Sources of persistent and mobile chemicals in municipal wastewater: a sewer perspective in Leipzig, Germany.

Persistent and mobile (PM) chemicals spread in the water cycle and have been widely detected, yet information about their sources is still scarce. In this study, 67 PM chemicals were analyzed in 19 wastewater samples taken in the sewer system of the city of Leipzig, Germany, covering different industrial, clinical, and domestic discharges. A total of 37 of these analytes could be detected, with highly variable median concentrations between substances (median: 0.5-800 µg L-1) and for single substances between samples (e.g., 1,4-diazabicyclo[2.2.2]octane) by up to three orders of magnitude, with the highest single concentration exceeding 10 mg L-1 (p-cumenesulfonic acid). The emission of PM chemicals into the sewer system was classified as stemming from diffuse (14 analytes) or point sources (23 analytes), while 9 analytes fulfill both criteria. Many so-called industrial chemicals were also discharged from households (e.g., tris(2-chloroethyl) phosphate or 1H-benzotriazole). Examples for analytes showing specific sources are tetrafluoroborate (traffic-related industry and metal production and finishing), ε-caprolactam (large-scale laundry), or cyanuric acid (likely swimming pool). Furthermore, a correlation between 1-cyanoguanidine and guanylurea was observed for the traffic-related industry. This study outlines that sewer sampling can provide valuable information on the sources of PM chemicals. This knowledge is a prerequisite for their future emission control at source or substitution as an alternative to end-of-pipe treatment in municipal wastewater treatment plants.

Performance and mechanisms of PropS-SH/Ce(dbp)3 coatings in the inhibition of pyrite oxidationtion for acid mine drainage control.

Inhibition of tailings oxidation could availably control the generation of acid mine wastewater from its source. Organosilanes serving as a high-efficiency inhibitor of the oxidation of pyrite, bring some problems including safety hazards caused by large amounts of organic solvents, difficult high-temperature curing, poor long-term properties, and so on. In our work, the PropS-SH/Ce (dbp)3 (PS/Ce (dbp)3) passivator with excellent passivation performance and self-healing properties was prepared by choosing 3-mercaptopropyltrimethoxysilane (PropS-SH) and dibutyl phosphate (Ce (dbp)3) as the main passivating agent and the repair agent, respectively. We reduced the ratio of ethanol to water by adjusting the pH of the organosilane condensation and also achieved room-temperature curing by extending the curing time. Electrochemical and chemical leaching experiments results showed that the most appropriate addition of Ce (dbp)3 was 0.2 wt% for enhancing the passivation performance of the passivated coating. In a 6-month chemical leaching experiment, the PS/Ce (dbp)3-0.2 passivation coating cured at room temperature showed a better passivation effect and maintained 90.55% and 78.54% of total Fe and SO42- passivation efficiencies. The passivation and self-healing mechanisms were investigated by FT-IR, XPS, 29Si NMR, and other characterization methods, which were as follows: silane formed a cross-linked mesh structure by Si-O-Si bonding, in which Ce (dbp)3 was physically filled. And the Si-OH on the surface of the passivation film formed Fe-O-Si bonds with the hydroxyl groups on the surface of the pyrite, thus attaching to the surface of the pyrite and isolating the oxidation medium. When the passivation coating was locally damaged, the oxidation reaction caused a change in pH, which accelerated the dissolution of Ce (dbp)3 in the passivation layer. Ce3+ underwent a valence change and formed a CeO2 precipitate, while dbp- could form a complex with Fe2+ on the pyrite surface, both of which worked together to repair the broken passivation coating and prevent the oxidation reaction.

Involvement of phosphoesterases in tributyl phosphate degradation in Sphingobium sp. strain RSMS.

A tri- and dibutyl phosphate (TBP/DBP) non-degrading spontaneous mutant, Sphingobium SS22, was derived from the Sphingobium sp. strain RSMS (wild type). Unlike the wild type strain, Sphingobium SS22 could not grow in a minimal medium supplemented with TBP or DBP as the sole source of carbon or phosphorous. Sphingobium SS22 also did not form any of the intermediates or end products of TBP or DBP degradation, namely DBP, butanol or inorganic phosphate. Proteomic analysis revealed the absence of three prominent proteins in Sphingobium SS22 as compared to wild type. These proteins were identified by MALDI mass spectrometry, and they showed similarities to phosphohydrolase- and exopolyphosphatase-like proteins from other bacteria, which belong to the class of phosphoesterases. Cellular proteins of Sphingobium SS22 showed none or negligible phosphodiesterase (PDE) and phosphomonoesterase (PME) activities at pH 7 and displayed approximately five- and approximately twofold less DBP and monobutyl phosphate (MBP) degradation activity, respectively, in comparison to the wild type strain. In-gel zymographic analysis revealed two PDE and PME activity bands in the wild type strain, one of which was absent in the Sphingobium SS22 mutant. The corresponding proteins from the wild type strain could degrade DBP and MBP. The results demonstrate the involvement of phosphoesterase enzymes in the TBP degradation pathway elucidated earlier.