Take the dyeing and printing wastewater:
Dye production wastewater contains acids, alkalis, salts, halogens, hydrocarbons, amines, nitro and dyes and their intermediates and other substances, and some also contain pyridine, cyanide, phenol, benzidine, and heavy metals such as mercury, cadmium, chromium. These wastewater components are complex. It is toxic and difficult to treat. Therefore, the treatment of dyestuff production wastewater. According to the characteristics of the wastewater and its discharge requirements. Selection of appropriate treatment methods. For example: the removal of solid impurities and inorganic substances, coagulation and filtration can be used; removal of organic and toxic substances mainly using chemical oxidation, biological methods and reverse osmosis, etc.; decolorization can generally be used in the coagulation and adsorption method composed of the process, the removal of heavy metals can be used in the ion-exchange method and so on.
Take food wastewater:
The food industry has a wide range of raw materials, a wide range of products, discharged wastewater water, water quality varies greatly. The main pollutants in the wastewater are (1) floating in the wastewater solids, such as leaves, peels, minced meat, poultry feathers, etc.; (2) suspended in the wastewater in the material oil, protein, starch, colloidal substances, etc.; (3) dissolved in the wastewater in the acids, alkalis, salts, sugars, etc.: (4) raw materials entrained in the mud and sand, and other organic matter, etc.; (5) disease-causing bacterial toxins, etc.. Food industry wastewater is characterized by high content of organic matter and suspended solids, easy to rot, generally no major toxicity. Its harm is mainly to make the water body eutrophication, so as to cause the death of aquatic animals and fish, prompting the deposition of organic matter under the water to produce odor, deterioration of water quality, pollution of the environment. Food industry wastewater treatment in addition to appropriate pretreatment according to the characteristics of water quality, generally appropriate to use biological treatment. If the water quality requirements are very high or because of the high content of organic matter in the wastewater, two-stage aeration pool or two-stage biofilter, or multi-stage biological carousel. Or the joint use of two biological treatment devices, can also be used anaerobic - aerobic tandem biological treatment system.