6 months. According to information from the Yongji Municipal People's Government portal website, a 100m3/d domestic sewage treatment station was built in Yongji Prison in Shanxi Province, and the construction period is 6 months. Yongji was called Puban in ancient times, also known as Zhiyi. Yongji straddled the Pujin Pass and was an important road between the Qin and Jin Dynasties. It was the political, economic, cultural and military center of the ancient Hedong region.