Heavy metals Mn, Fe, Ni, Cu and Zn in human hair samples using energy dispersive X-ray fluorescence analysis

This paper presents the results of analysis of energy-dispersive X-ray fluorescence (EDXRF) applied on the human hair. We determined the concentrations of heavy metals Mn, Fe, Ni, Cu and Zn of 29 hair samples of sanitation workers and 5 samples of students were assumed to be environmentally healthy group. The accuracy and precision of the method for the elements were evaluated through the analysis of a standard hair sample. We compared the concentrations of human hair from an occupationally exposed group of sanitation workers and a control group (students). The hair of the exposed group showed a range of concentrations of 6-28 ppm Mn, 20-195 ppm Fe, 258-549 ppm Ni, 452-1182 ppm Cu and 334-1556 ppm Zn, while that of the control group has a range of 7-26 ppm Mn, 22-61 ppm Fe, 309558 ppm Ni, 438-700 ppm Cu and 224-876 ppm Zn

Bioelectricity production in compost, soil, and plant microbial fuel cells

Microbial fuel cell (MFC) studies are often conducted using liquid-phase carbon sources because of the simplicity of carbon delivery. Therefore, MFC studies dedicated to solid-phase carbon sources are still limited. Notwithstanding, solid organic waste can lead to environmental concerns associated with solid waste management and greenhouse gas emissions. This thesis focuses on solid-phase carbon sources from kitchen waste, soil, and living plants as a source of carbon for MFCs.The first study investigated bioelectricity production using kitchen waste in compost MFC (CMFC) treated with different C/N ratios and salinities. CMFC of lower C/N ratio (C/N 24) under non-saline conditions produced the highest bioelectricity. Further, adding 10 g/L of NaCl did not improve power production.Based on established understandings that salinity can be detrimental to power production and that power performance of MFCs depends on the carbon source, the second study investigated bioelectricity production using weeping alkaligrass (Puccinellia distans), a salt-tolerant grass, in potting mix or sandy loam soil at different salinities. The performance of plant MFC (PMFC) was compared to soil MFC (SMFC). Both PMFC and SMFC performance was best at a salinity level of 6 g/L of NaCl. The bioelectricity production in PMFC with potting mix was higher compared to bioelectricity production in PMFC with sandy loam soil. The presence of alkaligrass in MFCs increased bioelectricity production by 14-fold. Experiments under different photoperiod conditions (24/0 h, 16/8 h, 9/15 h, 0/24 h) have shown that bioelectricity production declined in shorter photoperiods and was affected by frequent changes during the photoperiods test.iiMajor challenges to implementing MFC technology include the cost of electrode materials. The use of low-cost material like biochar has been studied in the past. Hence, the third study was dedicated to understanding the effects of biochar application on the production of bioelectricity, methane, and plant biomass. This work examined the potential of using biochar as an alternative anode to the standard carbon felt anode in SMFC and PMFC with rice (Oryza sativa) and alkaligrass. Over 125 days, the highest bioelectricity production was obtained from rice PMFC, followed by alkaligrass PMFC, and SMFC. The bioelectricity production of MFCs with biochar anodes was between 16–75% of the bioelectricity production of MFCs with carbon felt anodes. Methane emissions of MFCs with biochar anodes were found to be lower than those of MFCs with carbon felt anodes. In brief, biochar is promising for bioelectricity production and for reducing methane emissions without significantly decreasing plant biomass yield.Understanding temporal trends in a particular research area and broadening research networks are necessary for integrated research efforts. The final study, therefore, focused on bibliometric analysis to evaluate global research trends in the MFC field. Interest in MFC has been growing rapidly since 2008. Researchers from China and the USA have contributed 60% of total publications globally, leading 70 other countries. Progress in MFC research encompasses material science, nanotechnology, ceramics, biochar, artificial neural networks, and economics assessment.La plupart des études portant sur les piles à combustible microbiennes (MFC) utilisent une source de carbone en phase liquide pour faciliter la distribution de carbone. Par conséquent, les études MFC dédiées aux sources de carbone en phase solide sont encore limitées. De plus, l'utilisation de déchets organiques solides peut entraîner des préoccupations environnementales résultant de la gestion des déchets solides et l'émission de gaz à effet de serre. Cette thèse porte sur l'utilisation de déchets de cuisine et de plantes vivantes, comme sources de carbone en phase solide pour les MFC.La première étude a permis de caractériser la production d'électricité de MFC utilisant des déchets de cuisine dans du compost (CMFC) contenant différents rapports de C/N et différents taux de salinités. Les meilleurs rendements en électricité ont été observés dans les CMFC ayant les plus faibles ratios de C/N et un environnement avec non-salin. En outre, l'ajout de 10 g/L de chlorure de sodium n'a pas permis d'améliorer la production d'énergie.La seconde étude a permis d'évaluer et de comparer l'effet de la salinité et de la composition du sol sur la performance énergétique de piles microbiennes utilisant une source de carbone en phase solide ayant (PMFC) ou n'ayant pas de plantes (SMFC). La plante utilisée pour les essais était la puccinellie à fleurs distantes (Puccinellia distans), une graminée tolérante au sel. Les deux phases solides comparées étaient un mélange d'empotage riche en matière organique et un sol limoneux sableux traités à différents taux de salinité. On a observé que la performance électrique des MFC était la meilleure à un taux de salinité de 6 g/L. De plus, la production de bioélectricité dans les PMFC utilisant le mélange d'empotage était plus élevée que dans les PMFC utilisant le sol limoneux sableux. L'emploi de la puccinellie à fleurs distantes dans les MFC d'augmenter la production de bioélectricité de 14 fois. Des essais effectués sous différentes photopériodes (durées du jour et de la nuit) ont montré que la production de bioélectricité diminuait sous les durées de jour plus courtes et qu'elle était affectée par les changements fréquents des durées. La troisième étude a été consacrée à l'étude des effets de l'application du biocharbon, comme remplacement à l'anode en feutre de carbone, sur la production de bioélectricité, de méthane et de la biomasse végétale. Le biocharbon a été choisi car il est peu couteux et qu'il a été démontré qu'il pouvait remplacer avantageusement les électrodes conventionnelles très couteuses. Des PMFC et des SMFC ont été utilisées pour les essais qui ont duré 125 jours. Les plantes utilisées dans les PMFC étaient soit du riz, soit de la puccinellie à fleurs distantes. Pour la durée complète des essais, la production de bioélectricité la plus élevée a été obtenue dans les PMFC au riz, suivis par les PMFC à la puccinellie à fleurs distantes et par les SMFC. La production moyenne de bioélectricité des MFC avec les anodes de biocharbon était de 16 à 75% de celles des MFC équipées d'anodes en feutre de carbone. Les émissions de méthane des MFC avec des anodes de biocharbon étaient plus faibles que celles des MFC avec des anodes en feutre de carbone. L'utilisation du biocharbon comme anode dans les MFC est donc prometteur pour la production de bioélectricité car il permet de réduire les coûts d'implantation, de réduire les émissions de méthane et cela, sans diminuer significativement le rendement de la biomasse végétale

Effect of C/N ratio and salinity on power generation in compost microbial fuel cells

In this work, compost Microbial Fuel Cells (cMFCs) were used to generate electricity from a mix of fruit and vegetable wastes, and soil with different C/N ratios and salinities. Experiments were carried out in 500 mL cMFCs equipped with carbon felt anodes and manganese dioxide cathodes. The cMFCs were loaded with fresh compost and operated at 20\u201323 \ub0C for up to 97 days. The low C/N ratio (C/N 24) had a greater power production with a maximum power density of 5.29 mW/m2 (71.43 mW/m3), indicating a more favorable condition for microbial growth. High-saline cMFCs produced lower power, suggesting that their level of salinity (10 g/L of NaCl) inhibited electricigenic microorganisms. The closed-circuit cMFC showed an improved degradation of organic matter by 6% to 8% compared to the control MFC operated in an open circuit mode (no external resistor attached).Peer reviewed: YesNRC publication: Ye

Heavy metals mn, fe, ni, cu, and zn in human hair samples using energy dispersive x-ray fluorescence analysis

This paper presents the results of analysis of energy-dispersive X-ray fluorescence (EDXRF) applied on the human hair. We determined the concentrations of heavy metals Mn, Fe, Ni, Cu and Zn of 29 hair samples of sanitation workers and 5 samples of students were assumed to be environmentally healthy group. The accuracy and precision of the method for the elements were evaluated through the analysis of a standard hair sample. We compared the concentrations of human hair from an occupationally exposed group of sanitation workers and a control group (students). The hair of the exposed group showed a range of concentrations of 6-28 ppm Mn, 20-195 ppm Fe, 258-549 ppm Ni, 452-1182 ppm Cu and 334-1556 ppm Zn, while that of the control group has a range of 7-26 ppm Mn, 22-61 ppm Fe, 309- 558 ppm Ni, 438-700 ppm Cu and 224-876 ppm Zn

A general framework for sustainability assessment of sheet metalworking processes

The sheet metalworking industries possess minimal knowledge in the area of sustainability despite having served as sub-contractors to various industrial sectors. This also highlights that suitable indicators for measuring the sustainability performance of sheet metalworking operations are poorly addressed. As sustainability assessment is regarded as a vital part of sustainable development, this paper has been aimed at establishing a general framework for sustainability assessment of sheet metalworking processes. The main attention was paid to two important processes—the cutting operations with a CNC turret punch press machine and sheet metal bending operations with CNC press brake machine. Stepwise guidelines to implement the proposed framework in sheet metalworking industries are consequently presented. Besides, this study contributes to developing an applicable sustainability indicator set for assessing such manufacturing processes. It makes a valuable contribution to advancing the narrow body of knowledge on the under-researched scope