Municipal Sewage Treatment

The municipal wastewater originates primarily from domestic water use (such as kitchen and bathroom wastewater, laundry wastewater). High organic matter content, abundant nitrogen and phosphorus nutrients, and high suspended solids characterize it.

Key pollutants(CODcr, BOD5),suspended solids (SS), nitrogen pollutants(ammonia nitrogen, total nitrogen), phosphorus pollutants(total phosphorus), as well as trace amounts of oils and fats and anionic surfactants(e.g., detergent residues).

Typical pollutant concentration range:

CODcr: ≤300mg/L
SS: ≤350mg/L
NH3-N: ≤35mg/L
TP: 10mg/L
TN: 50mg/L
Animal and vegetable oils: ≤20mg/L

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Treatment process flow of Municipal Sewage Treatment

Wastewater
Pretreatment (screen + grit chamber)
Aeration tank (biological degradation, aeration and oxygen supply)
Secondary sedimentation tank (sludge separation, supernatant disinfection and discharge, sludge treatment)
Reuse/discharge of qualified water

Efflunt Standards: The sewage discharge shall comply with Grade A of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002).

Activated sludge process for wastewater treatment

Pre-treatment: The sewage first passes through a screen and a grit chamber to remove large suspended solids and sand particles, achieving initial purification.

Biological treatment (aeration tank): The sewage enters the aeration tank and mixes with activated sludge (containing microbial flocs).

Settling and separation (secondary sedimentation tank): The mixed liquid enters the sedimentation tank, where the activated sludge (containing microorganisms) settles and separates.

Sludge treatment: The remaining sludge undergoes concentration, dewatering, and other processes to reduce its volume and is ultimately disposed of harmlessly (such as through landfill, incineration, or resource utilization).

Core advantages: By combining microbial metabolism (biodegradation) with physical separation (sedimentation), it efficiently removes organic pollutants, is suitable for urban sewage purification, and can be extended to improved processes such as A/O and oxidation ditches, flexibly meeting the demands of nitrogen and phosphorus removal.