Odour emissions characterization from wastewater treatment plants by different measurement methods

During last decades several techniques were proposed for the measurement of odours in environmental field but until now no one was applied and diffused between worldwide countries. These due to the presence of a large number of variables correlated to fast and continuous variability of odours, their low concentration in environment, the meteorological conditions, the difficulty to sampling a representative volume of air. In Europe the dynamic olfactometry method was standardized in 2003 by EN 13725 and was proposed for the measurement of odour emissions. At same time several Countries have specific guidelines that norm in different way the assessment of odours. The scope of this study is to compare and evaluate the principal odour measurement methods (GC-MS, dynamic olfactometry, and electronic nose), nowadays applied in technical practices and reported in current scientific literature, used to identify and characterize the odour emissions from a wastewater treatment plant, with the aim of analysing the weaknesses and strengths of the different techniques. The study of the correlation between odour concentrations measured by different methods was also presented. The evaluation and analyses of the different odour measurement techniques have been carried out at the ISWA Institute of the Department of Civil Engineering, Stuttgart University. The investigated samples, collected at the different odour sources at wastewater treatment plant (WWTP) LFKW located at Stuttgart University Campus (Northern Germany), are analysed by dynamic olfactometry, electronic nose (eNose) and gas chromatography and mass spectrometry (GC-MS). The results obtained highlight the various data on the odour concentrations between different measurement methods at each sampling source of WWTP. Odour indexes were proposed to compare and evaluate the different sensorial and analytical techniques. Copyrigh

Microstructural investigation of LID sensitive mc-PERC solar cells

Light induced degradation can lead to a severe efficiency loss in multi-crystalline PERC solar cells depending on bulk Si material properties and solar cell processing parameters, known as mc-LID or LeTID. Various defect models have been suggested which indicate a clear distinction to BO- and FeB-LID mechanisms. Cu is known to cause light induced degradation and therefore is one of the possible causes of mc-LID in PERC cells. However, until now, a direct microstructural proof of its presence is still missing. In this contribution, we investigate mc-LID sensitive PERC cells which show the typical lateral appearance of mc-LID where structural defects, such as grain boundaries, show a reduced degradation. Investigations of grain boundaries from front and rear side with respect to the recombination activities (LBIC) in correlation to the crystalline structure (XRD Laue mapping) indicate that gettering at grain boundaries reduces degradation. Furthermore, enhanced rear recom bination at grain boundaries and scattered local spots of μm size is detected. At these regions with damaged rear passivation, Cu-containing microscopic particles are unveiled by microstructural investigations (SEM) and elemental micro-analysis (EDX). Target preparation (TEM) shows a Cu-filled channel that connects the Cu-containing microscopic particles and the silicon bulk. These observations indicate that the presence, diffusion, and precipitation of Cu might play a role in the mc-LID defect formation

Analysis of the 1/20 translocation in ram spermatozoa by flow cytometry

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Light induced degradation: Kinetic model and grain boundary impact on sponge-LID

High-performance multi-crystalline silicon material (HPmc-Si) dominates the market for casted p-type silicon. Solar cells made from HPmc-Si material might suffer from light induced degradation due to the so called sponge-LID mechanism. In this work, we present a kinetic sponge-LID model showing that the degradation follows a pairing reaction involving two reactants. This implies that sponge-LID is based on a different reaction scheme compared to the well-known models for boron-oxygen- or iron-boron-degradation. Based on our model, degradation rates are investigated reading the influence of temperature and illumination on the degradation. Finally, we present statistical results implying that Sigma-3 grain boundaries are less affected of the degradation than other grain boundary types. Using a detailed spatially resolved analysis of the effective carrier diffusion length, the different behaviour of grain boundaries and intra-grain regions is quantified

Electronic nose performance optimization for continuous odour monitoring in ambient air

Industrial plants with odour emissions affect the quality of air and are often cause of public complaints by the people living surrounding the plant. For this reason, the control of odour represent a key issue. The starting point for an effective odour control it‟s their objective quantification. The electronic nose represent the odour measurement technique with probably the greatest potential, but currently there is not a universally recognized procedure of their application for the continuous monitoring of environmental odours.The aim of this paper is to present and describe a novel procedure to training electronic noses in order to maximize their capability of operating a qualitative classification and estimating the odour concentration of ambient air. This novel approach will reduce the uncertainty and increase the reliability of the continuous odour measures. The research is carried out through a real case study application in a big liquid waste treatment plant (LWTP). The seedOA system, patented by the SEED group of the University of Salerno, was used as e.nose device. The characterization of the odour concentrations from the different treatment units and the identification of the principal odour sources is discussed