A laboratory study of the biodegradation of MTBE solubilised in water by a microbial consortium entrapped in a water-in-oil-in-water double emulsion

A stable water-in-oil-in-water (W1/O/W2) double emulsion containing in its inner aqueous phase a microbial consortium (60 mgprotein Ldouble emulsion−1) known to degrade methyl tert-butyl ether (MTBE) was prepared. The primary emulsion (W1/O) had a volume disperse phase (ϕ1) of 0.3 and was stabilized with 8% Span 80. The double emulsion had a volume disperse phase (ϕ2) of 0.3 and was stabilized with 0.2% polyacrylic acid (PAA). A maximum degradation rate of 12.4 mgMTBE gprotein−1 h−1 was achieved in a microcosm that contained an initial concentration of 146 mgMTBE Ldouble emulsion−1. This degradation rate was significantly lower (P < 0.05) than that exhibited by the free cells (48.7 mgMTBE gprotein−1 h−1), probably because the encapsulated cells metabolized an ingredient of the double emulsion as carbon source besides MTBE. Nevertheless, our results show that this biodegradation technique has great applicability potential.