title: Current state of sewage treatment in China.
abstract: The study reported and analyzed the current state of wastewater treatment plants (WWTPs) in urban China from the aspects of scale, treatment processes, sludge handling, geographical distribution, and discharge standards. By 2012, there were 3340 WWTPs in operation in China with a capacity of 1.42 × 10(8) m(3)/d. The number of medium-scale WWTPs (1-10 × 10(4) m(3)/d) counted for 75% of total WWTPs. On average, the chemical oxygen demand (COD) removal efficiencies of small-scale, medium-scale, large-scale and super-large-scale WWTPs were 81, 85.5, 87.5 and 86.5%, respectively. Generally speaking, the nutrients removal instead of COD removal was of concern. As to the different processes, oxidation ditch, anaerobic-anoxic-oxic (A(2)/O) and sequencing batch reactor (SBR) were the mainstream technologies in China. These technologies had minor difference in terms of overall COD removal efficiency. The sludge treatment in WWTPs was basically "thickening-coagulation-mechanical dehydration" and the major disposal method was sanitary landfill in China. The distributions of WWTPs and their utilization showed significant regional characteristics. The sewage treatment capacity of China concentrated on the coastal areas and middle reaches of Yangtze River, which were the economically developed zones. Besides, most WWTPs enforced the Class 1 or Class 2 discharge standards, but few realized wastewater reuse. Finally, existing problems were discussed, including low removal efficiency of nitrogen and phosphorus, emerging contaminants, low reuse of reclaimed water, poor sludge treatment and disposal, low execution standard of effluent, and emissions of greenhouse gas from WWTPs. Suggestions regarding potential technical and administrative measures were given.
authors.affiliation: School of Environment & Resource, Renmin University of China, 59 Zhongguancun Street, Haidian District, Beijing 100872, China.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Jin
authors.affiliation: School of Environment & Resource, Renmin University of China, 59 Zhongguancun Street, Haidian District, Beijing 100872, China. Electronic address: zgm@ruc.edu.cn.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhang
authors.affiliation: School of Environment & Resource, Renmin University of China, 59 Zhongguancun Street, Haidian District, Beijing 100872, China.
authors.forename: Huifang
authors.initials: H
authors.lastname: Tian
mesh_terms: D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D012722:Sewage
keywords: Existing problems; Future development; Geographical distribution; Scale; Treatment process; Wastewater treatment plants