Demand for clean energy has increased due to the proliferation of climate change impact from excessive emission of greenhouse gases (GHG) from the combustion of fossil fuels. H₂ is a clean energy source since water vapor is the only byproduct after its combustion. Growing microalgae offers a promising low-energy and low-cost approach for bioH₂ production. In this study, a bibliometric analysis was performed for the production of H₂ using microalgae to evaluate the conceptual, intellectual, and social structure of the dataset. In addition, a scoping review of articles was conducted to highlight recent advancements and identify future research recommendations. A total of 184 relevant publications over 23 years (2000–2022) were retrieved from the Scopus database for analysis. The results demonstrated an exponential increase in citations from 283 to 996 in the last decade, indicating the interest in bioH₂ production from microalgae. Results also revealed that the International Journal of Hydrogen Energy accounted for more than 25% of the published articles, of which China contributed almost 28%. Oxygen sensitivity of the H₂ase enzyme and sulfur deprivation were highlighted as the main limiting factors of bioH₂ production using microalgae. It was also evident that the most widely studied microalgae species were green algae, especially Chlamydomonas and Chlorella. Effective process modifications, particularly hybridizing microalgae with bacteria consortium and implementing oxygen regulating strategies, were shown to give up to a 10-fold increase in H₂ yield. This study also discusses recent developments in technologies, strategies, microalgal species, and optimizing controlling factors affecting bioH₂ production.

Due to rising population and industrialization, two-thirds of the world’s population may suffer water scarcity by 2025. Biodesalination is a promising sustainable practice targeting salt removal from seawater by micro-organisms, using lower energy consumption and resulting in less environmental impact. This study examined the evolution of biodesalination from 2007 to 2022 by applying bibliometric analysis. A scoping review was also conducted through content analysis of biodesalination publications. Using the Scopus database, the research trends, major contributors in the field, and recent advancements were identified. The study investigated a total of 80 peer-reviewed journal articles in the field of biodesalination. Results of the bibliometric analysis revealed that publications peaked in 2022 and citations in 2021, with values of 14 and 473, respectively. Results also revealed that the research trend in biodesalination is leaning towards the use of microbial desalination cells. Furthermore, advancements in the field focused on enhancing the nutrient medium to yield better growth rates for algae and cyanobacteria and improve desalination efficiencies to up to 40%. Other modifications focused on introducing microbial strains with increased salinity tolerance. Finally, an outline of future research potential was presented, focusing on nutrient medium modifications, specifically the substitution of chloride and sodium salts in the medium with nitrate and potassium minerals.

Bioaerosol emission at various WWTP treatment units has drawn attention due to their potential negative impacts on human health. This study conducted a bibliometric analysis of the global research on bioaerosol emissions from WWTPs from 1995 to 2022. The Scopus database was used to identify relevant articles and research trends, major contributors in the field, and recent developments. The study examined 122 articles in the field of bioaerosols in WWTPs. The analysis findings showed that publications and citations peaked in 2022, with values of 25 and 818, respectively. At the beginning of the study period, the USA, Poland, and Italy led the publications’ ranking, but with time, China emerged as the most influential country in the field. Recent advances in the field have revealed that spectral intensity bioaerosol sensors have contributed to the faster and more reliable identification and classification of bioaerosols. It was also observed that probabilistic techniques relying on mathematical models and assumptions to ascertain the risks associated with bioaerosols may result in false interpretations. Despite their high cost, epidemiological studies were best for assessing plant workers’ health risks. The outbreak has raised questions about accurately evaluating and modeling SARS-CoV-2 persistence, infectivity, and aerosolization over WWTP sites and environmental factors. Finally, the study highlighted the potential of three control treatment approaches: carbon absorption, UV irradiation, and ozone treatments, which proved efficient in reducing bioaerosol emissions.