Slow filtration technology with biochar: behavioral assessment of the physicochemical parameters of water

Given the population’s needs regarding the availability of treated water for communities, especially the most isolated ones, this study aimed to evaluate the behavior of physicochemical parameters: total iron (TI) and electrical conductivity (EC) as a function of pH, total dissolved solids (TDS) and temperature, in groundwater treatment, using slow filtration with cactus biochar as a filter layer. For this purpose, a hydraulic groundwater collection system (consisting of a pumping system and reservoirs) was used, coupled to a slow filter made of glass with a triple filtration layer (sand, biochar, and sand) and a constant filtration rate of approximately 3 m 3 /m 2 day, with variations in water level. Furthermore, the biochar was produced using biomass from the palm cactus, pyrolyzed at 450.0 °C for 30 min, without activation. Thus, the results indicated that EC correlated directly with temperature, with removals greater than 35% observed around 26.0 °C and pH 6.0. The TI also showed better removals (99.6%) under similar conditions, remaining below legal limits. The system was also efficient in reducing dissolved ions, evidenced by reduction in electrical conductivity. The minimal variations in pH and temperature were positive for the stability of the process. Therefore, it was observed that, although the large area required for slow sand filtration systems may limit their application in urban areas, the use of unconventional materials in this technology may represent an alternative for water treatment. Such studies may contribute to the development of more sustainable and accessible water treatment solutions for different application contexts.