A contaminated soil treatment optimization method based on multi-source data analysis

Abstract

The present application is suitable for the field of in-situ bioremediation of contaminated soil, and provides a contaminated soil treatment optimization method based on multi-source data analysis, which comprises: obtaining the current propionate / acetic acid ratio of the target treatment unit, and adjusting the dosing strategy parameters of the mixed electronic donor, including the fast-release electronic donor of lactic acid salt and the slow-release organic electronic donor, when the ratio deviates from the target ratio interval, until the current propionate / acetic acid ratio falls within the target ratio interval. The present application can reduce the additional amount of mixed electronic donor in the dechlorination stage controlled by DCE and / or VC conversion in the subsequent process, reduce the invalid consumption of fast-release components, and improve the stability, economy and fine control level of the dehalogenation bacteria repair process.

Description

Technical Field

[0001] This invention belongs to the field of in-situ bioremediation technology for contaminated soil, and particularly relates to an optimized method for the treatment of contaminated soil based on multi-source data analysis. Background Technology

[0002] Perchloroethylene (PCE), trichloroethylene (TCE), and other polyvinyl chloride (PCE) are typical chloroethylene pollutants, commonly found in contaminated sites such as chemical plants, electronics factories, and metal cleaning plants. For these contaminated sites, current technologies typically employ in-situ enhanced reduction dechlorination remediation using dehalogenating bacteria to gradually convert PCE and / or TCE into dichloroethylene (DCE) and vitamin C (VC), and further into ethylene. To maintain the reductive dechlorination activity of the dehalogenating bacteria, electron donors, such as lactate, ethanol, molasses, and emulsified vegetable oil, are usually added to the contaminated medium to provide the reducing equivalent required for dechlorination.

[0003] In actual remediation processes, multi-source data, including pollutant concentration, DCE and / or VC accumulation, ethylene production, pH, ORP, volatile fatty acids, electron donor balance, and dehalogenation bacteria abundance, are commonly used to monitor and assess the dechlorination process. When DCE and / or VC accumulation, abnormal pH, volatile fatty acid exceeding thresholds, or insufficient electron donors occur, adjustments are made to the electron donor dosage, frequency, or microbial agent dosage regimen.

[0004] However, the aforementioned control methods mainly rely on overt anomalies or alarm threshold triggers, typically involving passive corrections after a decrease in dechlorination rate or adverse changes in the system. When propionate, acetate, total volatile fatty acid concentrations, and pH do not reach preset alarm thresholds, existing technologies often treat these as normal fluctuations, rarely utilizing the proportion of fermentation products within these thresholds to determine the early fermentation state of the complex electron donor. This can lead to a mismatch between the release rhythm of the complex electron donor and the demands of the subsequent dechlorination stage, where DCE and / or VC conversion is the primary control process, thus increasing the subsequent addition of complex electron donors and ineffective consumption. Therefore, there is an urgent need for a method for remediating contaminated soil that can be pre-optimized during the early fermentation monitoring stage. Summary of the Invention

[0005] The purpose of this invention is to provide an optimized method for the remediation of contaminated soil based on multi-source data analysis, which aims to solve the problems mentioned in the background art.

[0006] This invention is implemented as follows: an optimization method for contaminated soil remediation based on multi-source data analysis, the method comprising:

[0007] When the target remediation unit is a dehalogenated bacterial remediation unit contaminated with PCE and / or TCE, and is in the early fermentation monitoring stage after the addition of compound electron donors, historical remediation samples matching the background conditions of the target remediation unit are screened from the soil remediation database; among them, compound electron donors include lactate-type fast-release electron donors and slow-release organic electron donors;

[0008] Calculate the early propionate / acetate ratio for each historical treatment sample, and the additional amount of complex electron donors generated per unit of ethylene during the dechlorination stage of the subsequent DCE and / or VC conversion into the main control process;

[0009] Determine whether the propionate / acetate ratio of each historical treatment sample shows a relationship of first decreasing and then increasing with the amount of additional complex electron donors generated per unit of ethylene. If so, determine the propionate / acetate ratio range corresponding to the low value range of the additional complex electron donors generated per unit of ethylene as the target ratio range.

[0010] Obtain the current propionate / acetate ratio of the target treatment unit, and when it deviates from the target ratio range, adjust the addition strategy parameters of lactate-type fast-release electron donor and slow-release organic electron donor in the compound electron donor until the current propionate / acetate ratio falls into the target ratio range.

[0011] As a further limitation of the technical solution of the present invention, the early fermentation monitoring stage after the addition of the compound electron donor refers to the monitoring stage within a preset period after the addition of the compound electron donor, and before the target treatment unit has entered the dechlorination stage where DCE and / or VC are converted into the main control process; during the monitoring stage, the concentrations of propionate, acetate, total volatile fatty acids and pH in the target treatment unit do not reach the preset alarm threshold.

[0012] As a further limitation of the technical solution of the present invention, the historical treatment sample that matches the background conditions of the target treatment unit specifically refers to a historical treatment sample that matches the target treatment unit in at least four of the following: pollutant type, pollutant medium type, initial PCE and / or TCE concentration range, initial DCE and / or VC concentration range, dehalogenation bacteria species or abundance, complex electron donor type, hydrogeological conditions, and initial pH and / or ORP conditions, and whose propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH did not reach the preset alarm threshold during the early fermentation monitoring stage.

[0013] As a further limitation of the technical solution of the present invention, the calculation process of the propionate / acetate ratio includes: obtaining the propionate concentration and acetate concentration corresponding to the same treatment unit and the same monitoring time point, unifying the units and removing outliers of the propionate concentration and acetate concentration, and taking the ratio of the processed propionate concentration to the acetate concentration as the propionate / acetate ratio.

[0014] As a further limitation of the technical solution of the present invention, the method for determining the additional amount of compound electron donor for unit ethylene generation includes: determining the statistical period after the historical treatment sample enters the dechlorination stage of DCE and / or VC conversion into the main control process, obtaining the total additional amount of compound electron donor added and the ethylene generation increment during the statistical period, and taking the ratio of the total additional amount added to the ethylene generation increment as the additional amount of compound electron donor for unit ethylene generation.

[0015] As a further limitation of the technical solution of this invention, the step of determining whether the propionate / acetate ratio of each historical treatment sample and the additional amount of complex electron donors generated per unit of ethylene show a relationship of first decreasing and then increasing, and if so, determining the propionate / acetate ratio range corresponding to the low value range of the additional amount of complex electron donors generated per unit of ethylene as the target ratio range includes:

[0016] Several historical treatment samples were sorted in ascending order of propionate / acetate ratio to obtain a sample sequence;

[0017] Extract the amount of additional ethylene-generating complex electron donors corresponding to each historical treatment sample in the sample sequence, and generate the trend of the additional amount change;

[0018] Determine whether there is a trough in the trend of the additional amount change, where the amount first decreases and then increases as the propionate / acetate ratio increases;

[0019] If it exists, the range of propionate / acetate ratios corresponding to the low value range of the additional amount in the valley segment is determined as the target ratio range.

[0020] As a further limitation of the technical solution of the present invention, there are stable sections before and after the valley section. The stable section refers to the section where the change in the amount of additional electron donors generated per unit of ethylene corresponding to adjacent historical treatment samples is less than a preset change threshold.

[0021] As a further limitation of the technical solution of the present invention, the addition strategy parameters include the mass ratio, volume ratio, single addition amount, addition concentration, addition interval and / or number of additions of lactate-type fast-release electron donor and slow-release organic electron donor.

[0022] As a further limitation of the technical solution of this embodiment of the invention, the adjustment of the addition strategy parameters of the compound electron donor includes: when the current propionate / acetate ratio of the target treatment unit is less than the lower limit of the target ratio range, reducing the proportion of lactate-type fast-release electron donor in the compound electron donor, reducing the single addition amount, extending the addition interval, and / or increasing the proportion of slow-release organic electron donor in the compound electron donor; when the current propionate / acetate ratio of the target treatment unit is greater than the upper limit of the target ratio range, increasing the proportion of lactate-type fast-release electron donor in the compound electron donor, shortening the addition interval, increasing the single addition amount, and / or supplementing lactate-type fast-release electron donor.

[0023] As a further limitation of the technical solution of this invention embodiment, within a preset monitoring time after each adjustment of the dosing strategy parameters, fermentation products and environmental safety are monitored once to obtain the propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH of the target treatment unit, and the current propionate / acetate ratio is recalculated; when the recalculated current propionate / acetate ratio still deviates from the target ratio range and the total volatile fatty acid concentration and pH have not reached the preset alarm threshold, the dosing strategy parameters are adjusted again; until the current propionate / acetate ratio falls into the target ratio range, the current adjustment is stopped; when the total volatile fatty acid concentration and / or pH reach the preset alarm threshold, the current adjustment based on the propionate / acetate ratio is stopped, and the corresponding alarm handling strategy is executed.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the dehalogenation remediation process for PCE and / or TCE contamination, existing technologies typically only adjust the complex electron donor addition strategy after DCE and / or VC accumulation, total volatile fatty acids, or pH reach a preset alarm threshold. This results in control lag and excessively high additional dosage. This invention utilizes the propionate / acetate ratio within a threshold range during early fermentation monitoring to determine the fermentation conversion rhythm of the complex electron donor. By combining this ratio with the correlation between historical remediation samples and the additional complex electron donor dosage per unit of ethylene production, a target ratio range is determined. This allows for preemptive adjustment of the addition strategy parameters before overt dechlorination stagnation occurs. This reduces the amount of complex electron donor required in the subsequent dechlorination stage, where DCE and / or VC conversion is the primary control process, minimizing ineffective consumption of fast-release components and improving the stability, economy, and precision control of the dehalogenation remediation process. Attached Figure Description

[0026] Figure 1 A flowchart of the method provided in the embodiments of the present invention;

[0027] Figure 2This is a flowchart illustrating the determination of the target ratio range in the method provided in this embodiment of the invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Figure 1 A flowchart of the method provided by an embodiment of the present invention is shown.

[0030] Specifically, an optimization method for contaminated soil remediation based on multi-source data analysis includes the following steps:

[0031] Step S100: When the target remediation unit is a dehalogenated bacterial remediation unit contaminated with PCE and / or TCE, and is in the early fermentation monitoring stage after the addition of compound electron donors, historical remediation samples matching the background conditions of the target remediation unit are screened from the soil remediation database; wherein, the compound electron donors include lactate-type fast-release electron donors and slow-release organic electron donors. The remediation unit refers to a spatial unit obtained by dividing the PCE and / or TCE contaminated site according to the distribution of contaminated media, sampling point location, groundwater flow direction, pollutant concentration distribution and / or remediation project layout, for independent monitoring, evaluation and adjustment of compound electron donor addition strategy parameters.

[0032] The early fermentation monitoring stage after the addition of the compound electron donor refers to the monitoring stage within a preset time period after the addition of the compound electron donor, and before the target treatment unit has entered the dechlorination stage where DCE and / or VC are converted into the main control process; during the monitoring stage, the concentrations of propionate, acetate, total volatile fatty acids and pH in the target treatment unit do not reach the preset alarm thresholds.

[0033] The historical treatment samples that match the background conditions of the target treatment unit specifically refer to historical treatment samples that match the target treatment unit in at least four of the following: pollutant type, pollutant medium type, initial PCE and / or TCE concentration range, initial DCE and / or VC concentration range, dehalogenation bacteria species or abundance, complex electron donor type, hydrogeological conditions, and initial pH and / or ORP conditions, and whose propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH did not reach the preset alarm threshold during the early fermentation monitoring stage.

[0034] In this embodiment of the invention, the dehalogenation bacterial remediation unit for PCE and / or TCE contamination can be any remediation unit in saturated zone soil, aquifer sediments, capillary rise zone soil, or soil-groundwater interface media. For this type of contaminated media, in-situ enhanced reduction dechlorination remediation is typically performed using dehalogenation bacteria, gradually converting PCE and / or TCE into DCE and VC, and further into ethylene. In this process, a complex electron donor is used to provide the reduction equivalent required for reduction dechlorination in the dehalogenation bacterial system. The complex electron donor includes lactate-type fast-release electron donors and slow-release organic electron donors. The lactate-type fast-release electron donor can be sodium lactate, calcium lactate, magnesium lactate, and / or lactic acid, and the slow-release organic electron donor can be emulsified vegetable oil, oil-based slow-release carbon source, solid slow-release organic substrate, or a combination thereof.

[0035] In existing technologies, multiple data sources, including PCE, TCE, DCE, VC, ethylene, pH, ORP, volatile fatty acids, electron donor balance, and dehalogenation bacteria abundance, are typically used to determine whether dehalogenation stagnation has occurred. The addition of compound electron donors is adjusted when DCE and / or VC accumulates, pH becomes abnormal, electron donors are insufficient, or volatile fatty acids exceed preset alarm thresholds. However, when propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH do not reach their corresponding preset alarm thresholds, existing technologies typically treat this as normal fluctuations and rarely utilize the proportion of fermentation products within these thresholds to optimize the compound electron donor addition strategy in the subsequent dechlorination stage, where DCE and / or VC conversion is the main control process.

[0036] The inventors discovered that when using a combination of lactate-type fast-release electron donors and slow-release organic electron donors for remediation, the lactate-type fast-release electron donor, upon entering the contaminated medium, will form volatile fatty acids such as acetate and propionate, as well as hydrogen gas, under the action of anaerobic microorganisms. Acetate typically indicates that the fast-release component has rapidly entered the later stages of fermentation, while propionate can represent relatively lagging intermediate products in the fermentation process. The propionate / acetate ratio is not simply used to determine whether an alarm is triggered, but rather reflects the conversion rhythm of the lactate-type fast-release electron donor during the early fermentation monitoring stage.

[0037] Although historical remediation samples with matching background conditions are comparable in terms of pollutant type, pollutant medium type, initial pollutant concentration range, dehalogenation bacteria species or abundance, type of complex electron donor, hydrogeological conditions, and initial pH and / or ORP conditions, these background conditions mainly reflect the initial state and overall remediation conditions of the remediation unit and cannot completely define the early fermentation process after the addition of complex electron donors. The conversion ratio of lactate-type fast-release electron donors to acetate, propionate, and hydrogen is also affected by factors such as local microbial community composition, local mass transfer conditions, micro-area water content, pore structure, local buffering capacity, uniformity of slow-release organic electron donor dispersion, and residence time of the added solution within the remediation unit. Therefore, even if multiple historical remediation samples have matching background conditions, their propionate / acetate ratios during the early fermentation monitoring stage may still differ; this difference usually does not necessarily cause propionate concentration, acetate concentration, total volatile fatty acid concentration, or pH to reach the preset alarm threshold, but it can reflect the differences in the actual fermentation conversion rhythm of complex electron donors in different remediation units.

[0038] When the propionate / acetate ratio is low, it indicates that lactate-type fast-release electron donors tend to be converted to acetate more rapidly in the early stages, resulting in a faster formation of the reducing environment. However, the release of complex electron donors is premature, which can easily lead to early ineffective consumption or competitive consumption. When the treated unit enters the dechlorination stage, where the conversion of DCE and / or VC is the main control process, the continuously available reducing equivalent may be insufficient, thus requiring an increase in the amount of complex electron donors added later. When the propionate / acetate ratio is in a moderate range, it indicates that lactate-type fast-release electron donors are not excessively released prematurely, and there is no significant fermentation lag. Acetate can maintain the activity of dehalogenating bacteria in the early stages, and an appropriate amount of propionate can continue to convert and supplement the reducing equivalent in subsequent stages. This makes the release rhythm of complex electron donors more compatible with the demand for the conversion of DCE and / or VC to ethylene, thus requiring a lower amount of complex electron donors per unit of ethylene production. A high propionate / acetate ratio indicates a relative accumulation of propionate, resulting in insufficient or delayed conversion of complex electron donors into usable reducing equivalents. This leads to untimely donor release in the subsequent dechlorination stage, where DCE and / or VC are the main control processes. Therefore, it is necessary to increase the proportion of lactate-type fast-release electron donors or supplement them, thus increasing the amount of complex electron donors generated per unit of ethylene. Consequently, in historical remediation samples with matched background conditions, the early propionate / acetate ratio and the amount of complex electron donors generated per unit of ethylene may show a correlation of first decreasing and then increasing.

[0039] However, in practical applications, the additional amount of complex electron donors generated per unit of ethylene occurs in the subsequent dechlorination stage, which has a time lag with the early fermentation monitoring stage. Moreover, the difference usually manifests as a small difference in resource consumption and does not necessarily affect the final achievement of the standard. Therefore, existing technologies usually pay little attention to the impact of the early propionate / acetate ratio on this subsequent indicator.

[0040] The soil remediation database can be a database of on-site remediation projects, a pilot-scale test database, a column experiment database, a microcosm experiment database, or a combination thereof. The soil remediation database may include pollutant detection data, pollutant medium data, dehalogenation bacteria data, compound electron donor addition data, fermentation product data, geochemical data, hydrogeological data, and remediation result data. Pollutant detection data may include the concentrations of PCE, TCE, DCE, VC, and ethylene, and their changes over time; pollutant media data may include the type of pollutant media, water content, permeability coefficient, particle size distribution, and organic matter content; dehalogenation bacteria data may include the types of dehalogenation bacteria, their abundance, and the abundance of related functional genes; compound electron donor addition data may include the ratio of lactate-type fast-release electron donors to slow-release organic electron donors, single addition amount, addition concentration, addition interval, and number of additions; fermentation product data may include propionate concentration, acetate concentration, and total volatile fatty acid concentration; geochemical data may include pH, ORP, DO, sulfate, nitrate, ferrous ions, and methane; hydrogeological data may include groundwater flow direction, flow velocity, aquifer thickness, and permeability parameters.

[0041] The above data can be obtained through mature existing technologies such as gas chromatography, gas chromatography-mass spectrometry, ion chromatography, high performance liquid chromatography, qPCR, water quality field testing instruments, routine laboratory physicochemical testing, and on-site hydrogeological surveys. The improvement of this invention does not lie in the data collection method itself, but in using the above data to screen historical treatment samples and determine the target ratio range.

[0042] Screening historical remediation samples from the soil remediation database that match the background conditions of the target remediation unit aims to reduce the interference of differences in pollutant composition, pollutant medium type, dehalogenation bacteria state, hydrogeological conditions, and complex electron donor type on the correlation between the propionate / acetate ratio and the additional complex electron donor generated per unit of ethylene. If the historical remediation samples differ too much from the target remediation unit, the propionate / acetate ratio in the historical remediation samples may be mainly affected by pollutant medium permeability, initial pollutant concentration, dehalogenation bacteria abundance, or complex electron donor type, and may not effectively reflect the early fermentation state in the target remediation unit. Therefore, this embodiment of the invention uses matching of at least four of the following as screening criteria: pollutant type, pollutant medium type, initial PCE and / or TCE concentration range, initial DCE and / or VC concentration range, dehalogenation bacteria species or abundance, complex electron donor type, hydrogeological conditions, and initial pH and / or ORP conditions.

[0043] In other embodiments, the screening criteria for historical remediation samples may further include temperature range, total organic carbon range, sulfate concentration range, nitrate concentration range, alkalinity range, methane generation level, water content range, permeability coefficient range, well placement method, initial dosage range of compound electron donors, and spatial depth range of the target remediation unit. These screening criteria do not require complete consistency with the target remediation unit, but rather require a preset similarity threshold. The preset similarity threshold can be determined based on the number of samples in the soil remediation database, the data integrity of the target remediation unit, and the allowable error in engineering. For example, the overall similarity can be calculated after normalizing each background condition, and historical remediation samples with an overall similarity of not less than 80%, 85%, or 90% can be used as historical remediation samples matching the background conditions. Alternatively, a sub-matching rule can be adopted, requiring at least four key background conditions to fall within the preset deviation range of the corresponding parameters of the target remediation unit. This ensures the comparability of historical remediation samples with the target remediation unit while avoiding an insufficient number of usable historical remediation samples due to the requirement for complete consistency.

[0044] The early fermentation monitoring stage characterizes the early fermentation state of the lactate-type fast-release electron donor after the addition of the compound electron donor. It occurs after the addition of the compound electron donor and earlier than the dechlorination stage, where DCE and / or VC are converted into the main control process. During this stage, the propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH in the target treatment unit do not reach the corresponding preset alarm thresholds, indicating that the target treatment unit has not yet exhibited acidification, abnormal accumulation of volatile fatty acids, or overt dechlorination stagnation, requiring immediate alarm intervention. In this embodiment of the invention, under this non-alarm state, the propionate / acetate ratio is used to further identify whether the fermentation conversion rhythm of the compound electron donor is suitable for the subsequent dechlorination stage, where DCE and / or VC are converted into the main control process.

[0045] The preset time period can be determined based on the type of compounded electron donor, the permeability of the contaminant medium, the temperature, and the initial contaminant concentration. Generally speaking, when the proportion of lactate-type fast-release electron donors is high, the permeability of the contaminant medium is good, and the temperature is high, the early fermentation response is faster, and the preset time period can be relatively earlier; when the proportion of slow-release organic electron donors is high, the permeability of the contaminant medium is low, the temperature is low, or the initial contaminant concentration is high, the early fermentation response is slower, and the preset time period can be relatively later.

[0046] As an example, the preset time period can be from the 3rd to the 30th day after the addition of the compound electron donor, preferably from the 7th to the 21st day. This time period is used to obtain the propionate and acetate concentrations and calculate the propionate / acetate ratio to characterize the early fermentation state of the lactate-type fast-release electron donor before entering the dechlorination stage, in which DCE and / or VC are converted into the main control process.

[0047] Furthermore, the optimized method for contaminated soil remediation based on multi-source data analysis also includes the following steps:

[0048] Step S200: Calculate the early propionate / acetate ratio for each historical treatment sample, and the additional amount of compound electron donors generated per unit of ethylene in the dechlorination stage of the subsequent DCE and / or VC conversion into the main control process.

[0049] The calculation process of the propionate / acetate ratio includes: obtaining the propionate concentration and acetate concentration corresponding to the same treatment unit and the same monitoring time point; unifying the units and removing outliers of the propionate concentration and acetate concentration; and taking the ratio of the processed propionate concentration to the acetate concentration as the propionate / acetate ratio.

[0050] The method for determining the additional amount of compound electron donors for unit ethylene production includes: determining the statistical period after the historical treatment sample enters the dechlorination stage of DCE and / or VC conversion into the main control process, obtaining the total additional amount of compound electron donors and the ethylene production increment during the statistical period, and taking the ratio of the total additional amount of compound electron donors to the ethylene production increment as the additional amount of compound electron donors for unit ethylene production.

[0051] In this embodiment of the invention, propionate and acetate concentrations can be obtained by collecting pore water, groundwater, or soil extracts from the corresponding treatment units of historical treatment samples and using conventional detection methods such as ion chromatography, high-performance liquid chromatography, or gas chromatography. After acquisition, the propionate and acetate concentrations are standardized to the same unit, and obvious outliers are removed. Preferably, when the acetate concentration is greater than a preset minimum effective concentration, the ratio of the treated propionate concentration to the acetate concentration is used as the propionate / acetate ratio to avoid distortion of the ratio due to excessively low acetate concentration.

[0052] The additional amount of compound electron donors added per unit of ethylene production can be determined based on the engineering dosage records and ethylene monitoring data of historical treatment samples. Specifically, during the statistical period after the historical treatment sample enters the dechlorination stage where DCE and / or VC are converted into the main control process, the total amount of compound electron donors added is obtained, and the ethylene production increment is determined based on the ethylene concentration changes at the beginning and end of the statistical period. Preferably, when the ethylene production increment is greater than the preset minimum effective production amount, the ratio of the total additional dosage to the ethylene production increment is taken as the additional amount of compound electron donors added per unit of ethylene production. The above detection and recording methods can all be implemented using mature existing technologies in this field.

[0053] Furthermore, the optimized method for contaminated soil remediation based on multi-source data analysis also includes the following steps:

[0054] Step S300: Determine whether the propionate / acetate ratio of each historical treatment sample and the additional amount of complex electron donors generated per unit of ethylene show a relationship of first decreasing and then increasing. If so, determine the propionate / acetate ratio range corresponding to the low value range of the additional amount of complex electron donors generated per unit of ethylene as the target ratio range.

[0055] Specifically, Figure 2 A flowchart for determining the target ratio range is shown.

[0056] The determination of whether the propionate / acetate ratio of each historical treatment sample shows a relationship of first decreasing and then increasing with the amount of additional complex electron donors generated per unit of ethylene, and if so, then the propionate / acetate ratio range corresponding to the low value range of the amount of additional complex electron donors generated per unit of ethylene is determined as the target ratio range, specifically includes the following steps:

[0057] Step S301: Sort several historical treatment samples in ascending order of propionate / acetate ratio to obtain a sample sequence;

[0058] Step S302: Extract the amount of additional ethylene-generating complex electron donors corresponding to each historical treatment sample in the sample sequence, and generate the trend of the additional amount change.

[0059] Step S303: Determine whether there is a trough in the trend of the additional amount change where the amount first decreases and then increases as the propionate / acetate ratio increases;

[0060] Step S304: If it exists, the range of propionate / acetate ratios corresponding to the low value range of the additional amount in the valley segment is determined as the target ratio range.

[0061] There are stable segments before and after the valley segment. The stable segment refers to the segment where the change in the amount of additional electron donors generated per unit of ethylene corresponding to adjacent historical treatment samples is less than a preset change threshold.

[0062] In this embodiment of the invention, step S300 serves the following purpose: it does not assume that any target treatment unit necessarily exhibits a relationship of decreasing followed by increasing early propionate / acetate ratios and subsequent addition of complex electron donors per unit of ethylene production. Instead, it first verifies this relationship using historical treatment samples that match the background conditions of the target treatment unit. Only when the aforementioned correspondence exists in the set of historical treatment samples can it be stated that the early propionate / acetate ratio can serve as a preliminary characterization parameter for the subsequent addition of complex electron donors to this type of target treatment unit, thereby allowing the determination of the target ratio range and pre-optimization. If the correspondence does not exist, the target ratio range is not determined based on the set of historical treatment samples, avoiding unreliable adjustments to the dosing strategy parameters of the target treatment unit.

[0063] Specifically, in step S301, the historical treatment samples are sorted from smallest to largest according to the propionate / acetate ratio. This is to transform the early fermentation states of different historical treatment samples into comparable sample sequences, allowing for trend analysis of the subsequent addition of complex electron donors for ethylene production per unit along the direction of change in the propionate / acetate ratio. In step S302, the addition of complex electron donors for ethylene production per unit corresponding to each historical treatment sample is extracted, and the trend of the addition amount is generated. This can be achieved through conventional data processing methods such as list sorting, curve fitting, moving average, piecewise regression, or trend line analysis.

[0064] In step S303, it is determined whether there is a trough segment in the trend of the additional electron donor quantity change, where the quantity first decreases and then increases with the increase of the propionate / acetate ratio. This can be achieved by identifying local minimum regions, segmented slope changes, differences between adjacent samples, or minimum regions of the fitted curve in the trend of the additional electron donor quantity change. The trough segment indicates that within this segment, the early fermentation state of the complex electron donor is well matched with the donor demand of the subsequent dechlorination stage, which is the main control process for the conversion of DCE and / or VC. Therefore, the additional amount of complex electron donor produced per unit of ethylene is relatively low.

[0065] In step S304, when the valley segment is identified, the range of propionate / acetate ratios corresponding to the low-value range of the additional amount within the valley segment is determined as the target ratio range. The low-value range can be determined based on the minimum amount of additional electron donors needed to generate complex ethylene within the valley segment and a preset tolerance. For example, an additional amount not exceeding 1.05 times, 1.10 times, or 1.20 times the minimum additional amount can be considered the low-value range. The above sorting, trend generation, valley identification, and interval extraction are all conventional data analysis methods that can be implemented based on historical remediation sample data in the soil remediation database.

[0066] Furthermore, the optimized method for contaminated soil remediation based on multi-source data analysis also includes the following steps:

[0067] Step S400: Obtain the current propionate / acetate ratio of the target treatment unit, and when it deviates from the target ratio range, adjust the addition strategy parameters of lactate-type fast-release electron donor and slow-release organic electron donor in the compound electron donor until the current propionate / acetate ratio falls into the target ratio range.

[0068] The dosing strategy parameters include the mass ratio, volume ratio, single dosing amount, dosing concentration, dosing interval, and / or number of dosings of lactate-type fast-release electron donors and slow-release organic electron donors.

[0069] The adjustment strategy parameters for the addition of the compound electron donor include: when the current propionate / acetate ratio of the target treatment unit is less than the lower limit of the target ratio range, reducing the proportion of lactate-type fast-release electron donor in the compound electron donor, reducing the single addition amount, extending the addition interval, and / or increasing the proportion of slow-release organic electron donor in the compound electron donor; when the current propionate / acetate ratio of the target treatment unit is greater than the upper limit of the target ratio range, increasing the proportion of lactate-type fast-release electron donor in the compound electron donor, shortening the addition interval, increasing the single addition amount, and / or supplementing with lactate-type fast-release electron donor.

[0070] Within a preset monitoring period after each adjustment of the dosing strategy parameters, fermentation products and environmental safety are monitored to obtain the propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH of the target treatment unit, and the current propionate / acetate ratio is recalculated. If the recalculated current propionate / acetate ratio still deviates from the target ratio range and the total volatile fatty acid concentration and pH do not reach the preset alarm threshold, the dosing strategy parameters are adjusted again. The adjustment is stopped when the current propionate / acetate ratio falls into the target ratio range. When the total volatile fatty acid concentration and / or pH reach the preset alarm threshold, the adjustment based on the propionate / acetate ratio is stopped, and the corresponding alarm handling strategy is executed.

[0071] In this embodiment of the invention, step S400 belongs to the actual control stage of the target treatment unit. Its purpose is to adjust the addition strategy parameters of the compound electron donor in advance and step by step according to the target ratio range determined in step S300, so that the target treatment unit can form an early fermentation state that matches the subsequent dechlorination requirements as much as possible before entering the dechlorination stage where DCE and / or VC are converted into the main control process.

[0072] Specifically, the current propionate and acetate concentrations of the target treatment unit are obtained, and the current propionate / acetate ratio is calculated as described above. If the current propionate / acetate ratio is within the target range, it indicates that the early fermentation state of the complex electron donor is similar to the state corresponding to the addition of a low-unit ethylene complex electron donor in historical treatment samples, and the current dosing strategy parameters can be maintained. If the current propionate / acetate ratio deviates from the target range, the dosing strategy parameters for lactate-type fast-release electron donors and slow-release organic electron donors are adjusted according to the direction of deviation.

[0073] When the current propionate / acetate ratio is less than the lower limit of the target ratio range, it indicates that the lactate-type fast-release electron donor in the target treatment unit is converting to acetate more rapidly, and the release rhythm of the compound electron donor is premature. In this case, the proportion of lactate-type fast-release electron donors in the compound electron donor can be reduced, the single dosage can be decreased, the dosage interval can be extended, and / or the proportion of slow-release organic electron donors in the compound electron donor can be increased to reduce premature release and ineffective consumption. For example, when the target ratio range is 0.35–0.55, and the current propionate / acetate ratio is 0.22, the mass ratio of lactate-type fast-release electron donors to slow-release organic electron donors can be adjusted from 60:40 to 50:50, or the single dosage can be reduced by 10%–20%, and the propionate and acetate concentrations can be re-detected after a preset monitoring time.

[0074] When the current propionate / acetate ratio exceeds the upper limit of the target ratio range, it indicates a relative accumulation of propionate in the target treatment unit, and a lag in the conversion of the complex electron donor into an effectively usable reducing equivalent. In this case, the proportion of lactate-type fast-release electron donors in the complex electron donors can be increased, the dosing interval shortened, the single dosing dose increased, and / or supplemental lactate-type fast-release electron donors can be added to enhance the supply of available reducing equivalents in the early stages. For example, when the target ratio range is 0.35–0.55, and the current propionate / acetate ratio is 0.72, the mass ratio of lactate-type fast-release electron donors to sustained-release organic electron donors can be adjusted from 40:60 to 50:50, or a small dose of lactate-type fast-release electron donors can be added between the original dosing cycles, and the current propionate / acetate ratio can be recalculated after a preset monitoring time.

[0075] The above adjustments can be implemented in a phased manner. This involves monitoring fermentation products and environmental safety after each adjustment, and using the recalculated propionate / acetate ratio to determine if another adjustment is necessary. The magnitude of each adjustment is not limited and can be determined based on the deviation of the current propionate / acetate ratio from the target range, the permeability of the target treatment unit, temperature, total volatile fatty acid concentration, pH, and the allowable dosage for construction. For example, if the deviation is small, only the dosing interval or a small adjustment to the ratio may be needed; if the deviation is large, the ratio, single dosage, and dosing interval can be adjusted simultaneously. Phased adjustments avoid the risk of abnormal accumulation of total volatile fatty acids or abnormal pH changes caused by a one-time, large change in the compound electron donor dosing strategy parameters.

[0076] Within a preset monitoring time after each adjustment of the dosing strategy parameters, the propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH of the target treatment unit are acquired, and the current propionate / acetate ratio is recalculated. If the current propionate / acetate ratio still deviates from the target ratio range, and the total volatile fatty acid concentration and pH have not reached the preset alarm threshold, the next round of dosing strategy parameter adjustment continues; if the current propionate / acetate ratio falls into the target ratio range, the current round of adjustment is stopped; when the total volatile fatty acid concentration and / or pH reach the preset alarm threshold, the current round of adjustment based on the propionate / acetate ratio is stopped, and the corresponding alarm handling strategy is executed. The alarm handling strategy may include reducing the total dosage of compound electron donors, reducing the proportion of lactate-type fast-release electron donors, extending the dosing interval, supplementing buffers, strengthening extraction and reinjection, or increasing the monitoring frequency, etc.

[0077] Through the above method, this invention does not passively adjust the process only after DCE and / or VC have accumulated significantly, pH is abnormal, or total volatile fatty acids exceed the threshold. Instead, it optimizes the process by utilizing the propionate / acetate ratio within the threshold during the early fermentation monitoring stage. This method enables the release rhythm of the complex electron donors to be closer to the low-addition state corresponding to the target ratio range, thereby reducing the amount of complex electron donors needed to generate per unit of ethylene in the subsequent dechlorination stage, which is the main control process for converting DCE and / or VC. This reduces the ineffective consumption and repeated replenishment of fast-release electron donors, and improves the stability and economy of the dehalogenation remediation process.

[0078] This invention is applicable to saturated zone soils, aquifer sediments, capillary rise zone soils, or soil-groundwater interface media contaminated with PCE and / or TCE, and is particularly suitable for in-situ enhanced reduction dechlorination remediation scenarios employing the synergistic addition of lactate-type fast-release electron donors and slow-release organic electron donors. For remediation units with risks associated with subsequent DCE and / or VC conversion control, but where early fermentation products and pH have not yet reached alarm thresholds, this invention provides a more refined optimization method for the compound electron donor addition strategy parameters, demonstrating promising prospects for field application.

[0079] It should be understood that although the steps in the flowcharts of the various embodiments of the present invention are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the various embodiments may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0080] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0081] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An optimization method for contaminated soil remediation based on multi-source data analysis, characterized in that, The method includes: When the target remediation unit is a dehalogenated bacterial remediation unit contaminated with PCE and / or TCE, and is in the early fermentation monitoring stage after the addition of compound electron donors, historical remediation samples matching the background conditions of the target remediation unit are screened from the soil remediation database; among them, compound electron donors include lactate-type fast-release electron donors and slow-release organic electron donors; Calculate the early propionate / acetate ratio for each historical treatment sample, and the additional amount of complex electron donors generated per unit of ethylene during the dechlorination stage of the subsequent DCE and / or VC conversion into the main control process; Determine whether the propionate / acetate ratio of each historical treatment sample shows a relationship of first decreasing and then increasing with the amount of additional complex electron donors generated per unit of ethylene. If so, determine the propionate / acetate ratio range corresponding to the low value range of the additional complex electron donors generated per unit of ethylene as the target ratio range. Obtain the current propionate / acetate ratio of the target treatment unit, and when it deviates from the target ratio range, adjust the addition strategy parameters of lactate-type fast-release electron donor and slow-release organic electron donor in the compound electron donor until the current propionate / acetate ratio falls into the target ratio range.

2. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 1, characterized in that, The early fermentation monitoring stage after the addition of the compound electron donor refers to the monitoring stage within a preset time period after the addition of the compound electron donor, and before the target treatment unit has entered the dechlorination stage where DCE and / or VC are converted into the main control process; during the monitoring stage, the concentrations of propionate, acetate, total volatile fatty acids and pH in the target treatment unit do not reach the preset alarm thresholds.

3. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 1, characterized in that, The historical treatment samples that match the background conditions of the target treatment unit specifically refer to historical treatment samples that match the target treatment unit in at least four of the following: pollutant type, pollutant medium type, initial PCE and / or TCE concentration range, initial DCE and / or VC concentration range, dehalogenation bacteria species or abundance, complex electron donor type, hydrogeological conditions, and initial pH and / or ORP conditions, and whose propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH did not reach the preset alarm threshold during the early fermentation monitoring stage.

4. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 1, characterized in that, The calculation process of the propionate / acetate ratio includes: obtaining the propionate concentration and acetate concentration corresponding to the same treatment unit and the same monitoring time point; unifying the units and removing outliers of the propionate concentration and acetate concentration; and taking the ratio of the processed propionate concentration to the acetate concentration as the propionate / acetate ratio.

5. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 1, characterized in that, The method for determining the additional amount of compound electron donors for unit ethylene production includes: determining the statistical period after the historical treatment sample enters the dechlorination stage of DCE and / or VC conversion into the main control process, obtaining the total additional amount of compound electron donors and the ethylene production increment during the statistical period, and taking the ratio of the total additional amount of compound electron donors to the ethylene production increment as the additional amount of compound electron donors for unit ethylene production.

6. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 1, characterized in that, The steps to determine whether the propionate / acetate ratio of each historical treatment sample shows a correlation between the initial decrease and subsequent increase in the amount of additional complex electron donors generated per unit of ethylene, and if so, to define the propionate / acetate ratio range corresponding to the low value range of the additional complex electron donors generated per unit of ethylene as the target ratio range, include: Several historical treatment samples were sorted in ascending order of propionate / acetate ratio to obtain a sample sequence; Extract the amount of additional ethylene-generating complex electron donors corresponding to each historical treatment sample in the sample sequence, and generate the trend of the additional amount change; Determine whether there is a trough in the trend of the additional amount change, where the amount first decreases and then increases as the propionate / acetate ratio increases; If it exists, the range of propionate / acetate ratios corresponding to the low value range of the additional amount in the valley segment is determined as the target ratio range.

7. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 6, characterized in that, There are stable segments before and after the valley segment. The stable segment refers to the segment where the change in the amount of additional electron donors generated per unit of ethylene corresponding to adjacent historical treatment samples is less than a preset change threshold.

8. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 1, characterized in that, The dosing strategy parameters include the mass ratio, volume ratio, single dosing amount, dosing concentration, dosing interval, and / or number of dosings of lactate-type fast-release electron donors and slow-release organic electron donors.

9. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 8, characterized in that, The adjustment strategy parameters for the addition of the compound electron donor include: when the current propionate / acetate ratio of the target treatment unit is less than the lower limit of the target ratio range, reducing the proportion of lactate-type fast-release electron donor in the compound electron donor, reducing the single addition amount, extending the addition interval, and / or increasing the proportion of slow-release organic electron donor in the compound electron donor; when the current propionate / acetate ratio of the target treatment unit is greater than the upper limit of the target ratio range, increasing the proportion of lactate-type fast-release electron donor in the compound electron donor, shortening the addition interval, increasing the single addition amount, and / or supplementing with lactate-type fast-release electron donor.

10. The optimized method for contaminated soil remediation based on multi-source data analysis according to claim 9, characterized in that, Within a preset monitoring period after each adjustment of the dosing strategy parameters, fermentation products and environmental safety are monitored to obtain the propionate concentration, acetate concentration, total volatile fatty acid concentration, and pH of the target treatment unit, and the current propionate / acetate ratio is recalculated. If the recalculated current propionate / acetate ratio still deviates from the target ratio range and the total volatile fatty acid concentration and pH do not reach the preset alarm threshold, the dosing strategy parameters are adjusted again. The adjustment is stopped when the current propionate / acetate ratio falls into the target ratio range. When the total volatile fatty acid concentration and / or pH reach the preset alarm threshold, the adjustment based on the propionate / acetate ratio is stopped, and the corresponding alarm handling strategy is executed.

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