Food waste recycling trial at hawker centres and markets

A two-year on-site food waste recycling trial at Ang Mo Kio Blk 628 Market and Tiong Bahru Market was launched by the National Environment Agency (NEA) on Thursday, to test the economic viability and operational feasibility of two different types of on-site food waste recycling systems. The systems are leased by NEA from two vendors – Eco Wiz (SG) and VRM Operations (Singapore), and the vendors would also be in-charge of maintaining the systems. The pilot trial is expected to conclude in Dec 2017.

Zero Waste SG visited the 2 trial markets for the launch, which include both hawker centres and wet markets. Ang Mo Kio Blk 628 Market (with 218 stalls) generates about two tonnes of food waste per day, while Tiong Bahru Market (with 342 stalls) generates about three tonnes of food waste per day. Most of the food waste are generated from market slab stalls and table cleaning operations. The food waste recycling systems could reduce up to 80% of the total waste generated from both locations.

Before the implementation of the food waste recycling trial, NEA and the two vendors conducted a food waste audit of the markets to understand the type and amount of food waste, and also conducted training sessions with the stallholders and table cleaners at the two hawker centres.

Ang Mo Kio Blk 628 Market

Eco Wiz (SG) is the vendor for the Ang Mo Kio Blk 628 Market. Stallholders are each given a covered bin for storage of food waste, and the bins come in 3 different sizes to cater to the different amount of food waste generated from different stalls. The stallholders will separate food waste from other waste and store it in their food waste bins. When the bin is full, the stallholder will bring it to the bin centre of the hawker centre, where the food waste recycling machine is housed, and transfer the food waste into a larger food waste storage bin for recycling.

Table cleaners will clear the tables and separate the food waste into a food waste container on their trolleys. When the food waste container is full, the cleaner will bring it to the bin centre and transfer the food waste into the larger food waste storage bin.

The recycling machine by Eco Wiz is able to convert one tonne of food waste into water within 24 hours. Microorganisms in the machine break down and digest the food waste, and the water is currently reused in the machine (the water can also be used for non-potable purposes such as cleaning the bin centre). The recycling machine can reduce 95% of the volume of the food waste, leaving about 3-5% of residue that is disposed.

Tiong Bahru Market

VRM Operations (Singapore) is the vendor for the Tiong Bahru Market. Stallholders are each given a covered bin and they will separate food waste from other waste and store it in their food waste bins. When the bin is full, the stallholder will bring it to the bin centre of the hawker centre or to the designated cages for the vendor to transfer to the bin centre.

At the tray return and clearing stations at the hawker centre, the cleaner will separate the food waste into a food waste container. The vendor will collect the food waste containers in cages and transfer them to the bin centre.

The recycling machine by VRM grinds up the food waste fed into it and mixes it with microorganisms, and the resulting mixture is stored on-site in 15 1,000-litre capacity tanks. When the tanks are full, they are transported to VRM’s off-site facility to convert the food waste into bio-fertilisers for agricultural purposes.

Feedback From Stallholders and Cleaners

The feedback from stallholders and cleaners were largely positive. Most of them said that they were not used to the sorting of food waste in the beginning, but with the training and over time, they got used to it. Although some find it slightly inconvenient to sort waste, they understand that this is for recycling and doing good for the environment, and thus support the pilot programme. One stallholder even brought her food waste from home for recycling at the market.

Thoughts on the Food Waste Recycling Pilot

Our thoughts after visiting the food waste recycling pilot at the two hawker centres:

1) Contamination problems over time

With the strong leadership, support and education by NEA in these two food waste recycling trials at the markets, it looks like it is operationally feasible to have food waste sorting and recycling, without too much contamination with plastic disposables and inorganic waste (as observed at the two markets).

This is in contrast to the pioneer food waste recycling company, IUT Global, which closed down in 2011, citing increased operating costs due to the need to sort out and dispose plastics and inorganic contaminants from food waste collected.

Hopefully, the trial would show that with sufficient education, support from the government, and the right operations, it is possible to achieve and scale up food waste recycling with little contamination problems over time.

2) Economic and environmental considerations

The other issue to consider from the trial is which recycling system is more economically viable, taking into consideration the recycling machine and maintenance costs, manpower and energy costs, and other savings in water and waste disposal. Together with another district-wide food waste recycling trial at Clementi, where food waste would be collected and co-digested with sludge at the Ulu Pandan Water Reclamation Plant to produce biogas from anaerobic digestion, these 3 systems would be evaluated for cost effectiveness by NEA and MEWR.

We hope that besides considering cost effectiveness and economic and operational aspects of the different systems and trials, MEWR and NEA would also look into the life cycle analysis or environmental aspects of the systems, and assess which one has the lowest environmental impacts, such as energy and water consumption, waste reduction, carbon emissions from transport, and potential energy generated and carbon emissions reduction.

3) Potential of food waste composting in the community

Besides using food waste digesters for recycling food waste, would it be possible to consider composting too? The main advantages of using digesters are that all types of food waste can be processed and in a short time. On the other hand, composting using microorganisms or worms can only process uncooked food such as vegetable and fruit scraps (and exclude meat) and takes a few months. However, composting is done manually and involves less capital costs, and is a good way to engage people and develop community bonding in the process.

With over 850 community gardens in Singapore, some of these gardens could be sites for community composting too. For small hawker centres and markets, it might not be viable to have an on-site food waste recycling machine. A suggestion would be to partner with a community garden nearby that can take in the vegetable and fruit scraps from stallholders and maybe even residents from the community. The food waste would be composted in composting bins placed in the garden and the compost used in the garden or for town landscaping purposes.