Majority voting between triple redundant integrated circuits is used in order to provide an SEU hardened output signal. The thin client approach offers significant advantages over thick client approaches that rely on on-vehicle maps and map matching systems, including reduced complexity of on-board equipment and elimination of map integrity issues. The fixed film media can be a cross-flow media and can optionally include a web of textile material integrated within the fixed film media to enhance bacterial growth within the fixed film media or optionally the anoxic vertical serpentine configuration could be applied to an activated sludge operation. Strategies for live person detection can include: detecting a short period of sound followed by a sustained pause, analyzing the talking speed andor speed variability of detected speech, recognizing one or more words typical of a live person, and providing a verbal prompt and detecting an expected reply. The invention also provides a novel child safety device which is positioned within the door aperture for preventing passage of the child therethrough.