My Executive


    Aug 08, 2013

    Challenges in way of recycling food waste

    Food wastage in Singapore hit a record high last year, increasing by 26 per cent, compared to 2007.

    But one challenge to recycling such waste here is collecting it, said Dr Tong Yen Wah from the National University of Singapore.

    Last year, 703,200 tonnes were generated, up from 558,900 tonnes produced in 2007.

    But only about 12 per cent of last year's waste was recycled, a slight increase of 1.7 per cent from the previous year's.

    My Paper spoke with Dr Tong, an associate professor with the department of chemical and biomolecular engineering, on the difficulties of food-waste recycling.

    What are the challenges of food-waste recycling on a national scale?

    The challenge is that food waste is generated in a distributed fashion.

    This involves all households, restaurants and even factories that make food. So, (waste) is all over the place, and collecting it is a problem.

    Why is it difficult for homes and hawker centres to recycle food waste?

    When households have food waste, the simplest (way to get rid of it) is to throw it down the rubbish chute.

    If you want to collect food waste, then you need waste-collection agencies. So, you either pay for them to collect the waste, or you make some (money) by collecting the waste.

    At the moment, it is not very profitable and not easy to collect.

    The other thing is that people do not separate food waste. At hawker centres, when we throw away food, there might be plastic or paper (in the same bin). When people mix these in, it makes it more difficult to reuse or convert (the food waste) into something else.

    If there is a way to separate these easily, or if people consciously separate the food they throw, it would make it more feasible to reuse (the waste).

    What are some ways to recycle food waste?

    The simplest way is by reusing it. Reusing spent grains from beer brewing as animal feed is easy.

    The other way is to use (the waste) as compost. Food waste is easily degradable, so you can use it in farms as fertiliser.

    The process of anaerobic digestion (of food waste) also produces biogas. At this stage, the problem isn't in technology, but in logistics.

    If we can overcome that, then the most useful method (to reuse food waste) is to convert it into biogas because you can get energy out of it.

    Then, you can recover the energy and use it to supplement what we need.

    For example, at hawker centres, if you collect all the food waste, you could produce biogas for cooking.

    You cannot replace town gas entirely, but the biogas from food waste can probably reduce the amount (of town gas) that you buy by 30 per cent.