The main sources of urban sewage are domestic wastewater, such as washing dishes, washing clothes, taking a bath, and some of it comes from kitchen wastewater, restaurant water, and toilet flushing water. The other part comes from more rainwater, which accounts for a large proportion of rainwater. Of course, for sewage treatment plants, rainwater is relatively easy to deal with.
More than 90 percent of urban pollution is water, the rest is solid material. In addition to containing high organic matter, as well as nitrogen, phosphorus, inorganic matter, but also contains pathogenic microorganisms and more suspended matter and heavy metals.Urban sewage is generally characterized by high nitrogen and phosphorus content.
The main characteristic of municipal sewage is good biodegradability, so it is better to adopt biochemical treatment method. In the process of treatment, the key lies in the regulation tank, oxidation tank and sedimentation tank. The main function of the regulating tank is to make the water quality even, adjust the amount of water, so that the sewage evenly into the subsequent treatment unit. The oxidation tank reduces the content of organic pollutants and nitrogen and phosphorus in sewage. The function of the sedimentation tank is to accelerate the separation of mud and water. Polyacrylamide (PAM) is mainly used in flocculation and sedimentation of municipal sewage treatment and sludge dewatering. General municipal sewage treatment uses cationic polyacrylamide (CPAM). Cationic polyacrylamide (CPAM) has a variety of active groups, and many substances affinity, adsorption form hydrogen bond. Mainly flocculated negatively charged colloidal sewage, and with turbidity removal, decolorization, adsorption, adhesion and other functions, suitable for dyeing, paper, food, construction, metallurgy, mineral processing, coal powder, oil fields, aquatic products processing and fermentation industries organic colloidal content of higher wastewater treatment, especially suitable for urban sewage, urban sludge, paper sludge and other industrial sludge dehydration treatment.
