Study On Biodegradation Of MTBE Using Upflow Membrane Fixed-Bed Reactors

Methyl tert-butyl ether (MTBE), one of the most commongroundwater pollutants due to its wide usage as an unleaded gasolineoxygenate additive, has created a significant and unacceptable risk todrinking water and groundwater resources, and has posed a significanthealth threat. Therefore, the study on remediation of MTBE has animportant significance. Traditional physicochemical technologies forMTBE removal such as adsorption, air stripping and advanced oxidationhave some drawbacks, such as high costs, secondary pollution anddifficulty in maintenance. Biological degradation for MTBE remediationappears to be an economical, energy efficient, and environmentally soundapproach, and has become an active research area in the past few years.In this paper, the aerobic biodegradation of MTBE was investigated intwo continuous upflow membrane fixed-bed reactors (UFBRs). Theinfluence of hydraulic retention time (HRT), influent mass concentrationand temperature conditions on MTBE removal efficiency were investigated.The results showed that the UFBR with porcelain granule and the UFBRwith granular activated carbon were successfully started up within 114 daysand 66 days, respectively. The HRT was a key factor to the MTBE removalefficiency. When the influent mass concentration was 25±1 mg/L, the MTBE removal efficiency of the UFBR with porcelain granule increasedfrom 58.66％to 84.95％, while the MTBE removal efficiency of the UFBRwith granular activated carbon increased from 60.59％to 87.49％as theHRT increased from 5.8 h to 23.8 h. The MTBE removal efficiencydecreased as the influent mass concentration increased. When the HRT was18.6 h, the MTBE removal efficiency of the UFBR with porcelain granuledecreased from 93.22％to 83.15％, while the MTBE removal efficiency ofthe UFBR with granular activated carbon decreased from 94.87％to83.92％as the influent mass concentration increased from 5 mg/L to 25mg/L. Under low temperature conditions, the performance of UFBR wasseriously affected. Within the whole experimental period, the volatilizationof MTBE was between 4％and 10％, which is relatively low compared tototal MTBE removal efficiency, indicating the biodegradation played amajor role in the MTBE removal.On the basis of plug flow characteristic, and according to an amountof experimental research and kinetic analysis, the UFBR could be describedby Eckenfelder model.All in all, the UFBR can be an effective approach to remediate thegroundwater contaminated by MTBE. According to the proposed model,the key factor to improve the performance of UFBR was to optimize thestructure and design of the reactor.