Removal of highly polar micropollutants from wastewater by powdered activated carbon

Due to concerns about ecotoxicological effects of pharmaceuticals and other micropollutants released from wastewater treatment plants, activated carbon adsorption is one of the few processes to effectively reduce the concentrations of micropollutants in wastewater. Although aimed mainly at apolar compounds, polar compounds are also simultaneously removed to a certain extent, which has rarely been studied before. In this study, adsorption isotherm and batch kinetic data were collected with two powdered activated carbons (PACs) to assess the removal of the polar pharmaceuticals 5-fluorouracil (5-Fu) and cytarabine (CytR) from ultrapure water and wastewater treatment plant effluent. At pH 7.8, single-solute adsorption isotherm data for the weak acid 5-Fu and the weak base CytR showed that their adsorption capacities were about 1 order of magnitude lower than those of the less polar endocrine disrupting chemicals bisphenol A (BPA) and 17-α-ethinylestradiol (EE2). To remove 90% of the adsorbate from a single-solute solution 14, 18, 70, and 87mg L−1 of HOK Super is required for EE2, BPA, CytR, and 5-Fu, respectively. Effects of solution pH, ionic strength, temperature, and effluent organic matter (EfOM) on 5-Fu and CytR adsorption were evaluated for one PAC. Among the studied factors, the presence of EfOM had the highest effect, due to a strong competition on 5-Fu and CytR adsorption. Adsorption isotherm and kinetic data and their modeling with a homogeneous surface diffusion model showed that removal percentage in the presence of EfOM was independent on the initial concentration of the ionizable compounds 5-Fu and CytR. These results are similar to neutral organic compounds in the presence of natural organic matter. Overall, results showed that PAC doses sufficient to remove >90% of apolar adsorbates were able to remove no more than 50% of the polar adsorbates 5-Fu and CytR and that the contact time is a critical paramete

Методические указания к выполнению лабораторной работы "Моделирование автономного инвертора напряжения" по дисциплине "Методы расчета и моделирования преобразователей"

Настоящими методическими указаниями рекомендуется пользоваться при выполнении лабораторных работ по дисциплине "Методы расчета и моделирования преобразователей" на виртуальном лабораторном стенде (ВЛС), представляющем собой персональный компьютер (PC) с инсталлированным на нем пакетом программ MatLab/Simulink/SimPowerSystems

Einfluss von biogenen Wasserinhaltsstoffen auf die Eliminierung von 17alpha-Ethinylestradiol, Bisphenol A und Ciprofloxacin durch Adsorption an Pulveraktivkohle

The demand for potable water increases worldwide while fresh water resources are continuously decreasing. Therefore, procedures and processes for preserving water resources by removing or preventing water pollution become ever more important. Besides pathogens, organic trace pollutants cause major concerns in waste water reclamation schemes like managed aquifer recharge or direct production of potable water. Conventional waste water treatment plants (WWTP) show insufficient removal for micro-pollutants which show adverse effects on the environment in trace concentrations. In this study the removal of micro-pollutants by adsorption to powdered activated carbon and retention by nanofiltration (PAC/NF) was investigated. Therefore two substances, Bisphenol A and ethinyestradiol, were spiked to WWTP effluent which was treated by a PAC/NF pilot plant. The substances were chosen as indicators for moderately non polar and non polar micro-pollutants. With powdered activated carbon dosages of 100 mg/l or 350 mg/l, respectively, 99.9% of Bisphenol A and 99.8% ethinyestradiol were retained by the pilot plant. With respect to the highest concentrations detected in the environment to date, these removal rates lead to concentrations that do not show effects on the environment. These removal rates were primarily achieved by adsorption to powdered carbon. To investigate the adsorption of micro-pollutants from WWTP effluent, further experiments were performed to evaluate the adsorption kinetics and isotherms of ethinyestradiol, Bisphenol A, and additionally of Ciprofloxacin as a charged and polar micro-pollutant. All of them showed slower adsorption kinetics in WWTP effluent compared to adsorption in 5 mM phosphate buffer. Adsorptive capacity was also reduced by the presence of the WWTP effluent. Depending on the physical-chemical proprieties of the adsorbate, different mechanisms lead to reduced adsorptive capacities. Therefore no correlation between polarity and adsorptive capacity was found in WWTP effluent in contrast to adsorption in 5 mM phosphate buffer. Further investigation showed effects of biogenic WWTP effluent compounds like humic substances, proteins or carbohydrates on the adsorption of micropollutants in WWTP effluent. For the WWTP effluent of this study, humic acids and proteins as well as their subunits were identified as major compounds. Substitutes for carbohydrates, humic substances and proteins were selected to evaluate their influence on the adsorption of ethinyestradiol, Bisphenol A, and Ciprofloxacin to powdered activated carbon. Results showed that the influence depends on the physical-chemical properties of the adsorptive. In the presence of the substitutes, the non polar ethinyestradiol displayed a reduction of the adsorptive capacity, while the moderately non polar Bisphenol A as well as the polar and charged Ciprofloxacin showed enhanced adsorption. The results indicate that polar and ionic interactions could be responsible for this influence on the adsorption processes. The conducted experiments lead to the assumption that hydrophobic interactions play an important role in the removal of micro-pollutants from WWTP effluent

Ethik, Recht und Kommunikation als Grundlagen professionellen Verhaltens in der Medizin. Ein Beitrag zur theoretisch und praktisch begründeten integrierten Vermittlung im Medizinstudium

Many of the pharmaceuticals and personal care products occurring in municipal sewage are ionizing substances, and their partitioning behaviour is affected by ionic interactions with solid matrices. In activated sludge systems, such interactions have currently not been adequately understood and described, particularly for zwitterionic chemicals. Here we present an assessment of the effects of pH and iron salt dosing on the sorption of ciprofloxacin onto activated sludge using laboratory experiments and full-scale fate modelling. Experimental results were described with Freundlich isotherms and showed that non-linear sorption occurred under all the conditions tested. The greatest sorption potential was measured at pH = 7.4, at which ciprofloxacin is speciated mostly as zwitterion. Iron salt dosing increased sorption under aerobic and, to a lesser extent, anoxic conditions, whereas no effect was registered under anaerobic conditions. The activated sludge model for xenobiotics (ASM-X) was extended with Freundlich-based sorption kinetics and used to predict the fate of ciprofloxacin in a wastewater treatment plant (WWTP). Scenario simulations, using experimental Freundlich parameters, were used to identify whether the assessed factors caused a significant increase of aqueous ciprofloxacin concentration in full-scale bioreactors. Simulation results suggest that a pH increase, rather than a reduction in iron salt dosing, could be responsible for a systematic deterioration of sorption of ciprofloxacin in the WWTP