Reduction and Accumulative Characteristics of Dissolved Heavy Metals in Modified Bioretention Media

Abstract

Twelve bioretention filter columns with different media were designed to study the effects of media on dissolved heavy metals in bioretention systems by changing three test conditions (inflow concentration, discharge ratio, and recurrence interval). The results showed that the average load reduction efficiency of the bioretention soil media (BSM)+10%water treatment residue, BSM+10%green zeolite, and BSM+10%medicinal stone for Cu and Zn was larger than 80%. The highest volume reduction efficiency is 39.25% by BSM+coconut bran. Among the three factors selected in tests, inflow concentration had the biggest degree of influence, followed by discharge ratio and recurrence interval. The media of the upper, middle, and lower layers of each filter column were detected before and after the treatment to study the accumulative characteristics of heavy metals in the bioretention system. The accumulation of Cu, Zn, and Cd in the media of BSM+medicinal stone, BSM+fly ash, BSM+vermiculite, and BSM+turfy soil was relatively low. The contents of the three metals were positively correlated with urease and negatively correlated with protease in the media, but no obvious rule was showed in the accumulation of dissolved heavy metals with depth.

Distribution of Heavy Metals in Vegetative Biofiltration Columns

“…The only variable considered was the plant. Previous studies have shown that metal distribution in vegetative systems is affected by some other factors such as inflow concentration, discharge ratio and recurrence interval on metals accumulation [43]. It was found that heavy metals are mostly accumulated in soils and roots.…”

Urban stormwater nutrient and metal removal in small-scale green infrastructure: exploring engineered plant biofilter media optimisation

“…In an effort to optimise plant biofilters, the introduction of engineered growth media such as zeolite (see Li et al 2014), perlite (see Le Coustumer et al 2012) and vermiculite (see Li et al 2018) in combination with traditional loamy sand as a carbon source (see Bratieres et al 2008) may potentially increase stormwater remediation efficacy and biofilter longevity (Chandrasena et al 2017). It is therefore important to not only optimise growth media, but also to consider the effects of the media on plant health and vitality (Malézieux et al 2007).…”