Wastewater treatment process
The treatment of industrial wastewater can be divided into the following methods at present
1, membrane separation method
In the treatment of industrial wastewater, the application of membrane separation technology can treat various wastewater. Using ultrafiltration membranes to treat oily wastewater can make the oil removal rate reach 97%-100%. Use acid and alkali resistant inorganic membrane to treat alkaline papermaking black liquor, no need to adjust the pH value, use membranes with different pore diameters to recover useful components such as cellulose and lignin, and the treated water can be used to cook pulp and realize closed circuit of papermaking wastewater Circulation: The mud-film mixing process is used to treat tannery wastewater, and the removal rates of CODCr, S2-, and Cr6+ are 86.14%, 88.39% and 54.5%, respectively. In addition, the use of membrane technology can also treat catering wastewater, pharmaceutical and chemical wastewater, dye wastewater, etc.
2. Ion exchange resin method
Ion exchange resin has exchange. The functions of selection, adsorption and catalysis are mainly used in industrial wastewater treatment to recover heavy metals and precious and rare metals, purify toxic substances, and remove acidic or basic organic substances such as phenols, acids and amines in organic wastewater. The application of IER for industrial wastewater treatment can not only regenerate resin, but also has simple operation, mature process conditions and short process. It has been adopted by some large enterprises at present, and its application prospects are very good.
3. Biodegradation method
At present, printing and dyeing and papermaking wastewater are the two main factors causing environmental pollution. The dye industry wastewater has a deep color. Although the degree of reduction in the chromaticity of the dye wastewater treated by physical methods is large, the removal rate of COD is poor, the treatment cost is expensive, and it is easy to cause secondary pollution, while the chemically synthesized organic matter will cause When water is poisoned, the use of biodegradation method can not only overcome the above problems, but also has the following advantages:
① No pretreatment of pollutants is required;
② Anti-inflammation effect on other microorganisms;
③ Pollution of heavy and toxic pollutants
④The degradation product has a broad spectrum.
White rot fungi and P. chrysosporium chrysosporium are two good strains that can degrade the printing and dyeing wastewater containing essential elements.
4, coagulation precipitation method
Coagulation sedimentation method is a method of purifying industrial wastewater using coagulants. Coagulants usually include inorganic polymer flocculants, organic polymer flocculants and biological polymer flocculants. At present, the most widely used in water treatment are the polyaluminum salt and composite polyaluminum salt in inorganic polymer flocculants. Polyaluminum chloride (PAC) and polyaluminum sulfate (PAS) are the two most widely used polyaluminum salts in the industry. Experiments have shown that PAC has a highly effective flocculation effect on the treatment of petrochemical wastewater. The pH value has little effect, and the color of the treated water is good. It can be used as a flocculant for the recovery and treatment of petrochemical sewage. It has a good effect on removing turbidity and COD (chemical oxygen demand) in treating river water (the turbidity is lower than 4mg/L, and the COD is lower than 6 mg/L). The flocculation effect of PAS is much better than that of traditional aluminum sulfate flocculants. It has a wide range of temperature applications and is suitable for the flocculation treatment of drinking water, industrial water and most wastewater. It can be used to treat river water whether it is turbidity or COD removal. The treatment effect. In recent years, in order to improve the flocculation effect of a single polyaluminum salt, people have synthesized new polymer composite aluminum salt flocculants, such as polyaluminum ferric chloride (PAFC), polyaluminum ferric sulfate (PAFS), and polyaluminum ferric sulfate chloride. (PAFCS), polymeric silicon (phosphorus) aluminum (iron), etc. These polymer composite aluminum salt flocculants are widely used to treat drinking water, industrial water, mine wastewater, oily wastewater from oil fields, domestic water, natural Yellow River water, raw water from the Yangtze River, printing and dyeing wastewater, etc.