Influence of operating conditions on sulfate reduction from real mining process water by membrane biofilm reactors
| Autor: | Marcelo Aybar, Benjamín Poch, José Ignacio Suárez, Alex Schwarz, Bruce E. Rittmann, Patricio Martínez, Ivan Nancucheo |
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| Rok vydání: | 2019 |
| Předmět: |
Environmental Engineering
Health Toxicology and Mutagenesis Hydrogen sulfide 0208 environmental biotechnology Alkalinity 02 engineering and technology 010501 environmental sciences Wastewater 01 natural sciences Waste Disposal Fluid Mining Water Purification chemistry.chemical_compound Bioreactors Mass transfer Environmental Chemistry Sulfate-reducing bacteria Sulfate 0105 earth and related environmental sciences Autotrophic Processes Membranes Bacteria Precipitation (chemistry) Sulfates Public Health Environmental and Occupational Health Biofilm Membranes Artificial General Medicine General Chemistry Pollution 020801 environmental engineering Membrane Chemical engineering chemistry Biofilms Oxidation-Reduction Water Pollutants Chemical Hydrogen |
| Zdroj: | Chemosphere. 244 |
| ISSN: | 1879-1298 |
| Popis: | Two H2-based membrane biofilm reactor (H2-MBfR) systems, differing in membrane type, were tested for sulfate reduction from a real mining-process water having low alkalinity and high concentrations of dissolved sulfate and calcium. Maximum sulfate reductions were 99%, with an optimum pH range between 8 and 8.5, which minimized any toxic effect of unionized hydrogen sulfide (H2S) on sulfate-reducing bacteria (SRB) and calcite scaling on the fibers and in the biofilm. Although several strategies for control of pH and gas back-diffusion were applied, it was not possible to sustain a high degree of sulfate reduction over the long-term. The most likely cause was precipitation of calcite inside the biofilm and on the surface of fibers, which was shown by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) analysis. Another possible cause was a decline in pH, leading to inhibition by H2S. A H2/CO2 mixture in the gas supply was able to temporarily recover the effectiveness of the reactors and stabilize the pH. Biomolecular analysis showed that the biofilm was comprised of 15-20% SRB, but a great variety of autotrophic and heterotrophic genera, including sulfur-oxidizing bacteria, were present. Results also suggest that the MBfR system can be optimized by improving H2 mass transfer using fibers of higher gas permeability and by feeding a H2/CO2 mixture that is automatically adjusted for pH control. |
| Databáze: | OpenAIRE |
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