{"title":"Effects of batch and continuous-flow operation on biotreatment of Mn(II)-containing mine drainage","authors":"Obey Gotore , Miho Watanabe , Kunihiro Okano , Naoyuki Miyata , Taiki Katayama , Tetsuo Yasutaka , Yuki Semoto , Takaya Hamai","doi":"10.1016/j.jes.2024.05.038","DOIUrl":null,"url":null,"abstract":"<div><p>The biotreatment of mine drainage containing dissolved manganese (Mn) using Mn(II)-oxidizing bacteria is challenging. Sequencing-batch (SBRs) and continuous-flow reactors (CFRs) packed with limestones and inoculated with the mine-drainage microbial community were compared to determine the removal efficiency of Mn(II) from mine drainage. Mn(II) removal in CFRs was 11.4%±0.0% (mean ± standard deviation) in the first two weeks and; it slightly increased to 13.6%±0.0% after four weeks, and more than 94% of Mn(II) was removed under the steady-state treatment phase. The performance of SBRs was more effective, wherein 24.4%±0.1% of Mn was removed in the first two weeks, and in four weeks, surpassed 66.6%±0.2%. Rapid Mn(II) removal observed in the start-up of SBR resulted from higher microbial metabolic activities. The adenosine triphosphate (ATP) content of the microbial community was four-fold more than in CFR, but comparable during the steady-state phase. The Mn-oxide deposits occurring in the SBR and CFR at steady-state were mixed phases of birnessite and woodruffite, and the average Mn oxidation valence in the SBR (+3.73) was slightly higher than that in the CFR (+3.54). During the start-up treatment, the closest relatives of <em>Methyloversatilis, Methylibium</em>, and <em>Curvibacter</em> dominated the SBR, whereas putative Mn oxidizers were associated with <em>Hyphomicrobium, Pedobacter, Pedomicrobium, Terricaulis sp</em>., <em>Sulfuritalea</em>, and <em>Terrimonas</em> organisms. The growth of potential Mn-oxidizing genera, including <em>Mesorhizobium, Rhodococcus, Hydrogenophaga, Terricaulis sp</em>., and ‘<em>Candidatus</em> Manganitrophus-noduliformans’ was observed under the steady state. The SBR operation was effective as a prior start-up treatment for mine drainage-containing Mn(II), through which the CFR performed well as posterior bio-treatment.</p></div>","PeriodicalId":15788,"journal":{"name":"Journal of Environmental Sciences-china","volume":null,"pages":null},"PeriodicalIF":5.9000,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Environmental Sciences-china","FirstCategoryId":"93","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1001074224002778","RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
The biotreatment of mine drainage containing dissolved manganese (Mn) using Mn(II)-oxidizing bacteria is challenging. Sequencing-batch (SBRs) and continuous-flow reactors (CFRs) packed with limestones and inoculated with the mine-drainage microbial community were compared to determine the removal efficiency of Mn(II) from mine drainage. Mn(II) removal in CFRs was 11.4%±0.0% (mean ± standard deviation) in the first two weeks and; it slightly increased to 13.6%±0.0% after four weeks, and more than 94% of Mn(II) was removed under the steady-state treatment phase. The performance of SBRs was more effective, wherein 24.4%±0.1% of Mn was removed in the first two weeks, and in four weeks, surpassed 66.6%±0.2%. Rapid Mn(II) removal observed in the start-up of SBR resulted from higher microbial metabolic activities. The adenosine triphosphate (ATP) content of the microbial community was four-fold more than in CFR, but comparable during the steady-state phase. The Mn-oxide deposits occurring in the SBR and CFR at steady-state were mixed phases of birnessite and woodruffite, and the average Mn oxidation valence in the SBR (+3.73) was slightly higher than that in the CFR (+3.54). During the start-up treatment, the closest relatives of Methyloversatilis, Methylibium, and Curvibacter dominated the SBR, whereas putative Mn oxidizers were associated with Hyphomicrobium, Pedobacter, Pedomicrobium, Terricaulis sp., Sulfuritalea, and Terrimonas organisms. The growth of potential Mn-oxidizing genera, including Mesorhizobium, Rhodococcus, Hydrogenophaga, Terricaulis sp., and ‘Candidatus Manganitrophus-noduliformans’ was observed under the steady state. The SBR operation was effective as a prior start-up treatment for mine drainage-containing Mn(II), through which the CFR performed well as posterior bio-treatment.
期刊介绍:
The Journal of Environmental Sciences is an international journal started in 1989. The journal is devoted to publish original, peer-reviewed research papers on main aspects of environmental sciences, such as environmental chemistry, environmental biology, ecology, geosciences and environmental physics. Appropriate subjects include basic and applied research on atmospheric, terrestrial and aquatic environments, pollution control and abatement technology, conservation of natural resources, environmental health and toxicology. Announcements of international environmental science meetings and other recent information are also included.