Methods for Water Environment Multi-Interface Governance and Restoration in Rivers and Lakes

Abstract

The present disclosure relates to water environment governance technology, and particularly discloses an urban river/lake water environment multi-interface governance and restoration method. The method is a multi-interface coordinated governance and restoration method based on “control for bottom, regulation for middle and governance for top”, including: “control for bottom”—controlling the emission of sediment nutritive salts and the dormancy and recovery of algae; “regulation for middle”—regulating primary productivity in a water body to inhibit the recovery of the algae; and “governance for top”—reducing nitrogen and phosphorus nutrients of an air-water interface to control the reproduction and growth of the algae. In the present disclosure, the water body governance and restoration technology based on interface coordination can effectively inhibit the outbreak of cyanobacteria and avoid extreme conditions in the ecosystem.

Claims

1. A method for water environment multi-interface governance and restoration in river and lake, comprising: performing an accurate locating and in-situ treatment on pollutants at a sediment-water interface to control an emission of sediment nutritive salts and a dormancy and recovery of algae; establishing a submerged vegetation system in a eutrophic water body to regulate primary productivity in the eutrophic water body and inhibit the recovery of the algae; and using a micropower biological-ecological coupled purification system to enhance a dissolved oxygen level in an air-water interface and the eutrophic water body, enhance and activate biological reactions in the air-water interface and the eutrophic water body, reduce nitrogen and phosphorus nutrients in the air-water interface and the eutrophic water body, and control reproduction and growth of the algae.

2. The method according to claim 1, wherein a high-throughput sequencing technology and a pollutant source apportionment technology are firstly used to perform the accurate locating on a sediment to be governed, and then an electrodialysis-vacuum negative pressure dewatering technology is used to perform the in-situ dewatering treatment on the sediment to be governed.

3. The method according to claim 2, wherein performing the accurate locating and in-situ treatment further comprises: taking sediment samples at different positions of the sediment-water interface in a river/lake water area to be governed, extracting microbial DNA in the sediment samples, performing 16sRNA high-throughput sequencing analysis to obtain abundance of alkaline phosphatase phoD functional flora in the sediment samples at the different positions, and determining a sampling position of the sediment sample with the abundance of alkaline phosphatase phoD functional flora of greater than 25% as a determined position of the sediment to be governed; measuring an emission flux of bioavailable phosphorus of the sediment at different depths at the determined position of the sediment to be governed, and determining a depth range where the emission flux is greater than 0.6 mg/L as a depth of the sediment to be governed; and performing dewatering treatment on the sediment to be governed on a basis of the determined position and the depth of the sediment to be governed, further comprising: firstly using nitrate to adjust pH of a water body of an area to be governed to 7.5-8.3, and changing dominant flora in the sediment in cooperation with low-oxygen aeration; and then placing the sediment to be governed in a low-voltage high-current electric field, and performing dewatering treatment on the sediment under vacuum negative pressure conditions.

4. The method according to claim 1, wherein establishing a submerged vegetation system in a eutrophic water body further comprises: cultivating emerging plants in a water area to be governed to improve anti-wind wave and anti-water flow capabilities of the water area to be governed; and using a modified clay molecular sieve, phosphorus-accumulating bacteria, grass seeds of submerged plants, and silty clay to prepare a modified clay molecular sieve ecological base, and uniformly adding the modified clay molecular sieve ecological base to the eutrophic water body of the area to be governed.

5. The method according to claim 4, wherein the grass seeds of the submerged plants comprise grass seeds of Potamogeton crispus and Vallisneria spiralis.

6. The method according to claim 5, wherein preparing the modified clay molecular sieve ecological base comprises: weighing the modified clay molecular sieve and the silty clay in a ratio of 1:1, adding the grass seeds and the phosphorus-accumulating bacteria, and uniformly mixing the mixture.

7. The method according to claim 1, wherein the micropower biological-ecological coupled purification system comprises a solar micro-aeration cycle device, a composite high-efficiency microbial agent, a carrier filler and aquatic plants cultivated thereon.

8. The method according to claim 7, wherein using the micropower biological-ecological coupled purification system further comprises: using a polyester fiber matrix material as the carrier filler, cultivating emerging plants and submerged plants on the carrier filler, and using the solar micro-aeration cycle device to aerate the eutrophic water body to control a dissolved oxygen concentration of the eutrophic water body to be not less than 3.0 mg/L; and after plant roots of the aquatic plants are developed, adding the composite high-efficiency microbial agent to the filler and the plant roots.

9. The method according to claim 8, wherein the polyester fiber matrix material has a specific surface area of 1:1000 and a porosity of 96-98%.

10. The method according to claim 8, wherein the solar micro-aeration cycle device comprises solar panels and a flowing water reaeration device; wherein the solar panels are located at an upper part of the device and used to supply energy to the flowing water reaeration device at a lower part at an output power of 100 w-20 kw, and the flowing water reaeration device is located at the lower part of the device, provided with an impeller, and driven by electric energy of the solar panels to promote the cycle of the eutrophic water body and drive the micropower biological-ecological coupled purification system to move.

Description

DETAILED DESCRIPTION

[0057] In order to understand the above objectives, features and advantages of the present disclosure more clearly, the solution of the present disclosure will be further described below. It should be noted that in the case of no conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other.

[0058] Many specific details are explained in the following description in order to fully understand the present disclosure, but the present disclosure may also be implemented in other manners different from those described here. Obviously, the embodiments in the specification are only a part of the embodiments of the present disclosure, rather than all the embodiments.

[0059] The preferred implementations of the present disclosure will be described in detail below in conjunction with embodiments. It should be understood that the following embodiments are given for illustrative purposes only, and are not intended to limit the scope of the present disclosure. Those skilled in the art can make various modifications and substitutions to the present disclosure without departing from the objective and spirit of the present disclosure.

[0060] The experimental methods used in the following embodiments are conventional methods unless otherwise specified.

[0061] The materials, reagents and the like used in the following embodiments are commercially available unless otherwise specified.

Embodiment 1

[0062] In this embodiment, a heavily polluted river (the water surface had a length of about 20 m, a width of about 2 m and a total area of 40 m.sup.2, a river section for disposing equipment was at the shore, the water depth was 1-2 m, the water quality was inferior to the water quality standard Class V according to the Environmental Quality Standards for Surface Water, and the dissolved oxygen was less than 2.0 mg/L) was taken as the governance and restoration object.

[0063] The governance and restoration method specifically included the following steps:

[0064] S1, accurate locating and in-situ treatment were performed on pollutants at a sediment-water interface to control the emission of sediment nutritive salts and the dormancy and recovery of algae:

[0065] (1) Sediment samples were taken at different positions of the sediment-water interface in a river/lake water area to be governed, microbial DNA was extracted from the samples, 16sRNA high-throughput sequencing analysis was performed to obtain abundance of alkaline phosphatase phoD functional flora in the sediment samples at the different positions, and the sampling position of the sediment sample with the abundance of alkaline phosphatase phoD functional flora of greater than 25% was determined as the position of the sediment to be governed.

[0066] (2) Emission flux of bioavailable phosphorus of the sediment at different depths was measured at the determined position of the sediment to be governed in step (1), and a depth range where the emission flux was greater than 0.6 mg/L was determined as the depth of the sediment to be governed.

[0067] The emission flux of bioavailable phosphorus was calculated by using a pore water diffusion model method. Based on the concentration gradient of deposit interstitial water and overlying water, the emission flux of bioavailable phosphorus of the sediment was calculated according to Fick's first law.

[0068] Calculation formula:

F=φ.Math.D.sub.S(c/Z).sub.z=0

wherein F is the diffusion flux of molecules at the deposit-water interface, mg.Math.(m.sup.2.Math.d).sup.−1; [0069] φ is the porosity of the deposit, %; [0070] D.sub.S is the actual diffusion coefficient of the molecules, cm.sup.2.Math.s.sup.−1; [0071] (c/Z).sub.z=0 is the concentration gradient of the molecules at the deposit-water interface, mg.Math.(L.Math.cm).sup.−1; and [0072] the empirical relationship between D.sub.S and φ is D.sub.S=φ.sup.2Do(φ≤0.7), D.sub.S=φDo(φ>0.7).

[0073] (3) Dewatering treatment was performed on the sediment to be governed on the basis of the determined position and depth of the sediment to be governed in step (1) and step (2): [0074] firstly using nitrate to adjust pH of a water body of an area to be governed to 7.5-8.3, and changing dominant flora in the sediment in cooperation with low-oxygen aeration of 50 mg/L; and then placing the sediment to be governed in a low-voltage high-current electric field with a voltage of 12 V and a current of 10 A, and performing dewatering treatment on the sediment under vacuum negative pressure conditions.

[0075] After the nitrate was added, the dominant flora in the sediment was transformed from Clostridia to Gamma-proteobacteria at the class level, its relative abundance could reach 60.0%, and anaerobic florae such as sulfobacteria was effectively inhibited.

[0076] Denitrifying florae such as Rhodanobacter, Thiobacillus and Thermomonas appeared at the genus level, thereby creating a good and stable habitat for the ecosystem at the bottom of the water body and realizing the objective of regulating intercellular water in the sediment.

[0077] A carbon fiber bundle with excellent conductivity used as a conductive current collector and conductive carbon black and graphite powder used as key conductive materials were blended with plastic and thermoformed to prepare a novel electrode material whose conductivity and mechanical properties all satisfied electrodynamic dewatering, thereby solving the problems of high price and poor mechanical properties in the traditional electrode materials (such as precious metal coated electrodes and graphite).

[0078] After the treatment, the water content of the sediment is reduced to about 50%, and the volume of the sediment is reduced by 20-30%. Then, there is no need to perform ion exchange membrane treatment on the dewatered sludge. Compared with the traditional sediment dewatering technology, the dewatering cost and the subsequent treatment cost of electrodynamic sludge dewatering are reduced by 30% or above and about 40% respectively. After the governance, the water quality is significantly improved, reaching Class III according to the standards for surface water.

[0079] S2, a submerged vegetation system was established in a eutrophic water body to regulate primary productivity in the water body and inhibit the recovery of the algae:

[0080] (1) Emerging plants were cultivated in a water area to be governed to improve anti-wind wave and anti-water flow capabilities of the water area to be governed. The cultivation density of the emerging plants was 5-6 plants/m.sup.2, and the emerging plants were respectively selected from one or more of Pontederia cordata, Typha orientalis and Canna indica and one or more of native organisms.

[0081] (2) A modified clay molecular sieve, phosphorus-accumulating bacteria, grass seeds of submerged plants and silty clay were used to prepare a modified clay molecular sieve ecological base, and the modified clay molecular sieve ecological base was uniformly added to the water body of the area to be governed.

[0082] The preparation method of the modified clay molecular sieve ecological base included: weighing the modified clay molecular sieve and the silty clay in a ratio of 1:1, adding the grass seeds and the phosphorus-accumulating bacteria, and uniformly mixing the mixture.

[0083] The addition amount of the grass seeds was 40-60 seeds/m.sup.2, and the grass seeds were Potamogeton crispus seeds and Vallisneria spiralis seeds in a number ratio of 2:1. The addition amount of the phosphorus-accumulating bacteria was 50% (v/v) relative to the total volume of the modified clay molecular sieve and the silty clay.

[0084] A preparation method of the modified clay molecular sieve included: selecting water body sediment and shore clay, and using the clay after drying, grinding and sieving, or purchasing a professional clay sewage treatment agent; and adding the treated clay to a chitosan solution to form a slurry, or spraying the chitosan solution on the constantly stirred clay (referring to CN 102502969A), where the amount of the chitosan was 1%-1.5% (w/w) of the clay.

[0085] The phosphorus-accumulating bacteria were commercially available products, for example, anaerobic phosphorus-accumulating bacteria that can be purchased from Yangzhou Haicheng Biotechnology Co., Ltd. The product was in the form of bacterial powder, and the content of the phosphorus-accumulating bacteria was up to 95% or above.

[0086] The first addition amount of the modified clay molecular sieve ecological base was not less than 500 g/m.sup.2. The modified clay molecular sieve ecological base was supplementally added every 5-7 days after the first addition, and the supplemental addition amount was 50% of the first addition amount.

[0087] S3, a micropower biological-ecological coupled purification system was used to enhance the dissolved oxygen level in an air-water interface and the water body, enhance and activate biological reactions in the air-water interface and the water body, reduce nitrogen and phosphorus nutrients in the air-water interface and the water body and control reproduction and growth of the algae:

[0088] (1) A polyester fiber matrix material having a specific surface area of 1:1000 and a porosity of 97% was used as a carrier filler, thereby providing a carrier for adherence of microorganisms and cultivation of emerging plants and submerged plants. In addition, the carrier filler can promote the root division and growth of aquatic plants and the seed drop and growth of wild plants, enhance the viability of plants and expand the range of plant roots.

[0089] (2) A solar micro-aeration cycle device was installed in the middle position of the carrier, the emerging plants and the submerged plants were cultivated in other positions of the carrier. The cultivation density of the emerging plants was 5-6 plants/m.sup.2, and the emerging plants may be respectively selected from one or more of Pontederia cordata, Typha orientalis and Canna indica and one or more of native organisms. The cultivation density of the submerged plants was 40-60 plants/m.sup.2, and the submerged plants may be selected from Elodea nuttallii (preferred in cold seasons) and Vallisneria spiralis (preferred in warm seasons). The formed micropower biological-ecological coupled purification system was placed in the water body of 0.5 m or above.

[0090] (3) Solar panels in the solar micro-aeration cycle device converted solar energy into electric energy, the electric energy generated from the solar energy was transmitted to a flowing water reaeration device through circuit connection, and the flowing water reaeration device drove an impeller to run under the driving force of the electric energy and drove the cycle flow of the surrounding water body, thereby creating a suitable aerobic environment for the surrounding area, and enhancing the dissolved oxygen level of the water body by not less than 3.0 mg/L. The output power of the electric energy was 100 w-20 kw, the cycle flux driving the cycle flow of the water body was 100-50000 m.sup.3/h, and the flowing water distance or action range was 100-3500 m.

[0091] (4) After the plant roots of the micropower biological-ecological coupled purification system were developed, a composite high-efficiency microbial agent was added to the filler and the plant roots. The microbial agent was mainly extracted and domesticated from nature, and had the feature of efficiently decomposing organic matter, ammonia nitrogen, total nitrogen and other pollutants.

[0092] After the system ran for 2 months, the density of cyanobacteria and the germination rate of the submerged plants in water were tested.

[0093] A phytoplankton net was used to take a phytoplankton sample, the density of cyanobacteria was counted with a microscope, and at the same time, submerged plant seedlings were counted to calculate the germination rate of seeds.

[0094] The results showed that the number of cyanobacteria was reduced by about 60% as compared with the case with no treatment, and the seed germination rate of the submerged plants reached 82.5%.

[0095] Only specific implementations of the present disclosure are described above, so that those skilled in the art can understand or realize the present disclosure. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be realized in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but must conform to the widest scope consistent with the principles and novel characteristics disclosed herein.