Publications by authors named "R Sierra-Alvarez"

The widespread presence of per- and polyfluoroalkyl substances (PFAS) in the environment, driven by extensive industrial use, has raised global concerns due to their persistence and adverse health effects. Despite the increased regulatory focus on a sub-set of well-known PFAS, over 12,000 compounds exist, many poorly characterized. Our study assessed hidden PFAS concentrations, undetectable by standard LC-MS/MS analysis, in contaminated groundwater.

View Article and Find Full Text PDF

This study aimed to compare microscopic counting, culture, and quantitative or real-time PCR (qPCR) to quantify sulfate-reducing bacteria in environmental and engineered sludge samples. Four sets of primers that amplified the and gene encoding the two key enzymes of the sulfate-reduction pathway were initially tested. qPCR standard curves were constructed using genomic DNA from an SRB suspension and dilutions of an enriched sulfate-reducing sludge.

View Article and Find Full Text PDF

3-Nitro-1,2,4-triazol-5-one (NTO) is an ingredient of new safer-to-handle military insensitive munitions formulations. NTO can be microbially reduced to 3-amino-1,2,4-triazol-5-one (ATO) under anaerobic conditions if an electron donor is available. Conversely, ATO can undergo aerobic biodegradation.

View Article and Find Full Text PDF

The need for effective technologies to remediate the insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO) is emerging due to the increasing use by the US Army and environmental concerns about the toxicity and aqueous mobility of NTO. Reductive treatment is essential for the complete degradation of NTO to environmentally safe products. The objective of this study is to investigate the feasibility of applying zero-valent iron (ZVI) in a continuous-flow packed bed reactor as an effective NTO remediation technology.

View Article and Find Full Text PDF

Antimony (Sb) is a toxic and carcinogenic metalloid that can be present in contaminated water generated by mining operations and other industrial activities. The toxicity of Sb (III) and Sb (V) to aerobic microorganisms remains limited and unexplored for anaerobic microorganisms involved in hydrogen (H) and methane (CH) production. This study aimed to evaluate the toxicity of Sb (III) and Sb (V) upon aerobic and anaerobic microorganisms important in biological wastewater treatment systems.

View Article and Find Full Text PDF