Patrons of hawker centres or coffee shops that offer incentives for tray returns are more likely to clean up after themselves.
Four eating places with such incentives - two of them return a deposit when a tray is given back, one has a reward scheme, and another gives patrons 20 cents for every tray returned - have seen tray return rates of between 50 and 97 per cent.
In comparison, the average tray return rate at eateries without such schemes is about 20 to 30 per cent, said Public Hygiene Council chairman Edward D'Silva.
Food hall Timbre+ in one-north and the newly opened Yishun Park Hawker Centre, both run by the Timbre Group, make use of a radio frequency identification (RFID) tray return system.
A diner first puts down a $1 deposit for a tagged tray at a food stall, and when he is done with his meal, drops the tray off at a conveyor belt with an RFID reader. When the reader detects that a tray has been returned, a machine returns the deposit.
Timbre+, which has been open for 15 months, has a tray return rate of 97 per cent, said Mr Edward Chia, Timbre Group's managing director.
The rate is about 60 per cent at Yishun Park Hawker Centre, which opened last month, but Mr Chia said he is confident the rate would be similar there by the year end.
At Our Tampines Hub, diners earn reward points that can be redeemed for free items such as drinks for every tray returned.
The current tray return rate is more than 70 per cent, said a spokesman.
At Jurong West Hawker Centre, diners receive 20 cents for each tray returned. No deposit is required, and there are also three roaming robots to help diners who are unable to carry their own trays.
The tray return rate there is between 50 and 60 per cent.
The benefits of patrons returning their own trays are multi-fold.
Said a spokesman for Our Tampines Hub: "Apart from ensuring that the table is cleared for the next user, tray returns ensure that no leftover food is left unattended as this attracts pests and even birds, which makes the dining environment unpleasant and unhygienic."
Mr Chia agreed. "When customers return their trays, it helps the operator optimise manpower resources. Cleaning aunties could be deployed to a central washing area, where they can stand in one spot, instead of having to patrol the area to clean the tables.
"This would reduce the physical strain on them too."
The National Environment Agency (NEA) said tray return rates at its hawker centres vary.
Schemes such as the one at Yishun Park Hawker Centre and Our Tampines Hub are initiatives taken by the appointed managing agents, said the NEA spokesman.
"The aim is to bring about a change of behaviour and instil a greater sense of responsibility," added the spokesman.
Administrative executive Joyce Lee, 45, said she was initially motivated to return her tray by the reward system at Our Tampines Hub, and it has now become a habit.
But Mr D'Silva noted that in the long run, monetary incentives may not help to nurture heartfelt civic values. "Returning our own trays is a good habit with several positive benefits... If people realise this on their own, we could evolve into a more gracious society."
The low tray return rates at food places with no incentive schemes could be due to the location of tray return stations and their lack of visibility, he added.
NEA said it is working on having centralised or conveniently located tray return stations that will be integrated with centralised dishwashing facilities for its existing hawker centres.