The basic characteristics of chemical wastewater are:
(1) Water quality has complex components and many by-products. The reaction raw materials are often solvents or cyclic compounds, which increases the difficulty of wastewater treatment.
(2) The high content of pollutants in wastewater is due to the incomplete reaction of raw materials and the large amount of solvent media used in raw materials or production entering the wastewater system;
(3) There are many toxic and harmful substances, and many organic pollutants in fine chemical wastewater are toxic and harmful to microorganisms, such as halogen compounds, nitro compounds, dispersants or surfactants with bactericidal effects.
(4) There are many biodegradable substances, low B/C ratio and poor biodegradability;
(5) High chroma of wastewater.
Common processing technology of 1
(1) The commonly used physical methods are filtration, inclined tube precipitation (linked with products) and air flotation (linked with products). Filtration method uses porous granular layer to intercept impurities in water, mainly to reduce suspended solids in water. In the filtration treatment of chemical wastewater, plate-and-frame filters and microbial filters are generally used, and microporous tubes are made of polyethylene, with adjustable pore size and convenient replacement. Inclined tube precipitation method is a process of solid-liquid separation by using the sedimentation of suspended particles in water and the natural sedimentation under the action of gravity field. Air flotation is a method to bring out suspended particles by generating and adsorbing tiny bubbles. These three physical methods are simple in process and convenient in management, but they are not suitable for removing soluble wastewater components and have great limitations. At the same time, you can check more technical documents of China Sewage Treatment Engineering Network.
(2) Chemical method is to remove organic and inorganic impurities in water through chemical reaction. There are mainly chemical coagulation (connected with the product reaction tank), chemical oxidation, catalytic oxidation and inclined tube precipitation (connected with the product hopper) (connected with the box) and so on. Chemical coagulation (related to product dosage) is mainly aimed at tiny suspended solids and colloidal substances in water. Through the coagulation and flocculation caused by adding chemicals, the colloid is destabilized to form precipitation and removed. Coagulation can not only remove fine suspended particles with the particle size of 10-3~ 10-6mm from wastewater, but also remove chromaticity, microorganisms and organic matter. This method is greatly influenced by the changes of water temperature, PH value, water quality and water quantity, and the removal rate of some organic and inorganic substances with good solubility is low. Chemical oxidation is usually a method to remove organic pollutants from chemical wastewater by oxidation with oxidant. Organic and inorganic toxic substances contained in waste water can be converted into non-toxic or less toxic substances after chemical oxidation and reduction, thus achieving the purpose of purifying waste water. Commonly used methods include air oxidation, chlorine oxidation and ozone oxidation. Air oxidation method is mainly used to treat wastewater containing strong reducing substances because of its weak oxidation ability. Cl2 is a commonly used oxidant, which is mainly used to treat organic wastewater containing phenol and cyanide. Ozone is used to treat wastewater, which has strong oxidation ability and no secondary pollution. Ozone oxidation method and chlorine oxidation method have good water treatment effects, but they have high energy consumption and high cost, and are not suitable for treating chemical wastewater with large water volume and relatively low concentration. Electrochemical oxidation is an electrolytic cell in which the organic pollutants in wastewater are removed by redox reaction on the electrode, and the pollutants in wastewater lose electrons at the anode of the electrolytic cell and are oxidized. In addition, Cl- and OH- in water can also be discharged at the anode to generate Cl2 and oxygen, which indirectly oxidizes and destroys pollutants. In fact, in order to strengthen the oxidation of anode and reduce the internal resistance of electrolyzer, some sodium chloride is often added to wastewater electrolyzer for so-called electrochlorination. After adding NaCl, chlorine and hypochlorite can be generated at the anode, which also has a strong oxidation effect on inorganic and organic substances in water. In recent years, some new electrode materials have been found in electro-oxidation and electro-reduction, and some achievements have been made, but there are still some problems such as high energy consumption, high cost and large side effects.
(3) Biological method (link product biochemistry) (link case) is a process of degrading and transforming organic matter by using the metabolism of microorganisms. With the development of chemical industry, the composition of pollutants is becoming more and more complex, and wastewater contains a lot of organic pollutants. It is difficult to meet the requirements of treatment only by physical or chemical methods. Using the metabolism of microorganisms, the organic pollutants in wastewater can be stabilized and made harmless. Biochemical treatment methods are mainly divided into aerobic treatment and anaerobic treatment, and aerobic treatment methods are mainly divided into activated sludge method and biofilm method. Activated sludge is a method to treat wastewater by using suspended microbial flocs, which is called activated sludge. It is composed of aerobic microorganisms and organic and inorganic substances metabolized and adsorbed by them, and has the ability to degrade organic pollutants in wastewater. Biofilm method is through the contact between wastewater and biofilm, biofilm adsorbs and oxidizes organic matter in wastewater. Anaerobic biological treatment of wastewater refers to the process of decomposing organic matter in wastewater into methane and carbon dioxide under the action of anaerobic microorganisms (or facultative microorganisms) without molecular oxygen, so it is also called anaerobic digestion. Anaerobic biological treatment is actually a complex biochemical process. The research shows that the anaerobic process mainly depends on the joint action of three main groups of bacteria, namely, hydrolytic acid-producing bacteria, hydrogen-producing acetic acid-producing bacteria and methanogenic bacteria.
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