PRB Technology Incorporating Acidic Ground Conditions and Bio-Geochemical Clogging – A Critical Review

Groundwater acidity resulting from pyrite oxidation in acid sulphate soil terrain presents a severe threat to the environment. The exposure of low-lying acidic coastal belts to the atmospheric oxygen, exacerbated by phreatic surface lowering in dry seasons and activities like infrastructure development and agriculture, leads to pyrite oxidation and sulfuric acid production in soil. This paper reviews the challenges posed by acid sulphate soils by emphasising the environmental and infrastructure damage caused by acidic soil leaching into water bodies. Permeable reactive barriers (PRBs) have emerged as a promising method of passive treatment for mitigating groundwater acidity in pyritic terrain. This review mainly focuses on the effectiveness of PRBs in low-lying floodplains by addressing the bio-geochemical clogging that diminishes the reactivity and porosity of PRBs over time. This paper also summarises the numerical methods needed to design PRBs in acidic terrains by identifying gaps in current research that could enhance the accuracy of future PRB designs. This comprehensive review contains valuable insights into the ongoing efforts of addressing the challenges associated with groundwater contamination in regions containing acid sulphate soil.