Filtración sostenible para la provisión de agua potable en comunidades rurales en desarrollo utilizando biochar generado localmente

Abstract

The availability of a drinking water treatment system in developing rural communities is limited or the existing water treatment plant is inefficient, which does not guarantee the quality and safety of the resource for human consumption. Therefore, it is necessary to implement an accessible and highly efficient system that has sustainable solutions. The implementation of biochar as a filter bed in this type of systems is little researched, but due to its large use in sewage treatment and chemical pollutants removal and its ease of production, this research aimed to evaluate the efficiency of biochar as a filter media for drinking water treatment for developing communities. The study includes the production of biochar using as residual biomass: eucalyptus (E), bamboo (B) and banana stem (R), through two slow pyrolysis process denominated “a” and “b”, which differ from each other by their temperature and pyrolysis time, with average values around 300 °C and 60 minutes and 400 °C and 107 minutes, respectively. The efficiency of these materials in the filtration process with several types of water (raw, flocculated, and settled) at a rate of 120 m3 /m2 /d, was evaluated, finding that biochar derived from bamboo and manufactured under process “b” (Bb) was the best material filter. Then, under the same operating conditions, Bb was assessed in three different granulometry, determining that the finest effective size (0.65 mm) was the best in the filtration process. Subsequently, this biochar was compared with conventional filter materials such as gravel, sand and anthracite, with several types of water (raw, flocculated and settled) and at different filtration rates (120 and 240 m3 /m2 /d), for the removal of physical parameters (turbidity and color). Thus, it was found that the best filtration media was precisely biochar, with average turbidity and color removal efficiencies, respectively, of 64.37 and 45.08 % for raw water, 93.9 and 90.75 % for flocculated water, and 80.79 and 69.03 %, for settled water. Similarly, the removal of chemical and biological parameters was assessed at a rate of 180 m3 /m2 /d, obtaining the following efficiencies for biochar: copper 75.9 %, aluminum 90.72 %, iron 95.7 %, nitrates 10.9 %, total coliforms 94.3 % and fecal coliforms 88.9 %. Consequently, it was determined that the efficiencies achieved by biochar to remove these metals and total coliforms were the highest among the compared filter beds. Additionally, it was possible to demonstrate that the volume of washing water required by the biochar is lower than that of the other beds. Finally, the efficiencies of turbidity and color removal for mixed beds were assessed (combining various materials), finding that for the treatment of flocculated and settled water, biochar contributes to improving the performance of sand and anthracite in the filtration process. Also, it helps to reduce the volume of water required by these beds during the washing process. The results point to locally produced biochar as a viable option for the provision of drinking water in developing rural communities and an alternative to take into consideration for the achievement of the sixth Sustainable Development Goal by 2030: universal access to water, sanitation, and hygiene