Domestic wastewater is mainly a variety of detergents and sewage, garbage, feces, etc. used in urban life, mostly non-toxic inorganic salts, Domestic wastewater contains more nitrogen, phosphorus, sulfur, and disease-causing bacteria.
Features
Domestic sewage contains a large amount of organic matter, such as cellulose, starch, sugar and fat protein; also often contains pathogenic bacteria, viruses and parasite eggs; inorganic salts of chloride, sulfate, phosphate, bicarbonate and sodium, potassium, calcium, magnesium, etc.. The general characteristics of nitrogen, sulfur and phosphorus containing high, under the action of anaerobic bacteria, easy to produce malodorous substances.
Solution
◆ Physical treatment method：
The wastewater treatment method that separates and recovers pollutants in suspension (including oil film and oil beads) that are not dissolved in wastewater by physical action can be divided into gravity separation method, centrifugal separation method and sieve filtration and retention method. The treatment method based on the principle of heat exchange also belongs to the physical treatment method.
◆ Chemical treatment method：
The wastewater treatment method that separates and removes pollutants in dissolved or colloidal state in wastewater or converts them into harmless substances by chemical reaction and mass transfer. In the chemical treatment method, the treatment units based on chemical reaction by adding chemicals are: coagulation, neutralization, redox, etc.; while the treatment units based on mass transfer are: extraction, vapor extraction, blowing off, adsorption, ion exchange, as well as electrodialysis and reverse osmosis. The latter two processing units are also collectively known as membrane separation technology. Among them, the treatment unit using mass transfer has both chemical and physical effects associated with it, so it can also be separated from the chemical treatment method and become another category of treatment methods, called physical chemical method.
◆ Biological treatment method：
Through the metabolic action of microorganisms, organic pollutants in solution, colloid and microfine suspension in wastewater are transformed into stable and harmless substances. The biological treatment method can be divided into two types: aerobic biological treatment and anaerobic biological treatment, depending on the microorganism in action. wastewater biological treatment uses the aerobic biological treatment method, and by tradition, the aerobic biological treatment method is divided into two types: activated sludge method and biofilm method. The activated sludge method is a treatment unit in itself, and it has a variety of operation methods. Treatment equipment belonging to the biofilm method include biofilter, bio-rotary, biological contact oxidation pond and biofluidized bed. The bio-oxidation pond method is also known as the natural biological treatment method. Anaerobic biological treatment, also known as biological reduction treatment, is mainly used to treat high concentration organic wastewater and sludge, and the treatment equipment used is mainly digesters.
◆ Biological contact oxidation method：
The biological contact oxidation method is used to treat wastewater, that is, the biological contact oxidation process is used to fill the biological reaction tank with fillers, and the oxygenated wastewater is submerged in all the fillers and flows through the fillers at a certain flow rate. The biofilm is covered on the filler, and the wastewater comes into contact with the biofilm. Under the action of the metabolism of microorganisms on the biofilm, the organic pollutants in the wastewater are removed and the wastewater is purified. The treated wastewater is discharged into the biological contact oxidation treatment system and mixed with Domestic wastewater for treatment, chlorine disinfection and then discharged to the standard. Biological contact oxidation is a biofilm process between the activated sludge method and biofilter, which is characterized by the installation of filler in the pool, aeration at the bottom of the pool to oxygenate the sewage, and make the sewage in the pool in a flowing state, in order to ensure full contact between the sewage and the filler submerged in the sewage, to avoid uneven contact between the sewage and the filler in the biological contact oxidation pool, this aeration device is called blast aeration.