Algae removal route
1 air floatation
The air floatation method removes algae from the dissolved gas system to supply dissolved water, and the algae in the water adhere to the water through the bubbles in the water to float on the surface of the pool and scrape off with a scraper. Air floatation algae removal is a physical separation of algae from the water, which is very suitable for algae removal. The algae removal effect is good, and it will not cause adverse effects, and the sensory index will also be greatly improved. The air floatation process needs to increase the return pressure water and dissolved gas system, and the investment and operating costs have increased, and the operation and management difficulty has also increased. The air-floating process has a good algae removal effect, but it is not thorough. If the algae is more than 100 million, it must be combined with other processes to ensure the quality of the effluent.
2 chemical killing algae
Chemical algicide is a disinfectant that kills algae in the water and is removed by subsequent precipitation and filtration processes. The method is simple and easy to operate. However, if a disinfectant such as liquid lv is added in a large amount, it will produce a tri-material, and the algal toxin also has a risk of exceeding the standard. Ozone pre-oxidation has a good auxiliary effect on algae removal. In the water plant using ozone-activated carbon advanced treatment process, pre-ozone is used instead of the raw liquid lv to remove algae. Ozone kills algae through the lytic algae cells. The algal toxins released after the destruction of the algae can also be partially decomposed and removed by ozone. At the same time, ozone has a certain effect on removing the odor caused by algae secretions.
Organic removal route
1 pretreatment
The pretreatment process is generally used as an auxiliary measure for other processes. In the first stage, substances with higher standards and higher indexes are reduced or changed in nature, which facilitates the removal of subsequent processes.
The pretreatment technology is mainly biological pretreatment and strong oxidation treatment technology.
Application of biological pretreatment technology
Biological pretreatment is the removal of ammonia nitrogen and some organic matter by biological action. The biological pretreatment technology of micro-polluted water sources has been researched and applied at home and abroad for more than 30 years, and has been widely recognized by people. As a pretreatment of micro-polluted water source, the main advantages of biological treatment are: significant effect on removal of NH3-N, NO2-N and AOC, and certain removal effects on organic matter, chroma, odor, TOC and turbidity. The disadvantage is that the land occupation is large, and the treatment effect has a great influence on the water quality and water temperature of the water source.
Application of pre-oxidation technology
Mainly use pre-chlorination, pre-ozone technology, permanganate pre-oxidation technology and chlorine dioxide pre-oxidation technology.
Prechlorination
Pre-chlorination has been widely used in China for algae removal and degradation of organic matter, and the cost is low. However, the disinfection by-products of chlorine and organic matter generated in water are very harmful to the human body, and should be gradually eliminated as a pretreatment in micro-polluted water sources. .
Pre-ozone
Pre-ozone technology is mainly used to eliminate iron and manganese in groundwater, remove color and smell, and degrade high molecular organic matter in water. It is also used to improve flocculation and clarification. In the application of pre-ozone engineering, the main purpose is to assist coagulation. If necessary, consider strengthening the removal of algae, color and organic pollutants. The ozone dosage is generally 0.2-2.0 mg/L.
Studies have shown that the effect of pre-ozone control disinfection by-products is also relatively stable. In the case of pre-ozone dosage of about 1.0 mg / L (0.23 mg O3 / mg DOC), the removal rate of trihalomethane precursor is about 23%, high. The algae removal rate was as high as 47% during the algae period. In the process of ozone pre-oxidation treatment, ozone does not reduce the organic matter content in the water to control the precursor of the disinfection by-product, but mainly oxidizes the hydrophobic organic matter with the larger mass of the attacking molecule. Most of these organic substances have an aromatic structure or an unsaturated double bond, which is easily attacked and has a small break and is converted into a hydrophilic substance. Ozone pretreatment achieves the purpose of controlling the amount of disinfection by-products by changing the physicochemical properties of organic matter in water and reducing the chlorination activity of organic matter in water. However, it should be noted that when the raw water contains a relatively high concentration of bromide ions or when the ozone is excessively added, the ozone pre-oxidation converts the bromide ions into bromate ions, and the concentration of brominated trihalomethane, bromoacetic acid, etc. in the water is increased. high.
The pre-ozone process occupies less land, and the process effect is not affected by factors such as season and temperature, and the effect is stable. However, ozone needs to be prepared on site and the operating cost is high.
Permanganate pre-oxidation
Potassium permanganate is a strong oxidant, which can selectively interact with organic pollutants in water and destroy the unsaturated functional groups of organic matter. It was used to remove odor and color in water in the 1960s with good effects. In recent years, a permanganate composite agent has been developed, which has significant oxidative coagulation, algae removal, odor removal, and removal of trace organic pollutant equivalent energy to surface water, and can also reduce trihalomethane formation potential. The intermediate state and new ecological components produced by the permanganate complex during the oxidation process can enhance the removal of trace organic pollutants in water. In addition, the new ecological manganese dioxide has a certain adsorption effect on various trace organic and inorganic pollutants in water, which can improve the removal effect of various organic pollutants and heavy metals in water.
Chlorine dioxide pre-oxidation
The application of chlorine dioxide pre-oxidation is still relatively rare, but the pre-oxidation of chlorine dioxide has a better removal effect on aromatic hydrocarbon compounds, which can control the formation of trihalomethanes (THMs) and reduce the formation of total organic halogens. Colored materials have a good decolorizing effect. Pre-oxidation with chlorine dioxide results in less organic by-products and less toxic effects. The inorganic by-products mainly include chlorite and chlorate. Studies have reported that the adverse effects of chlorite and chlorate are mainly due to its strong oxidative properties and toxic effects on the human nervous system. Long-term drinking can lead to anemia. At present, research in this area needs further study.
Chlorine dioxide also requires on-site preparation, and depending on the preparation method, the reaction conditions need to be strictly controlled to prevent explosion. When chlorine dioxide is used for pre-oxidation to remove organic matter, iron and manganese, the dosage is 1 to 1.5 mg/L, and the specific dosage needs to be determined according to the water quality. The concentration must be controlled below the explosion-proof concentration, and safety explosion-proof measures must be set. Inert materials should be used in contact with chlorine dioxide; separate rooms should be provided for each agent, and measures should be taken to remove and contain residual or leaking agents.
Through the above comparison, it can be seen that the purpose of the pre-ozone process and the biological pretreatment process are different: pre-ozone mainly degrades organic matter and removes chromaticity and smell by strong oxidative property; and biological pretreatment is through biological action. Removal of ammonia nitrogen and some organic matter. In addition, the project is located at the mouth of the Yellow River, with low temperature in winter, using biological pretreatment methods, the effect of treating organic matter is poor, occupying a large area, and it is necessary to heat the pool body at a high cost. If it is not kept warm, the biological reaction tank is difficult to discharge mud, which affects the operation. After considering the implementation of increased pollution control, the quality of raw water will be improved. This project will not consider biological pretreatment for the time being. The pre-chlorination method will undoubtedly generate a large amount of chlorination disinfection by-products, which will bring harm to drinking water safety. Permanganate and ozone pre-oxidation are relatively economical and have a good removal effect on heavy metals, which can be considered together with the subsequent advanced treatment process.
Fruits And Vegetables,Fresh Fruits And Vegetables,Fresh Fruit And Veggies,Fresh Vegetables
Xi'an Gawen Biotechnology Co., Ltd , https://www.seoagolyn.com