Assessment of cockle shells, walnut shells, and gingko shells as filter media for low impact development technologies

Abstract

In this study, biowaste such as walnut shells (WS), cockle shells (CS), and gingko shells (GS) was evaluated for applicability as soil filter media in low impact development (LID) techniques. Biowastes used in the experiment showed light-weight, high porosity, and high permeability characteristics compared with sand or gravel which are conventionally used in LID. Especially, CS and WS showed high non-point pollutant removal efficiency due to protrusion of filter media surface and macroand micro-porous. CS were found to be suitable for the infiltration capacity, as it showed high filtration and pollutant reduction. WS exhibited high heavy metal removal performance but was found to have possibility of organic matter leaching. GS were evaluated to be adaptable to green roof as filter media with light-weight and constant filtration capability. The findings of this research are useful for the application of biowaste as filter media in LID techniques.