Using Permeable Reactive Barriers to Remediate Heavy Metal-Contaminated Groundwater through a Laboratory Column Experiment

Somean Yin,Sokchhay Heng,Gemunu Herath,Senajith Kalpage

doi:10.3844/ajessp.2017.103.115

Somean Yin, Sokchhay Heng + Show 2 more

Open Access

https://doi.org/10.3844/ajessp.2017.103.115

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Abstract

Recently, groundwater sources are being polluted by various activities such as agriculture, livestock, decentralized wastewater treatment systems and acid rain. Groundwater can also be polluted by landfill leachate, sewage, mine tailings, non-engineered deep well disposal of liquid waste and seepage from industrial waste lagoons. There are many studies reported contaminated groundwater remediation using Permeable Reactive Barrier systems (PRBs) and many countries happen to use this system to eliminate groundwater contaminants. This study reports the outcomes of the batch and the column test experiments conducted to evaluate the removal efficiency of four heavy metals: Cd(II), Cu(II), Fe(II) and Pb(II) using five locally available reactive materials (in Sri Lanka) with grain sizes less than or equal to 2.0 mm: Red Soil (RS), Laterite Soil (LS), Bangadeniya Soil (BS), Burnt Clay Tile (BCT) and Coconut Shell Biochar (CSB) as PRB materials. Seven columns (A-G) were filled with the reactive material of CSB (column E) and reactive material mixtures; RS + CSB (column A), LS + CSB (column B), BCT+CSB (column C), BS + CSB (column F), RS + LS (column G), with a weight ratio of 50:50 and RS + BCT + CSB (column D) with a weight ratio of 100/3:100/3:100/3. The results showed that the reactive materials filled in column A, B, D, F and G removed the metal concentrations, with a removal efficiency of over 90%, except Cd in the column with BCT + CSB mixture. Considering both the removal efficiency and the hydraulic conductivity of the columns, materials in column A, B, D and F are more effective than the others as PRB adsorbents for heavy metal remediation, while columns C and E have lower removal efficiency.

Highlights

There are many heavy metal elements present in the earth’s crust as well as metal elements released from industrial effluents such as microelectronics, electroplating, battery manufacture, metallurgical and fertilizer industries, or acid rain breaking down soils releasing heavy metals into streams, lakes, rivers and groundwater (Munagapati et al, 2009)
Knowing the particle size distribution, it is easy to improve the hydraulic conductivity of a mixture by changing the mixed proportion of Coconut Shell Biochar (CSB) with the other reactive materials
The test conducted on CSB was very difficult because it is rich of ash contents

Summary

Introduction

There are many heavy metal elements present in the earth’s crust as well as metal elements released from industrial effluents such as microelectronics, electroplating, battery manufacture, metallurgical and fertilizer industries, or acid rain breaking down soils releasing heavy metals into streams, lakes, rivers and groundwater (Munagapati et al, 2009). These metals can dissolve in groundwater by natural processes or degradation of soil pH. Heavy metals may cause diseases to humans such as lung damage, renal damage, Wilson’s disease (neurological or psychiatric symptoms of liver disease, compounded with heavy metal deposits), insomnia, dermatitis, nausea, chronic asthma, headache, dizziness, rapid respiration, coughing and cancer, etc. (Meena et al, 2005; Guzel et al, 2008)

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