The Xi'an No. 4 Wastewater Treatment Plant is currently undergoing a remodeling project. The main components of the project include the remodeling of the existing fine and ultra-fine grids and bioreactor tanks, and the construction of a new bioreactor tank, five high-efficiency sedimentation tanks, two V-shaped filter tanks, and a final settling tank, among other facilities. Upon completion of the renovation, the WWTP will be able to provide wastewater treatment services to the old city and northern suburb areas within the first ring road of Xi'an, improving water quality within a 90-square-kilometer area. After the upgrading, the effluent from the plant will meet the surface quasi Class IV standard, effectively improving the water quality of the Cao Yun Ming Nullah area and the Weihe River Basin, improving the surrounding air quality, and creating a fresh, healthy and livable environment. In addition, the implementation of the project will have a positive effect on improving the urban investment environment and realizing sustainable economic and social development. Therefore, it can be determined that the fourth sewage treatment plant in Xi'an is undergoing reconstruction works.