Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85287, United States; Center for Bio-mediated & Bio-inspired Geotechnics, Arizona State University, 425 E University Dr, Tempe, AZ 85281, United States; School for Engineering of Matter, Transport and Energy, Arizona State University, 501 E Tyler Mall, Tempe, AZ 85281, United States.
Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85287, United States; Center for Bio-mediated & Bio-inspired Geotechnics, Arizona State University, 425 E University Dr, Tempe, AZ 85281, United States.
J Hazard Mater. 2022 Mar 5;425:128054. doi: 10.1016/j.jhazmat.2021.128054. Epub 2021 Dec 9.
Lignocellulosic sulfate-reducing bioreactors are an inexpensive passive approach for treatment of mining-influenced water (MIW). Typically, microbial community acclimation to MIW involves bioreactor batch-mode operation to initiate lignocellulose hydrolysis and fermentation and provide electron donors for sulfate-reducing bacteria. However, batch-mode operation could significantly prolong bioreactor start-up times (up to several months) and select for slow-growing microorganisms. In this study we assessed the feasibility of bioreactor continuous-mode acclimation to MIW (pH 2.5, 6.5 mM SO, 18 metal(loid)s) as an alternate start-up method. Results showed that bioreactors with spent brewing grains and sugarcane bagasse achieved acclimation in continuous mode at hydraulic retention times (HRTs) of 7-12-d within 16-22 days. During continuous-mode acclimation, extensive SO reduction (80 ± 20% -91 ± 3%) and > 98% metal(loid) removal was observed. Operation at a 3-d HRT further yielded a metal(loid) removal of 97.5 ± 1.3 -98.8 ± 0.9% until the end of operation. Sulfate-reducing microorganisms were detected closer to the influent in the spent brewing grains bioreactors, and closer to the effluent in the sugarcane bagasse bioreactors, giving insight as to where SO reduction was occurring. Results strongly support that a careful selection of lignocellulose and bioreactor operating parameters can bypass typical batch-mode acclimation, shortening bioreactor start-up times and promoting effective MIW metal(loid) immobilization and treatment.
木质纤维素硫酸盐还原生物反应器是一种廉价的被动方法，可用于处理受采矿影响的水（MIW）。通常，微生物群落对 MIW 的适应涉及生物反应器批处理操作，以启动木质纤维素水解和发酵，并为硫酸盐还原菌提供电子供体。然而，批处理操作可能会显著延长生物反应器的启动时间（长达数月），并选择生长缓慢的微生物。在这项研究中，我们评估了生物反应器连续模式适应 MIW（pH 2.5、6.5 mM SO、18 种金属（loid））作为替代启动方法的可行性。结果表明，用废啤酒糟和甘蔗渣的生物反应器在水力停留时间（HRT）为 7-12 天的情况下，在 16-22 天内以连续模式实现了适应。在连续模式适应过程中，观察到大量的 SO 还原（80±20%-91±3%）和>98%的金属（loid）去除。在 3 天的 HRT 下运行，进一步得到了 97.5±1.3%-98.8±0.9%的金属（loid）去除率，直到运行结束。在废啤酒糟生物反应器中，硫酸盐还原微生物更靠近进水口，而在甘蔗渣生物反应器中则更靠近出水口，这表明 SO 还原发生的位置。研究结果强烈支持，仔细选择木质纤维素和生物反应器操作参数可以绕过典型的批处理适应，缩短生物反应器的启动时间，并促进有效的 MIW 金属（loid）固定和处理。
