Study on Ecological Technology of Water Pollution Control
Water environment is one of the most important basic ecological environments for human survival and healthy development. In the last century, China's economy developed at a high speed, but it also paid a painful price, the root of which was the serious destruction of the water environment. This paper will take the water purification method of aquatic plants as an example to study the ecological technology of water pollution control.
Keywords: ecological technology research on water pollution control
China Library Classification Number: S89 1+.5 Document Identification Number: a document number:
First, the purification mechanism of aquatic plants
1, plant characteristics and resistance.
Aquatic plants have formed special characteristics in their own morphology and anatomical structure because they have lived in the environment of hypoxia and weak light for a long time. Roots, stems and leaves form a complete ventilation tissue to ensure the needs of organs and tissues for 02; The fleshy leaves, such as the thick cuticle of cattail epidermis, well-developed palisade tissue, and close arrangement of root, stem and leaf epidermal cells in pollution spots, can resist the decline of assimilation function and excessive transpiration caused by pollution, and enhance the anti-pollution ability and resistance of cattail plants.
2. Absorption and enrichment of plants
Aquatic plants have developed roots, which are beneficial to absorb substances in water. For example, Eichhornia crassipes needs a lot of N and P nutrients in the process of growing lotus, which has obvious effect on purifying eutrophic water. When Typha plants absorb heavy metals in wastewater, the order of absorption capacity is root > underground stem > leaf, and various elements are absorbed from the habitat according to a certain proportion to form a new dynamic balance, but it is necessary to prevent poisoning caused by excessive absorption of a certain element. Plants absorb pollutants, especially heavy metal ions, pesticides and other synthetic organic substances, which are enriched and fixed in the body or soil to reduce the content of pollutants in water. The results showed that Pb and Zn entered cattail, mainly accumulated on the cell wall of cortical cells, and only a small amount entered protoplasm, indicating that cell wall had high affinity for heavy metals.
3. Sedimentation, adsorption and filtration in the purification tank
Aquatic plants in the purification pond grow vigorously, with developed roots and large contact area with water, forming a dense filter layer. Such as cattail, its underground stems and roots form a crisscross underground stem network. When the water flow is slow, heavy metals and suspended particles are blocked from settling to prevent loss with the water. At the same time, ion exchange, chelation, adsorption and precipitation are carried out on its surface. Insoluble colloid is adhered and adsorbed by root system, and agglomerated bacteria colloid settles suspended organic matter and metabolites.
4. Biochemical effect
The biochemical function of plants also plays an important role in the process of purifying sewage, and a lot of research has been done in this regard. O2 produced by photosynthesis and O2 in the atmosphere are directly transported to various parts of plants and diffused into water. On the one hand, the root system oxidizes and decomposes the sediments around the root system by releasing O2; On the other hand, many anaerobic and aerobic communities are formed in the bottom of water and matrix soil, which creates conditions for microbial activities and then forms? Rhizosphere? . In this way, plant metabolites and residues and dissolved organic carbon provide food sources for colonies in wetlands; At the same time, a large number of microorganisms form a gray biofilm on the substrate surface, which increases the number of microorganisms and the area of catabolism, so that pollutants (enrichment or sedimentation) in plant roots are decomposed by microorganisms or removed by biodegradation. In eutrophic water, denitrifying bacteria and ammonifying bacteria can also rely on microorganisms in the roots of aquatic plants to accelerate the transformation process of NH3 ~ N to N02-N and N03-N, which is convenient for the absorption and utilization of aquatic plants and reduces the release of nutrients from sediments into water.
5. Competitive inhibition of phytoplankton.
In the water with serious eutrophication, algae grow wildly and the water quality deteriorates. After planting aquatic plants, they compete with phytoplankton for nutrients and necessary light and heat conditions, and at the same time secrete algae-inhibiting substances, which destroy the normal physiological and metabolic functions of algae and force them to die to prevent the toxins they bring. This can improve the transparency of water body, increase the content of Do in water, promote the growth of submerged plants and bacteria, and further purify water quality.
As shown in the following figure, the water purification capacity of each underwater acoustic equipment is described in detail:
Second, the influence factors of aquatic plants on water pollution control
1, plant types and community composition
In the study of improving plant treatment effect, an important research content is how to choose suitable plant species and determine the combination of different plants. Floating plants are commonly used in constructed wetlands, and Eichhornia crassipes has the best purification effect from the removal effect. The emergent plants reed and cattail are used most frequently. Obviously, the purification effect of different species or the same species in different wetland environments will be quite different.
The gradual recovery of aquatic ecosystem depends on its self-purification ability and environmental capacity, which in turn depends on the formation of stable and optimized aquatic plant communities. Submerged plant community is the basis for Caohai to establish an optimized ecosystem. In the history of Caohai Lake, submerged plants have always been the most important producers in the lake.
2. Plant coverage and sewage concentration
Potamogeton crispus has a strong absorption and enrichment effect on N, P, Pb, Zn, Cu and as in water and sediments [l3]. Absorbing capacity is related to its biomass and population coverage. When the coverage of POTAMOGETON crispus is 50%, the biomass and purification efficiency are the largest. Experts studied the effects of different phosphorus concentrations on the physiological activities of water lily and water chestnut leaves. The results showed that with the increase of phosphorus nutrition level, the content of inorganic phosphorus in leaves increased gradually, while chlorophyll decreased with the increase of phosphorus content. Considering the effect of phosphorus on two plant indexes, the optimum concentration of water chestnut is 0. 1 mmol/L, while water lily is 0. 5 mmol/l, if it exceeds or falls below this concentration, its physiological activities will be adversely affected. The results of this study indirectly reflect the absorption of phosphorus by different plants, which provides reference for the selection of phosphorus removal plants.
3. Environmental factors
The factors affecting the removal rate of aquatic plants are related to factors such as light, water temperature, dissolved oxygen, pH, nutrients, wind and waves, and different life forms of aquatic plants have different sensitivities to these factors. All aquatic plants have their suitable growing season and temperature, and the transparency of water becomes the limiting factor for submerged plants. A large number of research results show that there are light compensation points and compensation depths in a certain depth of water, and only above the light compensation (point) depth can submerged plants carry out normal photosynthesis and respiration and plants grow.
Three, the ecological restoration technology of water pollution
1, species selection and community configuration
Species selection firstly analyzes and studies the history and current distribution of aquatic plants in polluted areas, and determines aquatic plant species according to their existing habitat conditions under the conditions of conforming to natural environment characteristics, strong pollution resistance, good purification effect, strong stress resistance and obvious landscaping effect.
Step 2 introduce the method
Collect emergent plants, floating leaves and submerged plants in Dianchi Lake and its surrounding rivers and dams, especially plants that grow healthily in polluted environment and emergent plants that live in water for a long time, and plant them in seedling base by whole plant transplantation or cutting transplantation. Relatively speaking, emergent plants and floating plants are more tolerant to water pollution than submerged plants, so emergent plants and floating plants follow the principle of biodiversity when introduced, and submerged plants follow the principle of adaptability when introduced.
3. Plant reproduction
Plant reproduction depends on sufficient, healthy and adaptable seedling supply, suitable natural conditions, rich nutrition supply and scientific management. At present, there are three measures for seedling propagation, one is seed collection and sowing, the other is asexual propagation, and the third is tissue culture. Because the collection and planting of seeds are too slow and the cost of tissue culture is too high, the source of recovered seedlings of aquatic plants is mainly asexual propagation in seedling base, that is, natural tillering and cutting propagation. At the same time, with the gradual implementation of ecological restoration in Dianchi Lake, more aquatic plant seedlings can be obtained from the natural wetlands around Dianchi Lake that have been restored in advance.
4. Cultivation techniques
(1) The cultivation technique of emergent plants, in which the water level is lowered from March to June every year (so that the water level in the planting area does not exceed 0.2 m), seedlings are taken from the nursery base, transplanted to the target waters with roots and soil, and the water level is gradually raised after the plants germinate.
2) Cultivation techniques of submerged and floating plants, in 3? In June, the water level was adjusted, and seedlings were raised from the seedling base, and live and mature seedlings were directly planted in the target waters with seedling carriers. Cutting can be used for shallow water planting.
3) The cultivation techniques of floating plants are basically the same as those of submerged plants.
In a word, ecological engineering is mainly to cultivate aquatic plants on the substrate made of local endemic aquatic plants to form floating islands of aquatic plants, and realize their ecological functions such as purifying water quality, improving biodiversity and improving natural ecological landscape by using the comprehensive effects of plants, aquatic animals and microbial communities inhabited by plant roots.
refer to
[1] Wen Meili. Fang guoxiang. Chen. Li Xinhua. Pollution Status and Comprehensive Control Countermeasures of Shiyan Reservoir in Shenzhen [Journal Paper]-Tropical Geography 2009( 1)
[2] Tie Jingxi. Ginger. Measures taken by Liu Haiyuan to remove algae from the source water of the Yellow River [journal paper]-Journal of North China Institute of Water Resources and Hydropower 2009(5)
[3] Qin Yanfang aquatic plant filter bed purification of Taihu Lake [Dissertation] Master's Dissertation 2006
[4] Li Tao TEDA artificial ecological river water quality maintenance ecological control technology [dissertation] Master in 2006.
[5] Money is rich. Ma Jingying. Research progress of Hong Xiaoping's water eutrophication and its prevention and control technology [journal paper]-Journal of Qinghai University (Natural Science Edition) 2002,20 (1)
[6] Li Xianming. Discussion on the Prevention and Control Measures of Urban Water Eutrophication in Wang Jianan [Journal Papers]-Henan Aquatic Products 20 10(4)
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