赤泥微生物脱碱试验及机理探究

赤泥是制铝行业产生的碱性工业废渣，其强碱性是制约赤泥综合利用的主要因素。利用微生物对赤泥进行脱碱以降低赤泥对环境的危害。探究了巨大芽孢杆菌菌粉添加量、处理时间、液固比、培养方式及空气供应等条件对赤泥脱碱的影响。借助XRD、SEM分别对赤泥及脱碱渣进行矿相组成和表面形貌分析，利用HPLC对菌株进行产酸分析。结果表明，在赤泥用量20 g、菌粉添加量20 g、液固比7.5，震荡培养条件下，赤泥试样的pH可从10.3降至6.5左右，且最终可以保持在7.5；赤泥中主要的含碱矿物钙霞石衍射峰明显减弱，碳酸钙衍射峰加强；经过处理之后的脱碱渣物理结构更加规则；赤泥pH降低是微生物代谢产生的酸中和作用所致，巨大芽孢杆菌代谢有机酸主要为丙酸和苹果酸。

Experiment and Mechanism of Microbial Dealkalization in Red Mud

Red mud is an alkaline industrial waste produced in aluminum industry, and its strong alkalinity prove to be the primary factor restricting the comprehensive utilization of red mud. Microbial dealkalization of red mud was studied to reduce the harm to the environment. The effects of Bacillus megatherium powder addition amount, treatment time, liquid-solid ratio, culture method and air supply on the dealkalization of red mud were investigated. The mineral-phase composition and surface morphology of red mud and its dealkalization slag were characterized by XRD and SEM test, and acid production of strain was analyzed by HPLC. The results show that pH value of red mud samples drops from 10.3 to 6.5, and keeping a constant figure at 7.5 under the conditions including shock culture, amount of red mud of 20 g, amount of bacteria powder of 20 g, the ratio of liquid to solid of 7.5. The XRD analysis implies that the diffraction peak of calcium nepheline tremendously weakened, while that of calcium carbonate is strengthened. The SEM results exhibit a more regular physical morphology of dealkalization slag treated by microorganism. The decrease of pH of red mud results from the neutralization of acid produced by microbial metabolism. The HPLC data demonstrates that the organic acids metabolized by Bacillus megaterium are mainly propionic acid and malic acid.