The sewage treatment system is divided into primary, secondary and tertiary, of which the primary is pre-treatment, mainly to remove large particle suspended solids and some organics in the sewage. The second level is biological treatment, which decomposes various complex organic substances in sewage into simple inorganic substances through microbial metabolism; At the same time, the function of aerobic microorganisms in activated sludge is used to convert nh3-n in sewage into small molecule organic nitrogen compounds such as no-2-n, o-3-n, etc. The third level is advanced treatment, which further degrades or converts the refractory substances into harmless substances.
1、 Process characteristics of sewage treatment system:
1. Nature of sewage:
The composition of domestic sewage is very complex (such as containing a large amount of codcr), and the concentration of pollutants is high (such as codcr above 1000 mgl), which is characterized by poor biodegradability;
2. Influent water quality and quantity vary greatly:
Due to the high concentration of pollutants in domestic sewage, it is required that the incoming water quality and quantity change little;
3. Short hydraulic retention time:
Due to the variety and high concentration of pollutants contained in domestic sewage (generally between 1000~2000mgl), the hydraulic retention time is required to be short;
4. The biodegradability of pollutants is poor.
5. The effluent quality standard is strict.
2、 Problems and countermeasures of urban drainage system:
The main problems in urban sewage system include:
1. The concentration of urban population leads to the increase of water consumption per capita;
2. Due to the economic development, the amount of wastewater generated increases;
3. Increase in wastewater production due to industrial development;
4. The acceleration of urbanization has led to an increase in municipal construction and so on.
Put forward corresponding countermeasures against the above problems:
1. Strengthen water management.
2. Improve the reuse rate of industrial wastewater.
3. Increase investment in municipal projects.
4. Strengthen the transformation of existing sewage treatment plants.
Post time: Nov-15-2022