Municipal wastewater is industrial wastewater and runoff sewage within the urban area. In general, it is collected by the city pipe and is treated by the city sewage treatment plant. In addition to containing a large number of organic matter, bacteria and viruses in urban sewage, the amount of industrial wastewater (about 60 ~ 80% of the total amount of urban sewage) water quality is becoming more and more complex and the pollution of runoff sewage is becoming more and more serious due to the high development of industry. The treatment of municipal sewage involves many aspects. It is necessary to make comprehensive planning for the sewer system, the location and treatment technology of sewage treatment plants, and the utilization and discharge requirements of sewage after treatment.
Municipal sewage is generally collected into sewage treatment plants for treatment, and can be specifically divided into primary treatment, secondary treatment, and tertiary treatment.
Primary processing is also known as primary processing. The object of treatment is the floating and suspended objects in sewage. We can use the sieve interception method -- screen mesh, grid filtration, gravity separation method — sand settling tank, sedimentation tank, grease trap, air floating tank, centrifuge, cyclone separator, centrifuge, etc.
Secondary treatment refers to the removal of pollutants in sewage to meet the requirements. The key point should be according to different sewage treatment degree, scale, water quality characteristics to determine the treatment process, such as activated sludge and biofilm method.
Tertiary treatment, also known as depth treatment, can make up for the lack of secondary treatment, and use chemical and physical chemical and biological methods, such as neutralization,artificial wetl method, etc.
Two typical processes
● Treatment process 1: grid - anaerobic - aerobic - sedimentation tank -UV sterilization - discharge
●Treatment process 2: grid - biochemical treatment - constructed wetland - collection tank - sodium hypochlorite disinfection - discharge
River treatment and black and smelly water treatment:
Ecological river management refers to the construction of a healthy, complete and stable watercourse aquatic system through artificial restoration measures within the control line of the watercourse on the basis of meeting the basic functions of the watercourse such as flood control, drainage and water diversion
The main reason for the black and smelly water body is the excess of organic matter in the water, which leads to the decrease of dissolved oxygen in the water and the formation of anaerobic environment. The organisms in the water cannot breathe enough oxygen and die, resulting in the abnormal development of water components. This method lies in the micro-generation.The functions of activation, induction and purification of substances gradually improve the dissolved oxygen in water, promote metabolism, and recover through water treatment.
