The occurrence of man-made antibiotics in natural environment has aroused attentions from both scientists and publics. However, few studies tracked antibiotics from their production site to the end of disposal environment. Taking the coastal region of Hangzhou Bay as the study area, the fate of 77 antibiotics from 6 categories in two-step wastewater treatment plants (WTPs, i.e. pharmaceutical WTP and integrated WTP) was focused; and the antibiotics in both dissolved and adsorbed phases were investigated simultaneously in this study. The ubiquitous occurrence of antibiotics was observed in the two-step WTPs, with antibiotic concentrations following the order of PWTP (LOQ - 1.0 × 105 ng·L−1) > IWTPi (for industrial wastewater treatment, LOQ - 3.7 × 103 ng·L−1) > IWTPd (for domestic sewage treatment, LOQ - 1.3 × 103 ng·L−1). And the types of antibiotics detected in excess sludge and suspended particles were in accordance with those in wastewater. Quinolones were invariably dominant in both dissolved and adsorbed fractions. High removal efficiencies (median values >50.0%) were acquired for the dissolved quinolones (except for DFX), tetracyclines, β-lactams, and lincosamides. Anaerobic/anoxic/oxic achieved the highest aqueous removal of antibiotics among the investigated treatment technologies in the three WTPs. PWTP and IWTP removed 9797 and 487 g·d−1 of antibiotics, respectively; and a final effluent with 126.4 g·d−1 of antibiotics was discharged into the effluent-receiving area (ERA) of Hangzhou Bay. Source apportionment analysis demonstrated that the effluents of IWTPd and IWTPd contributed respectively 39.3% and 8.9% to the total antibiotics in the ERA. The results illustrate quantitatively the antibiotic flows from engineered wastewater systems to natural water environment, on the basis of which the improvements of wastewater treatment technologies and discharge management would be put forward.
When using spectral methods, a consistent method for tuning the expansion order is often required, especially for time-dependent problems in which oscillations emerge in the solution. In this paper, we propose a frequency-dependent p-adaptive technique that adaptively adjusts the expansion order based on a frequency indicator. Using this p-adaptive technique, combined with recently proposed scaling and moving techniques, we are able to devise an adaptive spectral method in unbounded domains that can capture and handle diffusion, advection, and oscillations. As an application, we use this adaptive spectral method to numerically solve Schrödinger’s equation in an unbounded domain and successfully capture the solution’s oscillatory behavior at infinity.
To distinctively identify two objects at the deep-subwavelength scales requires sharp superfocusing to overcome the diffraction limit. However, conventional superfocusing effect and information-carrying capacity are limited by the focal length and single focusing field (only electric or magnetic field), which are hard to be apparently improved. Here, we introduce the concept of “dual-foci superfocusing”, an advanced focusing form that can provide either one or two focusing spots, simultaneously converging both electric and magnetic fields and presenting an effect of electromagnetostatic space-division multiplexing. The physical mechanism of the dual-foci superfocusing is analyzed and synthesized by an original theory of shaping functional fields using hybrid-magnitude evanescent modes. Through a terahertz plasmonic array, the dual-foci superfocusing is numerically demonstrated, whose metric (ratio of focal length to focusing-spot size) is sufficiently improved from traditional 1–1.8 up to 2.8. The proposed methodology could be exploited as a platform to investigate the novel concurrent characteristics of superfocusing and might represent an important step toward the development of beam manipulation and sophisticated holography.