UV–Vis LED-assisted photo-Fenton process for mineralization of losartan and hydrochlorothiazide: optimization using desirability function

Environmental Science and Pollution Research - This study presents the results obtained for the optimization of the mineralization of losartan (LOS) and hydrochlorothiazide (HCTZ) using the...     

Development of Artificial Neural Network Based Metamodels for Inactivation of Anthrax Spores in Ventilated Spaces Using Computational Fluid Dynamics

ABSTRACT

Linear, quadratic, and artificial neural network (ANN)-based metamodels were developed for predicting the extent of anthrax spore inactivation by chlorine dioxide in a ventilated three-dimensional space over time from computational fluid dynamics model (CFD) simulation data. Dimensionless groups were developed to define the design space of the problem scenario. The Hammersley sequence sampling (HSS) method was used to determine the sampling points for the numerical experiments within the design space. A CFD model, comprised of multiple submodels, was applied to conduct the numerical experiments. Large eddy simulation (LES) with the Smagorinsky subgrid-scale model was applied to compute the airflow. Anthrax spores were modeled as a dispersed solid phase using the Lagrangian treatment. The disinfectant transport was calculated by solving a mass transport equation. Kinetic decay constants were included for spontaneous decay of the disinfectant and for the reaction of the disinfectant with the surfaces of the three-dimensional space. To enhance the mixing of the disinfectant with the room air, a momentum source was included in the simulation. An inactivation rate equation accounted for the reaction between the spores and the disinfectant. The ANN-based metamodels were most successful in predicting the number of viable bioaerosols remaining in an arbitrary enclosed space. Sensitivity analysis showed that the mass fraction of the disinfectant, inactivation rate constant, and contact time had the most influence on the inactivation of the spores.

IMPLICATIONS This investigation presents a framework for the development of user-friendly models; metamodels for the prediction of the number of viable spores remaining in an indoor room during disinfection from accurate but time-consuming CFD studies. During any decontamination event, to know when to stop pumping in the disinfectant and to know what level of log reduction of the spores have been achieved before even starting decontamination would provide valuable guidance. The neural network based metamodels can be applied to obtain quick and relatively accurate answers. This would be necessary when immediate information is required during emergencies.     

Microfluidic quantification of multiple enteric and opportunistic bacterial pathogens in roof-harvested rainwater tank samples

Potable and non-potable uses of roof-harvested rainwater (RHRW) are increasing due to water shortages. To protect human health risks, it is important to identify and quantify disease-causing pathogens in RHRW so that appropriate treatment options can be implemented. We used a microfluidic quantitative PCR (MFQPCR) system for the quantitative detection of a wide array of fecal indicator bacteria (FIB) and pathogens in RHRW tank samples along with culturable FIB and conventional qPCR analysis of selected pathogens. Among the nine pathogenic bacteria and their associated genes tested with the MFQPCR, 4.86 and 2.77% samples were positive for Legionella pneumophila and Shigella spp., respectively. The remaining seven pathogens were absent. MFQPCR and conventional qPCR results showed good agreement. Therefore, direct pathogen quantification by MFQPCR systems may be advantageous for circumstances where a thorough microbial analysis is required to assess the public health risks from multiple pathogens that occur simultaneously in the target water source.     

Rüstungsaltlasten

In the investigation of arsenic warfare agents in ammunitions scrap, a differentiation of inorganic and organic arsenic compounds is necessary. This study describes a method that allows this differential determination. By GC/MS CLARK I, some stabilizers and several phenylarsenic compounds could be identified in chemical warfare pellets.     

PAK- und Schwermetall-Aufnahme in Getreide Wechselseitige Beeinflussung

Die wechselseitige Beeinflussung der PAK- und Schwermetall-Aufnahme (Cu, Zn, Cd, Pb) durch Weizen und Gerste von einer durch Munitionsrückst?nde belasteten Nutzfl?che wird beschrieben. Die nachgewiesenen PAK in der Pflanze k?nnten auf Membranver?nderungen der Wurzeln durch Schwermetalle zurückzuführen sein.     

Detektoren zur Kartierung des Redox-chemischen Gewässermilieus

For the time being, simple and reliable methods which permit the imaging of the complex topography of contaminant plumes in groundwater are missing. The conventional methods for the punctual determination of contaminant concentrations cannot fulfill this demand. To successfully implement and utilize. Natural Attenuation, these deficits have to be overwhelmed. The detectors described in the following represent only part of the probing device system the authors have developed; it shall enable their user to image different aspects of plume topography and its time dependent change by monitoring within the undisturbed groundwater aquifer in groundwater measuring levels:

? relative freights of contaminants and trace contaminants by passive samplers [4] and

? redox milieu parameters by detectors.

The detectors offer multi-purpose, tape-like probing devices of unlimited length. They are charged with a defined reserve of reactive substances. During monitoring actions, the derector tape hangs vertically stretched by a weight preferably covering from the top to the bottom of the whole water column. During the reaction period, the detector may be relaunched for repeated visual inspection. The colour changes of the detectors enable the identification of a row of parameters in the vertically (depth-) oriented profile by unbroken optical/visually perceivable imaging:

? Position of Redox potential thresholds for Mn-IV-Mn-II, Fe-III-Fe-II, Sulfate-Sulfide

? Position of ochre precipitation and iron-sulfide precipitation horizons

? Relative freights of the sum of substances effecting reduction (period until defined oxidant reserve has been reduced)

? Relative freights of the sum of substances effecting iron-sulfide oxidation (period until defined reductant reserve has been reduced)

? Position of dissolved iron-II ions containing horizons

? Position of dissolved hydrogen-sulfide ions/hydrogen-sulfide containing horizons

? Relative freights of iron-II ions (period until defined oxidant reserve has been reduced)

? Relative freights of hydrogen-sulfide ions/hydrogen-sulfide (period until defined oxidant reserve has been reduced). Furthermore, the detectors are also suitable for the examination of waters even of great depth, as for example artificial or natural lakes, sea and ocean basins.

     

Computational fluid dynamics analysis of the effects of reactor configuration on disinfection efficiency.

The efficacy of disinfection processes in water purification systems is governed by several key factors, including reactor hydraulics, disinfectant chemistry, and microbial inactivation kinetics. The objective of this work was to develop a computational fluid dynamics (CFD) model to predict velocity fields, mass transport, chlorine decay, and microbial inactivation in a continuous flow reactor. The CFD model was also used to evaluate disinfection efficiency in alternative reactor designs. The CFD reactor analysis demonstrates that disinfection efficiency is affected by both kinetics and mixing state (i.e., degree of micromixing or segregation). Residence time distributions (RTDs) derived from tracer analysis do not describe intrinsic mixing conditions. The CFD-based disinfection models account for reactor mixing patterns by resolution of the reactor velocity field and thus provide a better prediction of microbial inactivation than models that use an RTD.     

Combined effects of copper and food on the midge Chironomus riparius in whole-sediment bioassays

Effects observed in whole-sediment bioassays must be seen as the joint effect of all sediment characteristics. In whole-sediment bioassays, however, adverse effects on test organisms are usually attributed to the presence of contaminants and effects of food are often ignored. The aim of this study was to analyze the response of the midge Chironomus riparius to sediment spiked with different combinations of food and copper. The responses of C. riparius to these spiked sediments were assessed in 10-day whole-sediment bioassays. Decreases in survival, dry weight, and length of C. riparius were observed with increasing copper concentrations. However, an increase in the amount of food resulted in an increase of larval dry weight and length until copper concentrations reached a critical threshold of 200 mg/kg. In addition, an increase in the amount of food resulted in a decrease of accumulated copper in the larvae. The present study demonstrated that the combination of copper and food in the sediment determines the performance of C. riparius in whole-sediment bioassays. The dependency of C. riparius on high feeding levels, which mask toxic effects, questions its suitability as a test organism for whole-sediment bioassays. Because benthic communities in polluted ecosystems are often exposed to varying levels of both food and toxicants it is concluded that the trophic state of the ecosystem may alter the ecological risk of sediment-bound toxicants to opportunistic benthic invertebrates such as C. riparius.     

Municipal landfills exhale newly formed organotins

For the first time we are able to report the identification and quantification of several unexpected alkylated tin compounds such as dimethyldiethyltin, trimethylethyltin and propyltrimethyltin in European municipal waste deposits, by using GC-ICP-MS. Future studies will reveal whether their origin is from the degradation of butyl-, or octyltin compounds or simply products of de novo synthesis within the landfill environment.