Proposed Solutions
What are waterless urinals?
Waterless urinals are normal looking urinals without a pipe for water intake. As the name suggested, waterless urinals do not require water to flush but instead, they are drain by gravity through the drain pipe. The waste will flow through the drain pipe connected to the building’s plumbing system and into the water treatment plant.
How does it work?
Waterless urinals consist of two main parts; the urinal bowl and the S-trap that contains the urinal cartridge and sealant which is connected to the buildings sewage system/ water treatment plant. When the user uses the urinal, the urine will flow down the s-pipe where it passes through the sealant allowing it to pass through the cartridge before flowing down to the sewage system.
Benefits
Below are some benefits of using waterless urinals.
Water Savings
Conventional urinals usually use 4 to 12 litres of water per flush. According to the Changi Airport website, to reduce the water consumption in the airport, they use the low-flush urinals instead. It is logical that low-flush urinal uses lesser water, with only about 0.5 litres of water used per flush and it helps to save up to at least 3.5 litres of water used. However, with the installation of waterless urinals, it can help to save 0.5 litres of water more than what low-flush had saved since it does not use any flushing water.
Improve Hygiene
Waterless urinals are designed such that any liquid in the urinals will dry out between uses to prevent bacteria and viruses from thriving.
Meet Environmental Goals
As waterless urinals do not require any water for flushing, this will eliminate water usage and also reduce CO2 emission. According to Changi Airport, they installed on-off sensors in selected areas which helps to reduce water usage by 66% from 6 liters per minute to 2 liters per minute. However, if they implement the no-flush urinals, water usage would be further reduced.
The average bladder holds between 300 to 400 ml of urine and the average cistern will flush between 9 to 15 litres of water into the sewer. All of that liquid has to be treated to the sewage plant. The treatment generates about 10 to 26 kgs of CO2 emission every year. As our waterless urinals do not require 9 to 15 litres of water, only 300 to 400 ml of waste will be treated at the sewage plant, thus reducing the CO2 generated.
Evaluation
Comparison between low flush urinals and waterless urinals
Changi Airport is currently using low flush urinals in their male toilets which is their way of doing a part for the environment by reducing the water consumption. However, this urinals requires complicated plumbing works for water input and output which often prone to leaks or pipe erosion. Besides, low flush urinals are still not the best practices as it still uses up to 0.5L of water per flush. On the other hand, waterless urinals require only a drain pipe for its output and also does not require any water to flush and thus, able to save more water. (refer to Appendix B)
Limitations
Retrofits
For existing buildings to switch from conventional to waterless urinals, retrofitting is compulsory. Waterless urinals only require a drain line for the disposal of human waste. As a result, water pipes must be drained and capped to prevent damage to pipes. In addition to the removal of water pipes, as waterless urinals are installed differently from conventional urinals, adjustments to the drain line could be necessary. As a result, retrofitting is an integral part of installing waterless urinals to existing buildings.
More frequent maintenance required
Waterless urinal does not have flushing capability to remove debris and hair found in the urinal gradually. Hence, periodic maintenance required by cleaners to keep the waterless urinal clean.
Higher exposure risk
Due to the frequent maintenance of waterless urinals for debris and hair, cleaners will be exposed to the risk of urine splashing while cleaning the urinals, which is a health hazard.
References
