Norli Ismail

Biogas purification is essential for mitigating corrosion and environmental risks associated with acidic impurity gases. In this study, yeast–alginate hydrogel composite biosorbents prepared by Ca²⁺ gelation followed by Fe³⁺ secondary crosslinking were investigated for selective acidic-gas removal in a fixed-bed column system. Response surface methodology (RSM) was employed to optimize key operating parameters governing the biosorption process. The Fe³⁺-crosslinked yeast–alginate composites exhibited markedly enhanced removal of H2S and CO2 compared with non-Fe³⁺ controls, while CH4 loss remained consistently below 5%, indicating preferential removal of acidic gases over methane. Structural and physicochemical characterizations confirmed the formation of a stable mesoporous network with effective Fe³⁺ incorporation, and biological assays demonstrated preserved yeast viability after adsorption. Overall, these results highlight the potential of Fe³⁺-crosslinked yeast–alginate composite biosorbents as a selective and sustainable material for biogas purification and provide a foundation for further evaluation under continuous-flow conditions.

The prevalence of microplastics in the environment and their potential adverse impacts on wildlife and human well-being make them a pressing global ecological issue. The objective of this review is to provide better understanding prevalence and distribution of microplastics, factors influencing their concentration and transport, the sampling technique and polymer identification analysis used in various studies and future research needs. The identification of microplastic polymer types is also explored, including techniques such as Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. It also points out the many types of sampling equipment and materials, as well as sample preparation and analysis. Sampling method and polymer identification analysis of microplastics may vary on the circumstances of the location and question of the research. Suitable and standardize for both methods should be prioritized to ensure reliable and precise collection of data regarding the microplastic in river and estuarine.

Magnetic chitosan/cellulose nanofiber-Fe(III) [M-Ch/CNF-Fe(III)] composites were isolated for the elimination of Cr(VI), Cu(II), and Pb(II) from aqueous solution. Various analytical methods, such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), and thermogravimetric analysis (TGA) were employed to determine the morphological, physicochemical, and thermal properties of the isolated M-Ch/CNF-Fe(III) composites. It was found that the M-Ch/CNF-Fe(III) composites were porous materials, and they have the potential to be implemented as an adsorbent for heavy metals removal. The adsorption efficiency of M-Ch/CNF-Fe(III) composites was determined for Cr(VI), Cu(II), and Pb(II) elimination with changing pH (pH 1.0–8.0), adsorbent doses (0.05–1.0 g), time (15–90 min), and temperature (28–80 °C). In addition, isothermal and kinetics studies were conducted to assess the adsorption behavior and mass transfer phenomena of M-Ch/CNF-Fe(III) composites as an adsorbent for Cr(VI), Cu(II) and Pb(II) elimination from aqueous solution. The outcomes of the present study reveal that the M-Ch/CNF-Fe(III) composites could be utilized as an adsorbent for the Cr(VI), Cu(II), and Pb(II) elimination from industrial effluents.

The utilization of lignocellulose biomass as an alternative source of renewable energy production via green technology is becoming important, and is in line with sustainable development goal initiatives. Lignocellulolytic bacteria, such as Bacillus spp., can break down biomass by producing hydrolytic enzymes, which are crucial in the successful conversion of biomass or lignocellulosic material into renewable energy. This information gave rise to this study, where municipal solid waste sediments of a sanitary municipal solid waste landfill were sampled and screened, and lignocellulolytic bacteria were isolated and characterized. Samples were taken from four different locations at the Pulau Burung landfill site in Malaysia. Lignin and starch were used as sources of carbon to identify potential bacteria that exhibit multi-enzymatic activity. The growth rate and doubling time of bacterial isolates in lignin and starch were taken as the criteria for selection. Eleven bacterial isolates were screened for cellulase activity using iodine and Congo red dyes. The cellulase activity of these isolates ranged from 0.8 to 1.7 U/mL. We carried out 16S rRNA gene sequencing to identify the phyla of the selected bacterial isolates. Phylogenetic analysis was also conducted based on the 16S rRNA sequences of the bacterial isolates and related Bacillus species, and a tree was generated using the Neighbor-Joining method. In this study, Bacillus proteolyticus, Bacillus Sanguinis, Bacillus spizizenii, Bacillus paramycoides, Bacillus paranthracis and Neobacillus fumarioli were identified as promising bacteria capable of expressing lignocellulolytic enzymes and degrading the lignocellulosic biomass present in municipal solid waste.

Food waste is a rich organic matter that can potentially be converted into biogas as a source of renewable energy. The limitation in energy production lies in the presence of volatile fatty acid (VFA) during the anaerobic digestion of food waste due to the high degradation rate. The accumulation of VFA leads to a decrease in pH that exceeds the optimal pH range of 6.8–7.6 for methanogens, thus inhibiting methanogenesis and affecting biogas production. In the present study, a symbiotic culture of bacteria and yeast (SCOBY) and kombucha mixed inoculum and compost was applied as an alternative treatment method to alleviate inhibition. The digestion efficiency was evaluated on pH, total alkalinity (TA), total volatile fatty acid (TVFA), total solid (TS), and volatile solid (VS) throughout the digestion period of 80 days to analyse the stability of the system. The results revealed that SCOBY and kombucha mixed inoculum caused system instability, inducing inhibition at TVFA of 12,874.1 mg/L, while the pH dropped to 5.23. The inhibition in the digestion system with only the SCOBY inoculum occurred at TVFA of 11,908.3 mg/L, and the pH dropped to 5.67. The biogas and methane yield quantified from the mixed inoculum is 8.792E⁻⁴ L/L d, comparatively lower than the ethanol pre-fermentation treatment method. These findings indicate that the addition of compost improved the pH, VS, and TVFA.