The invention relates to a method for treating wastewater containing nitroaromatics and nitrohydroxyaromatics, as for example arises in the production of nitroaromatics or in the production of nitrohydroxyaromatics, by a two-stage method consisting of pre-reduction and wet oxidation. The liquid crystal display apparatus of this invention includes a first substrate 110a, a second substrate 110b and a vertically aligned liquid crystal layer 120 placed therebetween, and has pixels each including a first electrode 111, a second electrode 131 and a liquid crystal layer located therebetween. The usage of nano-structures in an ordered manner or of nano-tubes may create inside the nano-structure the super-mirror reflection conditions and makes these nano-structures act like wave-guide for this neutral radiation driving it and turning at angles greater than 90 degrees requiring a total thickness a few microns only. Small-signal analysis of the equivalent open-loop circuit allows extraction of transfer functions that yield a return ratio RR corresponding to the modeled component. The thermally stable enclosure can have a relatively small volume.