Food is a substance that we should treasure. Unfortunately this does not seem to be case in real life. According to the Food and Agriculture Office, about one-third of all food produced worldwide, worth around US$1 trillion, gets lost or wasted in food production and consumption systems. Every year, consumers in industrialized countries waste almost as much food as the entire net food production of sub-Saharan Africa (222 million vs. 230 million tons). At the end of the food chain, food waste is defined as the food lost during retail activities and final consumption, and relates more to consumer behaviour. In Europe and North America, consumers throw away 95 -115 kg of food per person each year while in industrialized Asia, the discards amounts to 80 kg per capita per year.

How do we turn food waste into a resource? There are various means.

  • Composting – organic matter that has been decomposed and recycled as a fertilizer and soil amendment
  • Animal feed – the feeding of food scraps to animals is, historically, the most common way of dealing with household food waste. Animals turn a third of ingested food into meat or dairy products
  • Biofuel – Used cooking oil is a common waste that can be turned into biodiesel
  • Energy – anaerobic digestion is the process by which organic matter such as animal or food waste is broken down in the absence of oxygen to produce biogas and biofertiliser

To convert food waste into a resource, there are challenges to be overcome along the value chain. At the sorting stage, unfamiliarity in how to handle food waste means that limited public efforts in recycling necessitates extra manpower for sorting.  During collection, temporary storage of food waste, if not properly carried out, can generate odour and create hygiene problems. Although scale is favoured to make recycling cost-effective, additional administrative effort is often needed to collect for high-density and high-rise buildings. Transportation effort and costs further arise when bringing waste from collection points to treatment facilities. These can be as high as two-thirds of the total operational costs. Post-treatment, maintaining quality control of the product is important as incomplete decomposition or product that is contaminated cannot be used e.g. unfinished compost for gardening. Lastly, there must be sufficient market capacity to absorb large amounts of the final recycled product e.g. how much local need is there for agricultural and landscaping use?

Many cities are looking at putting food waste recycling strategies in their urban settings. San Francisco city has instated a “zero waste” target by 2020 and has made the sorting and composting of food waste mandatory.  The city has a compost facility 89 kilometers east in Vacaville which supplies compost to the Napa and Sonoma wineries. In Sweden, Malmö city has also imposed mandatory sorting of household food waste whereby citizens recycle their food waste using waste grinders, vacuum systems or paper bags for garbage bins. The waste is anaerobically broken down to produce biogas to fuel city buses, garbage trucks, taxis and cars. The Adelaide city council in Australia provides Green Organics bins for residents for food scraps and peels, meat scraps and bones, teabags and coffee grounds, egg shells, dairy products, hair, shredded paper, tissue and paper towels. The bins are a way of making recycling more localised and with an abundance of urban gardens, Adelaide has high food waste recycling achievements of up to 90 percent. Compost and mulch produced by this method are certified to Australian Standards AS4454 which is suitable for public, landscape and agricultural use.

In Malaysia, the Kuala Lumpur Centre for Sustainable Innovation (KLCSI) is working on the design and establishment of an innovative food waste recycling scheme in a 1,000-resident public housing complex located in Kepong, in the Greater Kuala Lumpur area. Food waste will be collected from individual owners’ apartments, processed into compost on-site and used to nurture an urban farm for the residents.  The innovation of the waste recycling scheme is that it eliminates transportation costs, which is usually the largest component of operating costs for this type of business and, if successful, this scheme can be easily replicated across other communities in Malaysian urban areas.

In a survey of residents within the complex, findings showed that:

  • Almost 70 percent cooked at home meaning that regular shopping (85 percent) occurs once a week or more often. In other words, there is regular supply of food materials coming into the complex.
  • When asked why food goes to waste, almost 60 percent state that this due to spoilage, which is consistent with the local preference for fresh food.
  • Roughly 45 percent of the households sort their food waste but just 55 percent are prepared to take this waste to the local collection point.
  • Typically of urban dwellers in a high rise setting, more than 80 percent of those surveyed would not buy compost whether from food waste or other sources. This indicates the need for an urban garden as the outlet for the recycled food waste.

In KLCSI’s proposed plan, the residents are expected to generate about 1.0 to 1.5 tonnes of food waste every day; currently this waste is sent to a landfill for disposal. An area of about 0.2 acre under a national electricity pylon beside the complex has been identified as the proposed composting site. The preferred composting method is open air static piles composting, with manual turning and kept under canvas cover. For the composting mix, food waste will be the main feedstock with green waste as a bulking agent to control the initial moisture content.  It is anticipated that 1-2 workers will be required to run the daily composting operation. The basic works involved are sorting of food waste, loading of food waste, shredding of green waste, turning of compost piles, grinding and packing of finished compost. The capacity of each compost pile will be about 5 to 7 tonnes and the estimated compost amount produced from one pile after 5 months will be about 0.5 to 1.0 tonnes per month. The compost produced can be used as bio-fertilizer for internal consumption i.e. the planned urban farm or sold to other places.

So what can we learn? There is a need to change public behavior through education on food waste sorting and the use of recycled products. Mandatory sorting is needed (as shown in San Francisco and Malmö). Specific collection arrangements for high-rise buildings should be implemented e.g. designated food waste collection bins should be provided; there is potential to incorporate pneumatic chute disposal systems in newly designed buildings. Some cities have instated waste charging mechanisms and at the same time offered economic incentives for households to sort food waste in order to pay less. Food waste recycling operators must have viable business models, which mean that robust secondary markets for the finished products are vital.

This short was paper prepared for the CleanEnviro Summit Singapore, Sands Expo & Convention Centre, Marina Bay Sands, Singapore, 10 – 14 July 2016, by Dr Thomas S.K. Tang, KLCSI