Organic wastewater treatment is a common problem in current pollution control. Traditional methods include activated sludge method, biofilm method, anaerobic reactor method and oxidation pond method. The first two methods are currently the most widely used methods in secondary disposal plants. The advantages are that the technology is relatively mature and stable, and the effluent can reach the allowable discharge standard, but the shortcomings are also prominent. The capital investment is large and the operating cost is high, especially the operating cost. High, many units are daunting and unable to afford such high operating costs. Therefore, sewage is often discharged directly into rivers and lakes without treatment. The watershed pollution disasters that occurred in the Huaihe River Basin in 1994 were the direct consequences of the high cost of the traditional sewage disposal model. In order to achieve a sustainable development strategy, China's national conditions require us to develop a sewage disposal technology with low investment, high efficiency and low operating costs. In response to this reality, in the early 1990s, according to the magnetic properties of magnetized water to change some physical properties, improve biological functions, promote biological growth, improve agriculture, aquatic production and governance, and carry out magnetization-artificial ecosystem approach And the use of organic wastewater research, the recent 10 years of extensive experimental research and preliminary application prove that this method is effective, the practical application is successful, it is necessary to widely promote, and further improved in practice to maintain social economy A virtuous circle of sustainable development.
(1) Effect and analysis of COD removal
In the case of aerobic water, a series of experiments were carried out on various sewages by changing the magnetic induction intensity, water temperature and magnetization flow rate. The results show that the water temperature has no effect on the direct removal of COD by the magnetizer through the magnetizer. When the magnetization flow rate is 2.5 m/s, it is better to form nuclear magnetic resonance at this time, and the magnetization has a stronger ability to remove COD. Under normal temperature, the magnetization flow rate is about 2.5m/s and the magnetic induction intensity is 0.262~0.315T. The direct COD removal rate of the above-mentioned various types of sewage is 25.4%, the printing and dyeing wastewater is 21.2%, and the urban sewage is 16.4% (the magnetization flow rate is 2.5m). /s is 20.0%), rubber industry wastewater is 11.3%, papermaking wastewater is 8.1%, glucose water is 17.8%, starch water is 11.1%, and ammonia water is 8.1%. In addition, in order to find out the reason why the instantaneous magnetization directly reduces COD, the dissolved oxygen before and after magnetization of deionized water, tap water and urban sewage is also tested. The magnetization flow rate is 2.0m/s at room temperature, and the optimal magnetic induction intensity is 0.315T. The dissolved oxygen concentration before and after the four groups of deionized water magnetization is unchanged. The magnetic treatment has no effect on dissolved oxygen. The dissolved oxygen in the five groups of tap water is slightly reduced. Reduced by 4.1%; 12 groups of urban sewage, the dissolved oxygen after magnetization decreased by an average of 24.7%. This transient magnetization causes the degradation of sewage organic matter and the reduction of dissolved oxygen, which is called the direct effect of magnetic treatment of sewage. This effect is not the synthesis of organic matter caused by microbial enzymes in water, nor is it magnetization to break the chemical bonds of organic molecules in water, but magnetic treatment causes nuclear magnetic resonance to activate dissolved oxygen in water, which promotes the oxidation synthesis of some organic substances. This can be analyzed from three aspects: First, in the above experiment, glucose, water, starch water, and ammonia water are all prepared by distilled water, and there is no microorganism. It is obvious that the instantaneous magnetization reduces the COD of the sewage and is not the function of the microbial enzyme; the second is the water and organic matter. The chemical bond cleavage of the molecule requires a considerable amount of energy. For example, the hydrogen bond cleavage of water molecules requires 4 to 6 kcal/g of energy. Such low magnetic induction provides little energy to break the chemical bond. Finally, B Patrov's experiment confirmed the above conclusion to some extent. He passed the dissolved oxygen water continuously from the induced magnetic field, and the water produced 5×10-5% h2O2, which is a strong oxidant. The organic matter in the water can be directly oxidized and synthesized. In addition, we have also carried out experiments on repeated repeated magnetization of sewage. It can be seen that with the increase of the number of magnetizations, the ratio of COD removal per time is drastically smaller and tends to be horizontal. Therefore, when the magnetic treatment technology is applied to practice, the water flow between the magnetic processors should be restored for a period of time. Experience has shown that the hydraulic retention time is preferably about 2 to 3 days.
Magnetization under anaerobic conditions also has a good effect on improving the synthesis of organic matter in water, and is more significant. We took 4 groups of urban domestic sewage for experiment, the temperature was kept at 0 °C, the optimal magnetic induction intensity was still 0.315~0.368T, and the COD was tested by anaerobic culture for 10d, indicating that the magnetization increased the removal rate of COD by 21%-28%, the average was 24.5%. The effect can be clearly seen even by the naked eye, but the mechanism needs further study.
(2) Ecological effects of hydromagnetic treatment and indirect purification effects
The applied magnetic field has a biomagnetic effect on biological effects, which can be divided into biomolecular effects, cellular effects, tissue and organ effects, and overall effects. For example, viruses are simple macromolecular microorganisms, bacteria, and fungi are basically single-celled microorganisms, protozoa, and higher. The organism is composed of different functional organs, and its tissues and organs are composed of cells. Sewage has a wide variety of organisms, with different structures and functions. When they pass a magnetic field of a certain intensity, they are also affected differently. On the whole, some are suppressed and even die; some are activated to speed up metabolism and growth, and indirectly improve the role of purifying sewage. In this regard, I have done a series of experiments and analysis in the following aspects:
(a). Sewage magnetization has a strong sterilization effect. The magnetic induction intensity is 0.315~0.420T, the magnetization flow rate is 2.0~2.5m/s, and the three groups of water samples have a consistent sterilization rate of 74%~81%. However, continuous re-magnetization, the sterilization rate is not improved, indicating that some types of bacteria can resist the role of magnetic fields, and even activate their metabolic capacity, will grow and degrade organic matter faster. The reasons for magnetization disposal sterilization can be summarized as follows: First, under the direct action of the magnetic field, the BOD and COD are reduced to reduce the energy of the heterotrophic microorganisms and the C nutrients, resulting in the death rate of the water heterotrophic bacteria is greater than the proliferation speed, so that Negative growth phenomenon, the second is that the magnetic force directly acts on the water and enzymes in the bacterial cells, which inactivate or inactivate the enzyme. The decrease of BOD value is a reflection of the decrease of the total number of bacteria. On the one hand, under the direct action of external magnetic field, BOD decreases with the decrease of COD index. On the other hand, under the action of external magnetic field, functional microorganisms (mainly bacteria) in water body Affected, some bacteria have strong adaptability, and life metabolic activities are not disturbed or interfered with, but after a certain period of time, they can return to normal state. This part of the bacteria survives with greater adaptability, and most of the bacteria are exposed to external magnetic fields. Due to changes in the physical and chemical properties of water in and out of the body (such as electrical conductivity, surface tension, etc.) and the inactivation and inactivation of the enzyme, the death phenomenon occurs, and the number of functional bacteria is drastically reduced, resulting in a decrease in the BOD index. The reduction in BOD after magnetic disposal is a reflection of the decrease in the total number of bacteria in the water. In summary, it can be concluded that the external magnetic field acts on the microorganisms, and the harmful effects on the microorganisms are harmful, and there is also a favorable side. Magnetic treatment has a bactericidal effect. When the magnetic field strength is increased to 2100 GS (4A) or more, more than 70% of the bacteria can be killed. The application of magnetic field can be regarded as a sudden change of the living environment of microorganisms. The bacteria that can withstand the changes of the surrounding environment and the ion and electron transfer speed in the body continue to survive and maintain normal life metabolic activities. This part of the bacteria has stronger adaptability. Or it has stronger biological activity.
(b). Activated sludge magnetization will significantly increase its activity, thereby enhancing the efficiency of sewage disposal. We took 7 groups of activated sludge and observed the decolorization time of methyl blue after treatment with different magnetic strength at 37 °C, which indicated that the decolorization time at 0.367T decreased from 29h without magnetization to 24h, and the activity of sludge increased by 17%. Microorganisms that survive the magnetization have greater proliferation and metabolism. In order to prove this conclusion, three groups of papermaking mid-stage wastewater dilution water samples were taken and cultured at standard temperature after non-magnetization and magnetization treatment, and their BOD5 was measured. The latter were 13% higher than the former, and magnetic treatment was observed. It has both sterilization and activation of certain functional microorganisms and accelerates the degradation of organic matter.
(c). Magnetization greatly enhances the photosynthesis of algae and significantly increases dissolved oxygen in the water. Two sets of the same sewage experiment were taken at room temperature. After 3 days, the green algae in the magnetized water grew vigorously, and the algae could hardly be seen in the non-magnetized water. In addition, the effects of three groups of domestic sewage on the oxygen production capacity of algae were compared with those of the experimental magnetic treatment. The results showed that the algae had the highest oxygen production capacity when the magnetic induction intensity was 0.367T, which was 1.1 times higher than the average of non-magnetization. The relationship between solid carbon productivity and oxygen production capacity is estimated, and algae productivity will also increase by 1.1 times, which is consistent with the conclusion that agricultural magnetized water significantly increases crop yield and greatly increases seed germination rate. The main reasons are: 1 magnetized sewage accelerates the synthesis of organic matter, provides sufficient CNp and other nutrients for algae growth; 2 magnetization increases the permeability of biofilm, which creates favorable conditions for algae to absorb nutrients; 3 magnetization makes water penetrate Enhanced light, providing better light energy for algae photosynthesis. The increase of dissolved oxygen in water promotes the growth of microorganisms and the synthesis of organic matter in water, which promote the accelerated synthesis of organic wastewater.
(d). Sewage magnetization promotes the growth of higher aquatic organisms and facilitates the removal of pollutants. We experimented with loach. In three buckets (10L), one was unmagnetized, two were magnetized, and the magnetic strengths were 0.03T and 0.25T, respectively, and 1.5kg of loach was stocked. The other conditions were the same, after 3 months. The muddy yield of all magnetized water is higher than that of unmagnetized, and the average yield is increased by 15%-20%. In addition, experiments on the soil resistance of the loach and the assimilation of COD showed that 50 loach stocked in the unmagnetized bucket died on the fifth day, and 50 of the magnetized buckets survived on the seventh day. As higher aquatic animals synthesize and transform organic matter through the food chain, the COD of the three groups of water samples was measured indirectly after 7 days of water purification, indicating that the COD removal rate of the 2nd and 3rd buckets that were magnetized and muddy was less than that of non-magnetized. No muddy increase of 20%), and it is transformed into a useful product for human beings at a higher speed, turning waste into treasure and preventing secondary pollution.
(3) Magnetization-artificial ecosystem method to purify sewage application examples
As shown in Figure 2, in 1980, based on the original sewage station, a magnetization-artificial ecological disposal system project was constructed, which consisted mainly of secondary magnetization and three ecological pools. The disposal system covers an area of ​​770m2, and the average daily disposal of hospital sewage and ward sewage is 700t. The sewage is discharged directly into the pre-sinking adjustment ecological pool. The hydraulic retention time is about 4.0h. After the pump is lifted and the first-order magnetization, the ecological conversion tank for stocking a large number of fish is entered. The hydraulic retention is 2.0-2.5d, and the magnetization is re-magnetized and self-flowing. The goldfish pond of the vertical ecological filter tube has a residence time of 2.5-3.0 days, and is discharged through the ecological filter tube. The effluent reaches the third-grade ground water standard for hospital greening and cleaning. The station has been used for many years. In 1994, only one pool of sewage was discharged in the pre-sinking tank, and the number is small, which shows that the conversion rate of pollutants is high. In the system: 1 pre-sinking adjustment ecological pool area of ​​180m2, average water depth of 1.1 ~ 2.5m, is a facultative pool, pool surface wind eye lotus cover the absorption of sewage synthesis Np and other nutrients; 2 ecological conversion tank, diameter 25m, by the center The pond, the annular re-oxygenation ditch and the annular outer tank are composed of sewage receiving the first-stage magnetization from the pre-sinking tank, and tens of thousands of tilapia are stocked in the pond, and a large number of growing bacteria, algae and protozoa are swallowed to rapidly purify the water body, and Inflow into the central garden; 3 ecological filter 100m2, average water depth 2.3m, which stocks about 60,000 goldfish and lays many ecological filter tubes, accepts the flow of the central garden pool and the secondary magnetization, and continues the ecological transformation after the ecological The filter tube is filtered and discharged to complete the purification process. The removal rates of BOD (Biological Oxygen demand), COD, N, and p were 89.9%, 87.6%, 69.6%, and 73.6%, respectively. The total investment of the system engineering infrastructure is 270,000 yuan, equivalent to 386 yuan for the capital construction investment of 1t / d of sewage treatment; the annual operating cost is 7,500 yuan, equivalent to the annual operating unit price of 10.7 yuan of sewage treatment 1t / d, far lower than Table 1 The unit price of the investment and the unit price of the operation of the conventional secondary disposal. Not only that, because of the income from the process of sewage disposal, such as bullfrog, goldfish, tilapia, Chinese herbal medicines, grapes, etc., the annual income can also be 18,000 yuan, and the annual operating cost is more than 10 million yuan, forming a negative investment in the sewage disposal process. . Due to the magnetization effect in ecological disposal, the method greatly accelerates and improves the conversion rate and efficiency of pollutants, and turns waste into treasure, making it less investment, small land occupation, high efficiency, low operating cost, and no secondary pollution. And there is a new way of sewage disposal with certain output gains.
(4 Conclusion
Magnetic treatment is widely used in agriculture, medicine, aquaculture, industry and many other fields, especially life sciences. Based on these experiences, we propose to apply magnetic treatment technology and artificial ecosystem to the purification and disposal of organic wastewater, and focus on a series of experimental analysis and practical application of magnetic disposal, and obtain some useful knowledge.
(a) Magnetic treatment of organic wastewater. Under the aerobic conditions of water, the sewage can pass through a suitable magnetic field (0.315～0.368T), and the COD can be directly removed by 8% to 25% depending on the difference of water quality, and is not affected by water temperature. However, the magnetization is continuously repeated, and the removal rate per time decreases sharply with the number of magnetizations. The practical application shows that the hydraulic retention time of the magnetic processor is 2~3d. The reason why the magnetic treatment directly removes the COD is that the sewage is caused by a strong oxidant such as h2O2 generated in the magnetization, and is not a result of the biological enzyme action or the direct bond of the organic molecule molecular bond.
(b) Under anaerobic conditions, the magnetization of sewage is also significant for COD degradation. Experiments show that the water temperature of 40 °C can increase the COD removal rate by 21% to 28% compared with the non-magnetization under the above suitable magnetic field, but the mechanism is still Further research is needed.
(c) The direct sterilization rate of sewage magnetization can reach 70%-80% (probably small viruses, bacteria, etc.), but not all microorganisms can be killed, especially functional microorganisms, and the survival will be activated. Greater vitality improves wastewater purification capacity (about 17% of preliminary experiments).
(d) Magnetically treated sewage is beneficial to the growth of algae system and photosynthesis, which can double the oxygen production rate of water and the productivity of algae (green algae) to promote the purification of sewage by biological chains.
(e) Magnetic disposal should be used in conjunction with artificial ecosystems. The above-mentioned sewage disposal station is a successful example of this combination, with high disposal efficiency, low operating costs, waste water resources and waste turning into treasure, showing sustainable development and promotion. Broad application prospects. (Source: Environmental Alliance)
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