Study Aerobic Biodegradation Of BTEX Intensified Using Maifanite In Groundwater

Accidental leakage of gasoline, diesel and fuel oil from underground storagetanks or spillage during the transportation can lead to the contamination of soil andgroundwater with monoaromatic hydrocarbons （benzene, toluene, ethylbenzene andthree isomers of xylene, referred to BTEX）, which are regulated by many countriesdue to their neurotoxic, carcinogenic and teratogenic properties. Removal of BTEXcompounds from groundwater is essential, and much research work has been widelycarried out, among these remediation technologies, biological treatment is regarded asthe most economical and environmentally friendly approach. Microorganisms are ableto degrade BTEX under both aerobic and anaerobic conditions. Compare to theanaerobic biodegradation, the aerobic biodegradation can enhance the ability ofbiodegradation and the organics pollutant can be degraded into environmental friendlyCO₂and H₂O. Thus, the pivots of further researches of aerobic biodegradation.weresuggested.This study started from the collection, enrichment and acclimation of themicrobial population, then, the microorganism’s environment and column environment wereestablished. Firstly, the microorganism experiments studied the influence of thebiodegradable effect by bio-carrier, temperature, substrate’s concentration; second, thecolumn experments studied the influnen of the biodegradable effect by bio-carrier,temperature and phylogenetic analysis of systems based on16S rDNA sequences.By analyzing experiment data of batch and columns experiment, the conclusionare as follow.In batch experiment,（1） Maifanite had a intensed effect on the on thebiodegradation. Initial concentration of subtrate was40mg/L, At15℃, the order ofBTEX biodegradation was:ethylbenzene>m-xylene>toluene>benzene; At25℃, theorder of BTEX biodegradation was:ethylbenzene>toluene> benzene>m-xylene. At25℃, maifanite’s intensed effect in the maifanite microcosms are not as obvious as at15℃.（2） With the increase of ethylbenzene concentration, inhibition of ethylbenzeneon other substrates is more obvious, the substrate concentration is80mg/L, the orderof BTEX biodegradation was:benzene>toluene>m-xylene>benzene; substrateconcentration is40mg/L, the order of BTEX biodegradation was:benzene>toluene>ethylbenzene> m-xylene. In column experiment, the initial concentration ofpollutants was20mg/L, at25℃,the removal efficiency of BTEX in the maifanite column was about10%higher than in zeolite column system; At15℃, the removalefficiency of BTEX in the maifanite column was about15%higher than in zeolitecolumn system.（2） The initial concentration of pollutants was20mg/L, at15℃,phylogenetic analysis of systems based on16S rDNA sequences are studied, thisindicates that the presence of certain microbes that have the ability to degrade fourhydrocarbons, or the presence of different types of microbes, each of them with theability to degrade each substrate, respectively, several possible hydrocarbon degraderswere identified.Few reports have been published documenting the effect of bio-carriers onhydrocarbon biodegradation in groundwater. This study can provide basic researchmaterial on bioremediation and biological treatment of BTEX pollution.