High-efficiency in-situ remediation method for black and odorous sediment of rain sewage overflow type river and lake

Abstract

The present application belongs to the technical field of water environment treatment, and relates to a high-efficiency in-situ remediation method for black and odorous sediment of rain and sewage overflow type river and lake. The method comprises the following steps: 1) obtaining monitoring data of the rain and sewage overflow type river and lake; 2) configuring corresponding aeration control devices according to the oxygen demand range of the overflow pollution; 3) determining the types of microbial agents and the magnetization parameters of magnetizers according to the water quality of the overflow water body, the pollution degree of the sediment and the local climate; and 4) selecting the aeration control devices according to the stages of rain and sewage overflow, pumping out the mud-water mixture at the mud-water interface of the rain and sewage overflow type river and lake, adding microbial agents, then magnetizing or aeration-controlling, and then uniformly discharging the mud-water mixture to the mud-water interface of the rain and sewage overflow type river and lake to promote the flow of the water body until the in-situ remediation of the sediment of the rain and sewage overflow type river and lake is completed. The present application provides an economic and efficient high-efficiency in-situ remediation method for black and odorous sediment of rain and sewage overflow type river and lake, and solves the water environment problem of black and odorous sediment of rain and sewage overflow type river and lake after rain.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water environment treatment, and particularly relates to a river and lake sediment treatment method, and especially relates to a high-efficiency in-situ remediation method for black and odorous sediments of rain and sewage overflow type rivers and lakes. BACKGROUND

[0002] With the deepening of water environment improvement work, urban point source pollution has been effectively curbed, and direct discharge of sewage into rivers has been basically eliminated. However, the rapid expansion of cities, the sudden increase of population in the region, and the substantial increase of impervious area have posed great challenges to urban drainage and sewage treatment systems, especially in the central old city area, where drainage pipe networks are mixed, connected, and missed, causing a series of urban water environment and water ecological problems, such as initial rainwater runoff pollution, combined sewer overflow (CSO) pollution, etc., which will be important factors restricting urban water environment improvement and water ecological restoration for a long time in the future. CSO can discharge tens of thousands of tons of rain and sewage mixed water and pipe sediments into nearby rivers in a short time, which not only causes serious river pollution and serious damage to river and lake ecosystems, but also causes a large amount of new pipe sediments, thereby causing problems such as black and odorous water bodies and eutrophication in urban rivers and lakes. However, China needs to eliminate the problem of black and odorous water bodies by 2030, but the current situation of CSO is also difficult to solve in a short time. Therefore, how to solve the black and odorous problem caused by CSO is an urgent scientific problem, which is particularly important for realizing long-term improvement of urban water environment.

[0003] At present, there are many treatment technologies applied to river sediments, including artificial aeration oxygenation technology, chemical oxidation, microbial functional bacteria agent, and in-situ covering technology, etc., which can reduce the degree of black and odorous after rain to some extent. Among them, the microbial functional bacteria agent is more common, which mainly promotes the metabolic decomposition of pollutants and accelerates the transformation and removal of pollutants by improving the metabolic function of related functional microorganisms, thereby reducing the degree of black and odorous after rain.

[0004] Directly adding artificially domesticated and cultured high-efficiency degradation microbial agents to polluted water areas, and at the same time providing nutrients required by these microbial communities, thereby promoting the degradation of pollutants in water bodies or sediments. However, in the actual application process, there is competition between the added bacteria and the indigenous bacteria in the river, which sometimes leads to poor treatment effect of the microbial bacteria and long effective time. At the same time, under the high impact load of CSO, the implementation cost of the existing technology is extremely high, and the water body is also prone to black and odorous after rain after treatment. Therefore, it is urgent to solve the problems of low implementation efficiency and easy recurrence of black and odorous after treatment under the impact of CSO. SUMMARY

[0005] The application aims at solving the water environment problem of black odor of river and lake sediment after rain overflow in the background art, and provides an economic and efficient in-situ remediation method for black odor of river and lake sediment after rain overflow.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme: an in-situ remediation method for black odor of river and lake sediment after rain overflow, comprising the following steps:

[0007] 1) obtaining monitoring data of the river and lake after rain overflow, determining the present situation of the receiving water body, the pollution degree of the sediment and the oxygen demand range of the overflow pollution according to the monitoring data; the monitoring data includes water quality of the overflow water body, water volume of the overflow water and nutrient salt of the sediment;

[0008] 2) configuring corresponding aeration control devices according to the oxygen demand range of the overflow pollution;

[0009] 3) determining the type of microbial agent and the magnetization parameter of the magnetizer according to the water quality of the overflow water body, the pollution degree of the sediment and the on-site climate;

[0010] 4) determining the stage of rain and overflow, and selecting the aeration control device determined in step 2) according to the stage of rain and overflow, pumping out the mud-water mixture at the mud-water interface of the river and lake after rain overflow, adding the microbial agent determined in step 3), then magnetizing or aeration controlling, and then uniformly discharging the mud-water mixture to the mud-water interface of the river and lake after rain overflow, promoting the flow of the water body, until the in-situ remediation of the sediment of the river and lake after rain overflow is completed.

[0011] Preferably, the specific implementation mode of determining the present situation of the receiving water body, the pollution degree of the sediment and the oxygen demand range of the overflow pollution according to the monitoring data in step 1) is:

[0012] O demand ={1.4·L0·(1-e k1t )-(Cs-C)·(1-e k2t )+Cm}·V+O1+O2

[0013] Wherein:

[0014] The O demand is the oxygen demand of the water body, g;

[0015] The V is the volume of the water body, m 3 ;

[0016] The t is the oxygenation time, d;

[0017] The C is the dissolved oxygen content of the water body, mg L -1 ;

[0018] The L0 is the initial BOD5 concentration of the water body, mg L-1 ;

[0019] k1 is the BOD5 biochemical reaction constant, d -1 ;

[0020] Cs is the water body saturated dissolved oxygen content, mg L -1 ;

[0021] k2 is the water body reoxygenation rate constant, d -1 ;

[0022] Cm is the minimum dissolved oxygen content to maintain the water body oxidation condition, taking 2 mg L -1 ;

[0023] O1 is the sediment oxygen consumption rate;

[0024] O2 is the oxygen demand of the overlying water inorganic reducing substance content.

[0025] Preferably, the aeration control device in step 2) is a blower-micro-porous cloth gas pipe aeration system, pure oxygen-micro-porous pipe aeration system, pure oxygen-mixed flow oxygenation system, impeller suction gas push flow type aeration system, underwater jet aeration equipment and / or impeller type oxygenation machine.

[0026] Preferably, in step 3), the degree of sediment pollution is determined by measuring the content of pollutants in the sediment sample, calculating the pollution index of the corresponding pollutants by means of organic index method and pollution index method, and dividing the pollution degree according to the evaluation standard.

[0027] Preferably, in step 3), when the degree of sediment pollution is determined, the determination of pollutants in the sediment sample includes the organic matter index Org index -C, organic nitrogen index Org index -N and sulfide index AVS index ;

[0028] The function expression of the organic matter index Org index -C is:

[0029] Org index -C=OM(%) / 1.724

[0030] Wherein: OM is the measured content of organic matter in the sediment, unit: %.

[0031] The function expression of the organic nitrogen index Org index -N is:

[0032] Org index -N=TN*0.95

[0033] Wherein: TN is the measured total nitrogen content of the sediment, unit: g Kg-1 .

[0034] The sulfide index AVS index The functional expression is:

[0035] AVS index = C i / C0

[0036] Wherein:

[0037] C i The measured acid volatile sulfide content of the sediment, unit: g Kg -1 ;

[0038] C0 is the standard value corresponding to the environmental assessment, unit: g Kg -1 , the recommended value is 2.0 g Kg -1 .

[0039] The result of the step 3) according to the evaluation results to divide the sediment pollution level is:

[0040] Org index -C<0.05 belongs to low pollution, 0.05≤Org index -C<0.20 belongs to light pollution, 0.20≤Org index -C <0.50 belongs to moderate pollution, Org index -C≥0.50 belongs to severe pollution;

[0041] Org index -N<0.033 belongs to low pollution, 0.033≤Org index -N<0.066 belongs to light pollution, 0.066≤Org index -N<0.133 belongs to moderate pollution, Org index -N≥0.133 belongs to severe pollution;

[0042] AVS index <0.5 belongs to low pollution, 0.50≤AVS index <1.0 belongs to light pollution, 1.0≤AVS index <1.5 belongs to moderate pollution, AVS index ≥ 1.5 belongs to severe pollution.

[0043] Preferably, the type of microbial inoculant in step 3) is nitrifying bacteria, denitrifying bacteria, photosynthetic bacteria, bacillus, and / or composite bacteria; the composite bacteria is any combination of nitrifying bacteria, denitrifying bacteria, photosynthetic bacteria, and bacillus; the magnetizer in step 3) is a permanent magnetic pipeline magnetizer or an electromagnetic pipeline magnetizer; the magnetic field strength of the permanent magnetic pipeline magnetizer ranges from 50 mT to 500 mT, and the magnetization time is 1 min to 120 min; the magnetic field strength of the electromagnetic pipeline magnetizer ranges from 50 mT to 1500 mT, and the magnetization time is 1 min to 120 min.

[0044] Preferably, the use of microbial inoculants is to screen microbial species according to the characteristics of sediment pollution and overflow water quality:

[0045] When the ammonia nitrogen of overflow water quality exceeds Class V, the sediment is mainly polluted by nitrogen, and nitrifying bacteria, denitrifying bacteria, and composite bacteria are selected, and the ratio of nitrifying bacteria, denitrifying bacteria, composite bacteria, and water is 5:2:1:1000;

[0046] When the COD of overflow water quality exceeds Class V, the sediment is seriously polluted by organic matter, and denitrifying bacteria, bacillus, and composite bacteria are selected, and the ratio of denitrifying bacteria, bacillus, composite bacteria, and water is 1:10:5:1000;

[0047] When the sulfide of overflow water quality exceeds Class V, the sediment is seriously black and smelly, and denitrifying bacteria, bacillus, photosynthetic bacteria, and composite bacteria are selected, and the ratio of denitrifying bacteria, bacillus, photosynthetic bacteria, composite bacteria, and water is 1:10:15:5:1000;

[0048] Preferably, the optimal magnetic field strength of nitrifying bacteria, denitrifying bacteria, photosynthetic bacteria, bacillus, and composite bacteria is 45-120 mT, 20-70 mT, 8.9-46.6 mT, 2.5-17.5 mT, and 20-35 mT, respectively.

[0049] Preferably, the determination method of the magnetizer in step 3) is:

[0050] When the on-site water quality is Class V water, the sediment is moderately to severely polluted, the overflow water volume is ≥20000 m 3 / d, the oxygen demand is ≥6 t O2 / d, and the on-site power supply is stable, an electromagnetic pipeline magnetizer is selected;

[0051] When the on-site water quality is within Class V, the sediment is lightly to moderately polluted, the overflow water volume is <20000 m 3 / d, the oxygen demand is <6 t O2 / d, and the on-site power supply capacity is poor, a permanent magnetic pipeline magnetizer is selected;

[0052] The poor V class water quality is obtained according to the standard "Surface Water Environmental Quality Standard", and the standard number of the "Surface Water Environmental Quality Standard" is GB3838-2002.

[0053] Preferably, the stage of rainwater and sewage overflow in step 4) includes a rainwater and sewage overflow early stage, a 12 h stage before rainwater and sewage overflow, a 0~48 h stage after rainwater and sewage overflow, a 48~120 h stage after rainwater and sewage overflow, and a stage more than 120 h after rainwater and sewage overflow.

[0054] The specific implementation mode of the aeration regulation in step 4) is:

[0055] The dissolved oxygen regulation value in the rainwater and sewage overflow early stage is 4.5 mg L -1 ;

[0056] The dissolved oxygen regulation value in the 12 h stage before rainwater and sewage overflow is 6.0 mg L -1 ;

[0057] The dissolved oxygen regulation value in the 0~48 h stage after rainwater and sewage overflow is saturated dissolved oxygen, and the saturated dissolved oxygen is 7.5 mg L -1 ;

[0058] The dissolved oxygen regulation value in the 48~120 h stage after rainwater and sewage overflow is 6.0 mg L -1 ;

[0059] The dissolved oxygen regulation value in the stage more than 120 h after rainwater and sewage overflow is 4.5 mg L -1 .

[0060] Beneficial effects: Compared with the prior art, the advantages of the present application are: the present application provides a rain and sewage overflow type river and lake black and odorous sediment efficient in-situ remediation method, 1) obtain monitoring data of rain and sewage overflow type river and lake, determine the receiving water body present situation, sediment pollution degree and overflow pollution oxygen demand range according to the monitoring data; the monitoring data includes overflow water quality, overflow water quantity and sediment nutrient salt; 2) configure the corresponding aeration control device according to the overflow pollution oxygen demand range; 3) determine the type of microbial agent and the magnetization parameter of the magnetizer according to the overflow water quality, sediment pollution degree and on-site climate; 4) determine the stage of rain and sewage overflow, and select the aeration control device determined in step 2) according to the stage of rain and sewage overflow, the mud-water mixture at the mud-water interface of the rain and sewage overflow type river and lake is pumped out and the microbial agent determined in step 3) is added, then the mud-water mixture is uniformly discharged to the mud-water interface of the rain and sewage overflow type river and lake after magnetization or aeration control, the water body flow is promoted, and the in-situ remediation of the rain and sewage overflow type river and lake sediment is completed. The treatment idea and method provided by the present application are more targeted, and in the case of not greatly increasing the technical construction cost, the microbial metabolism function under the impact of CSO is strengthened through the cooperation of magnetization, aeration, microbial agent and other treatment technologies, and the problems of poor existing sediment remediation effect and repeated black and odorous after rain are solved. The magnetized water technology can improve the water body to the reactor, inhibit the growth of indigenous bacteria by adjusting different magnetization parameters, provide a better growth space for the microbial agent, shorten the response time of the microbial agent, and deliver the water body to the mud-water interface through the Venturi reactor, so as to realize the in-situ remediation of the black and odorous sediment. The present application is to strengthen the stability of microbial metabolism and function of the agent under the interference of external pollution such as agricultural non-point source and urban point source by magnetization and other methods, reduce the vulnerability of microbial molecular ecological network, and make the sediment microbial community more harmonious. The present application is to improve the stability of the sediment microbial ecological network by comprehensively considering the magnetization adaptability of different agents and indigenous microorganisms (the best value of magnetic field intensity to promote the growth and metabolism of related functional agent microorganisms), promote the metabolic rate of sediment pollutants under strong external interference, make the agent more adaptable, and improve the remediation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 is a diagram of the change of the sediment microbial network over time in the rain and sewage overflow type river and lake black and odorous sediment efficient in-situ remediation method provided by the present application, wherein, Figure 1 a is the visualization of MENs constructed from 0 days to 30 days under different sediment remediation methods; large modules with ≥5 nodes are displayed in different colors, and smaller modules are displayed in gray; Figure 1 Figure 1 h are time variation diagrams of network topology, specifically including n( Figure 1 b), L( Figure 1 c), average CC( Figure 1 d), average K(​Figure 1 e) Con ( Figure 1 f) GD ( Figure 1 g) and Trans ( Figure 1 h);

[0062] Figure 2 is the variation of the molecular ecological network hubs of the sediments under different remediation methods: wherein, Figure 2 a is the large modules (i.e. modules with ≥ 5 nodes) shown in circular layout of the 7 networks, note: the color of the nodes represents the main taxonomic groups, the red and blue links represent the positive and negative correlations between the nodes, respectively, the bar chart below each network shows the proportion of positive and negative links; Figure 2 b, Figure 2 c and Figure 2 d are the Zi-Pi plots showing the OTUs based on their module-based topological role distribution, the topological role of each OTU is determined according to the scatter plot of intra-module connectivity (Zi) and inter-module connectivity (Pi).

[0063] Figure 3 is the temporal dynamics of stability related to network composition and structure, wherein, Figure 3 a is the pattern of modularity persistence over time; Figure 3 b is the network vulnerability measured by the largest node vulnerability in each network; Figure 3 c is the composition stability of network communities over time; Figure 3 d is the robustness analysis refers to the relationship between the natural connectivity of microorganisms and the proportion of removed nodes;

[0064] Figure 4 is the variation of the key gene abundance in nitrogen and sulfur metabolism, wherein, Figure 4 a and Figure 4 b is the variation of the relative abundance of nitrogen and sulfur metabolic pathways; Figure 4 c is the metabolic pathway of nitrogen under different sediment remediation methods; Figure 4 d is the metabolic pathway of sulfur under different sediment remediation methods;

[0065] Figure 5 is an example of a certain municipal river remediated by the rainwater and sewage overflow type river and lake black and odorous sediment efficient in-situ remediation method provided by the present application. DETAILED DESCRIPTION

[0066] The present application provides a rainwater and sewage overflow type river and lake black and odorous sediment efficient in-situ remediation method, which specifically comprises:

[0067] 1) According to the monitoring data of long-term overflow sewage water quality, water quantity and sediment nutrient salt release, the present situation of the receiving water body, the pollution degree of the sediment and the oxygen demand range are determined;

[0068] Wherein, according to the water function area water quality target of the target water body, the oxygen demand range of the rain and sewage overflow type water body is determined, the overflow sewage, water quality, and sediment test indexes are determined by referring to the national standards, and the specific oxygen demand calculation is as follows:

[0069] O demand = {1.4·L0·(1-e k1t ) - (Cs-C)·(1-e k2t ) + Cm}·V + O1 + O2

[0070] Wherein:

[0071] O demand is the oxygen demand of water body, g;

[0072] V is the volume of water body, m 3 ;

[0073] t is the oxygenation time, d;

[0074] C is the dissolved oxygen content of water body, mg L -1 ;

[0075] L0 is the initial BOD5 concentration of water body, mg L -1 ;

[0076] k1 is the BOD5 biochemical reaction constant, d -1 ;

[0077] Cs is the saturated dissolved oxygen content of water body, mg L -1 ;

[0078] k2 is the water reoxygenation rate constant, d -1 ;

[0079] Cm is the minimum dissolved oxygen content for maintaining the oxidation condition of water body, taking 2 mg L -1 ;

[0080] O1 is the oxygen consumption rate of sediment;

[0081] O2 is the oxygen demand of inorganic reducing substances in overlying water.

[0082] 2) According to the oxygen demand range of the overflow pollution and the site conditions, the corresponding aeration control device is configured;

[0083] Exemplarily, the aeration is mainly air and oxygen (more than 98%), including air blower-micro-porous air distribution pipe aeration system, pure oxygen-micro-porous pipe aeration system, pure oxygen-mixed flow oxygenation system, impeller air suction and flow type aeration system, underwater jet aeration equipment, and impeller type oxygenation machine, and the main arrangement mode adopts the shore fixed type oxygenation station, which is arranged at 100 m downstream of the rain and sewage overflow port.

[0084] 3) According to the water quality of the overflow water body, the pollution characteristics and degree of the sediment, and the site climate and other factors, the type of microbial agent and the magnetization parameters used by the magnetizer are determined.

[0085] The pollution degree of the sediment is determined by measuring the content of pollutants in the sediment sample, calculating the pollution index of the corresponding pollutants by means of the organic index method and the pollution index method, and dividing the pollution degree according to the evaluation standard. The specific classification is shown in the following table:

[0086]

[0087] In addition, the magnetizer is mainly divided into a pipeline type permanent magnet magnetizer and a pipeline type electromagnetic magnetizer, and the corresponding magnetic field strength, magnetization frequency and the like are flexibly selected according to the site regulation stage. For example, when the site water quality in step 2) is inferior V-class water quality, the sediment is in moderate pollution to severe pollution, the overflow water volume is ≥20000 m 3 / d, the oxygen demand is ≥6 t O2 / d, and the site power supply is stable, an electromagnetic magnetizer should be selected. When the site water quality in step 2) is within V-class water, the sediment is in light pollution to moderate pollution, the overflow water volume is <20000 m 3 / d, the oxygen demand is <6 t O2 / d, and the site power supply capacity is poor, a permanent magnet magnetizer can be used. The magnetic field strength of the permanent magnet magnetizer ranges from 50 mT to 500 mT, and the magnetization time is 1 min to 120 min; the magnetic field strength of the electromagnetic magnetizer ranges from 50 mT to 1500 mT, and the magnetization time is 1 min to 120 min.

[0088] According to the pollution characteristics of the sediment and the overflow water quality characteristics, appropriate microbial agents are selected. The types of microbial agents are nitrifying bacteria agents, denitrifying bacteria agents, photosynthetic bacteria agents, bacillus agents and / or composite agents, wherein the composite agents are any combination of nitrifying bacteria agents, denitrifying bacteria agents, photosynthetic bacteria agents and bacillus agents. The present application provides several microbial agent dosing combination modes: when the ammonia nitrogen of the overflow water quality is superior to inferior V-class, the sediment is mainly polluted by nitrogen, nitrifying bacteria agents, denitrifying bacteria agents and composite agents are selected, and the proportion of nitrifying bacteria agents, denitrifying bacteria agents, composite agents and water is 5:2:1:1000; when the COD of the overflow water quality is superior to inferior V-class, the sediment is seriously polluted by organic matter, denitrifying bacteria agents, bacillus and composite agents are selected, and the proportion of denitrifying bacteria agents, bacillus, composite agents and water is 1:10:5:1000; when the sulfide of the overflow water quality is superior to V-class, the sediment is seriously black and smelly, denitrifying bacteria agents, bacillus, photosynthetic bacteria agents and composite agents are selected, and the proportion of denitrifying bacteria agents, bacillus, photosynthetic bacteria agents, composite agents and water is 1:10:15:5:1000.

[0089] 4) According to different stages of rainwater and sewage overflow, the technical parameters of magnetic treatment and aeration are selected, and the overlying water and microbial agents on the sludge-water interface are uniformly discharged to the sludge-water interface after magnetic treatment and aeration control, which realizes in-situ remediation of sludge and promotes water exchange and improves hydrodynamic conditions.

[0090] The control stages are mainly divided into five stages: before rainwater and sewage overflow, 12 hours before rainwater and sewage overflow, after rainwater and sewage overflow (0-48 hours), after rainwater and sewage overflow (48-120 hours), and after rainwater and sewage overflow (120 hours). The corresponding control methods are implemented according to different stages. As a preferred embodiment, the dissolved oxygen control value before rainwater and sewage overflow is 4.5 mg L -1 , and the magnetic intensity is 150 mT; the dissolved oxygen control value 12 hours before rainwater and sewage overflow is 6.0 mg L -1 , and the magnetic intensity is 300 mT; the dissolved oxygen control value after rainwater and sewage overflow (0-48 hours) is saturated dissolved oxygen, and the magnetic intensity is 500 mT; the dissolved oxygen control value after rainwater and sewage overflow (48-120 hours) is 6.0 mg L -1 , and the magnetic intensity is 300 mT; the dissolved oxygen control value after rainwater and sewage overflow (120 hours) is 4.5 mg L -1 , and the magnetic intensity is 150 mT.

[0091] In step 4), the sludge and water at the sludge-water interface are treated by a submersible pump, and are treated by a pipeline magnetic treatment device and an aeration device on the shore. First, the sludge and water and the microbial agents are treated by the pipeline magnetic treatment device, and the water molecules, pollutants and functional microorganisms are subjected to magnetic treatment under the action of the magnetic field, including opening of the hydrogen bond of the water molecules, greatly improving the oxygen carrying capacity of the water body; the pollutants are mineralized and decomposed under the action of strong oxidizing substances such as hydroxyl radicals formed by water molecules; the functional microbial agents are subjected to magnetic field treatment, and the microbial respiration metabolism and ecological niche competitiveness are significantly enhanced, and the metabolic rate of pollutants after rainwater and sewage overflow is accelerated. After a series of magnetic treatment, the oxidation conditions of the sludge-water interface are improved by the aeration device, and the sludge is released to different depths by the Venturi reactor, so as to promote the respiration metabolism of the functional microorganisms in the microbial agents and strengthen the ability of the functional microorganisms to respond to the impact of rainwater and sewage overflow; another part is increased by the underwater jet device, which increases water exchange and improves hydrodynamic conditions.

[0092] The principle of the magnetization reaction of the present application is that the water flow makes a cutting magnetic field movement when flowing through the magnetization device, the ions and molecular clusters in the water change under the action of the magnetic field, the molecular cluster long chain structure changes, the long chain structure breaks, the number of molecular clusters increases, that is, the molecular clusters are refined, the water molecule hydrogen bond changes, and thus the volume structure property of the water changes, leading to loose structure of the magnetized water, thereby improving the oxygen carrying capacity of the water body; at the same time, the paramagnetic ions and diamagnetic ions in the water are orderly arranged under the action of the magnetic field, the impurity molecules (pollutants) become more active and free, the number of free single molecules increases, thereby forming strong oxidizing substances such as hydroxyl radicals, promoting the mineralization and decomposition of pollutants, thereby improving the solubility, transparency, dissolved oxygen and the like of the water body, and reducing the COD and BOD of the water body; the specific magnetotactic property of the metal atoms such as Fe contained in the intracellular multi-enzyme or protein of microorganisms and the chemical reaction electrons is utilized to dynamically control the biochemical process of the transformation of pollutants in the sediment, including changing the permeability of the cell membrane, controlling the mass transfer rate of substances inside and outside the membrane, and the direction of electron transfer, not only strengthening the metabolic transformation of the functional microorganisms on the pollutants, but also moving the chemical reaction equilibrium of the pollutants to the left, achieving rapid removal of the pollutants.

[0093] Example 1: Municipal river black and odorous water body remediation and water environment improvement, the specific operation is as follows:

[0094] The on-site municipal river is brought a large amount of pollutants due to the river discharge of the pumping station, and the hydrodynamic condition of the river is poor, resulting in black and odorous water body, and the water quality of the river is inferior to the fifth class water body, the contents of organic matter, NH3-N and AVS are all high, causing serious black and odorous sediment.

[0095] The reactor magnetization device adopts an electromagnetic type, the magnetic field strength is 750 mT, the effective treatment capacity of the reactor is 150 m 3 / h, the water body enters the magnetization reactor at a flow rate of 2.5 m 3 / min, and the magnetization time is 5 min.

[0096] After the black and odorous water body of the river is magnetized for 30 days, the water transparency is improved by 66.67%; the water dissolved oxygen is improved by 5 mg / L; the water COD content is decreased by 62.5%; the NH3-N is decreased by 65.27; the AVS is decreased by 49.12%; and the pH is increased by 0.22. During the period, there are 12 times of rain and sewage overflow, the maximum rain and sewage overflow flow of a single time is 28000 m 3 / d, the black and odorous sediment gradually changes from black to gray, the oxidation degree is significantly improved, and the black and odorous phenomenon is inhibited after rain. As Figure 5 shown.

[0097] Table 1 Change of key bacterial flora in molecular ecological network under different remediation methods

[0098]

[0099] Table 2 Changes in key functional genes involved in nitrogen metabolism

[0100]

[0101] The microbial agent (CN) (the microbial agent used in this example is denitrifying bacteria CGMCC1.15316, Bacillus subtilis CGMCC1.821, photosynthetic bacteria CGMCC1.15148, and a composite microbial agent (the composite microbial agent is purchased from Biweifeng Biological Technology (Guangdong) Co., Ltd. Biweifeng Bidiqing series), denitrifying bacteria CGMCC1.15316, Bacillus subtilis CGMCC1.821, photosynthetic bacteria CGMCC1.15148, composite microbial agent, and water in a proportion of 1:10:15:5:1000, all of the above strains are public strains and can be purchased on the market, and the same applies), experimental microbial agent + aeration (CN_CFM) (in this example, the aeration device used is a pure oxygen-mixed flow oxygenation system), and experimental microbial agent + aeration + magnetization (CN_CFM_LDA) (the magnetization device used in this example is an electromagnetic magnetizer) remediation engineering were implemented in three sections of rain and sewage overflow type water bodies in Shenzhen. It was found that the microbial community and network topology in the river sediments remediated by different methods were significantly different (P<0.05) Figure 1 ), and further proved by random matrix that the sediment remediation method of microbial agent + aeration + magnetization (CN_CFM_LDA) significantly affected the microbial network structure and topological properties. The average path distance, average clustering coefficient, connectivity, and other network topological properties were positively correlated with the remediation time, which weakened the small-world characteristics of the original microbial network (P<0.05) Figure 1 ). Compared with other remediation methods, the positive correlation in the microbial molecular ecological network of the sediment was reduced by 17%-18%, thereby enhancing the competitiveness between microorganisms (P<0.05) Figure 2 ); and the network recovered based on microbial agent + aeration + magnetization (CN_CFM_LDA) was significantly reduced by more than 36% in fragility, while the species composition and stability of pollutant metabolism function were improved by more than 12%, and the fluctuation of natural connectivity was also reduced, further weakening the influence and transmission of external environmental pressure (such as rain and sewage overflow) in the entire microbial network (P<0.05) Figure 3 .In addition, the microbial molecular ecological network module center shifted from Actinobacteria and Bacteroidetes to Chloroflexi and Proteobacteria, etc. specific microbial flora of the microbial agent (Table 1). This microbial network succession significantly increased the number of key enzyme genes involved in nitrogen and sulfur metabolism, enhanced nitrification, denitrification, and assimilatory sulfate reduction, thereby increasing the removal rates of ammonia, nitrate, and acid volatile sulfide in the sediment by 43.42%, 250.68%, and 2.66%, respectively (Table 2, Figure 4). With the extension of repair time, the bacteria agent + aeration + magnetization (CN_CFM_LDA) repair river section after rain black phenomenon significantly weakened ( Figure 5 ).

Claims

1. A high-efficiency in-situ remediation method for black and odorous sediment of rain and sewage overflow type lakes and rivers, characterized in that: The method comprises the following steps: 1) obtaining monitoring data of the rain and sewage overflow type river and lake, determining the receiving water body status, the sediment pollution degree and the overflow pollution oxygen demand range according to the monitoring data; the monitoring data comprises overflow water quality, overflow water quantity and sediment nutrient salt; 2) configuring corresponding aeration control devices according to the overflow pollution oxygen demand range; 3) determining the types of microbial agents and the magnetization parameters of a magnetizer according to the overflow water quality, the sediment pollution degree and the on-site climate; 4) determining the stages of rain and sewage overflow, and selecting the aeration control devices determined in step 2) according to the stages of rain and sewage overflow, adding the microbial agents determined in step 3) to the mud-water mixture at the mud-water interface in the rain and sewage overflow type river and lake after the mud-water mixture is pumped out, and then the mud-water mixture is uniformly discharged to the mud-water interface in the rain and sewage overflow type river and lake after being magnetized or aeration controlled, so as to promote the water body flow until the in-situ remediation of the sediment in the rain and sewage overflow type river and lake is completed; In step 3), the sediment pollution degree is determined by measuring the content of pollutants in the sediment sample, calculating the pollution index of the corresponding pollutants by means of the organic index method and the pollution index method, and classifying the pollution degree according to the evaluation standard; The determination of the pollutants in the sediment sample in the step 3) for determining the degree of pollution of the sediment includes an organic matter index Org index - C, an organic nitrogen index Org index - N and a sulfide index AVS index ; The organic matter index Org index The functional expression of C is: Org index - C=OM (%) / 1.724 Wherein: OM is the measured content of sediment organic matter, unit: %; The organic nitrogen index Org index The functional expression of -N is: Org index -N=TN*0.95 TN = measured total nitrogen content of the sediment, in g Kg -1 ; The sulfide index AVS index The functional expression of which is: AVS index = C i / C0 Wherein: C i For measured acid volatile sulfide content of the sediment, unit: g Kg -1 ; Co is the standard value corresponding to the environmental assessment, unit: g Kg -1 , the recommended value is 2.0 g Kg -1 ; The result of classifying the sediment pollution degree according to the evaluation result in step 3) is: Org index - C < 0.05 belongs to low pollution, 0.05 < Org index - C < 0.20 belongs to light pollution, 0.20 < Org index - C < 0.50 belongs to moderate pollution, Org index - C > 0.50 belongs to heavy pollution; Org index - N < 0.033 belongs to low pollution, 0.033 < Org index - N < 0.066 belongs to light pollution, 0.066 < Org index - N < 0.133 belongs to moderate pollution, Org index - N > 0.133 belongs to heavy pollution; AVS index <0.5 belongs to low pollution, 0.50 < AVS index <1.0 belongs to light pollution, 1.0 < AVS index <1.5 belongs to moderate pollution, AVS index ≥ 1.5 belongs to heavy pollution.

2. The rain and sewage overflow type river and lake black-smelly sediment efficient in-situ remediation method according to claim 1, characterized in that: The aeration control devices in step 2) are a blower-micro-porous pipe aeration system, a pure oxygen-micro-porous pipe aeration system, a pure oxygen-mixed flow oxygenation system, an impeller suction aeration push-flow type aeration system, an underwater jet aeration equipment and / or an impeller type oxygenation machine.

3. The rain and sewage overflow type river and lake black-smelly sediment efficient in-situ remediation method according to claim 2, characterized in that: The types of microbial agents in step 3) are nitrifying bacteria agents, denitrifying bacteria agents, photosynthetic bacteria agents, bacillus agents and / or composite bacteria agents; the composite bacteria agents are any combination of nitrifying bacteria agents, denitrifying bacteria agents, photosynthetic bacteria agents and bacillus agents; the magnetizer in step 3) is a permanent magnet type pipeline magnetizer or an electromagnetic type pipeline magnetizer; the magnetic field strength of the permanent magnet type pipeline magnetizer ranges from 50 mT to 500 mT, and the magnetization time is 1 min to 120 min; the magnetic field strength of the electromagnetic type pipeline magnetizer ranges from 50 mT to 1500 mT, and the magnetization time is 1 min to 120 min.

4. The rain and sewage overflow type river and lake black-smelly sediment efficient in-situ remediation method according to claim 3, characterized in that: The use mode of the microbial agents is: the types of the microbial agents are selected according to the characteristics of the sediment pollution and the characteristics of the overflow water quality: When the ammonia nitrogen of the overflow water quality exceeds the V class, the sediment is mainly polluted by nitrogen, the nitrifying bacteria agents, the denitrifying bacteria agents and the composite bacteria agents are selected, and the proportion of the nitrifying bacteria agents, the denitrifying bacteria agents, the composite bacteria agents and water is 5:2:1:1000; When the COD of the overflow water quality exceeds the V class, the sediment is seriously polluted by organic matter, the denitrifying bacteria agents, the bacillus agents and the composite bacteria agents are selected, and the proportion of the denitrifying bacteria agents, the bacillus agents, the composite bacteria agents and water is 1:10:5:1000; When the sulfide of the overflow water quality exceeds the V class, the sediment is seriously black and smelly, the denitrifying bacteria agents, the bacillus agents, the photosynthetic bacteria agents and the composite bacteria agents are selected, and the proportion of the denitrifying bacteria agents, the bacillus agents, the photosynthetic bacteria agents, the composite bacteria agents and water is 1:10:15:5:1000.

5. The rain and sewage overflow type river and lake black-smelly sediment efficient in-situ remediation method according to claim 4, characterized in that: The optimal magnetic field intensity of the nitrifying bacteria, denitrifying bacteria, photosynthetic bacteria, bacillus and complex bacterial agent is 45-120 mT, 20-70 mT, 8.9-46.6 mT, 2.5-17.5 mT and 20-35 mT respectively.

6. The rain and sewage overflow type river and lake black-smelly sediment efficient in-situ remediation method according to claim 5, characterized in that: The determination mode of the magnetizer in the step 3) is that: When the on-site water quality is inferior V-class water quality, the sediment is in moderate to severe pollution, the overflow water volume is ≥20000 m 3 / d, the oxygen demand is ≥6 t O2 / d, and the on-site power supply is stable, an electromagnetic pipeline magnetizer is selected. When the on-site water quality is within V-class water, the sediment is in mild pollution and moderate risk, the overflow water volume is < 20000 m 3 / d, the oxygen demand is < 6 t O2 / d, and the on-site power supply capacity is poor, a permanent magnet type pipeline magnetizer is selected. The poor V type water quality is obtained according to the surface water environmental quality standard, and the standard number of the surface water environmental quality standard is GB3838-2002.

7. The rain and sewage overflow type river and lake black-smelly sediment efficient in-situ remediation method according to claim 6, characterized in that: The stage of rain and sewage overflow in the step 4) includes the rain and sewage overflow early stage, the rain and sewage overflow 12 h before stage, the rain and sewage overflow 0-48 h after stage, the rain and sewage overflow 48-120 h after stage and the rain and sewage overflow more than 120 h after stage. The specific implementation mode of the aeration regulation in the step 4) is that: Dissolved oxygen set point for early stage of storm overflow is 4.5 mg L -1 ; The dissolved oxygen set point for the 12 h period prior to stormwater overflow was 6.0 mg L -1 ; The dissolved oxygen control value in the 0-48 h stage after rainwater and sewage overflow is saturated dissolved oxygen, and the saturated dissolved oxygen is 7.5 mg L -1 ; The dissolved oxygen control value at the stage of 48-120 h after rainwater and sewage overflow is 6.0 mg / L -1 ; The dissolved oxygen set point value after the 120 h period following the stormwater overflow was 4.5 mg L -1 .

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