What innovative materials and technologies can be integrated into a bathroom design to create a truly zero-waste space, and how can these solutions be scaled up for widespread adoption in residential and commercial settings? Specifically, what opportunities exist for closed-loop systems, biodegradable materials, and recycling technologies to minimize waste and reduce the bathrooms environmental footprint? How can designers and engineers rethink traditional bathroom fixtures and appliances to prioritize sustainability and waste reduction, and what role can biomimicry and nature-inspired design play in this process?