The Application of Bio-pd(0) as a Biogenic Cathode in a Microbial Fuel Cell

The increasing concerns of climate change, energy generation, storage, consumption, and water pollution are topics that are gaining attention within modern research fields. This has led to numerous researchers devoting their efforts to developing green technologies that will alleviate these challenges with technologies that are energy efficient, cost-effective, and have low to no carbon dioxide emission. One of the most promising emerging technologies is the Microbial Fuel Cell (MFC) as bioelectricity generation and wastewater treatment is simultaneously achieved during microbial metabolism. However, MFCs are still incompatible with high energy demands due to practical limitations. The overall performance of an MFC depends on the microorganism, appropriate electrode materials, and suitable MFC designs. This work aims to improve the performance of an air-cathode MFC by optimizing the cathode electrode through the introduction of bio-Pd(0) as a catalyst. A consortium of Sulfate-Reducing Bacteria (SRB) isolated from a wastewater treatment plant and Pd(II) was used to fabricate the bio-Pd(0) catalyst through the reduction of Pd(II) by the consortium. The catalyst was characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) which revealed the presence of Pd(0) deposits on the cell surface of the bacteria. Following fabrication, the bio-Pd(0) catalyst was introduced to the cathode, and the MFC recorded a maximum power density of 0.044 mW m-3 and a peak voltage of 215.5 mV

Social Assistance in Developing Countries Database Version 5.0

The Social Assistance in Developing Countries Database is a user-friendly tool that provides summary information on social assistance interventions in developing countries. It provides a summary of the evidence available on the effectiveness of social assistance interventions in developing countries. It focuses on programmes seeking to combine the reduction and mitigation of poverty, with strengthening and facilitating household investments capable of preventing poverty and securing development in the longer term. The inclusion of programmes is on the basis of the availability of information on design features, evaluation, size, scope, or significance. Version 5 of the database updates information on existing programmes and incorporates information on pilot social assistance programmes in Latin America, Asia and Africa. It also adopts a new typology that distinguishes between social assistance programmes providing pure income transfers; programmes that provide transfers plus interventions aimed at human, financial, or physical asset accumulation; and integrated poverty reduction programmes. This new typology has, in our view, several advantages. It is a more flexible, and more accurate, template with which to identify key programme features. It provides a good entry point into the conceptual underpinnings of social assistance programmes

Protein from preprocessed waste activated sludge as a nutritional supplement in chicken feed

Five groups of broiler chickens were raised on feed containing varying substitutions of single cell protein from preprocessed waste activated sludge (pWAS) in varying compositions of 0:100, 25:75, 50:50, 75:25, and 100:0 pWAS: fishmeal by mass. Forty chickens per batch were evaluated for growth rate, mortality rate, and feed conversion efficiency (ηє). The initial mass gain rate, mortality rate, initial and operational cost analyses showed that protein from pWAS could successfully replace the commercial feed supplements with a significant cost saving without adversely affecting the health of the birds. The chickens raised on preprocessed WAS weighed 19% more than those raised on fishmeal protein supplement over a 45 day test period. Growing chickens on pWAS translated into a 46% cost saving due to the fast growth rate and minimal death losses before maturity.University of Pretoria support through the Research Development Programme (UP-RDP).Sedibeng Water.http://www.iwaponline.com/wst/toc.htmhb201

Computational simulation of flocculent sedimentation based on experimental results

Computerised interpolation algorithms as well as the empirical model for analysing the flocculent settling data were developed. A mechanistic semi-empirical model developed from fundamental physical principles of a falling particle in a viscous fluid was tested against actual flocculation column data. The accuracy of the mechanistic model was evaluated using the sum of the squared errors between the interpolated values (real values) and the model predictions. Its fitting capabilities were compared with Özer’s model using nine flocculent data sets of which four were obtained from literature and the rest was actual data from the performed experiments. The developed model consistently simulated the flocculation behaviour of particles in settling columns better than Özer’s model in eight of the nine data sets considered. It is recommended that the model’s performance be further compared with other models like the Rule based and San’s model. The errors due to the use of interpolated values when determining the performance of the empirical models need to be investigated. Furthermore, a three-way rather than two-way interpolation should now be achievable using the interpolation algorithm developed in this study thereby reducing the effects of interpolation bias. The above work opens the way to full automation of design of flocculation sedimentation basins and other gravitational particle separation systems which at present are designed manually and are susceptible to a wide range of human and random errors.National Research Foundation (NRF). Grant No. IFR2010042900080http://www.iwaponline.com/wst/toc.htmhb2013ai201

Self-assembled micro and nano rod-shaped porphyrin@Bi12O17Cl2 composite as an efficient photocatalyst for degradation of organic contaminants

Abstract Bi12O17Cl2 is a potential photocatalyst in practical applications due to its excellent photostability, visible light activity, and competitive bandgap energy. However, the fast recombination of photogenerated charge carriers makes it impractical for pollution mitigation. Recently, aggregated porphyrins have emerged as photosensitizers in light-dependent applications such as photocatalysis. Although Bi12O17Cl2 and porphyrin can function as separate photocatalysts, their photocatalytic properties in terms of visible light adsorption, charge separation and transport, can be improved when they are combined to form heterostructure. In this study, rod-shaped aggregated 5,10,15, 20-Tetrakis (4-carboxyphenyl) porphyrin was synthesized by CTAB-assisted, self-assembly strategy and Bi12O17Cl2 by a facile microwave method. The porphyrin and Bi12O17Cl2 were combined to generate a series of x %Porphyrin@Bi12O17Cl2 having 0.02% wt., 0.1% wt., 0.4% wt., 1% wt. and 10% wt. as compositions of porphyrin. The materials’ photocatalytic degradation efficiency was tested on Rhodamine B dye as a representative pollutant. The best and worst performances were reported for 1%Porphyrin@Bi12O17Cl2 and 10%Porphyrin@Bi12O17Cl2, respectively, which are 3.1 and 0.5 times increases in efficiency compared to pure Bi12O17Cl2. From the radical trapping experiment, electrons and superoxide were the dominant reactive species in the degradation process. The enhanced photocatalytic capability of the materials was attributed to the photosensitizing property of porphyrin and the heterojunction formation, which promotes the separation of photogenerated charge carriers. A plausible step-scheme (S-scheme) was proposed for the photocatalytic degradation mechanism. The S-scheme provided the high redox potential of the photogenerated charge carriers. The findings herein offer a new option for improving the photocatalytic performance of Bi12O17Cl2 for environmental applications through the photosensitization strategy. Graphical abstrac

Performance Evaluation of Selenite (SeO32−) Reduction by Enterococcus spp.

Lactic acid bacteria (LAB) such as Enterococcus spp. have an advantage over several bacteria because of their ability to easily adapt to extreme conditions which include high temperatures, highly acidic or alkaline conditions and toxic metals. Although many microorganisms have been shown to reduce selenite (SeO32−) to elemental selenium (Se0), not much work has been done on the combined effect of Enterococcus spp. In this study, aerobic batch reduction of different selenite concentrations (1, 3 and 5 mM) was conducted using Enterococcus hermanniensis sp. and Enterococcus gallinarum sp. (3.5 h, 35 ± 2 °C, starting pH > 8.5). Results from the experiments showed that the average reductions rates were 0.608, 1.921 and 3.238 mmol·(L·h)−1, for the 1, 3 and 5 mM SeO32− concentrations respectively. In addition, more selenite was reduced for the 5 mM concentration compared to the 1 and 3 mM concentrations albeit constant biomass being used for all experiments. Other parameters which were monitored were the glucose consumption rate, protein variation, pH and ORP (oxidation reduction potential). TEM analysis was also conducted and it showed the location of electron-dense selenium nanoparticles (SeNPs). From the results obtained in this study, the authors concluded that Enterococcus species’s high adaptability makes it suitable for rapid selenium reduction and biosynthesis of elemental selenium

Enterococcus spp. Cell-Free Extract: An Abiotic Route for Synthesis of Selenium Nanoparticles (SeNPs), Their Characterisation and Inhibition of Escherichia coli

Selenite (SeO32−), the most toxic and most reactive selenium (Se) oxyanion, can be reduced to elemental selenium (Se0) nanoparticles by a variety of bacteria, including Enterococcus spp. Previously, the orthodox view held that the reduction of SeO32− to Se0 by a wide range of bacteria was solely accomplished by biological processes; however, recent studies have shown that various bacterial strains secrete metal-reducing metabolites, thereby indirectly catalysing the reduction of these metal species. In the current study, selenium nanoparticles were synthesised from the abiotic reduction of selenite with the use of Enterococcus spp. cell-free extract. Once separated from the cell-free extract, the particles were analysed using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM) and a Zetasizer. The results revealed that the SeNPs were spherical in shape, containing both amorphous and crystalline properties, and the sizes with the highest frequency ranged close to 200 nm. Additionally, the obtained nanoparticles exhibited antimicrobial properties by directly inhibiting the viability of an E. coli bacterial strain. The results demonstrate not only the potential of abiotic production of SeNPs, but also the potential for these particles as microbial inhibitors in medical or similar fields