage return pipe, a sludge return pipe, and a nitrification section 62, a denitrification section 63, and a biochemical precipitation section 64, which are connected in sequence. The nitrification section 62 is equipped with a microporous aerator to provide an aerobic environment for microorganisms. The nitrification section 62 is connected to the alkali dosing component 44, and alkali is added to the nitrification section 62 by controlling the alkali dosing component. The outlet of the biochemical precipitation section 64 is connected to a drainage pipe 69. The water inlet end of the drainage return pipe is connected to the drainage pipe 69, and the water outlet end of the drainage return pipe is connected to the nitrification section 62. The drainage return pipe is provided with a drainage return pump 67. The sludge outlet of the biochemical precipitation section 64 is connected to a sludge discharge pipe. The sludge inlet end of the sludge return pipe is connected to the sludge discharge pipe, and the sludge outlet end of the sludge return pipe is connected to the nitrification section 62. The sludge return pipe is provided with a return sludge pump 68. The nitrification section 62 is equipped with a biochemical pH meter 66, which monitors the pH of the nitrification section 62 in real time to obtain the biochemical pH. The denitrification section 63 is equipped with an ORP meter 65, which monitors the ORP of the denitrification section 63 in real time to obtain the ORP value. The sludge from the biochemical sedimentation section is returned to the nitrification section via a sludge pump 68 or discharged periodically. The effluent from the biochemical sedimentation section is returned to the nitrification section via a reflux pump 67 or discharged to meet the discharge standards.

[0183] The collection tank level gauge 13, the physicochemical pump 21, the physicochemical pH meter 37, the buffer tank level gauge 42, the pre-adjusted pH meter 43, the alkali dosing assembly 44, and the acid dosing assembly 45 are respectively connected to a control unit. The control unit receives monitoring information from the collection tank level gauge 13, the physicochemical pH meter 37, the buffer tank level gauge 42, and the pre-adjusted pH meter 43 in real time, controls the operating frequency of the physicochemical pump 21, controls the alkali dosing operation of the alkali dosing assembly 44, and controls the acid dosing operation of the acid dosing assembly 45.

[0184] This embodiment provides a buffer tank 4 and controls the operating frequency of the physicochemical pump 21, controls the alkali addition operation of the alkali dosing component 44, and controls the acid addition operation of the acid dosing component 45 based on the monitoring information of the receiving and collecting tank level meter 13, the physicochemical pH meter 37, the buffer tank level meter 42, and the pre-adjusted pH meter 43, thereby solving the problem of irregular fluctuations in the front-end neutralization and coagulation treatment and realizing automatic control operation of the front and rear liquid levels.

[0185] The denitrification section is equipped with an ORP monitor with a monitoring target value of -60 to +60mv. If the ORP is still outside this range when an external carbon source is added to the denitrification section and the aeration volume in the nitrification section is sufficient, the effluent return flow of the biochemical precipitation section will be adjusted. If the ORP is high, the effluent return ratio will be reduced to 30-50%, and if it is low, the effluent return ratio will be increased to 100-150%.

[0186] Wastewater enters the collection tank 1 for temporary storage. In the collection tank 1, the aerator aerates through the aeration holes 12, and the wastewater in the collection tank 1 is used for mixing to obtain a preliminary uniform quality and quantity. The collection tank liquid level gauge 13 monitors the liquid level of the collection tank 1 in real time to obtain the collection tank liquid level. By controlling the working frequency of the physicochemical pump 21, the wastewater in the collection tank 1 is pumped into the physicochemical treatment tank 3 through the physicochemical water inlet pipe 22. In the physicochemical treatment tank 3, the wastewater enters the mixing zone 31, the flocculation zone 32, and the sedimentation zone 34 in turn for physicochemical reaction. The flocculation zone is provided with a stirrer 33, which is conducive to the full physicochemical reaction. The physicochemical treatment tank is provided with an inclined tube packing assembly 35, which can improve the sedimentation load and efficiency. The physicochemical pH meter 37 monitors the pH of the flocculation zone 32 in real time to obtain the physicochemical pH.

[0187] The biochemically treated wastewater flows into the buffer tank 4 through the physicochemical outlet pipe 36. The buffer tank level meter 42 monitors the buffer tank 4's liquid level in real time. The pre-adjusted pH meter 43 monitors the pre-adjusted pH of the buffer tank 4 in real time. Alkali is added to the buffer tank 4 by controlling the alkali dosing assembly 44, and acid is added to the buffer tank 4 by controlling the acid dosing assembly 45.

[0188] By controlling the operating frequency of the biochemical pump 51, the wastewater in the buffer tank 4 is pumped into the biochemical treatment tank 6 through the biochemical water inlet pipe 52. The wastewater undergoes a biochemical reaction in the biochemical treatment tank 6, and the treated water after the biochemical reaction is discharged through the drain pipe 69. The nitrification section 62 is provided with a microporous aerator to provide an aerobic environment for microorganisms. Alkali is added to the nitrification section 62 by controlling the alkali dosing component. The biochemical pH meter 66 monitors the pH of the nitrification section 62 in real time to obtain the biochemical pH. The ORP meter 65 monitors the ORP of the denitrification section 63 in real time to obtain the ORP value. The sludge is pumped into the nitrification section 62 through the sludge return pipe by controlling the return sludge pump 68, and the treated wastewater is pumped into the nitrification section 62 through the drainage return pipe by controlling the drainage return pump 67.

[0189] Example 8

[0190] This embodiment provides a method for treating acidic wastewater, comprising the following steps:

[0191] In step 1, wastewater from collection tank 1 is pumped into physicochemical treatment tank 3 via physicochemical pump 21. Collection tank level gauge 13 monitors the liquid level in collection tank 1 in real time. Buffer tank level gauge 42 monitors the liquid level in buffer tank 4 in real time. Based on the measured collection tank level and the buffer tank level, the physicochemical pump frequency is controlled in real time using the level-physicochemical pump frequency control relationship, achieving automatic and stable control.

[0192] The frequency control relationship of the liquid level physical and chemical pump is:

[0193]

[0194] Where f1 is the pump frequency, f0 is the initial set frequency, α is the frequency increment, t is time, h1 is the collection tank high level, and h2 is the buffer tank level. The automatic start-up conditions are time t (s) and the frequency increment α Hz / 100 seconds. Both t and α can be adjusted based on actual operating conditions. For reference, the value of α in the formula is 0.2-0.3 for a buffer tank low level of 0-3 m, and 0.05-0.15 for a buffer tank high level of 3-4 m. The pump stops if the buffer tank level exceeds 4 m.

[0195] Physicizing pump 21 is controlled based on data feedback from the collection tank level gauge 13. The initial frequency setting for physisicizing pump 21 is 30 Hz, with an upper limit of 40 Hz. In the low-level range of 1.5-3.0 m in the collection tank, the incoming water flow rate varies significantly. By directly linking the collection tank's online liquid level and the physisicizing pump's frequency control curve, automatic and stable control is achieved.

[0196] In the collection tank, the liquid level range is 3.0-4.5m. The frequency increase of the pump is regulated by time to control the outflow rate. The liquid level control is interlocked with the buffer tank in the rear section. The opening self-setting conditions are increased according to the liquid level of the buffer tank to increase the flexible regulation of the buffer and reduce the risk of rear-end operation.

[0197] When the high liquid level in the collection tank is above 4.5m, the pump is stopped and automatically regulated according to the frequency f1 of the physical and chemical pump before the high level.

[0198] Step 2: The wastewater in the physicochemical treatment tank 3 flows into the buffer tank 4 through the physicochemical outlet pipe 36. The physicochemical pH meter 37 detects the pH value of the physicochemical treatment tank 3 in real time to obtain the pH value of the physicochemical tank. The alkali dosing component 44 or the acid dosing component 45 is adjusted in real time according to the pH value of the physicochemical tank to add alkali or acid to the buffer tank 4.

[0199] The inlet flow rate is Q (L / h), the buffer tank pre-adjusted target pH value is x0, x0 is a preset value of 7-8, the physicochemical treatment tank pH value <7 is recorded as x0' (5-7), the physicochemical treatment tank pH value ≥7 is recorded as x0" (7-10), and the physicochemical treatment tank pH value is obtained online by a 37 physicochemical pH meter. According to the value of x0' or x0" obtained by the physicochemical pH meter, the pH value is pre-adjusted by adding acid or alkali.

[0200] The neutralization coefficient of the acid agent H2SO4 is Ng / mol, the mass concentration ratio y1 of the acid agent is 0.1-0.2, the density of the acid agent is ρ1kg / L, and the pre-adjusted acid agent dosage J1L / h is obtained by inputting the following formula into the PLC automatic control program.

[0201] The calculation method for adjusting the alkali dosing component 44 or the acid dosing component 45 to add alkali or acid to the buffer tank 4 in real time according to the pH value of the physicochemical tank is as follows:

[0202] When the pH value of the physicochemical pool is ≥7, the following formula is used to obtain the pre-acidification dosage:

[0203]

[0204] Wherein, J1 represents the pre-adjusted acid dosage, β represents, Q represents the inlet flow rate of the buffer tank, N represents the neutralization coefficient of the acid agent H2SO4, X″0 represents the pH value of the physicochemical treatment tank when the pH is greater than 7, ρ1 represents the density of the acid agent, y1 represents the mass concentration ratio of the acid agent, and X0 represents the pre-adjusted target pH value of the buffer tank. The neutralization coefficient of the alkali agent NaOH is Mg / mol, the mass concentration ratio of the alkali agent y2 is 0.1-0.2, and the density of the alkali agent is ρ2kg / L.

[0205] The initial alkali agent dosage J2L / h is input into the PLC automatic control program according to the following formula and obtained in real time.

[0206] When the pH value of the physicochemical pool is less than 7, the following formula is used to obtain the pre-adjusted alkali dosage:

[0207]

[0208] Among them, J2 represents the pre-adjusted alkali dosage, β represents, Q represents the buffer tank inlet flow rate, M represents the neutralization coefficient of the alkali agent NaOH, X0′ represents the pH value of the physicochemical treatment tank when the pH is less than 7, ρ2 represents the density of the alkali agent, y2 represents the mass concentration ratio of the alkali agent, and X0 represents the pre-adjusted target pH value of the buffer tank.

[0209] Refer to J1L / h and J2L / h for the outflow rate and pump type of the alkali dosing assembly 44 and the acid dosing assembly 45. The online feedback value of the pre-adjusted pH meter 43 is used to verify the automatic dosing program. If there is any deviation, the dosing safety factor β is appropriately adjusted to 0.9-1.2.

[0210] x0 is a preset value with a certain range. It can be manually adjusted according to the changing factors of the actual wastewater, such as the influence of buffer ions, changes in reaction conditions, instrument detection feedback time, etc. The ultimate goal is to control the pH of the acidic wastewater after physical and chemical treatment to the target range of 7-8 that is suitable for biochemistry.

[0211] In step 3, the wastewater from the buffer tank 4 is pumped into the biochemical treatment tank 6 via the biochemical pump 51. The treated wastewater is discharged through the drain pipe 69. A portion of the wastewater is returned to the biochemical treatment tank 6 via the drainage return pipe, and a portion of the sludge is returned to the biochemical treatment tank 6 via the sludge return pipe. A biochemical pH meter 66 monitors the pH of the nitrification section 62 in real time to obtain the biochemical pH value. The alkali dosing pump of the alkali dosing assembly 44 is controlled in different ranges based on the biochemical pH value.

[0212] After pre-adjustment, the pH value of the buffer tank is close to the target pH range of the biological treatment tank. However, due to the influence of microbial growth, dosing reaction time, instrument feedback time, etc., the pH value curve with running time often fluctuates greatly when the dosing rate is constant or changed. Controlling this fluctuation can ensure accurate dosing, save alkali, and maintain the biochemical stability of the system.

[0213] The alkali dosing pump is controlled according to different intervals. Different dosing cycles are set for each interval. The proportion of the dosing pump opening time in each cycle is different. The automatic control system reads the real-time changing pH value online. The pH value is linked to the interval dosing pump for linkage control. Finally, the pH value change curve over time fluctuates slightly within the target value range and tends to be flat.

[0214] Method for controlling the alkali dosing pump of the alkali dosing component 44 in different intervals according to the biochemical pH value:

[0215] Step 31: When the biochemical pH value x is in the first threshold range: x < 7.2. In this range, the dosing cycle is set to T1min, and the pump is initially set to be on for 0.5T1 and off for 0.5T1, that is, the dosing pump is on for a proportion of p0 = 50%. Based on the online pH value x, x is the pH value obtained by monitoring at the i-th cycle number, the pH change rate vpH / min, i is the i-th cycle number of the interval dosing (increasing with time, taking an integer, i in the first step starts at 3 and ends at 6), the on-time adjustment increase Δt(s) is designed based on the pH change rate, and the design basis is based on the difference between the pH value at the i-th cycle number within the i-th cycle time and the target interval threshold, as well as the proportional relationship between the difference and the pH change rate. ks is the amplitude modulation ratio time, k is 1.0-1.1, and the first on-time adjustment increase is as follows:

[0216]

[0217] The first real-time adjustment of the opening ratio is as follows:

[0218]

[0219] Where Δt1 is the first adjustment ramp, k is the modulation ratio time, x is the biochemical pH value, i is the i-th interval dosing cycle, T1 is the first dosing cycle, v is the pH change rate, p1 is the first real-time adjustment on-time percentage, and p0 is the initial on-time percentage of the dosing pump. p0 = 50%. If x increases over time, the formula uses "-"; if x decreases over time, the formula uses "+". The p1 value has an open control limit of 52% to 42%. The v value can be set between 0.005 and 0.015. This value is an empirical value for stable operation of water with different pH levels. T1 can also be manually set. To avoid overdosing, T1 is set between 1 and 2 minutes. The number of i cycles is generally 3, 4, 5, or 6 in the first sequence.

[0220] Calculation of on-time ratio: on-time ratio = on-time / on-time + off-time.

[0221] If the on / off time is set too short, such as <10s, the pneumatic valve will start and stop too frequently, accelerating equipment wear. If the on / off time is set too long, such as >200s, the valve opening and closing intervals are too long, risking excessive dosage and waste, and making it impossible to accurately adjust to the dynamic system. Therefore, this method initially sets the on / off time to no more than 40s.

[0222] Step 32: When the biochemical pH value x is within the second threshold range: 7.2 ≤ x < 7.5. In this range, the pH value after dosing adjustment reaches the second threshold range. The closer it gets to the target range, the smaller the number of adjustment cycles becomes, and the dosing ratio is lowered to accurately reduce the dosage. Because a small amount of dosing can cause significant pH changes in the high pH range of around 8, considering the impact of reaction time and lag adjustment, the second threshold range is initially set to 60% of the first threshold range to minimize fluctuations. The second opening adjustment increment is as follows:

[0223]

[0224] The second real-time adjustment ratio is as follows:

[0225]

[0226] Where Δt2 is the second opening adjustment increment, T2 is the second dosing period, and p2 is the second real-time adjustment opening ratio. The p2 value open setting control limit is 29% to 42%, T2 is set between 0.6 and 1 minute, and i is set to 2 or 3 in the second sequence.

[0227] Step 33: When the biochemical pH value x is within the third threshold range: 7.5≤x<7.8. In this range, the pH value x of the nitrification section is adjusted to the target range by controlling the dosing pump opening ratio in the previous dosing range. The third opening adjustment increment is as follows:

[0228]

[0229] The third real-time adjustment ratio is as follows:

[0230]

[0231] Where Δt3 is the third opening adjustment increment, T3 is the third dosing period, and p3 is the third real-time adjustment opening ratio. The p3 value open setting control limit is 9% to 26%, T3 is set at 0.5-0.6 minutes, and i in the third sequence is set at 1,2.

[0232] Step 34: When the biochemical pH value x is within the fourth threshold range: x≥7.8, the alkali dosing pump stops, ie, p4=0, and dosing stops.

[0233] After stopping the dosing, the pH value will fluctuate due to the water quality fluctuations of continuous water inflow and muddy water return. The system monitors the pH value online. Once it falls back to the control range corresponding to the above four steps, the corresponding opening and closing ratio of the alkali dosing pump will be adjusted according to the algorithm program set by the system.

[0234] Table 1 Existing interval control dosing

[0235] Serial number pH range Dosing pump start time s Dosing pump off time s Opening ratio % 1 x＜7.2 30 30 50％ 2 7.2≤x＜7.5 15 30 33％ 3 7.5≤x＜7.8 5 30 14％

[0236] Table 1 shows the operating data for the existing interval-controlled dosing system, which adjusts the opening ratio. The online pH operating curve of the existing interval-controlled dosing system, as shown in Table 1, shows that when the opening ratio is not adjusted, the operating pH fluctuates greatly, with the maximum change rate reaching 0.16 pH / min.

[0237] Table 2 Interval control dosing of this embodiment

[0238]

[0239]

[0240] As shown in Table 2, the interval-controlled dosing system of this embodiment performs real-time dynamic adjustment of the dosing pump's operating ratio, and the operating data is shown in Table 2. The online pH operating curve of the controlled dosing system of this embodiment, as shown in Table 2, shows that after adjusting the operating ratio, the pH fluctuations within the cycle operation become significantly smoother, essentially maintaining it within the target threshold range, ensuring stable system operation and avoiding drug waste.

[0241] The present invention can realize real-time linkage of multiple parameters, automatic and stable operation, reduce the impact of fluctuations, reduce the risk of process parameter association, and save operating costs.

[0242] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for treating acidic wastewater, characterized in that: The following steps are involved: Step 1: The wastewater in the physicochemical treatment pool (3) flows into the buffer pool (4) through the physicochemical outlet pipe (36); the physicochemical pH meter (37) detects the pH value of the physicochemical treatment pool (3) in real time to obtain the pH value of the physicochemical pool; Step 2, adjusting the pH value of the physicochemical pool in real time by adjusting the alkali dosing component (44) or the acid dosing component (45) by adding alkali or acid to the buffer pool (4); Step 3, pumping the wastewater after pH adjustment in the buffer tank (4) into the biochemical treatment tank (6), and detecting the pH value of the nitrification section (62) in the biochemical treatment tank (6) in real time by a biochemical pH meter (66) to obtain a biochemical pH value; Step 4, controlling the alkali dosing pump of the alkali dosing component (44) in different intervals according to the biochemical pH value to adjust the pH of the wastewater in the biochemical treatment tank (6); In step 5, the biochemical treatment tank (6) performs biochemical treatment on the wastewater after pH adjustment in step 4, and discharges the treated wastewater through the drain pipe (69).

2. The method for treating acidic wastewater according to claim 1, wherein: In step 2, the calculation method for adjusting the amount of alkali or acid added to the buffer tank (4) by the alkali dosing component (44) or the acid dosing component (45) in real time according to the pH value of the physicochemical tank is as follows: When the pH value of the physicochemical pool is ≥7, the following formula is used to obtain the pre-acidification dosage: Wherein, J1 represents the pre-adjusted acid dosage, β represents the dosage safety factor, Q represents the influent flow rate of the buffer tank, N represents the neutralization coefficient of the acid reagent H2SO4, X″0 represents the pH value of the physicochemical treatment tank when the pH is greater than 7, ρ1 represents the density of the acid reagent, y1 represents the mass concentration ratio of the acid reagent, and X0 represents the pre-adjusted target pH value of the buffer tank; When the pH value of the physicochemical pool is less than 7, the following formula is used to obtain the pre-adjusted alkali dosage: Wherein, J2 represents the pre-adjusted alkali dosage, β represents the dosage safety factor, Q represents the inlet flow rate of the buffer tank, M represents the neutralization coefficient of the alkali agent NaOH, X′0 represents the pH value of the physicochemical treatment tank when the pH is less than 7, ρ2 represents the density of the alkali agent, y2 represents the mass concentration ratio of the alkali agent, and X0 represents the pre-adjusted target pH value of the buffer tank.

3. The method for treating acidic wastewater according to claim 2, wherein: The pH value of the buffer tank (4) is detected in real time by a pre-adjusted pH meter (43) to obtain a pre-adjusted pH value, and the dosage safety factor β is adjusted according to the pre-adjusted pH value.

4. The method for treating acidic wastewater according to claim 1, wherein: In step 4, the method for controlling the alkali dosing pump of the alkali dosing component (44) in different intervals according to the biochemical pH value is as follows: Step 41: When the biochemical pH value x is within the first threshold range: x<7.2; in this range, the first opening is adjusted to increase the value as follows: The first real-time adjustment of the opening ratio is as follows: Wherein, Δt1 is the first adjustment increase during the on-time, k is the amplitude modulation ratio time, x is the biochemical pH value, i is the i-th cycle number of the interval dosing, T1 is the first dosing cycle, v is the pH change rate, p1 is the first real-time adjustment on-time ratio, and p0 is the initial on-time ratio of the dosing pump. When x increases with time, "-" is used in the formula; when x decreases with time, "+" is used in the formula. Step 42: When the biochemical pH value x is within the second threshold range: 7.2≤x<7.5, in this range, the second opening time is adjusted as follows: The second real-time adjustment ratio is as follows: Among them, Δt2 is the second opening adjustment increase, T2 is the second dosing cycle, and p2 is the second real-time adjustment opening ratio; Step 43: When the biochemical pH value x is within the third threshold range: 7.5≤x<7.8; in this range, the third opening time is adjusted as follows: The third real-time adjustment ratio is as follows: Among them, Δt3 is the third opening adjustment increase, T3 is the third dosing cycle, and p3 is the third real-time adjustment opening ratio; Step 44 : When the biochemical pH value x is within the fourth threshold range: x≥7.8, the alkali dosing pump stops, ie, p4=0, and dosing stops.

5. An acidic wastewater treatment device, characterized in that: It comprises a control unit, and a physicochemical treatment pool (3), a buffer pool (4), and a biochemical treatment pool (6) which are connected in sequence; The physicochemical treatment tank (3) is provided with a physicochemical pH meter (37); The buffer tank (4) is provided with an alkali dosing component (44) and an acid dosing component (45); The alkali dosing component (44) is in communication with the biochemical treatment tank (6); The biochemical treatment pool (6) is provided with a biochemical pH meter (66); The physicochemical pH meter (37), the alkali dosing component (44), and the acid dosing component (45) are respectively connected to the control unit.

6. The acidic wastewater treatment device according to claim 1, characterized in that: The physicochemical treatment tank (3) comprises a mixing zone (31), a flocculation zone (32), and a sedimentation zone (34) which are connected in sequence. The physicochemical pH meter (37) is arranged in the flocculation zone (32). The flocculation zone (32) is provided with a stirrer (33). The sedimentation zone (34) is provided with an inclined tube packing assembly (35).

7. The acidic wastewater treatment device according to claim 1, characterized in that: The buffer tank (4) is provided with a pre-adjusted pH meter (43), and the pre-adjusted pH meter (43) is connected to a control unit.

8. The acidic wastewater treatment device according to claim 1, characterized in that: The biochemical treatment pool (6) comprises a nitrification section (62), a denitrification section (63) and a biochemical precipitation section (64) which are connected in sequence. The nitrification section (62) is connected to an alkali dosing assembly (44). The biochemical pH meter (66) is arranged in the nitrification section (62); and an ORP meter (65) is arranged on the denitrification section (63).

9. The acidic wastewater treatment device according to claim 1, characterized in that: The biochemical treatment pool (6) comprises a drainage return pipe (671) and a sludge return pipe (681); the water outlet of the biochemical precipitation section (64) is connected to a drainage pipe (69), the water inlet end of the drainage return pipe (671) is in communication with the drainage pipe (69), the water outlet end of the drainage return pipe (671) is in communication with the nitrification section (62), and a drainage return pump (67) is provided on the drainage return pipe (671); the sludge outlet of the biochemical precipitation section (64) is connected to a sludge discharge pipe (641), the sludge inlet end of the sludge return pipe (681) is in communication with the sludge discharge pipe (641), the sludge outlet end of the sludge return pipe (681) is in communication with the sludge discharge pipe (641), and the sludge return pipe (681) is in communication with the nitrification section (62), and a sludge return pump (68) is provided on the sludge return pipe (681).

10. The acidic wastewater treatment device according to claim 1, characterized in that: The physicochemical treatment pool (3) and the buffer pool (4) are connected via a physicochemical water outlet pipe (36); the buffer pool (4) and the biochemical treatment pool (6) are connected via a biochemical water inlet pipe (52), and a biochemical pump (51) is provided on the biochemical water inlet pipe (52).

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