Toxicity effects of size fractions of incinerated sewage sludge bottom ash on human cell lines

Public health implications of antibiotic resistance in sewage water: an epidemiological perspective

The emergence and rapid spread of antibiotic resistance pose a major threat to global health, attributing to misuse and overuse of antibiotics resulting in antibiotics-resistant bacteria through natural mutation or transfer of resistance genes. A cross-sectional study was carried out, in which a total of 36 samples were systematically collected; of these, 26 were derived from the wastewater efflux and 10 from the receiving waters at several critical junctures along the Sutlej River. Herein, this study elucidated elevated levels of antibiotic resistance among bacterial isolates sourced from urban wastewater. Escherichia coli (E. coli) was the highest at 90% among the isolates, followed by Klebsiella pneumoniae (K. pneumoniae) at 58%, Pseudomonas aeruginosa (P. aeruginosa) at 55%, and Salmonella spp. at 53%. Many antibiotics were found to be more resistant including Ciproflaxacin, Co-Trimaxazole, Ampicillin and Tetracycline. Several antibiotic-resistance genes were found in isolated bacterial spp., such as Aminoglycosides (aadA), Sulfonamides (Sul1, Sul3), Tetracyclines (Tet (A/B/D)) and Cephalosporins (Bla_CTM X) at 41%, 35%, 29% and 12% respectively. Furthermore, the development of innovative wastewater treatment models and surveillance programs are crucial to counteract the dissemination of antibiotic resistance. To investigate the genetic determinants of antibiotic resistance, molecular analysis was performed, including DNA isolation, PCR amplification, and sequence analysis. The study helps investigate a diverse range of ARBs and ARGs in wastewater, which highlights the need of better laws for antibiotic usage and wastewater treatment processes. This investigation also stresses on regular monitoring of ARBs and ARGs in sewage wastewater. Through proactive interventions and sustained scientific inquiry, we can strive toward preserving environmental integrity and public health for successive generations.

Environmental implications of combustion of rice husk at high temperatures and for an extended period for energy generation

The most common alternative for the management and valorization of rice processing waste is the combustion of rice husk (RH) for energy generation. The environmental risk assessment of the ash generated during the combustion of the RH to obtain energy has remained understudied. Disposal of rice husk ash (RHA) on agricultural land is the most common outcome, which could pose a risk to both natural ecosystems and human health. The objective of this study was to characterize the physicochemical composition and the phytotoxicity, cytotoxicity, and genotoxicity of RHA obtained from three distinct combustion processes. The evaluation processes were 800-900 °C in up to 5 min (I), 800-900 °C in 15-20 min (II), and 600-700 °C in 15-20 min (III). Furthermore, the content, pH, and concentrations of Al, Cd, Cu, Fe, Mg, Mn, Mo, Na, Ni, and Ti present in the ashes were determined. The germination index for two vegetable seeds was subsequently evaluated. By measuring the mitotic index and frequency of chromosomal aberrations, the cytotoxicity and genotoxicity were determined. It was observed that RHA produced by combustion of RH at higher combustion temperatures for an extended period exhibited different physicochemical properties, in addition to higher levels of phytotoxicity, cytotoxicity, and genotoxicity.

Chemical characteristics of bottom ash from biomedical waste incinerators in Ghana

Biomedical waste (BMW) incineration is the most used alternative disposal method in developing countries, such as Ghana. The improper disposal of incinerator-generated bottom ash (BA) is a significant concern due to the hazardous nature of waste. A study was conducted at Tema Hospital (TGH) and Asuogyaman Hospital (VRAH) incinerator sites. The BA samples were sent to the Council for Scientific and Industrial Research, Institute of Industrial Research, Ghana. The BA samples were weighed with fisher analytical balance, ground, and sieved with standard grade meshes of 120, 100, and 80 to determine the BA particle size distribution. The chemical composition and heavy metals were analysed using X-ray fluorescence spectrometry (XRF) and atomic absorption spectroscopy (AAS) techniques. The results indicated the chemical composition of the analysed BA samples was CaCO₃ (49.90%), CaO (27.96%) and MgCO₃ (6.02%) for TGH and CaCO₃ (48.30%), CaO (27.07%), and SiO₂ (6.10%) for VRAH, respectively. The mean concentration (M) (kg m^-3) and standard deviation (SD) for TGH in the BA were 7.082 ± 0.478 (Ti), 4.657 ± 0.127 (Zn) and 4.271 ± 1.263 (Fe), while that of VRAH consisted of 10.469 ± 1.588 (Ti), 7.896 ± 2.154 (Fe) and 4.389 ± 0.371 (Zn). Therefore, the heavy metals' mean concentration at the BA is above the WHO permissible limits of soil, i.e., 0.056 kg m^-3 (Ti), 0.085 kg m^-3 (Pb), 0.100 kg m^-3 (Cr) and 0.036 kg m^-3 (Cu). Furthermore, the heavy metal mean concentrations of TGH and VRAH present in the BA analysed samples were ranked in descending order: Ti > Zn > Fe and Ti > Fe > Zn, respectively. It is therefore recommended that BA must be properly disposed of because of the hazardous nature of heavy metals present in the analysed samples, which are able to cause environmental and public health issues.

Towards understanding respiratory particle transport and deposition in the human respiratory system: Effects of physiological conditions and particle properties

Fly ash is a common solid residue of incineration plants and poses a great environmental concern because of its toxicity upon inhalation exposure. The inhalation health impacts of fly ash is closely related to its transport and deposition in the human respiratory system which warrants significant research for health guideline setting and inhalation exposure protection. In this study, a series of fly ash transport and deposition experiments have been carried out in a bifurcation airway model by optical aerosol sampling analysis. Three types of fly ash samples of different morphologies were tested and their respiratory deposition and transport processes were compared. The deposition efficiencies were calculated and relevant transport dynamics mechanisms were discussed. The influences of physiological conditions such as breathing rate, duration, and fly ash physical properties (size, morphology, and specific surface area) were investigated. The deposition characteristics of respiratory particles containing SARS-CoV-2 has also been analyzed, which could further provide some guidance on COVID-19 prevention. The results could potentially serve as a basis for setting health guidelines and recommending personal respiratory protective equipment for fly ash handlers and people who are in the high exposure risk environment for COVID-19 transmission.