ABSTRACT This article presents the issue of water access in the context of the Paraguayan Chaco and the alternative that the Non-Governmental Organization (NGO), Pro Comunidades Indígenas (PCI), along with indigenous and peasant communities in the area, has been experimenting with to address the problem; from water access to the challenge of its treatment and purification for human consumption. The methodological approach of this research is qualitative, employing participant observation and semi-structured interviews with technicians, coordinators of the implementing institution of the nature-based safe water system, and community leaders. Additionally, bibliographic consultations and review of PCI institutional documents were conducted to obtain secondary data. The results of this study provide a description of PCI's experiences and lessons learned about a nature-based safe water treatment system, which utilizes biofilters such as stone, gravel, sand, and charcoal. This article covers the trials for the construction of the sys- tem, explains its operation, and discusses its implementation in communities. The nature-based safe water system proves effective for small populations and provides a solution to a long-standing problem in the Chaco territory. Its construction is easy, short-term, and much less costly than conventional water treatment systems. Additionally, the joint construction of the system with the residents, technical training in its operation and maintenance, greatly contributes to its sustainability. This article contributes to the identification, application, and study of suitable water systems for areas with difficult access to this vital liquid, such as the Paraguayan Chaco. Furthermore, it is an innovative and eco-friendly system, meaning it is environmentally friendly.

RESUMEN Este artículo presenta la problemática del acceso al agua en el contexto del Chaco paraguayo y la alternativa que la Organización No Gubernamental (ONG), Pro Comunidades Indígenas (PCI), junto con las comunidades indígenas y campesinas de la zona, ha venido ensayando para buscar solución a la problemática; desde el acceso al agua hasta el desafío de su tratamiento y potabilización para el consumo humano. El enfoque metodológico de esta investigación es cualitativo, empleando la observación-participante y entrevistas semiestructuradas con técnicos, coordinadores de la institución ejecutora del sistema de agua segura basado en la naturaleza y líderes comunitarios. Además, se realizaron consultas bibliográficas y revisión de documentos institucionales de PCI para obtener datos secundarios. Los resultados de este estudio arrojan la descripción de las experiencias y las lecciones aprendidas de PCI sobre un sistema de tratamiento de agua segura basado en la naturaleza, que utiliza los llamados biofiltros, como piedra, grava, arena y carbón. Este artículo parte de los ensayos para la construcción del sistema, la explicación del funcionamiento de este hasta su implementación en las comunidades. El sistema de agua segura basado en la naturaleza resulta efectivo para poblaciones pequeñas y proporciona una solución a una problemática de larga data en el territorio chaqueño. Su construcción es fácil, de corto plazo y mucho menos costoso que el sistema convencional de tratamiento de agua. Así también, la construcción conjunta del sistema con los pobladores, la capacitación técnica a los mismos en su operación y mantenimiento, contribuyen enormemente a la sostenibilidad de este. Este artículo es una contribución a la identificación, aplicación y estudio de sistemas de agua adecuados para zonas de difícil acceso a este líquido vital, como es el caso del Chaco paraguayo. Además, se trata de un sistema innovador y ecológico, es decir, amigable con el medio ambiente.

Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm - 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus.