Removal mechanisms and kinetics of trace tetracycline by two types of activated sludge treating freshwater sewage and saline sewage

Understanding the removal mechanisms and kinetics of trace tetracycline by activated sludge is critical to both evaluation of tetracycline elimination in sewage treatment plants and risk assessment/management of tetracycline released to soil environment due to the application of biosolids as fertilizer. Adsorption is found to be the primary removal mechanism while biodegradation, volatilization, and hydrolysis can be ignored in this study. Adsorption kinetics was well described by pseudo-second-order model. Faster adsorption rate (k(2) = 2.04 × 10(−2) g min(−1) μg(−1)) and greater adsorption capacity (q(e) = 38.8 μg g(−1)) were found in activated sludge treating freshwater sewage. Different adsorption rate and adsorption capacity resulted from chemical properties of sewage matrix rather than activated sludge surface characteristics. The decrease of tetracycline adsorption in saline sewage was mainly due to Mg(2+) which significantly reduced adsorption distribution coefficient (K(d)) from 12,990 ± 260 to 4,690 ± 180 L kg(−1). Species-specific adsorption distribution coefficients followed the order of [Formula: see text]. Contribution of zwitterionic tetracycline to the overall adsorption was >90 % in the actual pH range in aeration tank. Adsorption of tetracycline in a wide range of temperature (10 to 35 °C) followed the Freundlich adsorption isotherm well. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11356-012-1213-5) contains supplementary material, which is available to authorized users

Interest Rate Pegging, Fluctuations, and Fiscal Policy in China

This paper proves in a New Keynesian model that interest rate pegging can explain the unusual business cycle fluctuations in China. It is traditional wisdom that when the nominal interest rate is inflexible, there is no unique equilibrium in macroeconomic models. We prove that a unique equilibrium exists if the nominal rate is pegged for a limited period, after which it switches to a flexible rate regime. The peg alters the propagation of external shocks, magnifies volatility of endogenous variables, and leads to instability of the economy. Besides, the model becomes more unstable when the peg duration extends, and when the pegged rate deviates from steady state. At the same time, fiscal multiplier increases under the peg, indicating fiscal policy may be more effective in mitigating economic fluctuations when monetary policy is restricted by interest rate pegging

Detectable MeV neutrinos from black hole neutrino-dominated accretion flows

Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes (BHs) have been theorized as the central engine of relativistic jets launched in massive star core collapse events or compact star mergers. In this work, we calculate the electron neutrino/anti-neutrino spectra of NDAFs by fully taking into account the general relativistic effects, and investigate the effects of viewing angle, BH spin, and mass accretion rate on the results. We show that even though a typical NDAF has a neutrino luminosity lower than that of a typical supernova (SN), it can reach $10^{50}-10^{51}~{\rm erg~s^{-1}}$ peaking at $\sim 10$ MeV, making them potentially detectable with the upcoming sensitive MeV neutrino detectors if they are close enough to Earth. Based on the observed GRB event rate in the local universe and requiring that at least 3 neutrinos are detected to claim a detection, we estimate a detection rate up to $\sim$ (0.10-0.25) per century for GRB-related NDAFs by the Hyper-Kamiokande (Hyper-K) detector if one neglects neutrino oscillation. If one assumes that all Type Ib/c SNe have an engine-driven NDAF, the Hyper-K detection rate would be $\sim$ (1-3) per century. By considering neutrino oscillations, the detection rate may decrease by a factor of 2-3. Detecting one such event would establish the observational evidence of NDAFs in the universe.Comment: 7 pages, 2 figures, 2 tables, accepted for publication in PR