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Demulsifier
Demulsifier: sometimes also known as destabilizing agent, it is mainly used for pretreatment of oily waste water containing emulsified oil before air flotation. Its variety includes some flocculants and coagulants.
In the flotation process, in order to improve the dispersion and flotation effect of pesticides (such as collectors), emulsifiers are first needed to emulsify the medicament. Some ore dressing agents are easy to emulsify, while the emulsified foam in the pulp will affect the subsequent process, resulting in the loss of concentrate overflow or the pollution of tailings wastewater to rivers. Therefore, demulsifier should be added to deal with the above situation.
When using demulsifier, the pH value of emulsion should be adjusted first. For strong alkali and strong acid emulsion, the pH value should be adjusted to the range of 1-10. In addition to physical demulsification methods (such as heating method, membrane separation method, electric field demulsification method), demulsifiers are also commonly used for chemical treatment in the wastewater treatment of oil-bearing emulsion in petroleum, chemical industry, wool spinning and mechanical processing industries. The commonly used demulsifier is a highly dispersive mixture composed of many components. The demulsifiers of water in oil emulsion are usually inorganic substances with cations such as H +, Al3 +, Fe3 +, etc., such as inorganic acid, ferric sulfate, etc.; while the demulsifiers of water in oil emulsion are generally anionic and non-ionic surfactants or mixtures of them.
Because some solids are difficult to dissolve in water, when one or several of them exist in large quantities in the aqueous solution, they can exist in the water in the form of emulsion under the agitation of hydraulic or external power. Theoretically, this system is unstable, but if there are some surfactants (soil particles, etc.), it makes the emulsification state very serious, and even two phases are difficult to separate. The most typical is the oil-water mixture in the oil-water separation and the water-oil mixture in the sewage treatment. In this two phases, a relatively stable oil-water or oil-in-water structure is formed, which is the theoretical basis The foundation is "double electric layer structure".
In this case, some chemicals are used to destroy the stable double electric layer structure and stabilize the emulsion system, so as to achieve the purpose of two-phase separation. Demulsifiers are used to destroy emulsification.
What are the advantages of 01 demulsifier?
1. The oil-water separation is fast and can be realized in 2 minutes. 2. No metal ions, avoid secondary pollution. 3. The flocculate is greatly reduced, and the subsequent sludge treatment capacity is reduced. 4. Low temperature can be used normally. 02 application scope of Demulsifier
It can effectively break the oil in water emulsion and shorten the time of oil-water separation. It is miscible with water and effective in a wide pH range. It is widely used in oil field wastewater treatment, such as olefin plant, oil refinery, steel plant and power plant.
Defoamer
Defoamer: mainly used to eliminate a large number of bubbles during aeration or stirring. Efficacy: 1. Low surface tension, high activity, strong defoaming power. 2. No change in heat and high temperature, low volatility. 3. Good chemical stability, chemical inertness, no reaction with other substances, and can be used under harsh conditions. 4. It has no physiological toxicity and has no effect on the use system. 5. It has the effect of eliminating and inhibiting foam, and the time of inhibiting foam can be more than 48 hours. What are the types of defoamers?
The effect of defoamer is related to the type of foaming solution, that is to say, some defoamers have significant effect on some foaming solutions, but have no effect on other foaming solutions. The commonly used defoamers can be divided into silicon (resin), surfactant, alkane and mineral oil according to their composition. (1) Silicon (resin): silicone defoamer is also called emulsion defoamer. The method of use is to emulsify and disperse silicone resin with emulsifier (surfactant) in water and then add it to wastewater. Silica powder is another kind of defoamer with good defoaming effect. (2) surfactants: such defoamer is actually an emulsifier, that is, the dispersing effect of surfactants, so that the foam forming material can be dispersed in the stable emulsion state, so as to avoid foaming. (3) Alkanes: Alkanes defoamer is a defoamer made by emulsifying and dispersing alkanes wax or its derivatives with emulsifier. Its application is similar to emulsified defoamer of surfactants. (4) Mineral oil: mineral oil is the main defoaming component. In order to improve the effect, sometimes mixed with metal soap, silicone oil, silica and other substances. In addition, in order to make mineral oil easily diffuse to the surface of foaming solution, or to make metal soap evenly disperse in mineral oil, various surfactants can be added sometimes. 02 application scope of defoamer
Water treatment process design, fast defoaming speed, long-lasting foam suppression, applied to pharmaceutical, paper, leather, printing and dyeing, biological treatment process of urban sewage, chemical cleaning and other foaming systems. This product uses the environmental protection formula, the product is non-toxic and harmless, does not affect the bacterial reproduction. It can also be used for defoaming of oil drilling fluid mud system.
PH regulator
PH regulator: used to adjust the pH value of acid wastewater and alkaline wastewater to neutral.
01 common pH regulator
When the pH value of acid containing wastewater is raised, alkali or alkaline oxide is used as neutralizer, while when the pH value of alkaline wastewater is lowered, acid or acid oxide is used as neutralizer. The neutralizing agents often used to adjust the pH value of acid wastewater are lime, limestone, dolomite, sodium hydroxide, sodium carbonate, etc. sulfuric acid and hydrochloric acid are generally used to adjust the pH value of alkaline wastewater. When neutralizing acid containing wastewater, some alkaline industrial wastes can also be used nearby, such as calcium carbonate waste discharged from chemical soft water station, calcium carbide waste discharged from organic chemical plant or acetylene generation station (main component is calcium hydroxide), stone ash screened from steel plant or calcium carbide plant, furnace ash from thermal power plant and boron mud from boric acid plant. In the treatment of alkaline wastewater, flue gas can also be used to neutralize the alkali in the wastewater by using the acid gases such as CO2 and SO2. When the pH value of wastewater is too large or too small, 40% NaOH and 98% H2SO4 can be used as pH value regulators for acid wastewater and alkali wastewater respectively in order to reduce the volume of solution tank and reagent tank required for pH value adjustment and realize the automatic control of pH value adjustment. At the same time, it can avoid the sludge problem caused by the use of lime alkali agent and reduce the chance of secondary pollution.
Redox agent
Redox agent: used for the treatment of industrial wastewater containing oxidizing or reducing substances. Two substances with different redox potentials can be used as oxidants or reducers relatively. However, the oxidants or reducers that can be used in wastewater treatment practice must meet the following requirements: ① have a good redox effect on the pollutants to be removed from wastewater; ② the substances generated after reaction shall be harmless to avoid secondary pollution; ③ the price is cheap and the source is reliable , ④ it can react rapidly at room temperature without heating, ⑤ the pH value needed for reaction is best neutral, not too high or too low. Common oxidants in water treatment
① After receiving electrons, it will be reduced to neutral atoms with negative charge ions, such as O2, Cl2, O3, etc.; ② after receiving electrons, it will be reduced to ions with negative charge, such as Cl + in hypochlorite ClO - in bleaching powder, sodium hypochlorite, etc., and Cl 4 + in chlorine dioxide will be reduced to CL by electrons- ③ the atoms with high valence positive charge are reduced to the atoms with low valence positive charge after receiving the electron, for example, Fe3 + in ferric chloride and mn7 + in potassium permanganate are reduced to Fe2 + and Mn2 + after receiving the electron. 02 common reducing agent in water treatment
① After the electron is given, it is oxidized to neutral atom with positive charge, such as iron filings, zinc powder, etc.; ② after the electron is given, the atom with negative charge is oxidized to atom with positive charge, such as boron element in sodium borohydride with negative 5 valence, which can reduce mercury ion to metal mercury under alkaline condition, and at the same time, it is oxidized to positive 3 valence; ③ the atom with positive charge of metal or non-metal After the electron is given, it is oxidized to an atom with a higher positive charge. For example, ferrous ion Fe2 + in ferrous sulfate and ferrous chloride is oxidized to ferric ion Fe3 + after one electron is given; sulfur dioxide SO2 and tetravalent sulfur in sulfite SO32 - are oxidized to hexavalent sulfur after two electrons are given to form SO42 -.
Disinfectant
Disinfectant: used for disinfection treatment after wastewater treatment and before discharge or reuse.
01 selection of disinfectants
After primary or secondary treatment, the water quality is improved, and the bacterial content is greatly reduced, but its absolute value is still considerable, and there is the possibility of pathogenic bacteria. Therefore, the wastewater should be disinfected before being discharged into the water body. At present, chlorination can produce harmful substances and affect human health, which is widely known because chlorine and organics in water have the function of oxidation and substitution. Oxidation can promote the removal of organics, while substitution is the combination of chlorine and organics, forming halides with mutagenic or carcinogenic activity. The maximum concentration of THMs is 100 μ g / L in the United States, 25 μ g / L, 350 μ g / L and 100 μ g / L in Germany, Canada and Japan, respectively, and the upper limit of chloroform is 60 μ g / L in China's 1985 version of sanitary standard for drinking water. In view of this, the first is to control the appropriate dosage, and the second is to use other disinfectants, such as chlorine dioxide, ozone, ultraviolet radiation, to reduce the generation of harmful substances. See table 8-2 for the advantages, disadvantages and application conditions of various disinfectants. With reference to this table, the disinfectants that should be used can be preliminarily determined.
02 types and characteristics of disinfectants
Common disinfectants include hypochlorite, chlorine dioxide, ozone, ultraviolet radiation, etc. Hypochlorite disinfectants are liquid chlorine, bleaching powder, bleaching powder concentrate, chlorine tablets, sodium hypochlorite and other forms, mainly through the HOCl disinfection. The weakness of hypochlorite disinfectant is that it is easy to generate chlorinated hydrocarbon with the organic matter in the water, and the chlorinated hydrocarbon has been confirmed to be extremely harmful to human health. At the same time, the treated water will have some unpleasant smell. Hypochlorous acid disinfectant dust and chlorine released have strong irritating effects on human respiratory tract, eyes and skin. If it is accidentally splashed into eyes or touched skin, wash it with plenty of water immediately. The storage environment shall be cool, ventilated and dry, away from heat source and kindling, and shall not be stored and transported together with organic matters, acids and reducing agents. During transportation, rain and sunlight exposure shall be prevented, and the loading and unloading shall be conducted with light actions to avoid collision and rolling. When hypochlorite disinfectant is used for disinfection, substitution reaction often occurs, which is also the fundamental reason why hypochlorite disinfectant can produce chlorinated hydrocarbon, while ozone and chlorine dioxide disinfection occur pure oxidation reaction, which can destroy the structure of organic matter, improve the biodegradability of wastewater (BOD5 / CODcr value) and remove part of CODCr in water. Compared with ozone or ultraviolet disinfection, chlorine dioxide disinfection has lower one-time investment and higher operation cost (about 0.1 yuan / m3); while the latter has higher one-time investment and lower operation cost (about 0.02 yuan / m3). Ozone disinfection and ultraviolet disinfection can achieve the disinfection effect in a very short time. The total number of bacteria and total coliform bacteria in the effluent or reuse water of the secondary sedimentation tank after ozone disinfection and ultraviolet disinfection can meet the requirements, but their disadvantages are instantaneous reaction,