Municipal Wastewater Treatment using Fluidized bed Bioreactors with Biofilms Fixed on Natural Supports Derived from Cacti

Abstract In recent years, the population in Western Guatemala has grown, increasing the demand for water and basic services, alongside a rise in waste production. Notably, wastewater generation has had a significant environmental impact on water bodies, leading to eutrophication and other harmful effects that negatively influence the quality of life and health of people. This project focused on assessing the technical feasibility of using fluidized bed bioreactors under aerobic and anaerobic conditions, employing natural supports derived from cactus materials native to Guatemala as an improvement over conventional plastic support. The research was divided into four stages: 1. Characterization of wastewater from the basin of interest. 2. Collection, treatment, and characterization of two cactus materials ( Stenocereus spp. & Opuntia spp.) to be used as supports in the fluidized reactors. 3. Evaluation of treatment in fluidized bed bioreactors under aerobic and anaerobic conditions. 4. Development of mathematical models to describe the experimental data. The main results of the research included the removal of chemical oxygen demand (COD) in synthetic wastewater, achieving a range of 50% to 63% using fluidized bed reactors. During the research period, the Samalá River showed average COD values of 96.38 and 277. Biological oxygen demand (BOD) averaged 68.38 and 129.40. Nitrogen levels averaged 2.16 and 17.40. Phosphorus levels averaged 3.55 and 11.11. The most efficient natural support and treatment method was Stenocereus spp. with aeration, achieving a 86.76% reduction in COD. The reaction exhibited zero-order kinetics with an equation of K = −1.75 · 10 −4 ±0.15.