Location-dependent occurrence and distribution of metal-based nanoparticles in bay environments.

Metal-based nanoparticles (MNPs) are increasingly being released into the marine environment, posing potential environmental risks. However, factors governing the environmental occurrence and distribution of MNPs in bays still lack a comprehensive understanding. Herein, we collected seawater and sediment samples from two adjacent bays (Daya Bay and Honghai Bay, which have similar water qualities), and determined the particle concentrations and sizes of multi-element MNPs (Ti-, Cu-, Zn-, Ag-, Mn-, Pb- and Cr-based NPs) via single particle inductively coupled plasma-mass spectrometry (spICP-MS). The internal circulation in Daya Bay has resulted in an even distribution of MNPs' particle concentrations and sizes in both seawater and sediments, while the terrestrial discharge in Honghai Bay has led to a gradient-decreasing trend in MNPs' concentrations from nearshore to offshore. Moreover, the relatively high abundance of MNPs in Honghai Bay has contributed to 2.35-fold higher environmental risks than Daya Bay. Overall, this study has provided solid evidence on the critical but overlooked factors that have shaped the occurrence and distribution of MNPs, providing new insights for risk management and emission regulation.

A novel SAD process: Match of anammox and denitrification.

Anammox biotechnology has been widely applied for its attractive advantages, but its application has been seriously limited due to the instinctive drawback of nitrate production. In this work, a novel Sequential Anammox and Denitrification (SAD) system was developed for the advanced nitrogen removal by using solid carbon source (SCS) and coupling anammox with denitrification. The long-term operation results demonstrated that the SAD system could remove the total nitrogen (TN) efficiently, with the effluent TN concentration of 1.4 ± 0.5 mg N/L, the TN removal efficiency (NRE) of 99.3 ± 0.2%, and the TN removal rate (NRR) of 1.7 ± 0.1 kg/(m3·d). The determination results showed that SCS had a good property for sustained release of COD, with a dissolved organic yield (by COD) of 1.1 g-COD/g-rice. When the addition rate was set at 6 g-rice/7-days, the COD release rate of 0.9 kg-COD/(m3·d) from SCS matched the nitrate production rate of 1.2 × 10-1 kg-N/(m3·d) from anammox with consumption ratio of 7.5. The analysis on the microbial community revealed that Candidatus_Brocadia and Denitratisoma were the dominant functional bacteria for anammox and denitrification, which contributed to about 92.7% and 6.6% of the total nitrogen removal, respectively. This work is helpful for the innovation and application of anammox-based technology.