CN114702189A - Wastewater filtering treatment system and method - Google Patents
Wastewater filtering treatment system and method Download PDFInfo
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- CN114702189A CN114702189A CN202210353452.2A CN202210353452A CN114702189A CN 114702189 A CN114702189 A CN 114702189A CN 202210353452 A CN202210353452 A CN 202210353452A CN 114702189 A CN114702189 A CN 114702189A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/48—Treatment of water, waste water, or sewage with magnetic or electric fields
Abstract
The invention relates to a wastewater filtering treatment system and a method, and the method at least comprises the following steps: first-stage separation: separating at least part of hardness and sulfate radicals from the first-stage separation inlet water through a monovalent ion selective nanofiltration membrane in a phase-change-free mode to obtain at least first-stage separation product water; secondary separation: introducing the primary separation water in the form of secondary separation inlet water, and separating solute and solvent in the secondary separation inlet water by externally applying pressure higher than osmotic pressure of the solution so as to obtain at least secondary separation concentrated water; and (3) third-stage separation: the system at least comprises a first separation module used for at least completing the first-stage separation step, a second separation module used for at least completing the second-stage separation step and a third separation module used for at least completing the third-stage separation step.
Description
Technical Field
The invention relates to the technical field of water filtration treatment, in particular to a wastewater filtration treatment system and a wastewater filtration treatment method.
Background
The per-capita occupancy of water resources in China is only 1/4 per capita in the world, the ranking is 109 bits in the world, statistics shows that the total amount of wastewater discharged per year in China reaches 365 billions of cubic meters, most rivers and lakes are seriously polluted, and the situation aggravates the crisis of water resource shortage. Although a great deal of new water pollution prevention and control technologies are continuously emerging with the increasing attention of the country on environmental protection, particularly water environment protection, the treatment of industrial wastewater discharged from some industries, such as electric power, chemical industry, pharmacy, petroleum and coking industries, is a difficult problem in the environmental protection work.
Although there are many systems and methods for wastewater treatment, for example:
CN113480080A discloses a treatment method and a treatment device for zero discharge of high-salt organic wastewater, which comprises the steps of sequentially carrying out pretreatment, first ultrafiltration, first reverse osmosis, ion exchange, photocatalytic oxidation, second ultrafiltration, neutralization, second reverse osmosis, silicon removal and external pressure type ultrafiltration treatment on the high-salt organic wastewater, then carrying out nanofiltration treatment, selectively intercepting through nanofiltration, so that produced water rich in sodium chloride is subjected to reverse osmosis and sodium chloride evaporative crystallization treatment to produce sodium chloride, and concentrated solution rich in sodium sulfate is subjected to second photocatalytic oxidation reaction, ultrafiltration and sodium sulfate evaporative crystallization treatment to produce sodium sulfate. The invention realizes the high-efficiency removal of pollutants in the high-salt organic wastewater, so as to remarkably reduce the treatment cost of the prior art and improve the operation stability of an organic wastewater discharge treatment system.
However, in the prior art, pollutants and various elements in the wastewater are mostly removed to realize the recovery of high-purity purified water, but the wastewater usually contains more ions with recovery value, such as lithium ions and the like. Therefore, how to obtain higher ion recovery rate with lower operation cost while treating wastewater to realize water resource recycling is a problem to be solved at present.
Furthermore, on the one hand, due to the differences in understanding to the person skilled in the art; on the other hand, since the applicant has studied a great deal of literature and patents when making the present invention, but the disclosure is not limited thereto and the details and contents thereof are not listed in detail, it is by no means the present invention has these prior art features, but the present invention has all the features of the prior art, and the applicant reserves the right to increase the related prior art in the background.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a wastewater filtering treatment system and a wastewater filtering treatment method, which aim to solve the technical problems in the prior art.
The invention discloses a wastewater filtering treatment method, which at least comprises the following multistage separation steps:
first-stage separation: the wastewater after primary pretreatment can be used as at least part of primary separation inlet water, and at least part of hardness and sulfate radicals are separated through a monovalent ion selective nanofiltration membrane in a phase-change-free mode so as to obtain at least primary separation product water;
secondary separation: introducing the first-stage separation water produced in the form of second-stage separation water inflow, and separating solute and solvent in the second-stage separation water inflow by externally applying pressure higher than osmotic pressure of the solution so as to obtain at least second-stage separation concentrated water;
and (3) three-stage separation: introducing the secondary separation concentrated water in the form of tertiary separation inlet water, driving charged ions in the solution to perform directional migration through an externally applied electric field so as to obtain at least tertiary separation concentrated water capable of further extracting lithium ions,
at least in the first-stage separation step, at least part of the hardness and the sulfate radical which are separated can flow out along with the first-stage separation concentrated water, at least part of the first-stage separation concentrated water can flow back to the first-stage separation inlet water, at least another part of the first-stage separation concentrated water can be discharged, the backflow amount and the discharge amount of the first-stage separation concentrated water can be dynamically adjusted based on a set distribution ratio, and the dynamic adjustment mode of the distribution ratio is determined at least according to relevant parameter monitoring data obtained in the first-stage separation step.
According to a preferred embodiment, the distribution ratio is adaptively adjusted at least based on the real-time conditions of the lithium content in the primary separation feed water, the primary separation product water and the primary separation concentrate water, and the configuration and operating conditions of the corresponding equipment in the primary separation step.
According to a preferred embodiment, the preliminary pretreatment can include one or more of buffer conditioning, microfiltration, and activated carbon adsorption, and the pretreated produced water from the wastewater after the preliminary pretreatment can be mixed with at least a portion of the returned first-stage separation concentrate to form the first-stage separation feed water.
According to a preferred embodiment, the configuration of the respective device in the primary separation step can be adjusted at least on the basis of parameters relevant for its operation, wherein the adjustment can be determined at least on the basis of monitoring data of one or more of the parameters water quantity, pH, conductivity and lithium content.
According to a preferred embodiment, the monitoring frequency or the monitoring interval period of the relevant parameter of the operation condition of the corresponding equipment in the primary separation step is set based on a preset variation of the relevant parameter, wherein the preset variation of the relevant parameter can be adaptively changed at least along with the progress of the primary separation step and/or the adjustment of the operation condition of the corresponding equipment.
According to a preferred embodiment, the secondary separation step is able to obtain at least on one side of the applied pressure a secondary separated concentrate and on the opposite side a secondary separated fresh water having a lower lithium content than the secondary separated concentrate, wherein the adjustment of the respective device configuration in the secondary separation step can be referenced to the adjustment in the primary separation step.
According to a preferred embodiment, the three-stage separation step can be based at least on the permselectivity of the electrically driven membrane such that on one side a three-stage separated concentrate is obtained and on the opposite side a three-stage separated fresh water is obtained with a lower lithium content than the three-stage separated concentrate, wherein the adjustment of the respective device configuration in the three-stage separation step can be referenced to the adjustment in the first-stage separation step.
The invention also discloses a wastewater filtering treatment system, which is used for any one of the wastewater filtering treatment methods, wherein the wastewater filtering treatment system at least comprises: the first separation module is used for at least completing a first-stage separation step; a second separation module for performing at least a second stage of separation; and the third separation module is used for at least completing the three-stage separation step, wherein the first separation functional part configured by the first separation module can separate the first-stage separation inlet water through the monovalent ion selective nanofiltration membrane, and the separated first-stage separation concentrated water can be regulated and controlled in a flow path according to a set distribution proportion through the first separation concentrated water distribution part.
According to a preferred embodiment, the second separation fresh water obtained after the second separation module completes the second separation step can be stored and/or reprocessed in the form of second separation produced water in the second separation produced water tank for recovery of pure water resources.
According to a preferred embodiment, the tertiary separation fresh water obtained after the third separation module has completed the tertiary separation step can be returned to the buffer tank via a return line and mixed with the wastewater in the buffer tank for preliminary pretreatment.
The beneficial technical effects of the invention are as follows:
based on the interception rate of the monovalent ion selective nanofiltration membrane on ions with different valence, the selective separation of high-valence ions and low-valence ions is realized, so that the phase-change-free separation of partial hardness and sulfate radicals is realized, and the cost rise and the complication of the process flow caused by the fact that solid-liquid separation equipment is required to be additionally arranged in the precipitation phase-change separation method are avoided. At the same time, the remaining hardness in the water can be removed by the high efficiency resin in a manner that does not reduce the content of other major ions. The invention realizes the comprehensive recovery rate of the lithium ions of over 90 percent by optimizing and combining the process flow, and can reduce the operation cost to save the cost.
Drawings
FIG. 1 is a schematic diagram of a simplified module connection of a wastewater filtration treatment system of the present invention in a preferred embodiment.
List of reference numerals
100: a preprocessing module; 110: a precision filter; 120: an activated carbon component; 130: a buffer pool; 200: a first separation module; 210: a primary separation function section; 220: a first-stage separation water production tank; 230: a first-stage separation concentrated water distribution part; 240: a first-stage separation water inlet tank; 300: a second separation module; 310: a secondary separation water production tank; 400: and a third separation module.
Detailed Description
The following detailed description is made with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing the connection of the modules of the wastewater filtration treatment system of the present invention in a preferred embodiment.
The invention provides a wastewater filtration treatment method, which comprises a plurality of stages of separation steps, wherein, in a preferred embodiment, the wastewater filtration treatment method can at least comprise the following three stages of separation steps:
first-stage separation: the wastewater after primary pretreatment can be used as at least part of primary separation inlet water, and at least part of hardness and sulfate radicals are separated through a monovalent ion selective nanofiltration membrane in a phase-change-free mode so as to obtain at least primary separation product water;
secondary separation: introducing the first-stage separation water produced in the form of second-stage separation water inflow, and separating solute and solvent in the second-stage separation water inflow by externally applying pressure higher than osmotic pressure of the solution so as to obtain at least second-stage separation concentrated water;
and (3) three-stage separation: and introducing the secondary separation concentrated water in the form of tertiary separation inlet water, and driving charged ions in the solution to perform directional migration through an externally applied electric field so as to obtain at least tertiary separation concentrated water capable of further extracting lithium ions.
The invention also provides a wastewater filtration treatment system for the wastewater filtration treatment method, wherein the wastewater filtration treatment system is at least provided with a first separation module 200, a second separation module 300 and a third separation module 400 so as to respectively execute each stage of separation steps of the wastewater filtration treatment method. For each module of the wastewater filtration treatment system, the solution entering from the input may be referred to as feed water and the solution exiting from the output may be referred to as product water, wherein, particularly for the first separation module 200, the second separation module 300 and the third separation module 400, corresponding concentrate and fresh water may be obtained on different sides thereof, respectively, through the separation operation, and the concentrate or fresh water that can enter the next separation step is discharged from the output in the form of product water, while the opposite other solution can be stored, circulated, discharged, reused, etc.
According to a preferred embodiment, the primary separation function portion 210 of the first separation module 200 can receive the primarily pretreated wastewater and filter the wastewater by using a packed nanofiltration membrane, so that most of sulfate radicals and magnesium ions are separated into primary separation concentrated water by a nanofiltration process, the primary separation fresh water with low lithium-magnesium ratio is delivered to the primary separation water production tank 220 as the primary separation water production, and the primary separation concentrated water generated by the primary separation function portion 210 can be discharged to an energy recovery device for recycling and/or be circularly introduced into the primary separation water inlet tank 240. Alternatively, the first-stage separation concentrated water generated by the first-stage separation function part 210 may be adjusted by the first-stage separation concentrated water distribution part 230 based on a set distribution ratio, which is at least adaptively adjustable based on real-time conditions of the lithium content in the first-stage separation feed water, the first-stage separation product water, and the first-stage separation concentrated water, and the configuration and operation conditions of the first separation module 200, to control the input and output of the liquid of the first separation module 200.
According to a preferred embodiment, the one-stage separation function part 210 loaded with monovalent ion selective nanofiltration membranes may be composed of multiple stages of nanofiltration modules connected in series and/or in parallel, wherein the multiple stages of nanofiltration modules connected in series enable a water body to pass through more stages of nanofiltration modules, thereby improving the quality of the effluent; the multi-stage nanofiltration modules connected in parallel can improve the treatment capacity per unit time of the whole of the primary separation function part 210, thereby improving the water treatment efficiency of nanofiltration. The first separation module 200 can be provided with a plurality of communicating pipelines for the multistage nanofiltration assembly, so that the connection relationship of the multistage nanofiltration assembly can be switched at least by switching valves and the like, and the working mode of the first-stage separation function part 210 can be adjusted in time to adapt to different nanofiltration separation conditions.
Furthermore, each stage of nanofiltration assembly can also comprise a plurality of separation elements which are formed in a serial connection mode, and at least one separation element which does not synchronously perform separation work with other separation elements is arranged in the same nanofiltration assembly, so that when any separation element which performs the separation work is in a fault or blockage state and other abnormal conditions which may affect the separation effect, the abnormal separation element can be replaced by the separation element which is not in the working state, and the normal operation of the nanofiltration assembly is ensured. In other words, the first-stage separation function unit 210 can be configured in multiple stages and multiple stages, so as to flexibly adjust the configuration according to various operating conditions and/or operating parameters, wherein the operating conditions and/or operating parameters can be acquired in real time by the monitoring element and transmitted periodically.
According to a preferred embodiment, the monitoring element may monitor the primary separation, the secondary separation and/or the tertiary separation step in real time to obtain corresponding monitoring data, wherein the monitoring element may monitor for different characteristic parameters based on different separation devices configured in the primary separation, the secondary separation and/or the tertiary separation step. Preferably, the monitoring element is at least used for monitoring characteristic parameters such as water inflow and outflow, pH, conductance, ion content and the like.
Optionally, the monitoring element is capable of transmitting the monitoring data of the characteristic parameter to the central control module with a specific time and/or a specific event as a trigger condition, wherein the trigger condition of the specific time is to trigger the transmission task after a fixed or adjustable time period is reached by timing from the starting point, and the trigger condition of the specific event is to record from the starting point and trigger the transmission task after a predetermined event condition is reached.
Preferably, the first-stage separation concentrate flowing out of the first-stage separation function part 210 can be divided into a first-stage separation concentrate reflux and a nanofiltration drain by the diversion of the first-stage separation concentrate distribution part 230, wherein the concentrate reflux amount and the drain amount can be set based on the first-stage separation concentrate distribution ratio, so that at least part of the first-stage separation concentrate can carry part of the content of lithium ions to reflux to the first-stage separation inlet tank 240, thereby avoiding direct discharge of lithium ions mixed in the first-stage separation concentrate to reduce the recovery rate of lithium ions. The primary separation concentrated water distribution ratio can be adaptively adjusted based on the real-time conditions of the lithium content in the inlet water, the produced water and the concentrated water of the first separation module 200 and the configuration mode and the operating conditions in the first separation module 200. Further, the distribution ratio of the first-stage separation concentrated water can be approximately 1: 1 so that part of lithium ions mixed in the first-stage separation concentrated water can enter the first-stage separation produced water through the first separation module 200 again, and the phenomenon that the excessive first-stage separation concentrated water returns to the first separation module 200 again to reduce nanofiltration efficiency and effect is avoided.
The inlet and outlet arrangement direction based on the nanofiltration assembly can enable a plurality of separation elements connected in series to have corresponding arrangement sequence, the separation element closer to the inlet of the nanofiltration assembly can have a previous position sequence, the separation element closer to the outlet of the nanofiltration assembly can have a subsequent position sequence, and once the series connection relationship in the nanofiltration assembly is established, the flow direction of water flow in the nanofiltration assembly can be determined accordingly, namely, the water flow flowing in from the inlet of the nanofiltration assembly can flow out from the outlet of the nanofiltration assembly after flowing through the separation element in the subsequent position sequence.
Preferably, the inlet and outlet of the nanofiltration assembly can be communicated with a plurality of separation elements in a controllable opening and closing manner and/or the inlet and outlet of different separation elements can be communicated in a cross-position subsequence manner, so that part of the separation elements can be selectively opened and closed under the condition that the approximate flow direction of water flow in the nanofiltration assembly is not changed, and the corresponding separation elements can be started and stopped particularly under the conditions that a nanofiltration separation task is adjusted or a fault occurs and the like.
Furthermore, the activation and deactivation of the separation elements does not affect the order sequence of other separation elements in working state when the nanofiltration assembly is configured, that is, the water flow can still flow from the previous order sequence to the next order sequence, and when encountering the separation elements in deactivated state in the flow process, the water flow can directly flow from the separation elements in the previous order sequence to the separation elements in the next order sequence through the communication of the cross-order sequence, thereby realizing the allocation of the separation elements without affecting the flow direction.
The establishment of the separation element deployment mode can enable the separation elements which are not in the working state in the nanofiltration assembly to be timely put into nanofiltration separation work, and correspondingly, at least one separation element which is in the working state currently exists in the separation elements which can be deactivated, so that the at least one separation element can still be kept in the nanofiltration assembly not to be in the working state simultaneously with other separation elements. Generally, the more impurities in the water flow contacted by the separation elements in the previous subsequence are, the more easily the blockage or breakage of the nanofiltration membrane occurs, and the separation efficiency is affected, so the separation element which is not in the working state can be replaced by the separation element which needs to be stopped in the nanofiltration working process, wherein the separation element which needs to be stopped can be the separation element which is located at the forefront of the subsequence in the separation elements which are in the working state currently or the separation element which is in the working state currently and has continuous working time reaching the preset working time threshold, that is, the separation element can be stopped based on the influence factors of the sampling result of the effluent, the operation pressure monitoring data and/or the preset working time threshold.
Preferably, the deactivated separation elements are capable of regeneration, replacement or isolation. The regeneration of the separation element can be realized by rapidly backwashing the separation element, so that impurities trapped on the nanofiltration membrane are removed, and the filtration capacity of the separation element is recovered in a short time. The separation element with broken nanofiltration membrane or other structures which can not realize the recovery of the filtering capacity by regeneration and other means can be replaced with other intact separation modules under the detachable condition, so that the nanofiltration assembly can obtain the filtering capacity which is approximately equal to the previous filtering capacity again. For example, for a separation element which has reached a preset working time threshold, and in particular in the case of a relatively late ranking of the separation element, most of the impurities are filtered by the other separation elements preceding the ranking, so that the separation element can be put into nanofiltration again in a subsequent round without regeneration or replacement operations, depending on the criterion of reaching the preset working time threshold, while the frequency of backwashing operations is also reduced to save costs and reduce resource consumption; as a further example, for separating elements with reduced filtering capacity, in particular in the relatively early bit subsequences, if the separation effect is affected by the continued use of parameters which may affect the operating pressure of other separation elements connected in series therewith in the event that regeneration or replacement cannot be effected, the separation module can be temporarily isolated and put back into service when the filtration capacity of other separation elements within the nanofiltration assembly also drops to a corresponding degree, so as to maintain the stability of the operation of the whole nanofiltration assembly, but the overall filtering capacity of the nanofiltration assembly is reduced, the nanofiltration component can be used as the first stage of the precedent nanofiltration in a serial way by adjusting the connection relationship between the nanofiltration component and other nanofiltration components, and other nanofiltration components receive the water produced by the first nanofiltration and carry out subsequent secondary nanofiltration, thereby ensuring the quality of the first-stage separation produced water of the first separation module 200 in a multi-stage nanofiltration mode.
According to a preferred embodiment, the alternation of the separation elements in each stage of nanofiltration assembly is not a simple cycle alternation, but is performed based on the common regulation and control of a plurality of influence factors, such as the filtration and separation task conditions, the connection relationship between nanofiltration assemblies of different stages, the start-stop ratio of the separation elements in each stage of nanofiltration assembly, the preset working time threshold value, and the like, and the plurality of influence factors have mutual influence but not independent control, so that the plurality of influence factors need to be reasonably planned to realize the normal operation of the first separation module 200. For example, different connection relationships of the nanofiltration components can be used for different filtering and separating tasks, the two connection relationships can also affect the start-stop ratios of the separation elements in each stage of the nanofiltration components, the preset working time threshold can be correspondingly adjusted according to different start-stop ratios, and the preset working time threshold can also be adaptively adjusted based on the position sequences of different separation elements, namely, the preset working time threshold set for the separation module before the position sequence is smaller, and conversely, the preset working time threshold set for the separation module after the position sequence is larger, so that the separation modules in different position sequences can have corresponding gradient distinction based on the degree of separating impurities, and the corresponding preset working time threshold can be set according to the gradient, thereby ensuring that the separation module before the position sequence can be timely deactivated for regeneration or replacement, and the waste of cost and resources caused by frequent deactivation of the separation module behind the bit sequence is also avoided.
According to a preferred embodiment, the multi-stage nanofiltration components connected in series can realize the separation of magnesium and lithium step by step, so that the first-stage separation concentrated water can be returned or discharged or recycled, and the first-stage separation fresh water can be used as the first-stage separation water production water to flow to the first-stage separation water production tank 220, so that part of hardness and sulfate radicals can be separated without phase change through the nanofiltration membrane selective separation. Preferably, the operating pressure of the first separation module 200 can be controlled within the range of 3.7-4.3 MPa, so that the effect of magnesium-lithium separation is improved based on high pressure, and the content of lithium ions in the primary separation water is improved, so that more than 90% of magnesium ions and sulfate radicals are intercepted, and the primary separation water with low lithium-magnesium ratio is obtained.
Preferably, the nanofiltration membrane has a higher rejection rate for high-valence ions compared with low-valence ions based on the south-of-the-way effect, monovalent ions such as sodium ions, lithium ions and the like with a lower rejection rate can pass through the nanofiltration membrane, and sulfate ions, calcium ions, magnesium ions and the like which easily cause the hardness of water to be high are more easily intercepted by the nanofiltration membrane, so that the non-phase-change separation of at least part of ions is realized based on the different rejection rates of the nanofiltration membrane for the monovalent ions and the high-valence ions.
According to a preferred embodiment, the monitoring component, when monitoring the first separation module 200, may collect and transmit characteristic parameters of the flow rate, pH, conductivity, ion content, etc. of the first separation feed water, the first separation concentrate, and/or the first separation product water to obtain the monitoring data as shown in the following table. Preferably, the monitoring element is correspondingly selected based on different characteristic parameters when a specific event is taken as a trigger condition, wherein the specific event can be that the change value of the specific parameter reaches a set threshold value. Further, the change value of the specific parameter and the set threshold thereof both have a time attribute, wherein the time attribute of the former is the time elapsed for the change value when the monitoring data of the characteristic parameter changes from the first node to the second node, and the time attribute of the latter is the time expected to be required for the change value meeting the current situation to reach the set threshold, which is drawn by the user and/or the central control module based on the influence factors such as experience, big data, real-time operation state and the like.
Table 1 operational data of the first separation module 200 in a preferred embodiment
As can be seen from the above table, the water amount of the first separation module 200 changes stably during the normal operation of the wastewater filtration treatment system; the pH changes of the inlet water, the concentrated water and the produced water are synchronous, and no abnormal change value is found; the conductivity changes of the concentrated water and the produced water are synchronous, and no abnormal change value is found, so that the operation process of the first separation module 200 is stable.
Further, the following table is obtained after monitoring the lithium ion content of the inlet water, the produced water and the concentrated water of the first separation module 200:
table 2 lithium ion content monitoring data for the first separation module 200 in a preferred embodiment
According to the above table, during the operation of the first separation module 200, the content of lithium ions changes with the content of wastewater, and the overall data is relatively stable. Even if the lithium content fluctuates, the first separation module 200 can recover the normal operation in a short time based on the regulation and control of each stage of nanofiltration component, and can ensure the water quality of the first-stage separation water. Further, under the condition that the quality of the first-stage separation produced water cannot be guaranteed due to the fault which is difficult to control of the first separation module 200, the produced water and the concentrated water of the first separation module 200 are discharged or returned to the first-stage separation water inlet tank 240 through the first-stage separation concentrated water distribution portion 230 for temporary storage, so that the separation work is continuously completed after the first separation module 200 recovers the filtering function again.
According to a preferred embodiment, the data transmission rules of the monitoring element can be set at least on the basis of whether a specific event trigger condition is reached, i.e. without or not at all depending on a simple time period as a basis for transmission. In other words, the monitoring element can use the current node as the starting node of the next data transmission task after executing the current data transmission task round when the trigger condition is reached, and record the node as the stopping node and execute the data transmission task round again when the next trigger condition is reached, and then the process is repeated in a circulating manner.
Further, the trigger conditions set for each data transmission task may be different to adapt to different operation conditions, wherein when a specific event is taken as the trigger condition, the set threshold is set and adjusted at least based on the influence factors such as experience, big data, real-time operation state, and the like, and the time attributes corresponding to the set threshold may be the same in value.
For example, for monitoring the lithium ion content, especially when the lithium ion content of the inlet and outlet water of the first separation module 200 is monitored, the set threshold corresponding to the specific event may be an expected change value of the lithium ion content, and when the actual change value of the lithium ion content acquired by the monitoring element reaches the expected change value of the lithium ion content, a trigger condition is reached, and then data transmission is performed, and meanwhile, the actual time corresponding to the actual change value of the lithium ion content and the expected time corresponding to the expected change value of the lithium ion content may be compared to determine the operation condition of the device. Generally, if the actual time of the data transmission task of the current round is shorter, the stability of the operation of the equipment is relatively lower; and if the actual time of the data transmission task of the current round is longer, the running stability of the equipment is relatively higher. The comparison result of the actual time and the expected time of the data transmission task of the current round can be used for adjusting the setting mode of the setting threshold of the specific event of the next round. Further, the data transmission frequency of the monitoring element is varied based on the adjustment of the set threshold with the time attribute for a specific event, and the variation is usually linear.
When the operational stability of the first separation module 200 is reduced to be out of the defined range, the corresponding separation element needs to be deactivated, regenerated, replaced or isolated. Preferably, the preset content fluctuation value can be adjusted based on a plurality of influencing factors, including at least the task progress of the first separation module 200, the operating conditions of the separation elements, etc. The preset content fluctuation value can be reduced along with the progress of a nanofiltration task; the preset content fluctuation value can be adaptively reduced based on the deactivation or isolation of the separation element and adaptively increased based on the regeneration or replacement of the separation element, wherein the adaptive increase is adjusted according to the actual situation, and the influence of the monitoring precision caused by the setting of the overlarge preset content fluctuation value is avoided.
Compared with the specific time as the trigger condition of the data transmission task, the above setting can improve the sampling accuracy of the monitoring element, and can avoid setting too large time interval to cause delayed sending or missed sending of data, thereby affecting the operation stability of the first separation module 200; it is also possible to avoid setting too small time intervals to cause too many data to be transmitted, stored, calculated, and/or analyzed, which may cause too large loads of software and hardware and processing delays of data, which may also affect the operation stability of the first separation module 200. Improper data processing caused by data processing and/or transmission delay can be realized by returning effluent which does not meet the water quality requirement to perform separation again, and under the condition of avoiding data delay as much as possible, the separation efficiency and the separation effect of at least the first separation module 200 can be improved.
Preferably, the second separation module 300 and/or the third separation module 400 can perform the configuration of the multi-stage separation element with reference to the configuration of the first separation module 200, thereby achieving more precise control.
The central control module in communication connection with the monitoring element can comprehensively regulate and control at least one functional module to ensure the normal operation of the wastewater filtering treatment system. Preferably, when the first separation module 200, the second separation module 300, and/or the third separation module 400 are configured in a multi-stage and multi-stage manner, linked regulation and control can be realized, that is, when a connection relationship and/or an operation parameter of any one of the first separation module 200, the second separation module 300, and the third separation module 400 is changed, the central control module can adaptively regulate the connection relationship and/or the operation parameter of other modules based on a condition of the change, wherein the condition of the change may be normal alternation between components, isolation or replacement after a component failure, or adjustment caused by real-time change of related parameters such as flow rate of wastewater, water quality, and the like.
Preferably, when there is a condition that the quality of the effluent water is affected by the reduction or insufficiency of the filtering capacity among the factors triggering the change of the occurrence condition, the central control module can circulate the solution flowing at least in the abnormal filtering time range to the front of the corresponding module with the problem of the filtering capacity and recovered in a flow metering mode to perform filtering again based on the delay of data acquisition and transmission and/or the time consumed for recovering the filtering capacity of the corresponding module. Further, when the corresponding module with the filtering capability problem restores the filtering capability by triggering the change occurrence condition, other related modules can also be adaptively adjusted accordingly, so that the returned solution is not necessarily separated according to the previous filtering manner. Preferably, the central control module is capable of counting abnormal filtering time and estimating the flow of the solution to be returned based on factors such as the flow rate of the solution and the filtering capacity of each downstream module, so that the circulation valve is opened at the corresponding node to return the solution substantially equal to the estimated flow through the circulation pipe.
According to a preferred embodiment, a pretreatment module 100 for preliminary pretreatment can be disposed at the front end of the first separation module 200, wherein the pretreatment module 100 at least comprises a buffer tank 130 for accommodating wastewater, wherein the wastewater can be high-salt lithium-containing wastewater with high total hardness and lithium ion content less than or equal to 0.5g/L, and the wastewater filtration treatment system can at least realize wastewater treatment capacity more than or equal to 5m3H is used as the reference value. Optionally, a boron extraction treatment may be performed in the buffer tank 130 to remove boron in the wastewater, so as to improve the quality of the effluent of the buffer tank 130, wherein a boron selective adsorption resin method, a sulfuric acid precipitation method, an activated carbon adsorption method, a lime precipitation method, an electrocoagulation method, or an aluminum hydroxide adsorption method may be selected. Preferably, sulfuric acid is added to the buffer tank 130 to form a precipitate at least containing boric acid, and the precipitate is removed by a solid-liquid separation method, so that the produced water of the buffer tank 130 is acidic, and simultaneously, sulfate dissolved in the produced water of the buffer tank 130 can be removed by a subsequent separation process, for example, the first separation module 200 of the nanofiltration process.
Preferably, the pre-treatment module 100 may further include a precision filter 110 and/or an activated carbon assembly 120 between the buffer tank 130 and the first separation module 200, the precision filter 110 may be made of stainless steel, and a tubular filter element such as a PP melt-blown, wire-fired, folded, titanium filter element or activated carbon filter element is used as a filter element in the precision filter 110 to remove micro suspended matters, bacteria and other impurities in water, so that the quality of the effluent can meet the water inlet requirement of the primary separation function portion 210; the activated carbon filled in the activated carbon assembly 120 can perform activated carbon adsorption on the outlet water of the precision filter 110 to improve the water quality flowing into the first-stage separation water inlet tank 240. The primary separation inlet tank 240 is a storage tank or a storage tank device in which the first separation module 200 is disposed in front of the primary separation function unit 210 and is used for temporarily storing the active product water, and the primary separation inlet tank 240 is capable of receiving the pre-treated product water pre-treated by the pre-treatment module 100 and delivering the pre-treated product water as at least part of the primary separation inlet water to the primary separation function unit 210 to complete the primary separation task.
According to a preferred embodiment, the primary separated product water stored in the primary separated product water tank 220 can be transferred to the second separation module 300 under the pressure of the pump to separate the solvent from the primary separated product water based on the actively applied pressure, wherein the actively applied pressure should be greater than the osmotic pressure of the solution, so that the concentrated solution containing more solute can be obtained on one side of the applied pressure, and the permeate containing more solvent can be obtained on the opposite side of the reverse osmosis membrane to which the applied pressure is applied, thereby realizing the separation of the solute from the solvent and achieving the purpose of increasing the relative content of lithium ions.
Preferably, the second separation module 300 can be configured with at least one reverse osmosis separation component, wherein the reverse osmosis separation component can be a high pressure reverse osmosis separation component, such as a GTR4 plant. The several reverse osmosis separation components of the second separation module 300 can be configured in a multi-stage, multi-stage manner such that the reverse osmosis separation components accomplish different reverse osmosis separation tasks based on different series/parallel connections. When both the middle pressure reverse osmosis separation part and the high pressure reverse osmosis separation part are provided, the middle pressure reverse osmosis separation part can be provided upstream of the high pressure reverse osmosis separation part, that is, the middle pressure reverse osmosis separation part can be provided closer to the primary separation function part 210, wherein the configuration position does not refer to a geographical position but a position in the process flow.
Further, the second separation module 300 can be configured in a multi-stage manner, which is the same as or similar to the first separation module 200, so that the second separation module 300 can also realize accurate regulation and control of each reverse osmosis separation component, thereby ensuring normal operation of the second separation module 300.
Preferably, the permeate of the second separation module 300 can be delivered as reverse osmosis produced water to the secondary separation product water tank 310 for storage or further processing to obtain high purity purified water.
According to a preferred embodiment, the permeate of the second separation module 300 can be transferred as reverse osmosis concentrate to the third separation module 400 under the pressure of a pump, and the third separation module 400 makes the single solute particles including at least charged ions in the reverse osmosis concentrate migrate through an electrically driven membrane as an ion selective membrane under the action of an applied electric field to perform secondary concentration on the reverse osmosis concentrate, thereby obtaining the electrodialysis concentrate and the electrodialysis fresh water. Preferably, the third separation module 400 can include several electrodialysis separation elements, and the several electrodialysis separation elements can be in a multi-stage, multi-stage configuration that is the same or similar to the first separation module 200.
Preferably, the electrodialysis fresh water can be refluxed into the buffer cell 130 of the buffer cell 130 to be mixed with the wastewater introduced into the buffer cell 130 to enter the first separation module 200 after being subjected to the buffer conditioning.
Preferably, the electrodialysis concentrated water can be used for separating lithium ions at least in the form of lithium carbonate precipitation by adding a reagent such as sodium carbonate, and the lithium ions are recycled through a lithium salt preparation process.
According to a preferred embodiment, the wastewater filtering treatment system can remove the hardness of water through a high-efficiency adsorption resin in a mode of not reducing the content of other main ions, wherein the adsorption resin can be configured between any two functional modules. As can be seen from the figure, during the resin adsorption in a preferred embodiment, the lithium content of the inlet water and the produced water is changed within the range of 1200-1300mg/L without prominent tendency of change and attenuation, so that it can be confirmed that the removal of the water hardness by the adsorption resin (the water hardness is controlled to be less than 20mg/L) can ensure the stability of the lithium ion content, and the reduction of the lithium ion recovery rate can be avoided.
According to a preferred embodiment, after the wastewater with lithium content less than or equal to 500mg/L and high total hardness is subjected to separation and extraction and other operations of a wastewater filtration treatment system, the lithium ion content of the concentrated water in the third separation module 400 is more than or equal to 8.5g/L, and the lithium content of the concentrated water in the wastewater filtration treatment system is more than or equal to 8.5g/LThe comprehensive recovery rate of ions is more than or equal to 90 percent; the contents of iron, aluminum and silicon in the concentrated water of the third separation module 400 are respectively about 0.18mg/L, 0.31mg/L and 2.87mg/L, which meet the requirement of less than or equal to 10 mg/L; in the continuous operation of resin adsorption, the adsorption effect is good, and the total hardness is less than or equal to 20mg/L (CaCO)3And the lithium ions are not lost, so that the wastewater filtration treatment system can complete the recovery of the lithium ions while treating the wastewater. Further, the recovered lithium ions, which are substantially in the form of lithium carbonate, can be reused by the lithium salt preparation process.
It should be noted that the above-mentioned embodiments are exemplary, and that those skilled in the art, having benefit of the present disclosure, may devise various arrangements that are within the scope of the present disclosure and that fall within the scope of the invention. It should be understood by those skilled in the art that the present specification and figures are illustrative only and are not limiting upon the claims. The scope of the invention is defined by the claims and their equivalents. The present description contains a plurality of inventive concepts such as "preferably", "according to a preferred embodiment" or "optionally" each indicating that the respective paragraph discloses a separate concept, the applicant reserves the right to apply for divisional applications according to each inventive concept. Throughout this document, the features referred to as "preferably" are only an optional feature and should not be understood as necessarily requiring that such applicant reserves the right to disclaim or delete the associated preferred feature at any time.
Claims (10)
1. A wastewater filtering treatment method at least comprises the following multi-stage separation steps:
first-stage separation: the wastewater after primary pretreatment can be used as at least part of primary separation inlet water, and at least part of hardness and sulfate radicals are separated through a monovalent ion selective nanofiltration membrane in a phase-change-free mode so as to obtain at least primary separation product water;
secondary separation: introducing the primary separation water in the form of secondary separation inlet water, and separating solute and solvent in the secondary separation inlet water by externally applying pressure higher than osmotic pressure of the solution so as to obtain at least secondary separation concentrated water;
and (3) three-stage separation: introducing the secondary separation concentrated water in the form of tertiary separation inlet water, driving charged ions in the solution to perform directional migration through an externally applied electric field so as to obtain at least tertiary separation concentrated water capable of further extracting lithium ions,
wherein, at least in the first-stage separation step, at least part of the separated hardness and sulfate radical can flow out along with the first-stage separation concentrated water, at least part of the first-stage separation concentrated water can be refluxed to the first-stage separation inlet water, at least another part of the first-stage separation concentrated water can be discharged, and the reflux quantity and the discharge quantity of the first-stage separation concentrated water can be dynamically adjusted based on the set distribution proportion,
the dynamic adjustment of the distribution ratio is determined at least on the basis of the relevant parameter monitoring data obtained in the primary separation step.
2. The wastewater filtering treatment method according to claim 1, wherein the distribution ratio is adaptively adjusted based on at least real-time conditions of lithium contents in the primary separation feed water, the primary separation product water and the primary separation concentrate water, and configuration and operation conditions of corresponding devices in the primary separation step.
3. The method of claim 1 or 2, wherein the preliminary pretreatment comprises one or more of buffer adjustment, microfiltration and activated carbon adsorption, and the produced pretreated water from the preliminary pretreatment can be mixed with at least a portion of the returned first-stage separation concentrate to form the first-stage separation feed water.
4. The method for filtering and treating wastewater according to any one of claims 1 to 3, wherein the configuration of the corresponding equipment in the primary separation step can be adjusted at least based on relevant parameters of the operation condition, wherein the adjustment mode can be determined at least according to monitoring data of one or more parameters of water quantity, pH, conductivity and lithium content.
5. The wastewater filtering treatment method according to any one of claims 1 to 4, wherein the monitoring frequency or the monitoring interval period of the relevant parameter of the operation condition of the corresponding equipment in the primary separation step is set based on a preset variation of the relevant parameter, wherein the preset variation of the relevant parameter can be adaptively changed at least along with the progress of the primary separation step and/or the adjustment of the operation condition of the corresponding equipment.
6. The wastewater filtering treatment method according to any one of claims 1 to 5, characterized in that the secondary separation step can obtain secondary separation concentrated water at least at one side of the applied pressure and secondary separation fresh water with lower lithium content than the secondary separation concentrated water at the other opposite side, wherein the adjustment of the corresponding equipment configuration in the secondary separation step can be referred to the adjustment in the primary separation step.
7. The wastewater filtering treatment method according to any one of claims 1 to 6, characterized in that at least three stages of separation steps are provided with three stages of separation concentrated water on one side and three stages of separation fresh water with lower lithium content than the three stages of separation concentrated water on the other side based on the selective permeability of the electrically driven membrane, wherein the adjustment of the corresponding equipment configuration in the three stages of separation steps can be referred to the adjustment manner in the first stage of separation steps.
8. A wastewater filtration treatment system for use in the wastewater filtration treatment method of any one of the preceding claims, wherein the wastewater filtration treatment system comprises at least:
a first separation module (200) for performing at least one separation step,
a second separation module (300) for performing at least a second separation step,
a third separation module (400) for performing at least three separation steps,
the first separation function part (210) configured by the first separation module (200) can separate the first-stage separation inlet water through the monovalent ion selective nanofiltration membrane, and the separated first-stage separation concentrated water can be subjected to flow-through path regulation and control according to a set distribution proportion through the first separation concentrated water distribution part (230).
9. The wastewater filtration treatment system according to claim 8, wherein the secondary separated fresh water obtained after the secondary separation step is completed by the second separation module (300) can be stored and/or reprocessed in the form of secondary separated produced water into the secondary separated water production tank (310) for recovery of pure water resources.
10. The wastewater filtration treatment system according to claim 8 or 9, wherein the tertiary separated fresh water obtained after the tertiary separation step of the third separation module (400) is completed can be returned to the buffer tank (100) through a return line and mixed with the wastewater in the buffer tank (100) for preliminary pretreatment.
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