炸药化合物RDX(六氢-1,3,5-三硝基-1,3,5-三嗪)对人类健康的潜在神经毒性和致癌作用需要地下水修复策略来满足低清除目标。通过使用有机碳供体对天然微生物进行生物刺激,RDX的生物修复是可行的,但效率可能较低,或者根本不发生,在常见的共污染物高氯酸盐和硝酸盐的存在下。实验室测试比较了生物刺激与生物增强以实现RDX的厌氧降解,高氯酸盐,和硝酸盐;然后使用选定的生物增强方法在裂隙岩石含水层中进行了现场中试测试。RDX的减少不显著,高氯酸盐,或者硝酸盐被微生物在微观世界中观察到,有或没有通过添加乳酸的生物刺激。最初开发用于氯化挥发性有机化合物脱卤的微生物聚生体WBC-2的RDX降解能力测试,显示出一级生物降解速率常数为每天0.57至0.90(半衰期1.2至0.80天)。当用RDX和乳酸反复修正一年时,WBC-2持续降解而没有子产物积累。在含有高氯酸盐和硝酸盐的地下水的微观世界中,当用10%WBC-2生物增强时,RDX降解开始没有延迟。3%或5%WBC-2修正剂的RDX降解较慢,表明与细胞密度有直接关系。瞬态RDX子化合物包括亚甲基二硝胺,MNX,DNXWBC-2修正案,硝酸盐浓度立即下降到接近或低于检测,高氯酸盐降解的半衰期为25-34天。用WBC-2和乳酸进行的单井注入测试表明,RDX降解的开始与硫化物产生的开始相吻合,受初始高氯酸盐浓度的影响。中试注射测试中的生物降解率与微观世界中测得的生物降解率非常吻合。这些结果支持厌氧培养作为被RDX污染的场所的补救策略的生物强化,硝酸盐,和高氯酸盐.
The potential neurotoxic and carcinogenic effects of the explosives compound RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) on human health requires groundwater remediation strategies to meet low cleanup goals. Bioremediation of RDX is feasible through biostimulation of native microbes with an organic carbon donor but may be less efficient, or not occur at all, in the presence of the common co-contaminants perchlorate and nitrate. Laboratory tests compared biostimulation with bioaugmentation to achieve anaerobic degradation of RDX, perchlorate, and nitrate; a field pilot test was then conducted in a fractured rock aquifer with the selected bioaugmentation approach. Insignificant reduction of RDX, perchlorate, or nitrate was observed by the native microbes in microcosms, with or without biostimulation by addition of lactate. Tests of the RDX-degrading ability of the microbial consortium WBC-2, originally developed for dehalogenation of chlorinated volatile organic compounds, showed first-order biodegradation rate constants ranging from 0.57 to 0.90 per day (half-lives 1.2 to 0.80 days). WBC-2 sustained degradation without daughter product accumulation when repeatedly amended with RDX and lactate for a year. In microcosms with groundwater containing perchlorate and nitrate, RDX degradation began without delay when bioaugmented with 10% WBC-2. Slower RDX degradation occurred with 3% or 5% WBC-2 amendment, indicating a direct relation with cell density. Transient RDX daughter compounds included methylene dinitramine, MNX, and DNX. With WBC-2 amendment, nitrate concentrations immediately decreased to near or below detection, and perchlorate degradation occurred with half-lives of 25-34 days. Single-well injection tests with WBC-2 and lactate showed that the onset of RDX degradation coincided with the onset of sulfide production, which was affected by the initial perchlorate concentration. Biodegradation rates in the pilot injection tests agreed well with those measured in the microcosms. These results support bioaugmentation with an anaerobic culture as a remedial strategy for sites contaminated with RDX, nitrate, and perchlorate.