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The impact of tetracycline on simultaneous biological wastewater nitrogen and phosphorus removal and its fundamental mechanisms were investigated in this study. Compared with the control, a lower concentration of tetracycline (0.2 mg L À1 ) did not exert adverse effects on biological nutrient removal; however, the presence of 2 and 5 mg L À1 of tetracycline decreased the total nitrogen removal efficiency from 80.2% to 69.2% and 65.1% respectively, but they showed marginal influence on phosphorus removal. The mechanism studies showed that most of the influent tetracycline was adsorbed by sludge, which induced the release of extracellular polymeric substances (EPS) from a sludge matrix, decreased the protective role of EPS on bacterial cells, declined the viability of sludge, increased the sludge volume index, and caused the detachment of denitrifying bacteria from sludge. Thus, the denitrifiers were more easily contacted with tetracycline. Further investigation revealed that it was the denitrifiers instead of nitrifiers being negatively affected by tetracycline, and the generation of electron donor for denitrification via intracellular polyhydroxyalkanoates (PHA) decomposition was depressed. In addition, tetracycline inhibited the activities of nitrate reductase and nitrite reductase as it was a strong chelating agent which reduced the free copper ions.

Strontium tungstate nanorods with uniform morphology were controllably synthesized for the first time via a facile liquid–solid–solution (LSS) process through oil/water interface. These nanorods have diameters of about 50 nm and length of about 500 nm. XRD curves indicated that as-obtained nanorods were body-centered tetragonal phases with lattice parameters of a = 5.416 Å and c = 11.95 Å, which is consistent with the values reported in JCPDS card No. 08-0490. Study on the optical properties of as-obtained nanorods showed that SrWO 4 nanorods possess different optical properties from bulk counterpart. A mechanism of the formation process was also discussed.

A new idea of the nanorods preparation and a novel application of calixarenes are presented. Calix[4]arene was introduced into solvothermal system to produce one-dimensional inorganic nanomaterial. The obtained product was characterized by XRD and TEM. Results of the XRD analysis showed that the product was pure cubic phase of PbS with high crystallinity. TEM images revealed that the diameter and length of the PbS nanorods were about 200 nm and up to 3.5 µm, respectively. Optical properties of the product were also studied. PL emission image showed that the product exhibited an emission peak at 308 nm in ultraviolet region showing a blue shift of 14 nm compared to the bulk material. The formation mechanism of PbS nanorods in the presence of calix[4]arene is discussed.