Researchers find new use for wet wipe trimmings

Mr N. Chandrasekaran (left), mill manager at wet wipes manufacturer Kimberly-Clark, and Dr Akshay Jain, from Ngee Ann Polytechnic, who led the study.
Mr N. Chandrasekaran (left), mill manager at wet wipes manufacturer Kimberly-Clark, and Dr Akshay Jain, from Ngee Ann Polytechnic, who led the study.ST PHOTO: JONATHAN CHOO

They effectively remove moisture from waste before incineration

To get wet wipes into perfect rectangles, their edges have to be carefully sliced off by machines, leaving behind tonnes of material that are sent straight to the incinerator each day.

But thanks to a study by Ngee Ann Polytechnic (NP) researchers, this is no longer the case at a production facility in Tuas.

The 300 tonnes of trimmings produced each year at the facility of wet wipes manufacturer Kimberly-Clark are now being mixed with wet toxic waste and biowaste to absorb the moisture out of them. This mixture is then incinerated.

In their study, the researchers found that the wet wipes do a much better job than sawdust, which is the material traditionally used to absorb moisture from wet waste.

Self-sustained combustion of waste cannot take place if too much moisture is present.

Too much moisture also corrodes the furnace.

The study, conducted between April and October last year, found that the heating value - the amount of heat released when a substance burns - of the wet wipes is 60 per cent higher than that of sawdust.

NOT WASTED

Previously, it was going straight to incineration. But now, it has a second lease of life. '' 

MR CHRIS MESSER, sustainability business partner for Asia-Pacific at Kimberly-Clark, on wet wipe trimmings.

Their absorption capability is also 41/2 times higher.

"This makes a huge difference in the amount of material needed, and the energy and time required for the process," said Dr Akshay Jain, a manager at NP's Environmental & Water Technology Centre of Innovation, who led the study.

About one tonne of sawdust is needed for incinerating one tonne of waste.

However, the same job can be done with just 200kg of wet wipes, which is about five times lighter and reduces the energy needed to power the process by about eight times.

"As the overall mass you are actually burning is reduced by a lot, the time needed to burn the mass is also lower," Dr Jain added.

Replacing sawdust with wet wipes also reduces the amount of ash left behind after incineration, from 5 to 10 per cent, to just 0.5 per cent, hence reducing the amount of waste that is sent to Singapore's only landfill in Pulau Semakau, which is filling up at a rapid rate.

The discovery is now being put to use at two incineration plants run by Technochem Environmental Complex in Tuas, which burn about 46 tonnes of hospital biowaste and wet toxic waste each day.

Kimberly-Clark has also saved on the cost of throwing away the wet wipe trimmings, which are now given to Technochem for free.

Mr Chris Messer, Kimberly-Clark's sustainability business partner for Asia-Pacific, said: "Previously, it was going straight to incineration. But now, it has a second lease of life."

A version of this article appeared in the print edition of The Straits Times on October 27, 2017, with the headline 'Researchers find new use for wet wipe trimmings'. Print Edition | Subscribe