Kinetic Modeling of Escherichia coli Removal Mechanisms in Faecal Sludge on Unplanted Sand-Drying Beds Using Moringa Oleifera as a Conditioner

The study delves into the process of eliminating Escherichia coli in unplanted sand-drying beds by using Moringa Oleifera (MO) as a natural conditioner. Researchers created a comprehensive model to forecast the bacterial removal rate (Ko) by examining factors such as adsorption, diffusion, filtration, solar radiation, temperature, and MO conditioning. Field experiments, involving various sand bed configurations and operational conditions, were conducted at the University of Dar es Salaam's dewatering facility. The data indicated a non-normal distribution of fecal Sludge characteristics, necessitating non-parametric statistical tests for precise data analysis. The research indicates a significant reduction in bacteria, with E. coli levels dropping from 6.2 × 10^6 CFU/100 mL to 2.1 × 10^4 CFU/100 mL, representing a 3.3 log removal. Adsorption, diffusion, and filtration accounted for 64.3% of bacterial removal, while MO conditioning contributed 34.7%. Solar radiation and temperature had minimal effects and were therefore excluded from the model. The developed model, Ko = 1.5 * 10^-6 * (μ/d) * (T/μ) ^0.66 * (t)^-0.33 + 5.54/(tC^n), incorporates factors such as Sludge viscosity, particle diameter, temperature, contact time, MO concentration, and dilution factor. When validated, the model exhibited a strong correlation (R² = 0.8526) with experimental data. The study underscores MO's efficacy as a sustainable, environmentally friendly conditioner for enhancing bacterial removal in fecal Sludge treatment.