Arsenic treatment in Sargassum leachates
The degradation of beached Sargassum biomass releases arsenic (As)-rich leachates, posing environmental and health risks. A lab-scale anaerobic fixed-bed bioreactor using natural iron oxide-rich material was tested for As removal. Microbial and geochemical processes reduced As concentrations by 25–75%. Speciation analysis showed that while the input contained AsV, AsIII, and DMAsV, AsV was predominant in the reactor media. Microbial analysis revealed enrichment of prokaryotes involved in key redox reactions, including FeIII, nitrate, nitrite, sulfate, and sulfur reduction, as well as anaerobic FeII oxidation. These processes might include Feammox (ammonium oxidation coupled to FeIII reduction). Mineralogical analysis indicated transformation of FeIII phases and formation of nanogoethite, potentially promoting As immobilization via coprecipitation. Overall, interactions between iron oxides and Sargassum leachates under anaerobic conditions appear to enhance microbial processes that effectively sequester arsenic. This highlights the importance of microbial control in designing treatment systems for Sargassum leachates.
The degradation of beached Sargassum biomass releases arsenic (As)-rich leachates, posing environmental and health risks. A lab-scale anaerobic fixed-bed bioreactor using natural iron oxide-rich material was tested for As removal. Microbial and geochemical processes reduced As concentrations by 25–75%. Speciation analysis showed that while the input contained AsV, AsIII, and DMAsV, AsV was predominant in the reactor media. Microbial analysis revealed enrichment of prokaryotes involved in key redox reactions, including FeIII, nitrate, nitrite, sulfate, and sulfur reduction, as well as anaerobic FeII oxidation. These processes might include Feammox (ammonium oxidation coupled to FeIII reduction). Mineralogical analysis indicated transformation of FeIII phases and formation of nanogoethite, potentially promoting As immobilization via coprecipitation. Overall, interactions between iron oxides and Sargassum leachates under anaerobic conditions appear to enhance microbial processes that effectively sequester arsenic. This highlights the importance of microbial control in designing treatment systems for Sargassum leachates.
BRGM