Plant description

The Tsinghe WWTP in Beijing was constructed on Dec. 28th, 2000, and is in operation since August 2002. The capacity of the WWTP is 200,000 m3/d.

The main biological process is the reversed AAO process (Anoxic, Anaerobic, and Oxic), a modification of normal AAO process, which exchanges the sequence of anoxic and anaerobic tank.

Commissioned by

Tsinghe WWTP, Beijing Municipal Drainage Co. Ltd., Beijing, P. R. China

Executed by

XU Lijie, SHI Hanchang, DU Xin, etc.
State Key Joint Lab of Environmental Simulation and Pollution Control,
Department of Environmental Science & Engineering, Tsinghua University

Goal

The goal of the study was the analysis and improvement (optimization) of the WWTP performance in order to meet the new discharge criteria in the winter. The new Criterion (GB18918-2002) was the following:

• BOD5 <= 10mg/L
• SS <= 10mg/L
• COD <= 50mg/L
• TN <= 15mg/L
• NH4-N <= 8 mg/L (when the temperature is below 12°C)
• TP <= 1mg/L
  

Results

A recommendation for process optimization was made and the plans were executed. The optimized strategy suggested:

• To reduce the aerobic HRT with 10%
• To decrease the waste discharge to 1800m3/d
• To set the recycle ratio to 70% and the inner recycle ratio to 20%
• To dose FeSO4 (72g/L) with amount of 10.4m3/d when influent phosphorus kept high above 8mg/l.

Based on these recommendations, the effluent could reach the new criteria in the winter.