Fabrication and characterization of a novel Ba2+-loaded sawdust biochar doped with iron oxide for the super-adsorption of SO42- from wastewater

A review of passive acid mine drainage treatment by PRB and LPB: From design, testing, to construction

An extensive volume of acid mine drainage (AMD) generated throughout the mining process has been widely regarded as one of the most catastrophic environmental problems. Surface water and groundwater impacted by pollution exhibit extreme low pH values and elevated sulfate and metal/metalloid concentrations, posing a serious threat to the production efficiency of enterprises, domestic water safety, and the ecological health of the basin. Over the recent years, a plethora of techniques has been developed to address the issue of AMD, encompassing nanofiltration membranes, lime neutralization, and carrier-microencapsulation. Nonetheless, these approaches often come with substantial financial implications and exhibit restricted long-term sustainability. Among the array of choices, the permeable reactive barrier (PRB) system emerges as a noteworthy passive remediation method for AMD. Distinguished by its modest construction expenses and enduring stability, this approach proves particularly well-suited for addressing the environmental challenges posed by abandoned mines. This study undertook a comprehensive evaluation of the PRB systems utilized in the remediation of AMD. Furthermore, it introduced the concept of low permeability barrier, derived from the realm of site-contaminated groundwater management. The strategies pertaining to the selection of materials, the physicochemical aspects influencing long-term efficacy, the intricacies of design and construction, as well as the challenges and prospects inherent in barrier technology, are elaborated upon in this discourse.

Revealing the role of calcium alginate-biochar composite for simultaneous removing SO42- and Fe3+ in AMD: Adsorption mechanisms and application effects

The remediation of acid mine drainage (AMD) is particularly challenging because it contains a large amount of Fe³⁺ and a high concentration of SO₄^2-. To reduce the pollution caused by SO₄^2- and Fe³⁺ in AMD and realize the recycling of solid waste, this study used distillers grains as raw materials to prepare biochar at different pyrolysis temperatures. Calcium alginate-biochar composite (CA-MB) was further synthesized via the entrapment method and used to simultaneously remove SO₄^2- and Fe³⁺ from AMD. The effects of different influencing factors on the sorption process of SO₄^2- and Fe³⁺ were studied through batch adsorption experiments. The adsorption behaviors and mechanisms of SO₄^2- and Fe³⁺ were investigated with different adsorption models and characterizations. The results showed that the adsorption process of CA-MDB600 on SO₄^2- and Fe³⁺ could be well described by Elovich and Langmuir-Freundlich models. It was further proved by the site energy analysis that the adsorption mechanisms of SO₄^2- onto CA-MDB600 were mainly surface precipitation and electrostatic attraction, while that of Fe³⁺ removal was attributed to ion exchange, precipitation, and complexation. The applications of CA-MDB600 in actual AMD proved its good application potential. This study indicates that CA-MDB600 could be applied as a promising eco-friendly adsorbent for the remediation of AMD.