Elimination of polar micropollutants and anthropogenic markers by wastewater treatment in Beijing, China

Abstract

Anthropogenic contamination of surface waters in Asia is on the increase. While polar organic contaminants are gradually recognized for their impacts on aquatic ecosystems in the Western World, less is known about the situation in Asia. In developing countries like China, water resources are particularly vulnerable. We investigated the occurrence, elimination, and per capita loads of a wide range of pharmaceuticals, household chemicals and pesticides in five Beijing WWTPs representative for megacities in China, and compare the efficiency of different treatment processes. Based on initial screening for 268 micropollutants using high-resolution mass spectrometry, 33 compounds were examined in detail. Pollutant concentrations in raw wastewater ranged from <0.02μgL−1 for pesticides to >20μgL−1 for caffeine and the contrast agent iopromide. Concentrations in the WWTP effluents were generally <1μgL−1, except for some pharmaceuticals, iopromide (1.2–18μgL−1), caffeine (0.025–2.3μgL−1), and the artificial sweetener sucralose (2.7–3.5μgL−1). Elimination efficiencies varied greatly from <1% to close to 100%, with macrolides, some sulfonamides, metronidazole, iopromide, and 4-acetamidoantipyrine being the most persistent compounds. Total per capita loads of the investigated micropollutants were lower than in communal wastewater of Europe, amounting to 7.9–12.2 and 2.0–6.5gd−11000 inhabitants−1 in the influents and effluents, respectively, with an average release of ∼100kgd−1 by the 11.4 million people and 2.3millionm3 of wastewater treated per day. Since the wastewater effluents are often used for agricultural irrigation, residual organic pollutants pose a threat to food safety, the development of antibacterial resistance, and combined effects of micropollutants in the aquatic environment.