Practice of diatomite soil treatment

How to change the urban water-saving mode of “secondary biochemical treatment” and then “middle water treatment” in urban sewage treatment, and establish a set of technology to treat sewage to “middle water” once, saving the society valuable the funds, land resources, to create an ecological city, to protect our living environment, Mr. Bai Wang in Dali under the guidance of national academicians Mr. Wang Xiji, the completion of the "diatomite water treatment process," and developed into " The level of the sixth generation of technology, that is, the completion of the one-time treatment of urban sewage reached the level of GB18918-2002 level A standard. Taking the “Denglong River Project” of urban sewage in Dali City, Yunnan Province as an example, the diatomite soil treatment process and “Qingzhong Biochemical Process” are introduced as follows:

1. Removal mechanism of pollutants in diatomite soil treatment process

(1) Removal of SS

SS removal in sewage is mainly removed by adsorption, flocculation and precipitation of diatomite. The concentration of suspended solids in sewage treatment is not only related to the SS index of the effluent, but also related to the BOD5 and CODcr indicators of the effluent. This is because the composition of the suspended solids is mainly activated sludge flocs, so the sewage from the sewage treatment plant is controlled. The SS indicator is the most basic and important part. In order to remove suspended solids in water as much as possible, appropriate measures must be taken in the project. The common traditional biochemical measures have to choose the appropriate sludge loading rate to maintain the coagulation and sedimentation performance of the activated sludge, using a smaller secondary sedimentation surface. The load, the use of a lower effluent load, and the full use of the adsorption network of the activated sludge suspension layer. Through comprehensive comparison, the best method is to use diatomite water treatment agent, combined with high-efficiency hydraulic circulation clarification tank, which can make the removal rate of SS in wastewater reach 99%.

(2) Removal of BOD5

The removal of BOD5 in sewage is mainly achieved by the adsorption and metabolism of diatomaceous earth water treatment agent, and then the separation of adsorbed metabolites by muddy water is completed. At the initial stage of contact with the diatomite water treatment agent and sewage, a high removal rate of BOD5 occurs, which is caused by the organic particles and colloids in the sewage being adsorbed on the surface of the diatomaceous earth water treatment agent. However, this adsorption only acts on suspended solids and colloids in the sewage, and does not contribute to dissolved organic matter. The dissolution of the dissolved organic matter requires the ion exchange function of the diatomite soil, and a part of the organic matter in the sewage is synthesized into a new cell under aerobic conditions, and another part of the organic matter is catabolized to obtain the energy required for cell synthesis. The final product is a stable substance such as CO2 and H2O. Therefore, the residual BOD5 concentration in the treated sewage can be made very low. The effluent water quality is less than 10mg/L.

(3) Removal of CODcr

The principle of CODcr removal in sewage is basically the same as that of BOD5, but the removal rate of CODcr is related to the composition of domestic sewage in Luoshui Village. For those integrated sewage mainly composed of domestic sewage and its components and catering wastewater, the BOD5/CODcr ratio is often close to 0.5 or even greater than 0.5, and the CODcr value in the effluent can be controlled at a lower level. The urban sewage mainly composed of industrial wastewater has a small BOD5/CODcr ratio, and its sewage is less biodegradable. This type of sewage uses diatomite water treatment agent and uses high-efficiency hydraulic circulation clarifier sewage. The processing equipment will give full play to the outstanding characteristics of the process stronger than other processes, and the CODcr remaining in the treated sewage will obtain the highest effect, and the removal rate is above 90%, even above 95%. The test results of the Ding Deng River project inlet and outlet water indicators are as follows:

It can be seen from the above table that after treatment, the effluent meets CODcr ≤ 50 mg / L, which can fully meet the national first-level discharge standard (GB18918-2002).

(4) Removal of N

Nitrogen is an indispensable component of protein and is widely found in municipal wastewater. The nitrogen in the wastewater generally exists in the form of organic nitrogen, ammonia nitrogen, nitrite nitrogen and nitrate nitrogen. The main forms of nitrogen in domestic sewage are organic nitrogen and ammonia nitrogen. Among them, organic nitrogen accounts for 40-60% of domestic sewage, ammonia nitrogen accounts for 50-60%, and nitrite nitrogen and nitrate nitrogen only account for 0-5%. The basic principle of biological nitrogen removal in wastewater in traditional secondary biological treatment is: on the basis of converting organic nitrogen into ammonia nitrogen, the ammonia nitrogen is converted into nitrite nitrogen and nitrate nitrogen by the action of nitrification and denitrifying bacteria. Nitrogen is converted to nitrogen by denitrification to achieve the purpose of denitrification from wastewater.

The biological nitrogen removal process of wastewater is actually applied to the biological treatment of wastewater by the basic principle of nitrogen circulation in nature, and the transformation of biological decarbonization process by means of the coordinated action of different microorganisms and reasonable human operation control. The process of producing and removing ammonia nitrogen present in the raw wastewater into nitrogen gas and removing it from the wastewater. In the process of biological nitrogen removal of wastewater, firstly, under aerobic conditions, the ammonia nitrogen in the wastewater is oxidized to nitrite nitrogen or nitrate nitrogen by the action of aerobic nitrifying bacteria; then, under anoxic conditions, the anti-oxidation condition is utilized. Nitrifying bacteria (deaza bacteria) reduce nitrite and nitrate to nitrogen and escape from the water. In the process of nitrification and denitrification, the factors affecting the nitrogen removal efficiency are temperature, dissolved oxygen, pH and denitrifying carbon source. In the biological nitrogen removal system, the growth rate of nitrifying bacteria is slow, so there must be sufficient sludge sludge age, that is, the system must be maintained under a low sludge load condition, so that the sludge age of the system is greater than that of the maintenance nitrification system. Minimum mud age is required. The growth of denitrifying bacteria is mainly carried out under anoxic conditions, and a sufficient carbon source is required to provide energy to promote denitrification. The nitrification and denitrification reactions in the biological nitrogen removal system need to have the following conditions: nitrification stage: sufficient dissolved oxygen, DO value of 2 mg/L or more, suitable temperature, preferably 20 degrees, not lower than 10 degrees, sufficiently long sludge mud Age, suitable pH conditions. Denitrification stage: the presence of nitrate, anoxic conditions, DO value of about 0.2mg / L, sufficient carbon source (energy), suitable PH conditions. It is necessary to control the carbonation of sufficient sludge age and influent water. There is also a CODcr concentration, a TKN/CODcr ratio, and a P/CODcr ratio into the biological treatment tank. The TKN/CODcr value is less than 0.08, which has the effect of removing nitrate. If it is between 0.08-0.11, the nitrate cannot be completely removed. Between 0.11-0.14, the UCT process can not completely eliminate the nitrate in the anaerobic tank, and it is necessary to control the reflux. Than in order to reduce the impact of nitrate on anaerobic. If TKN / CODcr greater than 0.14, urban waste water can not be used in addition to phosphorus by biological denitrification. Due to the traditional A2/O and UCT processes, there are many structures, large land occupation, large investment, and complicated operation management. Especially for medium-sized urban sewage plants, it is rarely used, so it is not recommended. The traditional oxidation ditch has no phosphorus removal function, and there is no special anoxic tank. Denitrification is an anoxic zone formed between the aerators, so the denitrification capacity is limited.

The diatomite water treatment agent is used, and the high-efficiency hydraulic circulation clarifier sewage treatment equipment is used. Since the diatoms separate and remove the impurities coexisting with the diatom in the selection process, the equilibrium potential of the diatom surface is not formed. Equilibrium potential, when the water treatment is carried out, the diatomite water treatment agent is added into the sewage in a small amount, and is dispersed in the water body instantaneously under high-speed agitation or the pump blade that sucks the sewage, and the surface of the diatom is unbalanced. The potential energy neutralizes the chargeability of the suspended ions, causing the repulsion potential to be destroyed and forming a plume with the diatom. The electricity price is neutralized and precipitated, and the larger floc is integrated, and the gravity is precipitated to the bottom, plus diatoms. Huge surface area, large pore volume and strong adsorption force, using diatomite water treatment agent for adsorption, flocculation and filtration of Kjeldahl nitrogen (TKN), the fine and ultrafine micro-organic and inorganic substances in sewage The substance adsorbs to the surface of the diatom to form a chain structure. Diatoms composed of amorphous active silica have the property of being concentrated in a water body and freely settling into a diatom cake. In addition, the flocculation effect of the modified soil accelerates the speed at which diatoms are condensed to the bottom of the water to form diatom cake, so that the potential of the diatom is neutralized, the pollutants and bacteria are instantly separated from the water body.

(5) Removal of P

The phosphorus can be removed from the sewage, and the conventional method can be either chemical or biological.

Chemical phosphorus removal is to sewage adding trivalent salt (typically aluminum salts and iron salts, divalent iron should ensure that ferric iron is oxidized in the aeration tank), so that the sewage to form insoluble phosphate compounds , removed from the water by precipitation. The advantage of using chemical phosphorus removal is that the process is simple, and there is no need to add other facilities besides the dosing equipment, so it is especially suitable for the old plant to increase the phosphorus removal function. Disadvantages are large consumption of chemicals, increased amount of excess sludge, and increased processing costs. The addition of chemicals also consumes alkalinity in the water.

Biological phosphorus removal is a phosphorus-concentrating bacteria in sewage that is depressurized to release phosphate from the body, generating energy to absorb rapidly degrading organic matter, and converting it into PHB (poly-β-hydroxybutyric acid) for storage. When these polyphosphate bacteria enter aerobic conditions, they degrade the PHB stored in the body to generate energy, which is used for cell synthesis and phosphorus absorption, forming a high concentration sludge, and discharging the system together with the excess sludge to achieve the purpose of phosphorus removal. . The disadvantage is that in order to avoid the re-release of phosphorus in the excess sludge, there is a certain limit to the choice of sludge treatment process. The absorption of phosphorus in the aerobic section depends on the release of phosphorus in the anaerobic stage, which in turn depends on the anaerobic conditions of the anaerobic section (anaerobic requires neither molecular nor nitrate nitrogen) and can be rapidly The content of degraded organic matter (this value is generally 1/4 to 1/3 of the influent CODcr), that is, the smaller the P/CODcr ratio, the better. The phosphorus removal efficiency has a great relationship with the concentration of CODcr which is easily biodegraded into the biological treatment tank. When the concentration of biodegradable CODcr is less than 50 mg/L (the concentration of influent CODcr is about 150-200 mg/L) There is almost no phosphorus removal effect, and the P/CODcr ratio should be less than 0.025 to meet the phosphorus removal requirements. These conditions are difficult to achieve, for which the biological phosphorus removal process is generally not effective.

From the water quality of the general urban sewage treatment plant and the required targets, we believe that the best treatment process is the use of diatomite water treatment agent, and the use of high-efficiency hydraulic circulation clarifier sewage treatment equipment process, the process is The removal rate of total phosphorus can be stably ensured at 90% or even 99%, which is currently not achieved by any type of process; and the removal of heavy metal ions in sewage is particularly effective in removing phosphorus. Under the premise of meeting the requirements of phosphorus and nitrogen removal, the removal of BOD5, CODcr and SS can be solved simultaneously.

Second, the choice of water treatment process plan for sewage treatment plant production

In combination with the above-mentioned several main methods of nitrogen and phosphorus removal, A2/O, UCT, and oxidation ditch have large area and investment operation cost because of the need to set up a special secondary sedimentation tank; although the T-type oxidation ditch does not need to be set up The second settling tank, but because of the aeration device used to limit its water depth, the floor space is large, and the utilization rate is set, the volume utilization rate is very low; the traditional SBR (including the cyclic aeration method CAST), although the structure is small, The head loss is small, but the volume utilization rate is only 50%; the use of diatomite soil water treatment process and Qingzhong biochemical process (biochemical technology under the condition of small BC ratio) has small investment, small land occupation and low operating cost. The removal rate is high, the structure is simple, the energy consumption is small, the sediment can be recycled and reused, there is no secondary pollution, the adaptability is strong, and the change of climate, temperature and sewage concentration can be unaffected.

Third, diatom essence soil water treatment process and equipment

(a) diatomaceous earth

1. Properties and uses of diatomaceous earth

Diatomite [DIATEMITE] is a bio-genetic siliceous sedimentary rock deposited mainly from the remains of diatoms (a single-celled aquatic algae) and soft mud. It has high porosity, large specific surface area, strong adsorption, light weight, firmness, sound insulation, heat insulation, wear resistance, acid resistance and low thermal conductivity. It is widely used in water treatment, food, building materials, chemical industry, rubber, petrochemical, Medicine, metallurgy, paint, cosmetics, paint, machinery, energy, etc., water treatment agent, filter aid, filler, adsorbent, heat insulation material, catalyst carrier, chromatographic fixative, etc., is an indispensable material for modern industry. So far, no satisfactory replacement materials have been obtained.

2. Development of foreign diatomite

Diatomite mining accounts for a small proportion of the world's mining industry, from about one in ten thousand to two ten thousandths. After 1979, the diatomite mining industry is not growing fast. The main reason is that the world's diatomite resources are not abundant, especially the diatomite resources suitable for economic quality development are limited. The products are limited by the quality of the original ore, ie no need The ore reserves that can reach the quality of diatom concentrates are rare. The use of low-quality raw ore soils that need to be used for mineral processing is becoming more and more urgent. The low-grade original soil is preferably the fine ore dressing process, which has become an urgent problem for all countries in the world. The problem, but it has been difficult to solve so far, can not adapt to the requirements of the increasingly demanding diatom concentrate, so that the development of the diatomite industry is difficult to develop faster due to the constraints of raw materials.

Because diatomite mining is not large, there are few people studying diatomite mining. The development of diatomite, especially the development of low-grade ore, is not progressing due to lack of practical experience and theoretical guidance.

The physical properties, chemical composition and extremely complex symbiotic impurities of diatomite ore vary greatly from mine to mine, which increases the difficulty of development. In general, the main reason for the unsatisfactory growth of the world's diatomite mining industry is not the decline in demand, but the supply of high-quality raw ore soils due to the above reasons.

3. Development of diatomite in China

China's development of diatomite is only in its infancy, and it is far from sufficient in basic theoretical research and applied research. Compared with the leading countries in which diatomite application research is developed, it is only a budding.

Due to the lack of understanding of the basic knowledge of diatomite and the lack of practical experience, the existing authoritative departments and scientific research units in China have repeatedly misused other minerals as diatomaceous earth, which wastes a lot of manpower and financial resources. .

China ignores the basic theoretical research of diatomite and the exchange of information on foreign technology, which causes the research work to stay at a low level for a long time. Therefore, it lacks some deep basic theoretical research and high-level product development, and the research results are almost zero.

China's research on diatomite started late, and all kinds of professionals are very scarce. For this reason, some scholars who do not understand the knowledge of diatomaceous earth have gone abroad to study and organize seminars. As a result, the scientific and technological achievements that have emerged have been suppressed. The pure theory and even the fallacy of technology have been published in large numbers, so that the development of diatomite in China is regressing.

The export of diatomite soil products in China is almost zero, and it is still unable to get rid of the situation of relying on imports.

The development of diatomite industry is an urgent and important issue for China with abundant reserves. However, most of China's diatomite resources are medium- and low-grade “poor mines”. To this end, the primary problem of the large-scale development of diatomaceous earth in China is to solve the beneficiation process. Only the economic, applicable and feasible low-grade “lean ore” is preferred as the fine ore dressing process, and the diatomite industry in China can develop rapidly. Otherwise, it will continue to stay in the current status quo.

4. China's diatomite resources

Through more than 20 years of efforts, China has done some work on the investigation of diatomite resources. According to the currently known data, the formation and distribution of diatomite in China has the following characteristics:

China's diatomite mines are mainly distributed in the central and southwestern regions of Yunnan Province and in Jixian County, Zhejiang Province in the east, Jilin Province and Inner Mongolia in the northeast, Panxi District in Sichuan, and Leizhou Peninsula in Guangdong.

The formation period of diatomite ore in China has continued from the Miocene to the Holocene, and the scale of diatomite formed by the Neogene is generally larger.

China's diatomite ore is a non-marine deposit, which is dominated by freshwater lake facies.

The formation and distribution of diatomite in many parts of China are closely related to volcanic activity ( basalt ) since the Cenozoic.

Most of China's diatomite mines are of medium and low grade and must be used as raw materials for industrial products after mineral processing.

In China's 14 provinces, more than 70 diatomite mines have been identified, forming a three-legged situation in Jilin, Zhejiang and Yunnan. The eastern coast, western Xinjiang, northern Heilongjiang, southern Guangdong, Hainan, central Inner Mongolia, Hebei, Shandong, Sichuan, etc. all store a large amount of diatomite. Except for the good quality of Jilin Changbai Maanshan Mine, the country's original soil is of medium and low grade. The national invention patent technology "diatomite pure physical beneficiation process" developed by Professor Wang Qingzhong can optimize the original soils as fine soil. To this end, China's diatomite industry development can build a mineral processing plant in various places, near the supply of fine soil. In the past few hundred years, only the reserves that have been identified can be said to be too large to be mined.

(2) Achievements in the process of diatomite water treatment agent

Practice has proved that the diatomite water treatment agent is the core of the “diatomite water treatment process”, and the diatom essence water treatment process is suitable for urban sewage and various industrial wastewater treatment. The process has been rated as the first in China by an expert group composed of domestic water treatment experts and the China Diatomaceous Earth Association, and has world-leading technology. The sewage treatment projects built in Guangdong, Jiangsu, Yunnan, Guizhou, Guangxi and Inner Mongolia have successfully treated urban sewage and industrial wastewater to national emission standards and can be recycled under the monitoring of the provincial environmental monitoring center stations. The removal rates reached 92-92.8% of BOD5, 95% of CODcr, 99% of SS, 78% of TN, and 90.7% of TP. On October 4, 1996, an expert group composed of 18 experts from 14 departments of the competent department of Yunnan Province reviewed the sewage treatment process and tests, gave higher evaluation and recommended immediate promotion. The invention of the process, In order to control polluted wastewater, it provides the best technology that is both economical and applicable, so that the thorough cure of sewage from hope to reality

(1) In September 1996, a test for the treatment of urban sewage was carried out on the Mingtong River in Kunming. The results of the monitoring by the Yunnan Provincial Monitoring Center were as follows:

The above works achieved the best results of the undetected suspended solids, and the removal rates exceeded the traditional process.

(2) In September 1996, the drainage pollutants obtained in the wastewater treatment project of Kunming Zixiang Hotel and the sewage treatment project of Kunming Panlong Sanitary Ware Factory were fully used to meet the national first-level emission standards and a number of pollutants. The indicators far exceed the requirements of the national performance level 1 emission standards.

(3) In July 1997, the Kunming Daguan River sewage treatment project built with this technology far exceeded the national first-level discharge standard. The project sensationalized Kunming, and the Yunnan Daily published three layouts in one month. The Spring City Evening News also serialized three articles, and the Kunming Daily newspaper reported them, and foreign newspapers and periodicals also reported many times. More than a dozen TV stations, such as Yunnan TV Station and Kunming TV Station, have reported on radio stations. The provincial and municipal leaders personally visited the site and heard the news from outside the province.

(4) In March 1998, the construction of the sewage treatment station of Chengjiang Luchong Scenic Spot with this technology once again caused a sensation. From the first day of trial operation, it has received many provincial and municipal leaders and environmental protection authorities to visit. . Television, newspapers and periodicals have also reported many times.

(5) in June 1998, with the technology to build Liupanshui City, Guizhou Province Bureau of Mines Eagle Mountain coal mine 8000m3 day wastewater treatment /.

(6) Since March 1998, this technology has been used to participate in the key project of the 99th Expo, the emergency treatment test of cyanobacteria in Dianchi Lake. The test results show that the technology has achieved the best results.

(7) In March 1998, two urban sewage treatment demonstration projects of 1000m3/d and 4000m3/d were built on the Mingtong River in Kunming.

(8) In 2000, a 1000m3/d papermaking black liquor wastewater treatment project was built in the Ruili Paper Mill of Yunnan Province.

(9) In 2000, a 500m3/d electroplating waste liquid project was completed in Zhangpu Electroplating Factory, Guilin City, Guangxi Province.

(10) In January 2001, a 10,000m3/d urban sewage treatment project was completed in Hohhot, Inner Mongolia. Under the low temperature of minus 17 degrees, after the treatment of the process, the indicators of the effluent water quality meet the national emission standards. On February 21, 2001, Hong Kong Wen Wei Po C14 Hong Kong News featured a large-scale version of the "Invented diatomite treatment of sewage in the Mainland - a number of advantages over traditional techniques, which can be used as a reference for local sewage treatment programs", for urban sewage in Hohhot, Inner Mongolia Report the results of the project.

(11) In June 2002, Qingyuan City, Guangdong Province completed the first phase project of 200000m3/d urban domestic sewage treatment. The Guangzhou Daily reported many times.

(12) The second generation of Qingzhong water treatment technology in 2004 successfully completed the urban sewage effluent of 5000m3/d in Dali and reached the first-class A standard GB18918-2002 of Pollutant Discharge Standard of Urban Sewage Treatment Plant. Currently negotiating are: 50000m3/d urban sewage treatment project in Hohhot, Inner Mongolia; 30000m3/d urban sewage treatment project in Zhanjiang City, Guangdong Province (using BOT method); 200000m3/d urban sewage treatment project in Sanxiang Town, Zhongshan City, Guangdong Province.

(3) Pure physical mineral processing technology of diatomite

The process is the only process in the world that can use physical methods to optimize low-grade diatom original soil as fine soil. Compared with chemical method, ie pickling method, it has small investment, high efficiency, no pollution, less power consumption, and water consumption. It can be recycled, low cost, high recovery rate, easy operation, strong adaptability, compact equipment, continuous production and high separation efficiency. The main point of the process is that the original ore is collected and stacked according to different grades. Before the feeding, the original soil moisture was measured, and the water was thinned into a concentrated low-speed scrubbing machine according to the dry material. Then, it is poured into a high-speed dispersing machine and diluted with water to a low-concentration slurry. At this time, the coarse sand is removed in the equipment for removing the coarse sand. Then enter the high-speed mixer, add the diatomite ore special gravity magnetic water, the slurry produces static friction under the high-speed rotation of the blade, and the impurity particles in the original soil such as ferric oxide and aluminum oxide are negatively charged, and the gravity magnetic water is positively charged. The principle that silica maintains neutrality, the high-voltage static electricity generated by internal friction causes the impurities to not settle. After the slurry enters the negative pressure blasting equipment and the ultrasonic vibration equipment, it enters the rough selection equipment, selects the equipment, removes fine-grained crystalline silica, detrital minerals, and finally enters the diatom enrichment equipment. The non-settling clay and impurities are discharged outward, and the diatoms are freely settled and enriched into diatom cakes, thereby selecting diatoms in the ultra-low-grade diatom original soil as high-quality fine soil. The quality of the original soil collected only affects the recovery rate of the fine soil without affecting the quality of the fine soil. Because in the beneficiation process, only diatoms can be enriched as cakes, and the remaining impurities are sorted out. For this reason, the obtained fine soil has a purity of over 92%.

(4) Process for treating sewage by diatom concentrate treatment agent

The process not only has the comprehensive advantages of various conventional processes, but also makes up for the deficiencies of the various treatment processes, and has the special advantages that the conventional processes can not completely remove and reuse the sediment. The process not only has small investment, low power consumption, low cost, small land occupation, good processing quality, high removal rate, all pollutants can be taken away and reused, and has strong applicability, simple equipment and convenient operation, and can be used as various types. The industrial wastewater and urban sewage treatment of large, medium and small enterprises is an internationally advanced sewage treatment process that is superior to the traditional processes at home and abroad. It adopts diatomaceous earth pure physical beneficiation process and preferably purified diatomite to prepare a treatment agent. In the special sewage treatment equipment, due to the strong adsorption of diatom, the organic and inorganic substances in the sewage are adsorbed. Under flocculation, it instantly settles to the bottom to obtain clean water. Clear water can be recycled. The sediment which is adsorbed by diatoms and flocculated into cake can be completely separated and taken out. Because diatoms account for a certain amount, according to the different types of pollutants, they are separately made into diatomite series products. The construction cost of this process is only 40% of the biochemical method. The operating fee is only 50-60% of the coagulation method.

1. Modified diatomite to prepare diatomite water treatment agent

The diatom concentrate water treatment agent is a proprietary product obtained by the national invention patent. Diatom is a kind of unicellular algae. Its shape is extremely small, usually only a few microns to a dozen microns. Until the microscope is introduced, people gradually understand it. Diatoms are capable of photosynthesis, homemade organic matter, and are oxygen providers for aerobic animals in the waters. They grow and thrive in water at an alarming rate, and their remains deposit to form diatomaceous earth. After beneficiation, the impurities such as clay, quartz sand, and detrital minerals that are symbiotic with it are removed, and the diatom is enriched to more than 92%, which is called fine soil. The difference between diatomite and diatomaceous earth is the word "fine". There is no pure diatomaceous earth in the world. For this reason, there are many impurities in diatomaceous earth, and the content of diatom is small. It is difficult to treat the water when it is treated with water, and it is also possible to mix the water. After special purification, the enrichment of diatoms to more than 92% is called fine soil. The color is white, the compact density is 0.3-0.4g/ml, the specific surface area is 50-60m2/g, the quantity is 2-250 million/g, the pore volume is 0.6-0.8cm3/g, the pore radius is 2000-4000Ã…, and the water absorption rate can be absorbed. 3-4 times its own weight. It has the characteristics of light weight, porous, sound insulation, acid resistance, alkali, large specific surface area, stable chemical properties, thermal stability and strong adsorption capacity. In the water treatment, a certain amount of modified substances are added to the fine soil according to the type of sewage, and the diatomaceous earth water treatment agent for treating various water quality is modified and formulated.

2. The main points of diatomite treatment of sewage

The diatom separates and removes the impurities coexisting with the diatom during the selection process, so that the already balanced potential of the diatom surface forms an unbalanced potential. When the water is processed, the diatom concentrate treatment agent is added to the sewage in a small amount. In the high-speed stirring, or the pump blade that sucks the sewage, it is instantaneously dispersed in the water body. The unbalanced potential of the surface of the diatom can neutralize the chargeability of the suspended ions, so that the zeta potential of the micelle structure of the colloidal particles is reduced. Small or zero, in order to achieve the purpose of destabilization of colloidal particles, prompting the flocculation and precipitation of pollutants in the water. The repulsive potential is destroyed to form a plume with diatoms, the electricity price is neutralized and precipitated, and the larger floc is integrated, and the gravity is precipitated to the bottom, plus the huge surface area of ​​diatom, huge pore volume and Strong adsorption force adsorbs fine and ultrafine substances onto the surface of diatoms to form a chain structure. Diatoms composed of amorphous active silica have the property of being concentrated in a water body and freely settling into a diatom cake. In addition, the flocculation effect of the modified soil is accelerated, and the speed of diatoms and the like formed by condensing the diatoms to the bottom of the water is accelerated, so that the potential of the diatoms is neutralized, the pollutants and the bacteria are separated, and the water is separated from the water body, and the water is cleaned. Flowing up. And diatoms also have the function of self-dehydration, and when the sediment is discharged to the van type dewatering machine, it is dehydrated by mechanical pressing. The sediment is adsorbed and left on the filter cloth, and the water is filtered through the diatom and filtered to the outside of the filter cloth to the conditioning tank. The sediment is kept at a water content of about 57%, and the cake is bagged and taken away, so as to achieve the purpose of sewage treatment for clear water.

3. Sediment recycling and reuse

The sediment obtained after treating the sewage with diatom concentrate as a water treatment agent can be recycled and reused. Because the sediment contains a large amount of diatoms, clays, organic matter and inorganic salts, but the sediment will not deteriorate and rot. After the test, we made the sediment into light building insulation bricks and ordinary light building materials, because the sediment contains nitrogen and Phosphorus, which is an acidic soil improver, can also be used as a fertilizer for this purpose. The test does not harden the soil, but instead makes the hard soil looser. The company that undertakes the water treatment project is a mineral processing-based company. Since the ultra-low-grade original soil can be purified into fine soil, the diatomite in the sediment can be re-selected and concentrated into fine soil. of. The re-purified concentrate can be reused for wastewater treatment. There are two kinds of purification methods. One is to use a pure physical wet beneficiation process to build a nearby concentrator that specifically selects the fines in the sediment. The second is to use air selection. This method has been tested. The sediment is calcined at 850 °C with a push-plate kiln, a vertical kiln or a rotary kiln. At this time, the organic matter is volatilized, the clay is sintered, and the diatom melting point is 1200 degrees. Maintained in a complete state, and then sorted by a cyclone air classifier (third-stage cyclone head), the sintered clay and coarse-grained crystal minerals are sorted out, and the diatom is collected by the second stage with its special structure, third The grade is that the powder layer is recovered as a filler, and the enriched diatom is obtained and then modified into a water treatment agent.

(5) Comparison of the process of treating sewage with diatom concentrate and other processes

At present, there are two main types of methods for treating sewage at home and abroad: physical chemistry and biochemical methods.

1. The physical chemical method adopts a simple process flow of grid->sand->flocculation->precipitation->water. The advantages are small investment, small land occupation, energy saving, simple equipment, and good removal of heavy metals, phosphorus and chromaticity. But the disadvantage is that the removal of organic matter and nitrogen is not ideal. It is uneconomical to use it alone at low concentrations. In particular, the addition of various types of flocculants does not completely separate and remove the concentrated liquid at the bottom of the water, and eventually discharges to cause a more serious second pollution. At present, this method is commonly used in the sewage treatment of various enterprises. Generally, the sewage treatment cannot meet the national discharge standard. Because a large amount of sludge is unable to be treated, the landfill method is generally adopted. Therefore, this type of process is not an ideal process for wastewater treatment.

2, biochemical law

Oxidation ditch, A2/O, AB, ICEAS, and SBR processes are the mainstream. The advantage is that the process is relatively mature, and the removal of organic pollutants in the sewage and nutrients such as nitrogen and phosphorus have certain effects. However, the disadvantages are low CODcr removal rate, poor decolorization effect, large investment, large land occupation, high power consumption, complicated equipment and strict management requirements. In addition, the process has a big disadvantage, that is, a large amount of sludge is difficult to handle, and it is still prone to secondary pollution. For this reason, this type of process is not suitable for China's national conditions, and is not an ideal process for sewage treatment.

3. Comparison of diatomaceous soil treatment agent treatment wastewater and traditional methods

Take the project scale of 10000m ³ /d as an example

To thoroughly control sewage, we must seek practical new technologies and processes. At present, the traditional process of treating sewage at home and abroad cannot completely remove the sludge and water, and it is not possible to re-form the sludge into usable products. In addition, the serious shortcomings of various processes have made the sewage treatment work a difficult problem. To thoroughly control sewage, we must seek practical new technologies and processes. The process of treating wastewater by diatom soil treatment agent not only has the comprehensive advantages of various conventional processes, but also makes up for the deficiencies of various treatment processes, and has the special advantages that the conventional process can not completely remove and reuse the sediment. The process not only has small investment, low power consumption, low cost, small land occupation, good processing quality, high removal rate, all pollutants can be taken away and reused, and has strong applicability, simple equipment, convenient operation and continuous processing. It can be used as sewage treatment for all kinds of large, medium and small cities. It is an internationally advanced sewage treatment process that is superior to traditional domestic and foreign processes. The ideal process for treating sewage should be that the treated effluent has good water quality, low investment, low power consumption, small land occupation, low running cost, sludge can be completely separated and taken out, and can be processed into other products. The process proposed in the feasibility report is the ideal process that all the sewage treatment can't do now and only the process can do it. This is the advantage of this program.

4, process advantages

1. The investment cost is low. Compared with the traditional process, the process has a small footprint and a short process flow. Therefore, the total investment of the project above 10000T/d is only 50-65% of other processes.

2. The operating cost is saved. The bulk of the actual operating expenses is the pharmacy fee. The dosage is about 5 to 7 per 100,000, and the unit price of the water treatment agent is 2,100 yuan / ton (including freight), so each treatment of 1 cubic meter of sewage medicament The fee does not exceed 0.15 yuan, plus electricity and labor. The operating cost per 1 cubic meter of sewage is less than 0.40 yuan, and the operating cost is only 30-45% of other processes.

3. The total phosphorus removal rate of total phosphorus is high, and the removal of heavy metals has obvious effects. Due to the special role of the diatomite soil treatment process, there is a relatively high removal rate of total phosphorus, total nitrogen and heavy metals in the sewage.以本工艺在昆明明通河城市污水工业性试验为例，由云南省环境保护科研所参加，经省环境监测中心站测试，TN 33.51 mg/L 到7.12 mg/L,去除率78.7%，TP 8.58 mg/L 到0.79 mg/L 去除率91.8%。

4、治污与补水相结合,本工艺对悬浮物SS等指标特别明显，处理后的清水达到国家《城镇污水处理污染物排放标准》,水体清澈透明,完全可以满足补给水的要求。采用硅藻精土水处理工艺，治污与补水一次解决，一举两得可节省许多投资。

5、废渣处理简单且用途多样不会造成二次污染。硅藻精土水处理的废渣收集简单，废渣可以从排渣口直接装袋，也可以经机械脱水后运出厂外，不需要添加药剂处理。硅藻土本身具有质轻、隔热、保温特性、是无毒天然物质，故废渣可以制造保温砖、轻质建材，也可以做农田肥料，如果量大，还可以重新提取硅藻，生产硅藻精土水处理剂，循环使用。

6、管理费用低。由于该工艺简单，处理设施小，工艺流程短，因此操作管理方便，管理费用低

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