Hydraulic Performance Evaluation Of Multi-Layer Natural Media Filtration Systems Using A Structural Scoring Approach

Abstract

This study proposes a structural scoring model to evaluate the hydraulic performance of a simple multi-layer natural media filtration system based on appropriate technology principles. The model integrates pore size hierarchy and layer importance to quantify the structural arrangement of filtration media. Six filtration materials, including biofill, sand, zeolite 
gravel, coconut coir, palm fiber, and charcoal, were arranged into seven different layer combinations and tested under laboratory conditions with two replicates per treatment. A fixed water volume of 300 mL was filtered, and flow rate was calculated based on total filtration time. The results showed substantial variation in hydraulic performance, with flow rates ranging from 6.80 × 10−7to 2.70 × 10−6m³/s. The highest flow rate was observed in configurations dominated by coarse pore structures, whereas the lowest flow rate occurred in configurations containing finer media distributions and higher hydraulic resistance. Pearson correlation analysis produced a moderate negative relationship between structural score and flow rate (r = −0.587), indicating that higher structural scores tend to reduce flow velocity due to increased internal resistance within the layered filtration system. Linear regression analysis generated the equation Q =4.50 × 10−6 −3.99×10−8S, confirming the inverse relationship between structural arrangement and hydraulic behavior. 
The findings demonstrate that media arrangement plays a more important role than material composition alone in determining filtration performance. The proposed structural scoring model provides a simple and practical approach for evaluating and optimizing low-cost filtration systems, particularly for resource-limited and emergency conditions.