Design and Validation of a Modular Biochar-Based Water Purification System for Rural Communities

Abstract

Access to clean drinking water remains a global challenge, especially in rural, low-resource areas lacking conventional treatment infrastructure. This study introduces a low-cost, multi-stage modular water purification system designed for decentralized domestic use. It integrates coarse sedimentation, granular media filtration and biochar adsorption, using sustainable, locally sourced materials for affordability. A key feature is the use of cocoa shell-derived activated carbon produced via optimized pyrolysis and chemical activation, offering high adsorption capacity for contaminants while remaining cost-effective. The system was tested in a lab with contaminated water typical of rural sources. Results showed significant improvements: turbidity dropped by 65.7% (9.53 NTU to 3.27 NTU), total dissolved solids fell by 30.3% (29.67 mg/L to 20.67 mg/L), and microbial contamination decreased by over 92% (190 CFU/mL to <15 CFU/mL). Adsorption kinetics, analyzed with Langmuir and Freundlich models, favored Langmuir (R² > 0.98), with a maximum capacity of 4.05 mg/g for calcium ions. Performance met WHO and Nigerian drinking water standards, achieving over 90% compliance. Operating under gravity without external energy, the system costs ~USD 200 per unit, making it viable for low-income households. Its modular design supports easy maintenance and scalability. This work advances sustainable water purification by validating an empirical design with evidence-based results, highlighting biochar-based systems as a solution for water insecurity in resource-limited settings.