Preliminary development stage
Since 1949, China's sewage treatment industry has experienced initial development, mainly focusing on the dirty old urban sewage collection pipeline construction, sewage interception, urban black odor River and lake renovation and so on. Famous comprehensive renovation projects include Beijing Longxugou, Tianjin Chilong River and Sitong River, Shanghai zhaojiabin, Nanjing Qinhuai River, Wuhan Huangxiao River, etc. At the same time, China has also built or started to build a number of first-class sewage treatment plants during this period. For example, Beijing Gaobeidian Wastewater Treatment Plant has a daily treatment capacity of 400000 cubic meters.
However, at the same time, the domestic sewage treatment technology still stays in the relatively primary stage, making more use of the self purification of water body or the primary water treatment method, and does not take sewage treatment as an important part of urban development, and has not made great progress in technology, and is still in a relatively backward situation.
Sewage land use transformation stage
Since the 1860s, due to the further development of industry and agriculture, the concept of sewage agricultural irrigation has been developed. At this time, the pollution degree of sewage is relatively low, and many water shortage areas take sewage irrigation as experience to promote, such as the sewage irrigation area in the southeast suburb of Beijing, the sewage irrigation area in wubaoning of Tianjin, etc. In 1980, 1.333 million hectares of farmland were directly irrigated with sewage. It greatly improved the utilization efficiency of agricultural water resources in China, effectively alleviated the problems of water resources shortage and sewage pollution at that time.
In 1957, the Ministry of construction and construction, the Ministry of agriculture and health and other departments put sewage irrigation into the national scientific research plan. In the 1960s, the relevant departments also held the "Asia Africa Latin America International Symposium on sewage irrigation" at Beijing Gaobeidian sewage treatment plant. In view of the risk of sewage irrigation, the national sewage irrigation conference held in Shijiazhuang in 1972 proposed the "positive and prudent" sewage irrigation policy and formulated the temporary water quality standard for sewage irrigation to deal with the risk of sewage irrigation.