The Qinhuangdao Northern Wastewater Treatment Plant has a capacity of 2×25000m³/d. The project adopts the process of "BioDopp biochemical treatment + efficient precipitation + fiber rotary filter tank". Disinfection is carried out with the ultraviolet disinfection process, and deodorization is applied throughout the process. The effluent meets the requirement for class 1A in GB18918-2002 Pollutant Discharge Standard of Municipal Wastewater Treatment Plants.