Treatment method of dredged soil

Abstract

The invention relates to a dredged soil treatment method which comprises the following steps: carrying out water washing desalination treatment on dredged soil once or multiple times to obtain desalted dredged soil; and mixing the desalted dredged soil with a nutrient improver to obtain improved dredged soil, wherein the nutrient improver comprises wood vinegar. According to the treatment method of the dredged soil, the dredged soil is treated and can be used as greening planting soil, and resource utilization of the dredged soil is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the treatment of dredged soil, in particular to the treatment of port or river dredged soil. BACKGROUND

[0002] Dredged soil is a large amount of sediment produced in dredging engineering of water area such as port, river, etc., which usually has characteristics of high water content, high salinity and low organic matter. With the rapid development of global shipping industry, according to the statistics of International Shipping Association, the total amount of dredged soil produced each year has exceeded several billion tons. Traditional treatment methods such as stacking and shipping not only occupy a large amount of land resources, but also may cause secondary environmental problems such as soil degradation, groundwater pollution and the like due to migration of salinity and pollutants. How to efficiently treat dredged soil and convert it into valuable resources has become a technical problem to be solved.

[0003] The prior art discloses some treatment methods for dredged soil, however, these methods have problems of insufficient efficiency, high cost or limited improvement effect such as insufficient salinity leaching efficiency, still too high water content after dehydration when treating high salinity dredged soil. SUMMARY

[0004] To overcome at least one of the above-mentioned defects of the prior art, in a first aspect, an embodiment of the present application provides a treatment method of dredged soil, comprising the following steps:

[0005] carrying out one or more water washing desalination treatments on the dredged soil to obtain desalination dredged soil; and

[0006] mixing the desalination dredged soil with a nutrient amendment to obtain improved dredged soil;

[0007] wherein the nutrient amendment comprises vinegar.

[0008] In a second aspect, an embodiment of the present application provides an improved dredged soil obtained by the above-mentioned treatment method.

[0009] The treatment method of dredged soil of an embodiment of the present application can use the dredged soil as green planting soil by treating the dredged soil, and realizes the resource utilization of dredged soil. BRIEF DESCRIPTION OF DRAWINGS

[0010] The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated in and constitute a part of this specification. Illustrations in the drawings are for purposes of illustrating an embodiment and are not intended to limit the application, wherein:

[0011] Figure 1 The conductivity graphs of the original dredged soil of Example 1 and after the first water washing desalination treatment and the second water washing desalination treatment;

[0012] Figure 2The electrical conductivity graphs of the improved dredged soil sample from Example 1 on days 3, 5, 7, 14, and 28 of cultivation are shown.

[0013] Figure 3 The graph shows the cation exchange capacity of the improved dredged soil sample from Example 1 on days 3, 5, 7, 14, and 28 of cultivation.

[0014] Figure 4 The graph shows the organic matter content of the improved dredged soil sample from Example 1 on days 3, 5, 7, 14, and 28 of cultivation.

[0015] Figure 5 The conductivity graphs of the improved dredged soil sample from Comparative Example 1 on days 3, 5, 7, 14, and 28 of cultivation are shown.

[0016] Figure 6 The graph shows the organic matter content of the improved dredged soil sample from Comparative Example 1 on days 3, 5, 7, 14, and 28 of cultivation.

[0017] Figure 7 The conductivity graphs of the improved dredged soil sample from Comparative Example 2 on days 3, 5, 7, 14, and 28 of cultivation are shown.

[0018] Figure 8 The graph shows the organic matter content of the improved dredged soil sample from Comparative Example 2 on days 3, 5, 7, 14, and 28 of cultivation.

[0019] Figure 9 The graph shows the germination rate and number of germinations of ryegrass in different treatment groups of the application example.

[0020] Figure 10 Figures showing plant height and root length of ryegrass in different treatment groups of the application example;

[0021] Figure 11 The graph shows the fresh weight and dry weight of the aboveground and underground parts of ryegrass in different treatment groups of the application example. Detailed Implementation

[0022] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the description herein is for illustrative purposes only and not intended to limit the present invention.

[0023] One embodiment of the present invention provides a method for treating dredged soil, comprising the following steps:

[0024] Dredged soil is subjected to one or more water washing and desalination treatments to obtain desalinated dredged soil; and

[0025] The desalted dredged soil is mixed with the nutrient modifier to obtain a modified dredged soil.

[0026] The nutrient modifier comprises vinegar.

[0027] In an embodiment, the dredged soil is a port dredged soil or a river dredged soil.

[0028] In an embodiment, the desalted dredged soil can be naturally air-dried, ground through a 2mm sieve, and then measured for conductivity, cation exchange capacity, and organic matter content.

[0029] In an embodiment, the dredged soil can have a water content of 12-27wt%, such as 13wt%, 14wt%, 14.02wt%, 15wt%, 16wt%, 18wt%, 20wt%, 22wt%, 24wt%, 25wt%, 25.47wt%, 25.5wt%, or 26wt%.

[0030] In an embodiment, the dredged soil can have a conductivity of 3.0-6.0mS / cm, such as 3.8mS / cm, 3.88mS / cm, 4.0mS / cm, 4.1mS / cm, 4.2mS / cm, 4.5mS / cm, 4.8mS / cm, 5.0mS / cm, 5.2mS / cm, 5.4mS / cm, 5.5mS / cm, or 5.6mS / cm.

[0031] In an embodiment, the dredged soil can have a pH value of 8.0-9.0, such as 8.1, 8.2, 8.21, 8.25, 8.3, 8.4, 8.5, 8.56, 8.6, 8.7, 8.8, 8.86, or 8.9.

[0032] In an embodiment, the dredged soil can have an organic matter content of 3.4-4.2g / kg, such as 3.5, 3.51, 3.55, 3.6, 3.7, 3.8, 3.85, 3.9, 4.0, 4.03, 4.05, or 4.1.

[0033] In an embodiment, the dredged soil is washed with a washing liquid to desalt the dredged soil, and the washing liquid comprises water. Further, the washing liquid can be water or a sodium chloride solution, and the sodium chloride content in the washing liquid can be less than 0.5wt%, such as 0.3wt%.

[0034] In an embodiment, the washing liquid can be ballast water, which can be a 0.3wt% sodium chloride solution. Using ballast water as the washing liquid can achieve the goal of “waste treatment with waste”, which can ensure the desalination effect while significantly reducing water consumption.

[0035] In one embodiment, the mass ratio of the washing solution to the dredged soil is 0.6-1.0:1, for example, 0.7:1, 0.8:1, or 0.9:1.

[0036] In one embodiment, the dredged soil can be subjected to one or two water washing desalination treatments.

[0037] In one embodiment, the water washing desalination treatment comprises mixing the dredged soil with the washing solution and then washing the mixture, followed by suction filtration.

[0038] In one embodiment, the water washing desalination treatment comprises mixing the dredged soil with the washing solution, stirring the mixture into a uniform slurry, and then suction filtration. Further, after the solid after suction filtration is dried into a dry mud cake, the water content, conductivity, pH value, etc. can be measured.

[0039] In one embodiment, the water content of the desalinated dredged soil can be 14-22 wt%, for example, 15 wt%, 15.21 wt%, 15.5 wt%, 16 wt%, 18 wt%, 20 wt%, 20.36 wt%, 20.5 wt%, or 21 wt%.

[0040] In one embodiment, the conductivity of the desalinated dredged soil can be 0.3-2.1 mS / cm, for example, 0.35 mS / cm, 0.37 mS / cm, 0.4 mS / cm, 0.45 mS / cm, 0.5 mS / cm, 0.55 mS / cm, 0.6 mS / cm, 0.8 mS / cm, 0.9 mS / cm, 1.0 mS / cm, 1.2 mS / cm, 1.5 mS / cm, 1.7 mS / cm, 1.9 mS / cm, 1.97 mS / cm, or 2.0 mS / cm.

[0041] In one embodiment, the organic matter content of the desalinated dredged soil can be 3.0-4.1 g / kg, for example, 3.02 g / kg, 3.1 g / kg, 3.2 g / kg, 3.4 g / kg, 3.5 g / kg, 3.7 g / kg, 3.9 g / kg, 3.91 g / kg, or 4.0 g / kg.

[0042] In one embodiment, the pH value of the desalinated dredged soil can be 7.9-8.2, for example, 7.92, 8.0, 8.1, or 8.19.

[0043] In an embodiment, the mass ratio of the desalinated dredged soil to the pyroligneous liquid in the nutrient amendment is 1800-190000: 1, further can be 38000-190000: 1, for example, 1875: 1, 1900: 1, 2000: 1, 5000: 1, 10000: 1, 20000: 1, 30000: 1, 35000: 1, 37500: 1, 38000: 1, 40000: 1, 50000: 1, 80000: 1, 100000: 1, 120000: 1, 150000: 1, 180000: 1, 187500: 1. The pyroligneous liquid is obtained by wood distillation, which can also be pine pyroligneous liquid.

[0044] In an embodiment, the pine pyroligneous liquid is a liquid byproduct produced in the process of pine dry distillation (pyrolysis), mainly containing organic acids, phenols, ketones, alcohols and other components. Further, the preparation method of the pine pyroligneous liquid includes: dry distillation of pine at high temperature (for example, 300-500℃) under anaerobic conditions, and separating the condensed steam to obtain the pine pyroligneous liquid.

[0045] In an embodiment, the existing wood vinegar product containing pyroligneous liquid can be used as a nutrient amendment. Further, the pyroligneous liquid product can be diluted and used as a nutrient amendment. The dilution multiple is determined according to the ratio of the desalinated dredged soil to the pyroligneous liquid in the nutrient amendment.

[0046] In an embodiment, the desalinated dredged soil and the nutrient amendment can be mixed and cultured (or left standing) for more than 12 hours (0.5 days), further can be more than 1 day, and further can be more than 28 days. Further, the desalinated dredged soil and the nutrient amendment can be mixed and cultured at a water content of about 40wt%.

[0047] In an embodiment, the desalinated dredged soil and the nutrient amendment can be mixed and cultured for 0.5-30 days, further can be 7-30 days, for example, 2 days, 3 days, 5 days, 7 days, 9 days, 10 days, 12 days, 15 days, 20 days, 25 days, 27 days, 28 days or 29 days.

[0048] In an embodiment, the culture temperature of the desalinated dredged soil and the nutrient amendment after mixing can be 20-30℃, for example, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃ or 29℃.

[0049] In an embodiment, the culture humidity (relative humidity) of the desalinated dredged soil and the nutrient amendment after mixing can be 30-50%, for example, 32%, 35%, 38%, 39%, 40%, 41%, 42%, 45% or 48%.

[0050] In one embodiment, the modified dredged soil obtained by mixing the desalinated dredged soil with the nutrient amendment can be incubated for 28 days, and samples can be taken at 3, 5, 7, 14, and 28 days, respectively, and further dried and ground to measure the conductivity, cation exchange capacity, and other nutrient content indicators. Further, the incubation experiment can be performed in a constant temperature and humidity incubator at a temperature of 25°C and a relative humidity of 40%, and samples can be taken at 3, 5, 7, 14, and 28 days, and the obtained samples can be dried in a forced air drying oven at 85°C, ground, and sieved through a 2 mm sieve, and then measured.

[0051] In one embodiment, the modified dredged soil can have a water content of 2.5-6.0 wt%, such as 2.8 wt%, 2.9 wt%, 3.0 wt%, 3.05 wt%, 3.06 wt%, 3.1 wt%, 3.2 wt%, 3.4 wt%, 3.5 wt%, 3.8 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.2 wt%, 5.21 wt%, 5.3 wt%, or 5.5 wt%.

[0052] In one embodiment, the modified dredged soil can have a conductivity of 0.3-1.3 mS / cm, further 0.3-0.6 mS / cm, such as 0.33 mS / cm, 0.35 mS / cm, 0.4 mS / cm, 0.45 mS / cm, 0.5 mS / cm, 0.55 mS / cm, 0.6 mS / cm, 0.8 mS / cm, 0.9 mS / cm, 1.0 mS / cm, 1.2 mS / cm, or 1.28 mS / cm.

[0053] In one embodiment, the modified dredged soil can have a cation exchange capacity of 35-40 cmol / kg, such as 36 cmol / kg, 37 cmol / kg, 37.2 cmol / kg, 37.3 cmol / kg, 37.5 cmol / kg, 38 cmol / kg, 38.5 cmol / kg, or 39 cmol / kg. + + + + + + + + +

[0054] ​​​​​​​​​In an embodiment, the improved dredged soil has an organic matter content of 38-80 g / kg, for example, 40 g / kg, 40.7 g / kg, 41 g / kg, 43 g / kg, 45 g / kg, 48 g / kg, 50 g / kg, 55 g / kg, 60 g / kg, 65 g / kg, 70 g / kg, 72 g / kg, 72.8 g / kg, 73 g / kg, 75 g / kg, 78 g / kg, or 79 g / kg.

[0055] In an embodiment, the conductivity, cation exchange capacity, and organic matter content of various soil samples can be determined by LY / T 1251, LY / T 1243, and LY / T-1237 standard methods, and the water content of the soil samples can be determined by HJ 613-2011 standard method.

[0056] An embodiment of the present application provides an improved dredged soil obtained by the above-mentioned treatment method.

[0057] In an embodiment, the improved dredged soil can be used as a greening planting soil. Further, the improved dredged soil can be used as a planting soil for ryegrass.

[0058] The treatment method of the dredged soil in an embodiment of the present application realizes "waste treatment with waste" by using ballast water as the washing liquid in the water washing desalination treatment, and can greatly reduce water consumption while ensuring the desalination effect.

[0059] The treatment method of the dredged soil in an embodiment of the present application is simple, efficient, short in treatment period, and low in cost, and is particularly suitable for large-scale treatment of dredged soil.

[0060] The treatment method of the dredged soil in an embodiment of the present application obtains an improved dredged soil after treatment of the dredged soil, and the improved dredged soil has excellent indexes, meets the technical requirements for main control indexes of greening planting soil in the "Greening Planting Soil" (CJ / T 340-2016) standard, and can be used as a greening planting soil, and can be directly used in urban greening and ecological restoration engineering.

[0061] The treatment method of the dredged soil in an embodiment of the present application realizes effective conversion of the dredged soil from waste to resource by the synergistic application of desalination treatment and vinegar solution improvement, has good resource utilization and ecological utilization potential, and is suitable for efficient treatment and reuse of large-scale dredged soil.

[0062] The improved dredged soil obtained by the treatment method of the dredged soil in an embodiment of the present application has a significantly decreased conductivity, a significantly increased organic matter content, and a stable cation exchange capacity, and the overall performance meets the relevant standards of the "Greening Planting Soil", and the improved dredged soil can be used as a greening planting soil.

[0063] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates a method for treating dredged soil according to one embodiment of the present invention. At least some of the raw materials and testing methods involved in the embodiments and comparative examples are as follows.

[0064] Raw materials

[0065] 1. The dredged soil (original dredged soil) used was taken from 60 cm underground in the sediment-bearing area. Its surface was moist, its color was dark, and it was mainly composed of fine-grained soil. After natural air drying in the laboratory, it was passed through a 2 mm sieve, and its physicochemical properties were measured. The measured pH value of the dredged soil was 8.56, and its cation exchange capacity was 37.28 cmol. + / kg, moisture content 14.41wt%, electrical conductivity 4.04mS / cm.

[0066] 2. The wood vinegar product is produced by Shandong Jingmai Plant Information Technology Co., Ltd., and is a pine wood vinegar product, with a wood vinegar content of 100g / L.

[0067] 3. The fly ash used in the experiment came from a coal-fired power plant in Shanxi Province, China, and belonged to the F-type fly ash, which is mainly composed of aluminosilicate glass.

[0068] 4. Biochar is produced from corn stalks, specifically the corn stalks used as covering soil at a coal gangue dump in Changzhi, Shanxi Province. The specific preparation process is as follows:

[0069] Corn stalk biomass was dried in an 85℃ forced-air drying oven for 6 hours, then ground through an 18-mesh sieve and placed in a box-type resistance furnace under continuous nitrogen purging. The heating rate of the box-type resistance furnace was set to 10℃·min. -1 The material was pyrolyzed at a final temperature of 500℃ for two hours, during which nitrogen gas was continuously introduced. After cooling under the nitrogen gas flow, the material was taken out, ground through a 60-mesh sieve, and then transferred to a plastic-sealed bag for storage to obtain biochar material.

[0070] Test methods

[0071] 1. Measurement of conductivity

[0072] The conductivity of the sample was measured using the LY / T 1251 standard method.

[0073] 2. Determination of cation exchange capacity

[0074] The cation exchange capacity of the sample was determined using the LY / T 1243 standard method.

[0075] 3. Determination of organic matter content

[0076] The organic matter content of the sample was determined using the LY / T-1237 standard method.

[0077] 4. Water content

[0078] The water content of the sample was measured by the standard method of HJ 613-2011.

[0079] Example 1

[0080] S1: 0.3wt% salt-containing ballast water was used as the washing liquid, 200g of dredged soil sample was weighed and crushed in a beaker, and the washing liquid was added to the dredged soil sample so that the mass ratio of the washing liquid to the dredged soil was 0.8:1. After stirring for 3min until the mixture was uniform slurry, the mixture was filtered. After the dredged soil sample was dried into a mud cake, part of the sample was taken to measure the conductivity, and the results are shown in Table 1. Figure 1 (first filtration).

[0081] 100g of the sample after the first filtration was taken, and the mixture was prepared according to the water: mud ratio of 0.8:1. After stirring for 3min until the mixture was uniform slurry, the mixture was filtered for the second time. After the dredged soil sample was dried into a mud cake, part of the sample (i.e. desalted dredged soil) was taken to measure the conductivity, and the results are shown in Table 2. Figure 1 (second filtration). In addition, the pH value of the desalted dredged soil was measured to be 8.0. A sufficient amount of desalted dredged soil was prepared by repeating the above steps.

[0082] S2: The wood vinegar liquid product was diluted 200 times to obtain 16mL of diluted liquid. 300g of desalted dredged soil was mixed with the above diluted liquid in a preservation box, and the mass ratio of the desalted dredged soil to the wood vinegar liquid was 37500:1. After adjusting the water content of the mixed sample to 40wt%, the sample was placed in a constant temperature and humidity incubator, and incubated under the conditions of a temperature of 25℃ and a relative humidity of 40%. About 60g of the sample was taken out on the 3rd day, the 5th day, the 7th day, the 14th day and the 28th day of incubation, respectively, and dried in a 85℃ air drying oven. After grinding and passing through a 2mm sieve, the conductivity, cation exchange capacity and organic matter content of the sample were measured, and the results are shown in Table 3. Figures 2 to 4 .

[0083] Comparative Example 1

[0084] The desalted dredged soil was prepared by the same method as step S1 of Example 1. 300g of the desalted dredged soil was mixed with 30g of fly ash in a preservation box, and the water content of the mixed sample was adjusted to 40%. The sample was placed in a constant temperature and humidity incubator, and incubated under the conditions of a temperature of 25℃ and a relative humidity of 40%. About 60g of the sample was taken out on the 3rd day, the 5th day, the 7th day, the 14th day and the 28th day of incubation, respectively, and dried in a 85℃ air drying oven. After grinding and passing through a 2mm sieve, the conductivity and the organic matter content of the sample were measured, and the results are shown in Table 4. Figure 5 , 6 .

[0085] Comparative Example 2

[0086] The dredged soil was desalinated by the same method as step S1 of Example 1 to obtain desalinated dredged soil. 300 g of the desalinated dredged soil was mixed with 30 g of biochar in a preservation box, and then water was added to the mixed sample to adjust the moisture content to 40%. The sample was placed in a constant temperature and humidity incubator, and incubated at a temperature of 25°C and a relative humidity of 40%. About 60 g of the sample was taken out on the 3rd day, the 5th day, the 7th day, the 14th day and the 28th day of incubation, respectively, and then dried in a forced air drying oven at 85°C. After grinding and passing through a 2 mm sieve, the conductivity and organic matter content of the sample were determined. The results are shown in Table 1. Figure 7 8 .

[0087] Application Example

[0088] A pot experiment was conducted to study the effects of desalination and vinegar liquid modification on the planting performance of dredged soil using ryegrass as the planting plant. The original dredged soil, desalinated dredged soil and the soil modified by vinegar liquid were used for planting ryegrass. There were 8 groups of treatments (A1-A4 and B1-B4), each with 3 parallel samples, a total of 24 pots.

[0089] A1 is the original dredged soil. A2 is a sample obtained by mixing the original dredged soil with a diluted 1000-fold vinegar liquid product diluent, wherein the mass ratio of the original dredged soil to the vinegar liquid is 187500:1. A3 is a sample obtained by mixing the original dredged soil with a diluted 200-fold vinegar liquid product diluent, wherein the mass ratio of the original dredged soil to the vinegar liquid is 37500:1. A4 is a sample obtained by mixing the original dredged soil with a diluted 10-fold vinegar liquid product diluent, wherein the mass ratio of the original dredged soil to the vinegar liquid is 1875:1.

[0090] B1 is desalinated dredged soil. B2 is a sample obtained by mixing the desalinated dredged soil with a diluted 1000-fold vinegar liquid product diluent, wherein the mass ratio of the desalinated dredged soil to the vinegar liquid is 187500:1. B3 is a sample obtained by mixing the desalinated dredged soil with a diluted 200-fold vinegar liquid product diluent, wherein the mass ratio of the desalinated dredged soil to the vinegar liquid is 37500:1. B4 is a sample obtained by mixing the desalinated dredged soil with a diluted 10-fold vinegar liquid product diluent, wherein the mass ratio of the desalinated dredged soil to the vinegar liquid is 1875:1. The desalinated dredged soil was obtained by the same treatment as step S1 of Example 1.

[0091] ​The planting process of each pot is as follows: before sowing, the wood vinegar product diluent (16 mL) is uniformly mixed in the original dredged soil or desalted dredged soil (300 g), and 60 seeds of the same ryegrass are sowed in the pot after standing for 12 hours. During planting, the humidity and natural light are maintained, the germination rate is measured on the 15th day after sowing, the plant height is measured on the 25th day, the plant dry weight is measured on the 30th day, and the root development and leaf growth are observed. The specific results are shown in Table 1. Figures 9 to 11 .

[0092] According to Figure 1 , after two water washing and desalting treatments, the conductivity of the dredged soil significantly decreases by 83.66%, from the original value of 0.66 mS / cm, which meets the requirements of the Greening Planting Soil CJ / T340-2016 for salt content.

[0093] According to Figure 2 , the conductivity of the modified dredged soil of Example 1 shows a trend of first increasing and then decreasing with time. The conductivity is 944 μS / cm on the 3rd day, increases to 1277 μS / cm on the 5th day, and then gradually decreases to 587 μS / cm, 437 μS / cm and 331 μS / cm on the 7th day, the 14th day and the 28th day, respectively. This change trend may be related to the initial release and subsequent degradation of soluble organic matter in the wood vinegar, indicating that the addition of wood vinegar effectively reduces the soil salt content, which meets the requirements of greening soil.

[0094] According to Figure 3 , the cation exchange capacity of the modified dredged soil of Example 1 remains stable (37.21-37.30 cmol + / kg) during the entire culture period, which is not significantly affected by the addition of wood vinegar. This index is much higher than the minimum value (≥10 cmol + / kg) required by the standard, indicating that the dredged soil itself has good fertilizer retention capacity, and the addition of wood vinegar does not destroy its original structure, further verifying its applicability as a soil conditioner.

[0095] According to Figure 4 , the organic matter content of the modified dredged soil of Example 1 increases from 5.86 g / kg on the 3rd day to 79.82 g / kg on the 28th day, with a significant increase. This increase is mainly due to the continuous release and accumulation of active ingredients such as organic acids and phenols in the wood vinegar. The organic matter content on the 28th day completely meets the standard requirement of 12-80 g / kg, indicating that the wood vinegar can effectively improve the fertility of the dredged soil.

[0096] According to Figure 5 , 7It can be seen that the conductivity of the modified dredged soil of Comparative Example 1 and 2 reached the minimum after 28 days of culture, but was still higher than 400 μS / cm or remained at about 400 μS / cm. The conductivity of the modified dredged soil of Example 1 was 331 μS / cm after 28 days of culture. Thus, compared with fly ash and biochar, the use of wood vinegar to modify the dredged soil can reduce the conductivity to a greater extent.

[0097] According to Figure 6 It can be seen that the change of the organic matter content in the modified dredged soil of Comparative Example 1 was not large, and the organic matter content was basically stable in the range of 3.82-3.88 g / kg during the period from the 3rd day to the 28th day of culture, which was far lower than the organic matter content of the modified dredged soil of Example 1, and the content did not meet the standard requirement of 12-80 g / kg, indicating that the fly ash had a much smaller effect on the improvement of the organic matter content of the dredged soil than the wood vinegar, and the dredged soil modified by the fly ash was not suitable for use as a green planting soil.

[0098] According to Figure 4 , 8 It can be seen that the organic matter content of the modified dredged soil of Comparative Example 2 was 10.75 g / kg on the 7th day of culture, and the organic matter content of the modified dredged soil of Example 1 was 17.01 g / kg, which was significantly higher than that of Comparative Example 2. On the 28th day of culture, the organic matter content of Example 1 was 79.82 g / kg, and the content of Comparative Example 2 was still below 40 g / kg. The above results show that the effect of biochar on the improvement of the organic matter content of the dredged soil is much smaller than that of wood vinegar.

[0099] According to Figure 9 It can be seen that in the application examples, the overall germination rate of the ryegrass in the A1-A4 groups using the original dredged soil was low, and the germination rate of the A1 group was only 5%, and the germination rate of the A2-A4 groups added with wood vinegar was in the range of 3.33-11.67%. Some treatment groups (such as A2 and A3) had no seed germination in individual parallel pots. The overall germination rate of the ryegrass in the B1-B4 groups using the desalted dredged soil was significantly higher than that in the A1-A4 groups, and the germination rate of the B1-B4 groups was in the range of 65.83%-94.17%; among them, the germination rate of the B2 group was the highest, which was 94.17%; followed by the B3 group (90.83%) and the B1 group (72.5%), and the germination rate of the B4 group was the lowest, which was 65.83%. The above results show that in the modified dredged soil, the mass ratio of desalted dredged soil to wood vinegar is preferably 38000-190000:1.

[0100] According to Figure 10It can be seen that in the A1-A4 groups of the application examples, the average plant height of ryegrass in the A1 group is only 4.90 cm, and the A4 group is slightly higher at 7.80 cm, while the growth of the A2 and A3 groups on the 30th day makes it impossible to observe the biomass on the ground and thus no plant height is recorded. The A1-A4 groups generally exhibit low germination rate and low plant height, indicating that dredged soil without desalination treatment is difficult to support the normal growth and development of plants. The average plant height of ryegrass in the B1-B4 groups is 33.20 cm, 29.80 cm, 30.17 cm and 27.60 cm, respectively, which is significantly higher than that in the A1-A4 groups, reflecting that desalination treatment significantly alleviates the inhibition of salt stress on the growth of plant stems and leaves.

[0101] In addition, the average root length of ryegrass in the A1-A4 groups is 4.30 cm, 1.47 cm, 6.13 cm and 6.53 cm, respectively, among which the root length of the A2 group is the shortest, and the root length of the A3 and A4 groups is slightly improved, but the biomass is still low, indicating that although the root development is locally enhanced, the overall growth is difficult to maintain. Compared with the A1-A4 groups, the root length of ryegrass in the B1-B4 groups is significantly improved, reaching 9.30 cm, 10.80 cm, 11.30 cm and 9.73 cm, respectively. Among them, the root system growth of the B2 and B3 treatment groups is the most robust, indicating that appropriate use of vinegar on the basis of desalination can further optimize the rhizosphere environment, promote the activity of root meristem and nutrient absorption capacity, and thus enhance the coordinated development of the aboveground and underground parts of plants.

[0102] According to Figure 11 It can be seen that in the A1-A4 groups of the application examples, the biomass accumulation of ryegrass is extremely limited, with aboveground fresh weight of only 0.05 g and dry weight of 0.006 g in the A1 group. Although the plant height of the A4 group is slightly increased, the aboveground fresh weight decreases to 0.037 g, and the dry weight shows little difference. The A2 and A3 groups have no seedlings, so the biomass is 0. The underground part shows similar performance, with underground fresh weight ranging from 0.05 to 0.15 g and dry weight between 0.02 and 0.06 g in the A1-A4 groups, indicating that high salt background and improper concentration of vinegar will significantly inhibit biomass accumulation.

[0103] In the B1-B4 groups of application examples, the fresh weight of the aboveground part of ryegrass was 2.88 g (B1), 3.09 g (B2), 3.14 g (B3) and 2.19 g (B4), respectively, and the dry weight also increased synchronously. The fresh weight of the underground part was 2.10 g, 2.88 g, 2.78 g and 1.85 g, respectively, and the underground dry weight was 0.51 g (B1), 0.82 g (B2), 0.81 g (B3) and 0.48 g (B4). The B2 and B3 treatment groups showed the best aboveground and underground biomass accumulation effect, further indicating that when the mass ratio of desalination dredged soil to vinegar solution in the improved dredged soil is 38000-190000:1, it is more helpful to build a suitable micro-ecological environment, improve the rhizosphere aeration, provide soluble organic carbon, and enhance the microbial activity, and ultimately improve the overall biomass of ryegrass.

[0104] Unless specifically defined otherwise, the terms used in the present application are understood to have the meanings commonly used by those skilled in the art.

[0105] The embodiments described in the present application are only for exemplary purposes, and are not intended to limit the protection scope of the present application. Those skilled in the art can make various other replacements, changes and improvements within the scope of the present application, and thus the present application is not limited to the above-described embodiments, but is limited only by the claims.

Claims

1. A method for treating dredged soil, comprising the following steps: Dredged soil is subjected to one or more water washing and desalination treatments to obtain desalinated dredged soil; and The desalinated dredged soil is mixed with a nutrient amendment to obtain amended dredged soil; in, The nutrient improver includes wood vinegar.

2. The processing method according to claim 1, wherein, The dredged soil is desalinated by washing with a washing solution comprising water; and / or... The improved dredged soil may be used as soil for landscaping and planting; and / or The desalinated dredged soil is mixed with the nutrient improver and then incubated for more than 0.5 days.

3. The processing method according to claim 2, wherein, The washing solution is a sodium chloride solution; and / or, The mass ratio of the washing liquid to the dredged soil is 0.6–1.0:1; and / or, The water washing and desalination process includes mixing and washing the dredged soil with the washing liquid, followed by filtration.

4. The processing method according to claim 2, wherein, The washing solution is ballast water; and / or, The desalinated dredged soil was mixed with the nutrient improver and then cultured at a temperature of 20-30°C and a relative humidity of 30-50%.

5. The processing method according to claim 1, wherein, The electrical conductivity of the desalinated dredged soil is 0.3–2.1 mS / cm; and / or, The organic matter content of the desalinated dredged soil is 3.0–4.1 g / kg; and / or, The pH value of the desalinated dredged soil is 7.9 to 8.

2.

6. The processing method according to claim 1, wherein, The mass ratio of the desalinated dredged soil to the wood vinegar is 1800–190000:1; and / or, The desalinated dredged soil is mixed with the nutrient improver and then cultured for 0.5 to 30 days.

7. The processing method according to claim 1, wherein, The electrical conductivity of the improved dredged soil is 0.3–1.3 mS / cm; and / or, The cation exchange capacity of the improved dredged soil is 35–40 cmol. + / kg.

8. The processing method according to claim 1, wherein, The organic matter content of the improved dredged soil is 38–80 g / kg; and / or, The electrical conductivity of the improved dredged soil is 0.3–0.6 mS / cm; and / or, The mass ratio of the desalinated dredged soil to the wood vinegar is 38,000 to 190,000:

1.

9. The processing method according to claim 1, wherein, The improved dredged soil was used as planting soil for ryegrass.

10. An improved dredged soil, obtained by the treatment method according to any one of claims 1 to 9.

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