The aim of this work is to further develop an innovative sorting process for waste plastics - namely wet density separation in a centrifugal force field by means of a centrifugal force separator - and to investigate a new mode of operation, namely co-current flow operation. The second centrifugal force separator stage is to be used for further enrichment of the recyclable material in the product - in this case mainly polyolefins in the light fraction. The startup of the plant section and orientation tests are intended to ensure that, on the one hand, stable operation of the second centrifugal force separator is guaranteed and, on the other hand, that it is also operated with the optimal plant parameters, so that the best possible separation can be assumed. To determine stable operation of the centrifugal force separator, the recording of various operating points is described. In addition to the documentation of various measured values, it was assessed whether a stable and smooth vortex - suitable for operation - was formed. As an orientation test, first a statistical test series, which enables the simultaneous investigation and optimization of several plant parameters within the previously determined range, was performed. Based on the thereby found optimal plant parameters a test series with different residual materials of industrial origin, which provides a statement on the separation performance of the centrifugal force separator, was carried out. As a final point in this work, a plant concept for the Circulyzer 30 demonstration plant is developed, based on research activities from this and previous works. This is intended to be the first step of this type of plant towards an industrial plant.