Biofilter media gas pressure loss as related to media particle size and particle shape

Pressure loss (ΔP) is a key parameter for estimating biofilter energy consumption. Accurate predictions of ΔP as a function of air velocity (V) are therefore essential, to assess energy consumption and minimize operation costs. This paper investigates the combined impact of medium particle size and shape on the V - ΔP relationship. V - ΔP measurements were performed using three commercially available materials with different particle shapes: crushed granite (very angular particles), gravel (particles of intermediate roundness) and Leca® (almost spherical particles). A total of 21 different particle size fractions, with particle sizes ranging from 2 to 14 mm, were considered for each material. As expected, ΔP decreased with increasing particle size in agreement with earlier findings. ΔP, however, also showed a tendency to decrease with increasing particle roundness especially for fractions containing smaller particles. A new model concept for estimating V - ΔP across different particle size fractions and shapes was proposed. This model yielded improved prediction accuracy in comparison with existing prediction approaches.