Non-thermal plasma (NTP) is a promising technology for the improvement of indoor air quality (IAQ) by removing volatile organic compounds (VOCs) through advanced oxidation process (AOP). In this paper, authors developed a laboratory scale dielectric barrier discharge (DBD) reactor which generates atmospheric NTP to study the removal of low-concentration formaldehyde (HCHO), a typical indoor air VOC in the built environment associated with cancer and leukemia, under different processing conditions. Strong ionization NTP was generated between the DBD electrodes by a pulse power zero-voltage switching flyback transformer (ZVS-FBT), which caused ionization of air molecules leading to active species formation to convert HCHO into carbon dioxide (CO₂) and water vapor (H₂O). The impact of key electrical and physical processing parameters i.e. discharge power (P), initial concentration (C_in), flow rate (F), and relative humidity (RH) which affect the formaldehyde removal efficiency (ɳ) were studied to determine optimum conditions. Results show that, the correlation coefficient (R²) of removal efficiency dependence on the processing parameters follow the order R² (F) = 0.99 > R² (RH) = 0.96, > R² (C_in) = 0.94 > R² (P) = 0.93. The removal efficiency reached 99% under the optimum conditions of P = 0.6 W, C_in = 0.1 ppm, F = 0.2 m³/h, and RH = 65% with no secondary pollution. The study provided a theoretical and experimental basis for the application of DBD plasma for air purification in the built environment.

In order to expand the output of solar power systems for efficient integration into the national grid, solar energy resource assessment at site is required. A major impediment however, is the widespread scarcity of radiometric measurements, which can be augmented by satellite observation. This paper assessed the suitability of satellite-based solar radiation resource retrieved from the NASA-POWER archives at $$0.5^\circ \times 0.5^\circ$$0 . 5 ∘ × 0 . 5 ∘ spatial resolution over Ghana–West Africa, to develop a long-term source reference. The assessment is based on the criteria of comparison with estimations from sunshine duration measurement for 22 synoptic stations. Overall, the satellite-based data compared well with ground-based estimations by r = 0.6–0.94 ± 0.1. Spatiotemporally, the agreement is strongest over the northern half Savannah-type climate during March–May, and weakest over the southern half Forest-type climate during June–August. The assessment provides empirical framework to support solar energy utilization in the sub-region.

This paper highlights some of the commonly used bio-based materials studied for their applicability as adsorbents in wastewater treatment. Additionally, few processing techniques employed to enhance the ability and or affinity of the adsorbents for wastewater treatment have been discussed. More so, some of the commonly used characterization techniques such as Scanning Electron Microscopy (SEM), Fourier Transform InfraRed (FTIR) spectroscopy among others often employed in a bid to elucidate the properties and morphologies of the adsorbents as well as the potential mechanism(s) underlying the adsorbate-adsorbent interaction(s) has also been extensively conferred. The potential draw-backs, recommendations and future perspectives on the use of bio-based materials as adsorbents in wastewater treatment has also been discussed in the concluding section of this paper.

Fluoride is recognized as a vital ion for human and animal growth because of the critical role it plays in preventing skeletal and dental problems. However, when it is ingested at a higher concentration it can cause demineralization of teeth and bones resulting in fluorosis, therefore, the production of high-adsorptive capacity material which is also cost-effective is necessary for the treatment of fluorides. In this study, aluminium foil is valorised into alumina nanoparticles. The as-prepared alumina was modified with alum in two different ratios of 1:0.5 and 1:1 (alumina to alum w/w%) and later used as adsorbents for the removal of fluoride from groundwater. The adsorbents were characterized by Fourier transform infrared spectroscopy, point of zero charge and X-ray diffraction. Different factors that influence the removal efficiency of fluorides such as pH, initial concentrations, contact time and adsorbent dosage were studied and optimized using a simulated fluoride solution. The optimum conditions obtained were used to test real groundwater. The static experiment conditions were used to calibrate a PHREEQC geochemical model which was later used to simulate the fluoride sorption onto the modified alumina at different conditions. PHREEQC was also coupled with parameter estimation software to determine equilibrium constants for the surface reactions between the fluoride species and the adsorbent in a way that the simulations accurately reflect the outcomes of laboratory experiments. Isotherm studies were carried out on the adsorbents. Both Langmuir and Freundlich's non-linear models fitted well for the equilibrium data. However, with a higher coefficient of regression and low chi-square test values, the adsorption process was more of chemisorption on a monolayer surface. Kinetic studies were also carried out by using the non-linear equations from the pseudo-first-order and pseudo-second-order models. The pseudo-second-order model fitted well for the equilibrium data. The mechanism for the fluoride ion adsorption was also studied by the intraparticle (IP) diffusion model and was found that IP was not the rate-determining factor, and therefore the most plausible mechanism for the sorption process was ion exchange or attraction of fluoride ions to the sorbent surface. The findings obtained from this research show that readily available aluminium waste could be valorised into a useful product that could be employed in the removal of fluoride from water samples, including groundwater, that may contain too much fluoride and pose a risk to the general public's health.

On-site dry sanitation facilities, although cheaper than wet sanitation systems, suffer from high malodour and insect nuisance as well as poor aesthetics. The high odour deters users from utilizing dry sanitation toilets as an improved facility leading to over 20% open defecation in Sub-Saharan Africa. To address this malodour concern, this study first assessed odour levels, using hydrogen sulphide (H₂S) and ammonia (NH₃) as indicators, on two dry sanitation facilities named T1 and T2. The potential of using biomass (sawdust, rice husk, moringa leaves, neem seeds), ash (coconut husk, cocoa husk) or biochar (sawdust, rice husk, bamboo) as biocovers to remove or suppress odour from fresh faecal sludge (FS) over a 12-day period was investigated. Results showed that the odour levels for H₂S in both T1 (3.17 ppm) and T2 (0.22 ppm) were above the threshold limit of 0.05 ppm, for unpleasantness in humans and vice versa for NH₃odour levels (T1 = 6.88 ppm; T2 = 3.16 ppm; threshold limit = 30 ppm limit). The biomasses exhibited low pH (acidic = 5–7) whereas the biochars and ashes had higher pHs (basic = 8–13). Basic biocovers were more effective at H₂S emission reduction (80.9% to 96.2%) than acidic biocovers. The effect of pH on suppression of NH₃was determined to be statistically insignificant at 95% confidence limit. In terms of H₂S and NH₃removal, sawdust biochar was the most effective biocover with odour abatement values of 96.2% and 74.7%, respectively. The results suggest that biochar produced from locally available waste plant-based materials, like sawdust, can serve as a cost-effective and sustainable way to effectively combat odour-related issues associated with dry sanitation facilities to help stop open defecation.

Burgeoning air pollution is a pressing public health concern. However, due to the scarcity and sparsity of ground-based monitoring, its impact remains uncertain. This work demonstrates how satellite-derived NO₂ observations can identify persistent pollution hotspots and seasonal patterns in a data-scarce urban region. This work leveraged TROPOMI satellite data and Google Earth Engine to evaluate tropospheric NO₂ hotspot patterns in the Greater Accra Region of Ghana from 2019 to 2023. TROPOMI data revealed persistent NO₂ hotspots in urban and industrial areas, with overall peak concentrations reaching up to 3.3 × 10¹⁵ mol cm⁻². Seasonal analysis showed elevated NO₂ levels during the dry season, with a mean concentration of 2.3 × 10¹⁵ mol cm⁻², while lower levels were observed during the rainy season. Increased emissions and reduced dispersion influence this pattern due to stable atmospheric conditions. Google Earth imagery confirmed that the highest NO₂ concentrations were associated with the Heavy Industrial Area, highlighting the presence of extensive industrial facilities such as refineries, factories, and quarries. This integration of satellite observations with high-resolution geospatial tools provides a robust methodology for NO₂ source attribution, emphasizing the need for targeted emission control measures in industrial zones to mitigate air pollution and associated health risks.