One of the alkyl ethers with tert-Bu groups in their molecules which showed very poor biodegradability, tert-Bu Me ether (MTBE)  [1634-04-4] had no effect on the biodegradability of gasoline blended with it. Studies on the biodegradation of several alkyl ethers were carried out by measuring the O uptake rate in the presence of standard activated sludge as a source of microorganisms.