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This study conducts a comparative assessment of two dumpsites (abandoned and active dumpsite) around Osogbo metropolis Osun State Nigeria. Ten selected heavy metals (HMs) such as arsenic, copper, cobalt, cadmium, chromium, iron, nickel, manganese, lead and zinc were determined. The soil samples were collected, at strategic points to revealed variation in samples. The concentrations of HMs were quantitatively determined using atomic absorption spectroscopy. The results indicated that all the HMs determined were found between below detection limit (bdl) to 0.611 mg/kg and bdl –0.880 mg/kg for abandoned and active dumpsites, respectively. The concentration factor and geo-accumulation intensity revealed no contamination to strong contamination and from uncontaminated to strong contamination intensity, respectively. The concentrations for some of the HMs were below the tolerable recommendation level by National Environmental Standards and Regulation Enforcement Agency and Food and Agriculture Organization/World Health Organization in soil samples. This study recommends periodic monitoring and that possible decontamination of the dumpsite are crucial because these dumpsites were currently in use for crops cultivation such as maize, vegetable bananas, and some other arable plants. Also, HM concentrations in crops should be investigated and monitored at these dumpsites regularly in order to avert detrimental effects of HM pollution, which could manifest many years after exposure, as they are recalcitrant in the environment. [ABSTRACT FROM AUTHOR]

In this study, the pollution levels, sources, and ecological risks associated with five selected heavy metals (chromium, copper, iron, lead, and zinc)were evaluated in surface water, soil, and sediment systems along the Isipingo River, KwaZulu-Natal, South Africa. The surface water, soil and sediment samples collected along the river, were preserved, transported, and stored followed the standard procedures. Soil and sediment samples were digested for heavy metal determination using a microwave digestion system. The digested samples were quantitatively analysed using an inductively coupled plasma optical emission spectrometer (ICP-OES). The results demonstrate that majority of the targeted heavy metals were found below the detection limits in surface water except for iron (Fe), which was found within the concentration range of 9.54 to 46.76 µg/L. Lead was found below the detection limit in water, soil, and sediment samples, while other heavy metals were within the range not detected(ND)to 0.222 µg/kg dry weight and 0.212 µg/kg dry weight in soil and sediment respectively. The ecological risk assessment of the studied metals in soil and sediment systems from this riversignified that water from this river had less probable potential adverse effects on both animals and humans as well as benthic organisms. [ABSTRACT FROM AUTHOR]

The selectivity of catalytic materials suitable for oxygen reduction potential of bio‐electrochemical systems is very affluent. Therefore, exploring magnetite and static magnetic field as alternative option to promote microbial electron transfer comes in handy. In this study, the application of magnetite‐nanoparticles and a static magnetic field on a microbial fuel cell (MFC) in anaerobic digestion was investigated. The experimental set‐up included four 1 L biochemical methane potential tests: a) MFC, b) MFC with magnetite‐nanoparticles (MFCM), c) MFC with magnetite‐nanoparticles and magnet (MFCMM), and d) control. The highest biogas production obtained was 545.2 mL/g VSfed in the MFCMM digester, which was substantially greater than the 117.7 mL/g VSfed of the control. This was accompanied by high contaminant removals for chemical oxygen demand (COD) of 97.3%, total solids (TS) of 97.4%, total suspended solids (TSS) of 88.7%, volatile solids (VS) 96.1%, and color of 70.2%. The electrochemical efficiency analysis revealed greater maximum current density of 12.5 mA/m2 and coulombic efficiency of 94.4% for the MFCMM. Kinetically, the cumulative biogas produced data obtained were well fitted on the modified Gompertz models and the greatest coefficient of determination (R2=0.990) was obtained in the MFCMM. Therefore, the application of magnetite‐nanoparticles and static magnetic field on MFC showed a high potential for bioelectrochemical methane production and contaminant removal for sewage sludge. [ABSTRACT FROM AUTHOR]

The concentration levels of selected trace metals in coal samples collected from three different locations, namely Okaba coal deposit Kogi State, Onyeama coal deposit and Ribadu both in Enugu state, were investigated in this study. The representative coal samples were analysed for the presence of trace metals such as Cadmium, Chromium, Lead and Copper using an Atomic Absorption Spectrophotometer. The mean concentrations of 0.043 ± 0.007, 0.020 ± 0.006, 0.032 ± 0.006 and 7.245 ± 0.557 (mg/kg) were observed for the selected metals. The concentration of the selected metals investigated with the exception of Lead was found to be above detection limit for EPA – NBS standard and compared to the previous work done globally. The emission of coal has been attributed to the release of critical heavy metals such as Cadmium, Chromium, Lead and Copper, into the environment thereby posing a threat to human health and endangering the ecosystem. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? MFC breakdown, electrochemical principles for generating bioelectricity. MFC operation mechanism and applications. MFCs previous perspectives. RSA energy crisis, MFC technology viable solution. What is the implication of the main finding? MFC suggests that, in theory, bioelectricity can be produced from organic content using just chemical energy. MFC can be used in plant operations on a daily basis to cut operational costs. Existing research shows that MFCs are viable, but scaling-up is very necessary. For the current energy crisis in South Africa, MFCs may be a workable sustainable energy source. Microbial fuel cell (MFC) technology turns chemical energy into bioelectricity in a clean and efficient manner, lowering carbon emissions and increasing bioenergy production. It is a multifaceted technique that has the potential to be a panacea for clean water scarcity and sustainable, renewable energy. In this review, the approach focuses on scaling-up and application prospects at a commercial scale. An outlook on various, previously tried methodologies was generated in order to establish a viable bioelectricity scaling-up approach that is also cost-effective in its design. Precise themes were followed to evaluate previously produced models and methodologies for MFCs: principle and anatomical mechanisms, basic applications, bioelectricity scaling-up potentials from previous work and limitations, then an outlook on MFC feasibility and its wastewater treatment plant (WWTP) energy supply chain. The goal of this paper is to derive a viable approach from prior research in order to comprehend how MFC technology may be scaled-up for commercial and practical power output. Essentially, this article summarizes the current energy predicaments faced by South Africa and proposes MFCs as a new knowledge-contributing technology with electricity scaling-up potential. Conclusively, more research on MFC technique scaling-up operating factors is recommended. [ABSTRACT FROM AUTHOR]

This study was aimed at using the Central Composite Design (CCD) and Box-Behnken Design (BBD) to compare the efficiency and to elucidate the main interacting parameters in the upflow anaerobic sludge blanket (UASB) reactor, namely: Organic Loading Rate (OLR), Hydraulic Retention Times (HRT) and pH at a constant temperature of 35°C. Optimum HRT (15 h), OLR (3.5 kg.m-3.d-1) and pH (7) resulted in biogas production of 5,800 mL/d and COD removal of 80.8%. BBD produced a higher desirability efficiency of 94% as compared to the CCD which was 92%. The regression quadratic models developed with high R² values of 0.961 and 0.978 for both CCD and BBD, respectively, demonstrated that the interaction models could be used to pilot the design space. BBD model developed was more reliable with a higher prediction of biogas production (5,955.4 ± 225.3 mL/d) and COD removal (81.5 ± 1.014%), much close to the experimental results at a 95% confidence level. CCD model predictions was greater in terms of COD removal (82.6 ± 1.06% > 80.8%) and biogas production (4,636.31 mL/d ± 439.81 < 5,800 mL/d) which was less than the experimental results. Therefore, RSM can be adapted for optimizing various wastewater treatment processes. [ABSTRACT FROM AUTHOR]

The selectivity of catalytic materials suitable for oxygen reduction potential of bio-electrochemical systems is very affluent. Therefore, exploring magnetite and static magnetic field as alternative option to promote microbial electron transfer comes in handy. In this study, the application of magnetite-nanoparticles and a static magnetic field on a microbial fuel cell (MFC) in anaerobic digestion was investigated. The experimental set-up included four 1 L biochemical methane potential tests: a) MFC, b) MFC with magnetite-nanoparticles (MFCM), c) MFC with magnetite-nanoparticles and magnet (MFCMM), and d) control. The highest biogas production obtained was 545.2 mL/g VS fed in the MFCMM digester, which was substantially greater than the 117.7 mL/g VS fed of the control. This was accompanied by high contaminant removals for chemical oxygen demand (COD) of 97.3%, total solids (TS) of 97.4%, total suspended solids (TSS) of 88.7%, volatile solids (VS) 96.1%, and color of 70.2%. The electrochemical efficiency analysis revealed greater maximum current density of 12.5 mA/m 2 and coulombic efficiency of 94.4% for the MFCMM. Kinetically, the cumulative biogas produced data obtained were well fitted on the modified Gompertz models and the greatest coefficient of determination (R 2 =0.990) was obtained in the MFCMM. Therefore, the application of magnetite-nanoparticles and static magnetic field on MFC showed a high potential for bioelectrochemical methane production and contaminant removal for sewage sludge., (© 2023 The Authors. Chemistry - An Asian Journal published by Wiley-VCH GmbH.)