The invention relates to a method, devices and reagents which are used for Fenton reaction-based wastewater treatment. The overlay coating has inner and outer regions, with the inner region containing more chromium than the outer region. The method of driving a pixel element comprises charging the capacitive element in the pixel element through the semiconductor channel of the switching transistor in the pixel element and through the at least one nonlinear element while the semiconductor channel of the switching transistor maintains at the conducting state and the at least one nonlinear element maintains at the conducting state. An NMOS transistor is in the off state during loading and writing and is in the on state during reading. The adjustments limit the transmitted bandwidth and allow transmitted signals to meet an emission mask, while still enabling a receiver to recover the correct sample values of transmitted symbols. This arrangement provides savings associated with the provision of through-the-dock wiring access, easy removability for replacement, maintenance and servicing, and which is sealed against the environment.