A Laboratory Study on the Filtration and Clogging of the Sand-Bottom Ash Mixture for Stormwater Infiltration Filter Media

Ezequiel Segismundo,Byung-Sik Lee,Lee-Hyung Kim,Sang-Man Jeong

doi:10.3390/w9010032

Abstract

The performance of stormwater infiltration systems depends significantly on the infiltration/filtration characteristics of filter media. Sand media have been frequently used due to their abundance and acceptable pollutant removal efficiency. Bottom ash media, which was known to have a high sorption capacity, are being considered as alternative and/or complement filter media to enhance the overall treatment efficiency. To verify the applicability of bottom ash as filter media, a series of 1-D column infiltration tests were conducted in this study. The filtration and clogging characteristics of the sand-bottom ash mixtures at different mixing ratios were investigated with limitedly focusing on the Total Suspended Solids (TSS) present in stormwater runoff. As a result, the presence of bottom ash was identified to improve the TSS removal efficiency in spite of having a significant increase in clogging potential. All media configurations were observed to experience the premature clogging and the clogging state for varying and constant head flow conditions, respectively. The noticeable amount of crushed bottom ash particles brought by seepage force could be accountable for the rapid occurrence of clogging phenomena. Overall, a homogeneous sand filter is preferred as long as the lifespan of filter system is the primary concern.

Highlights

Urbanization is known to alter watershed hydrology; as land becomes covered with surfaces impervious to rain that leads to an increase in volume and rate of rainfall runoff, and water is redirected from evapotranspiration and groundwater recharge to stormwater runoff [1,2]
In the operation of best management practices (BMPs) employing filtration/infiltration as its primary mechanism, its function is inevitably reduced with time due to clogging as mirrored in the variation in the amount and quality of treated runoff
Both sand and bottom ash are the filter media selected in preparing different filter columns that were characterized by its media configurations

Summary

Introduction

Urbanization is known to alter watershed hydrology; as land becomes covered with surfaces impervious to rain that leads to an increase in volume and rate of rainfall runoff, and water is redirected from evapotranspiration and groundwater recharge to stormwater runoff [1,2]. The development of urban area is well known in increasing impervious areas that generate non-point source pollutants. To ease the negative effect of urbanization in the quantity and quality of stormwater runoff, stormwater management systems such as best management practices (BMPs) which include dry and wet ponds, constructed wetlands, tree box filters, infiltration trenches, rain gardens, etc. Structural BMPs are typically designed to reduce the negative impacts of the stormwater pollutants and increase the amount of urban particle control [4,5]. BMP structures usually employ filtration/infiltration and/or settling mechanism in treating stormwater runoff pollutants. In the operation of BMPs employing filtration/infiltration as its primary mechanism, its function is inevitably reduced with time due to clogging as mirrored in the variation in the amount and quality of treated runoff. Clogging is a common phenomenon that occurs in any filtration system and is defined as

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