CN114368885A

CN114368885A - Riverway bottom mud original site soil ecological remediation method

Info

Publication number: CN114368885A
Application number: CN202111391042.9A
Authority: CN
Inventors: 祝建中; 王恢复; 张欢; 朱秋子; 陈靓
Original assignee: Hohai University HHU
Current assignee: Hohai University HHU
Priority date: 2021-11-23
Filing date: 2021-11-23
Publication date: 2022-04-19

Abstract

The invention discloses a riverway bottom mud original site soil ecological restoration method, which comprises the steps of digging at least one oxidation ditch at two sides of a riverway to be treated, paving bottom mud which reaches fermentation conditions in the oxidation ditch, adding an organic conditioner, microorganisms, a passivator and soil before fermentation to improve the properties of the bottom mud, promoting pile aerobic fermentation, removing odor and peculiar smell in the bottom mud, and reducing the toxicity of heavy metals in the bottom mud.

Description

Riverway bottom mud original site soil ecological remediation method

Technical Field

The invention belongs to the technical field of ecological restoration, and particularly relates to a riverway bottom mud original site soil ecological restoration method.

Background

The sediment is deposited at the bottom of water bodies such as rivers, lakes, reservoirs, gulfs and the like for a long time, is an important component of a multiphase ecosystem of the water bodies, and is a gathering place of environmental pollutants in a wide space and a long time. The sediment contains a large amount of nitrogen and phosphorus nutrient elements, heavy metals and an organic conditioner difficult to degrade, and when the water environment changes, substances in the sediment can migrate along with the change of the water environment, so that the water quality of the overlying water body is influenced, and secondary pollution is formed. The bottom sediment remediation is one of the hot spots concerned in the environmental field, and the aerobic fermentation remediation is a widely adopted technical method for treating organic solid wastes worldwide, and the fermentation industry shows a continuous development situation along with the change of the environment and the development of science and technology. The aerobic fermentation treatment of the bottom sludge is a derivative method of bioremediation, during the fermentation process, microorganisms degrade polluting organic conditioners into inorganic substances by utilizing the activities of the microorganisms, release energy required by the growth activities of the microorganisms, and continuously breed the microorganisms while the material structures are continuously changed, so that more organisms are generated.

The traditional river course revetment mostly takes the stereoplasm as the main thing, has important effect such as to flood control drainage waterlogging, soil and water conservation. Along with the increasingly prominent ecological environmental problem of the river channel, the limitation effect of the hard revetment on the river channel ecology is increasingly prominent, and the application of the ecological revetment technology is also increasingly determined. Ecological bank protection except replacing traditional stereoplasm bank protection in river course treatment engineering, plays effects such as flood control, drainage, soil and water conservation, has following effect to river course treatment engineering still: (1) the ecological stability of the river channel is improved; (2) improving the self-purification capacity of the water body; (3) creating a good landscape.

At present, the methods for repairing and treating the bottom mud of the river mainly comprise 2 methods, namely in-situ repair and ex-situ repair. The sediment dredging method in the ectopic repair technology is to dig and transport the sediment in the river to other positions, and the sediment needs to be independently treated after being dug. The high bed mud of moisture content needs to be transported to other positions to general dystopy restoration, inevitably can accelerate the release of nitrogen, phosphorus in the bed mud in the transportation to need special place to be used for handling a large amount of bed mud, the treatment cost is higher.

Disclosure of Invention

The purpose is as follows: aiming at the situation and overcoming the defects of the prior art, the invention provides a riverway bottom mud original site soil ecological restoration method, which comprises the steps of treating riverway bottom mud in situ, carrying out fermentation aerobic fermentation and final soil formation, and planting green plants on the riverway bottom mud to realize the resource utilization of the riverway bottom mud.

The technical scheme is as follows: in order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a riverway bottom mud original site soil ecological restoration method comprises the following steps:

digging at least one oxidation ditch on two sides of a river channel to be treated, stacking dug soil on two sides of the oxidation ditch, and drilling deep holes at the bottom of the oxidation ditch;

step two, uniformly mixing the dewatered bottom mud with the water content of 50-80% with an organic conditioner, microorganisms, a passivator and soil to obtain a bottom mud mixture;

thirdly, laying the bottom mud mixture in the oxidation ditch, and carrying out aerobic fermentation for a period of time;

fourthly, digging tree pits in the oxidation ditch and planting green plants after the fermentation of the bottom mud mixture is finished;

and fifthly, backfilling soil into the oxidation ditch, and repairing and leveling the top of the oxidation ditch.

In some embodiments, in the first step, the depth of the oxidation trench is 90-100 cm, and the width of the narrowest part is 1-2 m. The width is determined by the amount of bottom mud.

In some embodiments, in the first step, the depth of the holes drilled at the bottom of the oxidation ditch is 30-50 cm, and the distance between the holes drilled is 20cm × 20 cm. The purpose of punching is to fully utilize the infiltration of soil to remove the excess water in the pile.

In some embodiments, the organic conditioner comprises one or more of garden waste and straws, the garden waste and the straws need to be crushed before being added, and the adding amount of the organic conditioner is 7-10 wt% of the mass of the bottom mud;

the microorganism is an aerobic microbial inoculum, and the inoculation amount is generally 0.05-5 wt% of the mass of the bottom mud;

the passivator comprises fly ash and powdered rock phosphate, wherein the adding proportion of the fly ash to the powdered rock phosphate is respectively 25 wt% and 20 wt% of the mass of the bottom mud;

the addition amount of the soil is 10wt% of the mass of the bottom mud;

the purpose of adding the additive is to ensure aerobic fermentation of the pile body to the maximum extent and remove odor and peculiar smell in the bottom mud.

In some embodiments, the sediment mixture obtained in step two satisfies, prior to fermentation: the pH value is 7.5-8.5, the water content is 50-65%, the C/N is 20-35, and the average suitable particle size is 25-75 mm.

In some embodiments, in the third step, the thickness of the bottom mud mixture laid in the oxidation ditch is 50-80 cm; the time of aerobic fermentation is about one month. When the weather is overcast and rainy, the bottom mud mixture of the oxidation ditch needs to be covered with waterproof geotextile.

In some embodiments, in the fourth step, the green plants comprise one or more of pond cedar and willow, the height of the tree seedlings is 1-3 m, the distance between pond cedar plants is 300cm, and the distance between willow plants is 400 cm.

In some embodiments, in step five, backfill soil is uniformly laid on the bottom mud mixture and the tree root soil balls, so that the appearance of the oxidation ditch after backfill is not different from that of the nearby ground.

Has the advantages that: according to the ecological restoration method for the original site soil of the river sediment, provided by the invention, a series of treatments are carried out on the river sediment at the original site under the condition that the river sediment is not transferred and transported out, so that the river sediment is finally subjected to soil and resource utilization, and the soil still retains higher organic conditioner content, namely the soil has rich fertility. The bottom mud is stacked in the structures at two sides of the river after being treated nearby, so that the method is simple and saves cost, and the environmental problem in the transportation process can not be caused.

By digging the bottom mud oxidation ditch and planting green plants on the bottom mud oxidation ditch, a field for fermenting the original site of the bottom mud is provided, and the green plants can be planted.

Drawings

FIG. 1 is an aerobic fermentation diagram of a riverway sediment soil ecological remediation method provided by an embodiment of the invention;

fig. 2 is a flow chart of the structure of the method shown in fig. 1.

In the figure: 1. an oxidation ditch; 2. tree root soil balls; 3. a fermentation layer; 4. a soil backfill layer; 5. Planting green; 6. deep holes.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

Example 1

Unless otherwise specified,% in the present application are mass percentages.

As shown in fig. 1 to fig. 2, the present embodiment provides an ecological remediation method for making bottom mud of a river into soil and planting green plants, including:

firstly, excavating an oxidation ditch 1 on two bank dikes of a river channel to be treated along each side of the river channel, and temporarily stacking excavated soil on two sides of the oxidation ditch in situ; carrying out deep hole drilling 6 treatment on the bottom of the oxidation ditch;

step two, finding a flat land, laying a layer of waterproof geotextile on the flat land, and uniformly stacking the dehydrated bottom mud on the geotextile; adding an organic conditioner, microorganisms, a passivator and soil into the bottom mud in sequence, and turning and stirring the bottom mud by using a fork or a shovel after materials are added each time, so as to ensure that additives can be uniformly distributed in the bottom mud to the maximum extent;

uniformly paving the bottom mud on the geotextile and the additives after uniform stirring in the oxidation ditch 1 without compacting, and ensuring that the paved bottom mud has certain fluffiness and porosity; then, other operations are not needed, the part of the bottom mud is naturally fermented for about one month, and when the rainy day occurs, a layer of waterproof geotextile is required to cover the oxidation ditch, so that the bottom mud mixture is prevented from being drenched in the aerobic fermentation process;

step four, after the natural fermentation of the bottom mud mixture in the bottom mud fermentation layer 3 in the step three is finished, digging a tree pit which is about 20cm larger than tree root soil balls in the fermentation layer 3 by using a shovel or other tools for planting green plants, and temporarily stacking the dug bottom mud mixture on two sides of an oxidation ditch;

planting the transported green plants with soil balls 2 at the roots in tree pits in the oxidation ditch 1, then backfilling the bottom mud mixture dug out in the fourth step into the oxidation ditch 1 by using a shovel, paving the bottom mud mixture around the soil balls 2 at the roots of the trees, and stopping backfilling when the bottom mud mixture is backfilled to be about 20-30 cm away from the top of the oxidation ditch 1;

step six, backfilling the excavated soil stacked on the two sides of the oxidation ditch 1 in the step one into the oxidation ditch 1 by using a shovel, wherein the oxidation ditch 1 comprises a fermented layer 3 and planted green soil-planting balls 2, the backfilled soil is directly laid on the fermented layer 3 and the tree root soil balls 2, the backfilling is stopped when the soil is backfilled to a position slightly higher than the top of the oxidation ditch 1 by about 2cm, and the high part is lightly compacted by using the shovel, so that the top surface of the ditch is smooth and the characteristic of softness is kept;

the soil loosening treatment of the bottom soil of the oxidation ditch has the advantages that the permeability of the soil at the bottom of the oxidation ditch can be increased, the fluidity of the air at the bottom of the oxidation ditch can be increased, the problem that the water content of a bottom mud mixture is possibly too high in the fermentation process is solved, and air conditions are provided for aerobic fermentation;

the treated bottom mud reaching the fermentation index has the pH value of 7.5-8.5, the water content of 50-65%, the C/N ratio of not less than 10 and the average proper granularity of 25-75 mm.

The treated bottom mud reaching the standard is laid on waterproof geotextile, and is mainly used for adding a series of materials such as organic conditioner and the like before fermentation to adjust the C/N ratio and the aerobic bacteria quantity of the bottom mud and change the toxic heavy metal form, the bottom mud porosity and the like in the bottom mud.

The organic conditioner is also called as a fermentation conditioner, comprises garden waste, straws and the like, is mainly used for keeping the structure and the permeability of a bottom mud mixture, can increase the porosity of a pile body, prevents the pile body from collapsing and can adjust the moisture in the fermentation process of the pile body within a proper range; the optimal range of adding the fermentation conditioner into the pile is 7-10%.

Adding microorganisms: the microbial inoculant in fermentation is generally an aerobic inoculant, and aims to shorten the time for fermentation materials to reach high temperature, the microbes play an important role in the fermentation reaction process of the substrate sludge, the inoculant can shorten the time for the fermentation materials to reach high temperature, and inhibit the generation of foul gas in the fermentation process, so that the odor and peculiar smell in the substrate sludge are removed and are not generated any more; the fermentation and decomposition process is shortened, pathogens are effectively killed, the fermentation quality is improved, and the addition amount of the inoculant is generally 0.05-5% of the mass of the pile.

The purpose of adding soil is to add inorganic matters into the bottom mud, adjust the water content of the bottom mud and increase the porosity of the bottom mud so that more oxygen is stored in the pores of the pile body for aerobic fermentation, and the addition of the soil is about 10 percent, which is more suitable.

The added heavy metal passivator is mainly used for reducing the toxicity of the residual heavy metal in the bottom sediment, and researches show that the existing forms of the heavy metal in the bottom sediment can be divided into a water-soluble state, an exchange state, an organic combination state, a carbonate and sulfide combination state, a residue state and the like, wherein the heavy metal in the first 3 forms has higher bioavailability, namely has higher toxicity to organisms, the heavy metal passivator can change the forms of the heavy metal, so that the bioavailability is reduced, and the aim of reducing the toxicity to the organisms is fulfilled, and the proper adding proportion of common passivators such as fly ash and ground phosphate rock is respectively 25% and 20%.

The stirring is conveniently and quickly carried out on the land leveled outside the ditch, various difficulties which are possibly met when the conditioner is added after the land is laid in the oxidation ditch 1 are avoided, and simultaneously, the uniformly mixed bottom mud and the additive can play a role in stirring when the bottom mud and the additive are transferred into the ditch by a shovel; the bottom mud laid in the ditch is not required to be compacted and has certain porosity, so that more air is in the pile body in the fermentation process, microbial aerobic fermentation conditions are provided, a large amount of organic matters in the bottom mud are decomposed into carbon dioxide, water, inorganic matters and biological cell substances through aerobic fermentation, the odor and the peculiar smell of the bottom mud are removed, and the bottom mud is improved into soil containing abundant humus.

Turning the fermented bottom mud out of the oxidation ditch 1 by using a shovel, and reserving 10-20 cm of bottom mud at the bottom of the ditch, wherein the content of organic matters and the porosity of the bottom mud are better than that of the soil at the bottom of the oxidation ditch; vertically planting the transported green plants in the middle position in an oxidation ditch 1, backfilling bottom mud turned out from two sides of the oxidation ditch into the ditch by using a shovel, covering green plant root soil balls 2, backfilling until the distance from the top of the oxidation ditch 1 is 20-30 cm, stopping backfilling the bottom mud, beginning to backfill the soil stacked on two sides of the oxidation ditch 1, uniformly paving the backfilled soil on the bottom mud and the green plant root soil balls 2, stopping backfilling when the soil is backfilled to be slightly higher than the top of the oxidation ditch 1 by about 2cm, and lightly compacting a high part by using the shovel so that the top surface of the ditch is smooth and the characteristic of softness can be kept, and the purpose is to ensure that the appearance of the oxidation ditch 1 after backfilling is not different from the adjacent ground and keep the appearance attractive; and mixing the residual bottom mud and the soil by using a shovel, paving the mixture on one side of the oxidation ditch 1 close to the river channel, compacting and leveling by using machinery, and building a river bank.

Preferably, the depth of the oxidation ditch 1 is not more than 1m, and the width of the bottom of the oxidation ditch is 1-2 m according to the amount of bottom mud of a river channel;

optionally, the depth of the oxidation ditch 1 is 1m, and the width of the oxidation ditch bottom is 1m, 1.5m or 2 m.

Preferably, the thickness of the bottom mud fermentation layer 3 is 50-80 cm;

optionally, the thickness of the bottom mud fermentation layer 3 is 50cm, 60cm, 70cm or 80cm, which is adjusted according to the actual situation of the bottom mud amount of the river channel at the current section.

Preferably, the thickness of the soil backfill layer 4 is 20-30 cm;

optionally, the thickness of the soil backfill layer 4 is 20cm or 30cm, which is adjusted according to the thickness of the bottom mud layer.

In the description of the present application, it is to be understood that the terms "central," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for the convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be considered limiting of the claimed invention.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims

1. A riverway bottom mud original site soil ecological restoration method is characterized by comprising the following steps:

2. The method for ecological restoration of the riverway bottom mud original site soil formation according to claim 1, wherein in the first step, the depth of the oxidation ditch is 90-100 cm, and the width of the narrowest part is 1-2 m.

3. The ecological restoration method for the original site soil of the river sediment according to claim 1, wherein in the first step, the depth of the holes drilled at the bottom of the oxidation ditch is 30-50 cm, and the distance between the holes drilled is 20cm x 20 cm.

4. The method for ecological restoration of an original site soil formation of river sediment according to claim 1, wherein the sediment mixture obtained in the second step meets the following requirements before fermentation: the pH value is 7.5-8.5, the water content is 50-65%, the C/N is 20-35, and the average suitable particle size is 25-75 mm.

5. The ecological restoration method for the original site soil of the river sediment according to claim 1, wherein the organic conditioner comprises one or more of garden waste and straws, the garden waste and the straws need to be crushed before being added, and the addition amount of the organic conditioner is 7-10 wt% of the mass of the sediment;

and/or the microorganism is an aerobic microbial inoculum, and the inoculation amount is generally 0.05-5 wt% of the mass of the substrate sludge;

and/or the passivator comprises fly ash and powdered rock phosphate, wherein the adding proportion of the fly ash and the powdered rock phosphate is respectively 25 wt% and 20 wt% of the mass of the bottom mud;

and/or the addition amount of the soil is 10wt% of the mass of the bottom mud.

6. The ecological restoration method for the original site soil of the bottom mud of the river channel as claimed in claim 1, wherein in the third step, the thickness of the bottom mud mixture laid in the oxidation ditch is 50-80 cm; the time of aerobic fermentation is about one month.

7. The ecological restoration method for the riverway bottom mud original site soil metaplasia as claimed in claim 1, wherein in the fourth step, the green plants comprise one or more of pond cedar and willow, the height of the tree seedlings is 1-3 m, the distance between pond cedar plants is 300cm, and the distance between willow plants is 400 cm.

8. The method for ecological restoration of the original site soil of the river sediment as claimed in claim 1, wherein in the fifth step, backfill soil is uniformly laid on the sediment mixture and the tree root soil balls, so as to ensure that the appearance of the oxidation ditch after backfilling is not different from that of the nearby ground.