A piezoelectric element includes a ceramic substrate, a piezoelectric made of a ceramic composition composed mainly of a PbMgNbO3PbZrO3PbTiO3 ternary system solid solution composition represented by the following general formula and containing 0. The process provides reduced fermentation time, increased ethanol yield and reduced fusel oil concentration. The apparatus further includes a trace gas permeable member coupled between the test line and the pump inlet, the foreline, or, in the case where the first vacuum pump is a turbomolecular pump, a midstage line. Transient flow conditions result in the tank water which helps avoid dead spaces and assists in agitating the membranes.