The Study On Biodcgradation Of Butyl Benzyl Phthalate In A Bioreactor

Phthalic acid esters (PAEs) as the extensive use of plasticizers are widely foundin environmental media, they are a class of environmental hormones which wouldcause poison effects to human bodies and animals. Butyl benzyl phthalate (BBP) iscommon in PAEs and has been listed as one of the key control pollutants by theUnited States environmental protection agency. BBP has poison effect and weakestrogenic effect in reproductive genetic and oxidative damage. This study researchedthe biodegradation of BBP in a bioreactor, which could provide the directexperimental foundation for the treatment of this kind of compound, it could alsowiden the practical applied field of bioreactors.The biodegradable efficiencies of BBP in the bioreactor achieved98.00%,93.07%and78.52%at the temperature of25℃,15℃and5℃respectively,corresponding to a5mg/L influent concentration and a hydraulic retention time (HRT)of8h. The lowest effluent concentration was0.09mg/L. Temperature, influentconcentration and HRT were all having an impact on the biodegradable efficiency ofBBP. The longer the HRT was, or the higher the temperature was, the better theremoval efficiency of BBP was. The higher the influent concentration in a certainrange was, the better the removal efficiency of BBP was.The possible metabolites of BBP degradation in the bioreactor were identified asbenzoic acid, phthalic acid(PA), diethyl phthalate(DEP) and di-n-butyl phthalate(DBP). The pathway of BBP biodegradation could be that BBP was degraded to DBPfirstly, further generated DEP, then PA, again transformed to benzoic acid and finallythoroughly degraded to carbon dioxide and water by microorganisms.The bioreactor can effectively remove the environmental endocrine activity in theinfluent. The environmental endocrine activity of effluent was obviously decreasedafter the treatment. The activity of β-galactosidase was decreased from19.3Miller to3.55Miller at the temperature of25℃, a5mg/L influent concentration and a HRT of8h, the effluent was more security.There were mainly coccus and bacillus in the biofilm.The existence of advantagebacterium at all the three temperatures included Arthrobacter, Corynebacterium,Achromatium, Pseudomonas and the percentages were9.4%,20.9%,25.5%,16.9%respectively at the temperature of25℃.As the temperature reducing the percentages roughly had a decreasing trend. In addition, there were other bacteria as Leptothrix,Flavobacterium, Acinetobacter etc. It maybe due to the influence of the experimentalenvironment their percentages were not high. In a variety of advantage bacteriumcommon cooperation, the bioreactor could realize the high biodegradable efficiencyof BBP.