Graves Duane, Smith Jacques J, Chen Linxi, Kreinberg Allison, Wallace Brianna, White Robby
Geosyntec Consultants Inc., Knoxville, TN, 37922, USA.
Geosyntec Consultants Inc., Knoxville, TN, 37922, USA.
J Environ Manage. 2017 Oct 1;201:357-365. doi: 10.1016/j.jenvman.2017.06.013. Epub 2017 Jul 7.
Flue gas desulfurization (FGD) is a well-established air treatment technology for coal and oil combustion gases that commonly uses lime or pulverized limestone aqueous slurries to precipitate sulfur dioxide (SO) as crystalline calcium salts. Under forced oxidation (excess oxygen) conditions, FGD byproduct contains almost entirely (>92%) gypsum (CaSO·2HO), a useful and marketable commodity. In contrast, FGD byproduct formed in oxygen deficient oxidation systems contains a high percentage of hannebachite (CaSO·0.5HO) to yield a material with no commercial value, poor dewatering characteristics, and that is typically disposed in landfills. Hannebachite in FGD byproduct can be chemically converted to gypsum; however, the conditions that support rapid formation of gypsum require large quantities of acids or oxidizers. This work describes a novel, patent pending application of microbial physiology where a natural consortium of sulfur-oxidizing bacteria (SOB) was used to convert hannebachite-enriched FGD byproduct into a commercially valuable, gypsum-enriched product (US Patent Assignment 503373611). To optimize the conversion of hannebachite into gypsum, physiological studies on the SOB were performed to define their growth characteristics. The SOB were found to be aerobic, mesophilic, neutrophilic, and dependent on a ready supply of ammonia. They were capable of converting hannebachite to gypsum at a rate of approximately five percent per day when the culture was applied to a 20 percent FGD byproduct slurry and SOB growth medium. 16S rDNA sequencing revealed that the SOB consortium contained a variety of different bacterial genera including both SOB and sulfate-reducing bacteria. Halothiobacillus, Thiovirga and Thiomonas were the dominant sulfur-oxidizing genera.
烟气脱硫（FGD）是一种成熟的用于处理煤炭和石油燃烧废气的空气处理技术，通常使用石灰或石灰石粉水浆将二氧化硫（SO）沉淀为结晶钙盐。在强制氧化（过量氧气）条件下，FGD副产品几乎完全（>92%）是石膏（CaSO·2HO），这是一种有用且有市场价值的商品。相比之下，在缺氧氧化系统中形成的FGD副产品含有高比例的汉内巴石（CaSO·0.5HO），从而产生一种没有商业价值、脱水特性差且通常被填埋处理的物质。FGD副产品中的汉内巴石可以通过化学方法转化为石膏；然而，支持快速形成石膏的条件需要大量的酸或氧化剂。这项工作描述了一种新颖的、正在申请专利的微生物生理学应用，其中利用硫氧化细菌（SOB）的天然菌群将富含汉内巴石的FGD副产品转化为具有商业价值的、富含石膏的产品（美国专利申请号503373611）。为了优化汉内巴石向石膏的转化，对SOB进行了生理学研究以确定其生长特性。发现SOB是需氧、嗜温、嗜中性的，并且依赖于充足的氨供应。当将培养物应用于20%的FGD副产品浆液和SOB生长培养基时，它们能够以每天约5%的速率将汉内巴石转化为石膏。16S rDNA测序显示，SOB菌群包含多种不同的细菌属，包括SOB和硫酸盐还原细菌。嗜盐硫杆菌属、硫弧菌属和硫单胞菌属是主要的硫氧化菌属。
