The occurrence of 21 selected pharmaceutically active compounds (PhACs) in river water was examined; meanwhile the presence and removal of these PhACs at different water treatment steps in two conventional drinking water treatment plants (DWTPs) were evaluated. Monitoring results showed that of all 21 target PhACs, twelve PhACs were ubiquitously detected in water samples from the Yangtze river and its two tributaries (Jialing River and Huaxi stream), whereas alodipine was not found in any river water sample. The concentrations of PhACs detected in Huaxi stream were statistically significantly higher than those found in the Jialing River and the Yangzi River because of the direct discharges of uncontrolled domestic sewage and poultry wastewater and the abuse of PhACs in the rural areas served by the Huaxi stream. An environmental risk assessment of PhACs based on the risk quotient value approach indicated that sulfamethoxazole, ofloxacin and dehydrated erythromycin and clofibric acid had a medium risk, and the mixture of the studied PhACs showed high risk for the aquatic ecosystems. Fourteen out of 21 target PhACs were found in the raw water of the two studied DWTPs with azithromycin having the highest concentration (about 20 ng/L). Following the conventional water treatment processes, the studied PhACs were found to be removed by an average of 54 and 48% in DWTP A and DWTP B, respectively. Among the target PhACs, six and three PhACs were detected in finished water of DWTP B and DWTP A, respectively. This is the first study in southwestern China reporting the presence of PhACs in surface water and drinking water.

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Utilization-associated products (UAPs) and biomass-associated products (BAPs) were quantified separately in this study to characterize soluble microbial products (SMPs) in a drinking water lab-scale biological aerated filter (BAF), and their basic characteristics were explored using gel filtration chromatography and three-dimensional excitation-emission matrix (3D-EEM) spectrophotometry with fluorescence regional integration analysis and parallel factor model. UAPs were observed increased with the increase of filter media depth and accumulated after BAF treatment, whereas BAPs were basically constant. 3D-EEM spectroscopy analysis result showed that tryptophan and protein-like compounds were the main components of UAPs and BAPs, and fulvic-acid-like substance was a major component of BAPs, rather than UAPs. In terms of molecular weight (MW) distribution, UAP MW presented a bimodal distribution in the range of 1-5 and >10 kDa, while BAP MW exhibited unimodal distribution with MW >20 kDa fraction accounting for more than 90 %. The macromolecules of UAPs accumulated after BAF treatment. This study provides theoretical support for in-depth study of SMP characteristics.

The relationship between soluble microbial products (SMPs) and extracellular polymeric substances is described, and the characteristics of SMPs in the biological wastewater treatment process, including molecular weight distribution, metal-chelating property, biodegradability, biotoxicity, and membrane fouling, are investigated. The SMPs produced by autotrophs are degradable and utilizable for heterotrophs, thereby confirming the biodegradation of SMPs. Soluble microbial product models are designed through three approaches: establishment of SMP kinetic models or combination with Monod equations, incorporation of SMP generation and degradation into the unified theory raised by Laspidou and Rittmann (2002a), and introduction of the concept of SMP into activated sludge models. The effects of process parameters on SMP concentration are elaborated, based on the optimum biological treatment process operating parameters that can effectively minimize SMP production. The progress of SMP research in water biotreatment systems is presented, and suggestions for future studies are made.