scholarly journals Effects of Contact Time and Flow Configuration on the Acid Mine Drainage Remediation Capabilities of Pervious Concrete

2021 ◽  
Vol 13 (19) ◽  
pp. 10847
Author(s):  
Sandisiwe Khanyisa Thisani ◽  
Daramy Vandi Von Kallon ◽  
Patrick Byrne
Keyword(s):  
Acid Mine Drainage ◽  
Contact Time ◽  
Mine Drainage ◽  
Permeable Reactive Barriers ◽  
Pervious Concrete ◽  
Gravity Flow ◽  
Flow Configuration ◽  
Acid Mine ◽  
Remediation Efficiency ◽  
Flow Configurations

This paper investigates the Acid Mine Drainage (AMD) remediation capabilities of pozzolanic pervious concrete Permeable Reactive Barriers (PRBs) with a specific focus on the effects of flow configuration and contact time on the remediation efficiency. Raw AMD was collected from an abandoned coal mine. Two flow configurations, gravity flow and column flow, were tested at a laboratory scale with gradually increasing contact times. The gravity flow configuration with two orders of magnitude less liquid-concrete contact time achieved AMD treated water quality equivalent to the high retention column flow configuration. Concentrations of iron, aluminium, sulphate, magnesium and sodium were reduced by more than 99%, 80%, 17%, 22% and 20%, respectively, at the tested limits while calcium and potassium concentrations were increased by up to 16% and 300%, respectively. The study findings indicate that the lifecycle costs of pervious concrete PRBs can be significantly reduced when the PRBs are operated under gravity flow.

Evaluation of Pore Volume, Connectivity and Clogging of Previous Concrete Reactive Barrier in Treatment of Acid Mine Drainage

2021 ◽  
Author(s):  
Stephen O. Ekolu ◽  
Fitsum Solomon ◽  
Frikkie de Beer ◽  
Louisette Bitandi ◽  
Rais N. Kilula ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Pore Volume ◽  
Mine Drainage ◽  
Permeable Reactive Barrier ◽  
Pervious Concrete ◽  
Permeability Test ◽  
Reactive Barrier ◽  
Acid Mine ◽  
Treated Effluent ◽  
Pore Clogging

Abstract It has recently been shown that pervious concrete is a promising, effective technology as permeable reactive barrier for treatment of acid mine drainage (AMD). However, pore clogging also occurs simultaneously during AMD treatment. In the present study, mixtures of pervious concrete were made and used in a column experiment during which pore clogging occurred in the samples. Pore volume, connectivity and other parameters of pervious concrete were evaluated using five (5) different methods comprising the volumetric method (VM), linear – traverse method (LTM), image analysis (IA), falling head permeability test and X - ray micro - computed tomography. It was found that pervious concrete effectively removed from AMD, about 90 to 99% of various heavy metals including Al, Fe, Zn, Mn and Mg. Cr concentration significantly increased in the treated effluent, owing to leaching from cementitious materials used in mixtures. The VM and LTM gave statistically similar pore volume results, while IA’s values were 20 to 30% higher than those of the conventional methods. The falling head permeability test and IA were found to be effective in quantifying pore clogging effects. Pervious concrete exhibited high pore connectivity of 95.0 to 99.7%, which underlies its efficacious hydraulic conductivity.

scholarly journals Quality of water recovered by treating acid mine drainage using pervious concrete adsorbent

Water SA ◽  
2019 ◽  
Vol 45 (4 October) ◽  
Author(s):  
AN Shabalala ◽  
SO Ekolu
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Acid Mine Drainage ◽  
Mine Drainage ◽  
Permeable Reactive Barrier ◽  
Pervious Concrete ◽  
Silica Sand ◽  
Reactive Material ◽  
Acid Mine

In this paper, a batch experiment was conducted to evaluate the water quality obtained from using pervious concrete (PERVC) technology to treat acid mine drainage (AMD). The study proposes an innovative application of PERVC as a permeable reactive barrier liner in evaporation ponds. The effectiveness of PERVC adsorbent in removing heavy metals was compared with that of zero-valent iron (ZVI) of particle size 1.0 to 1.8 mm. The AMD used in the study was obtained from abandoned gold and coal mines. PERVC mixtures consisted of granite aggregate and ordinary Portland cement CEM I 52.5R (CEM I) or CEM I containing Class F 30% fly ash (30%FA) as a cement replacement material. ZVI was prepared from a mixture of silica sand and iron grit of specific sizes. PERVC and ZVI media were used to conduct batch reactor tests with AMD, for a period of 43 days at a ratio of 1 L of reactive material to 3 L of AMD. The quality of treated AMD was compared against effluent discharge standards. The contaminants Al, Fe and Zn were effectively removed by both PERVC and ZVI. Also, both adsorbents reduced Ni, Co and Cu to levels below those measured in raw AMD. However, PERVC was more effective in removing Mn and Mg while ZVI was ineffective. Although PERVC removed more heavy metals and with greater efficiency than ZVI, the PERVC-treated water showed high pH levels and exhibited elevated Cr6+ concentrations, owing to leaching from the cement and fly ash materials used in PERVC mixtures.

Sign in / Sign up

Export Citation Format

Share Document