
Wastewater treatment plants serving apartment complexes, buildings, and residential areas sometimes experience effluent COD levels approaching regulatory limits, particularly following sudden load surges or shortly before scheduled compliance sampling. QCVN 14:2025/BTNMT, applicable to domestic wastewater from September 1, 2025, sets COD limits based on discharge volume and the receiving water body, while allowing dischargers to choose between TOC and COD parameters




