高效生物活性炭吸附工艺去除水体中甲基叔丁基醚的初步研究

通过对来自美国加州拉玛达(La Mirada)市污染点的原始菌源炭进行甲基叔丁基醚(MTBE)降解菌生物强化,试图建立具有更有效MTBE降解效果的生物活性炭(BAC)功能,尝试利用新形成的菌源炭覆盖新鲜椰壳活性炭(GAC)而达到新BAC功能的快速有效启动,并考察不同空床停留时间(EBCT)、GAC吸附饱和状态对BAC功能启动的影响。同时,对具有成熟BAC功能的炭柱中的混合菌落进行基于16SrDNA的聚合酶链反应(PCR)—变性梯度凝胶电泳(DGGE)分析,以确定混合菌落中的主要功能菌种属。结果表明,针对模拟的低MTBE浓度进水,新鲜GAC和菌源炭A添加体积分数分别为40%和60%的NAS柱出水MTBE质量浓度最终稳定低于0.005mg/L,平均去除率接近99%,出水MTBE完全达到美国环境保护署(EPA)的饮用水建议阈值(<20μg/L),建立了成熟的BAC功能;成熟的菌源炭可在30d左右通过覆盖法迅速实现新BAC功能的启动;EBCT的延长有利于新BAC功能的启动和维持,接种初期应尽量采用较长EBCT以保证取得足够和稳定的生物量;MTBE吸附饱和前后的GAC在启动新BAC功能时存在差异,鉴于吸附饱和GAC在接种初期会因MTBE解吸而造成出水MTBE浓度较高,建议采用新鲜活性炭覆盖需接种炭柱;BAC功能成熟炭柱中包括的5种主要菌种里有4种为未培养微生物,1种为未分类菌种,其理化性质和具体属性尚不明确。

An efficient BAC treatment process for removing MTBE from groundwater

Continuous bio-augmentation,by circulation of the culture solution containing acclimated MTBE degraders obtained from the contaminated soil samples,made the adsorber filled with the spent granular activated carbon(GAC) sample of the La Mirada remediation site an effective biological activated carbon(BAC) system in just over 3 months.New BAC system was established by covering this high efficient BAC on fresh GAC for the system quick start-up,the effect of empty bed contact time(EBCT) and MTBE preloading quantity of GAC on the new BAC system was investigated.The functional bacteria in mature BAC column was analyzed by 16S rDNA based polymerase chain reaction(PCR)-denatured gradient gel electrophoresis(DGGE) to identify the bacteria species.The results showed that more than 99% of MTBE was removed from the low MTBE concentrate influent,the effluent MTBE of column NAS was stably lower than 0.005 mg/L,which could fully meet the standard of EPA.Covering mature BAC could successfully start up the new BAC system in 30 days.Extension the EBCT was benefit to the start-up and operation of new BAC system,so we can prolong the EBCT in the beginning of inoculation stage so as to achieve enough and stable biomass.Considering desorption of MTBE from saturated GAC in the early inoculation stage would increase the effluent MTBE,the fresh GAC could applied to cover the inoculation carbon column.Among the 5 detected strains in mature BAC column,4 strains were uncultivated microorganisms,1 strain was declassified strains,its physical and chemical properties and specific attribute was not clear.