Waterless urinals has already made their debut in many cities and fastly replacing the old urinals which used water flush as cleaning. The water flushing urinals used to eminate a lot of amonia gas, giving foul order particularly at the public urinals which are generally poorly maintained.
The waterless urinals are cleaner choice and do not require water to flush. The technology avoid two factors responsible for foul smell (amonia gas), the water and bacteria. The urine contain urea which is degraded into amonia and carbon dioxide by the bacteria in presence of water. Thus by preventing generation of bacteria and removing the water source generated the foul free urinals.
The waterless urinals used a very simple science, the specific gravity of water (urine) and oils. In laymens word - oils are lighter than water and float on water. In the initial designs of the urinals unevaporating lipids having attached anti-bacterial molecules were used for this purpose. A number of different lipids and other similar molecules emerged along with different short of anti-bacterial molecules and has been secured by a number of patents. The always floating anti-bacterial oily material now prevented the urine exposure to air while allowing easy drainage of urine, not allowing the growth of bacteria and thus prevented ammonia production, reason for foul smell. This short of urinals proved successful, the lipid/oil-antibacterial were contained in cartridges which now served the purpose of barrier of exposure of urine to air while allowing the easy unidirectional flow.
However these short of urinals introduced by various companies in different cities worldover in around 2001 had drawback of requiring the expensive cardridge replacement every few months. Even though the urinal foul was removed, the smell from material of cartridges was uncomfortable for many people and due to which this short of urinals have been removed from some of cities.
In the very recent designs, the surface of urinals is coated with special material which is made friction free to provide shiny surfaces and have anti-bacterial properties. Moreover, the surface is made highly hydrophobic (similar to oil like designs) so that water (urine) does not stay in urinal surface and drained down. This shiny, frictionless, hydrophobic anti-bacterial surface generate the hygenic system and avoid the recurring cost of replacing the cartridges of previous designs.
Indian Scenario: Few cities has started installing waterless urinals like Delhi, Chennai and many others. Soon it will be a common thing visible and would be great additive to make and maintain the hygene at public urinals.
Research aspect: The concept once developed need to be supplemented with contineous improvement with research and development of new materials that can combat the few drawbacks with this technology. This leaves a plethora of application of material scientists (biologists??? - biologist has not turned towards this with their anti-bacterial organisms) and scope for development of new materials.