Pollution Characteristics and Risk Assessment of Heavy Metals in the Sediments of the Inflow Rivers of Dianchi Lake, China.

To explore the contamination status and identify the source of the heavy metals in the sediments in the major inflow rivers of Dianchi Lake in China, sediment samples were collected and analyzed. Specifically, the distribution, source, water quality, and health risk assessment of the heavy metals were analyzed using correlation analysis (CA), principal component analysis (PCA), the heavy metal contamination factor (Cf), the pollution load index (PLI), and the potential ecological risk index (PERI). Additionally, the chemical fractions were analyzed for mobility characteristics. The results indicate that the average concentration of the heavy metals in the sediment ranked in the descending order of Zn > Cr > Cu > Pb > As > Ni > Cd > Hg, and most of the elements existed in less-mobile forms. The Cfwas in the order of Hg > Zn > Cd > As > Pb > Cr > Ni; the accumulation of Hg, Zn, Cd, and As was obvious. Although the spatial variability of the heavy metal contents was pronounced, the synthetical evaluation index of the PLI and PERI both reached a high pollution level. The PCA and CA results indicate that industrial, transportation, and agricultural emissions were the dominant factors causing heavy metal pollution. These results provide important data for improving water resource management efficiency and heavy metal pollution prevention in Dianchi Lake.

A comprehensive assessment of upgrading technologies of wastewater treatment plants in Taihu Lake Basin.

To meet the increasingly stringent discharge standards of wastewater treatment plants (WWTPs) in the Taihu Lake Basin, the Chinese government successively established the National Special Water Project Program to develop new technologies to retrofit and upgrade existing wastewater treatment processes during the 11th, 12th, and 13th Five-Year Plans. However, there is a lack of systematic sorting of the existing research outcomes, and thus hinders the application and promotion of the upgrade technologies. Based on the outcomes of the National Special Water Project and a field survey, this research analyzed the current status of wastewater treatment in the Taihu Lake Basin and systematically integrated the retrofitting measures of WWTPs in terms of achieving the Grade IA of the national standard and local stricter discharge standards (DB 32/1072-2018 and DB 33/2169-2018). In particular, the boundary conditions, design parameters, specific recommendations of the technologies, and some typical engineering cases were provided accordingly. Finally, this study discussed the future development directions of WWTPs during the upgrade process from the perspective of carbon neutrality and digitalization. The present work will hopefully assist in retrofitting and constructing WWTPs to achieve the stricter effluent discharge criteria and help optimize the design and construction of WWTPs in the best way.