More composting to turn food scraps into fertiliser

With rising interest among gardeners, local groups devoted to the practice grow in numbers as well

The idea of giving raw vegetable scraps to worms which then "poo" out nutrient-rich fertiliser was so fascinating that gardening enthusiast Robin Rheaume, 51, decided to try it out last year.

But almost all 500g of the worms she bought for $100 from a local supplier "ran away" from the compost bin in her spare bathroom.

The Canadian, who has lived in Singapore for the last 25 years, found them dead the next day, encrusted on the bathroom floor.

She says: "It was a horrific sight."

She was determined to get to the root of the problem.

Canadian IT consultant and gardening enthusiast Robin Rheaume with her compost bin. She started a Facebook group, Singapore Vermicomposting, in 2015 for worm composting enthusiasts like herself to connect, trade information and share worms. ST PHOTO: DESMOND WEE

When the supplier did not pick up her calls, she did her own research and set up a Facebook group, Singapore Vermicomposting, in December 2015 for worm composting enthusiasts to connect, trade information and share worms.

She says: "There is a lack of worm composting information for urban dwellers living in high-rise buildings in the tropics." Her group now has more than 390 members.

Ms Rheaume, who works as an IT consultant for social enterprises and non-governmental organisations here, believes that the growing interest in composting comes hand in hand with that in urban farming and waste reduction.

She says: "The members in my group fall into three categories: urban gardeners who want good fertilisers for their plants, the environmentally conscious who want to reduce waste and those, like myself, who have an overlap of both interests."

In composting, organic waste, such as dried leaves and raw fruit and vegetable scraps, are left to sit in a container.

They are broken down by naturally occurring micro-organisms, such as bacteria and fungi, into finer nutrient-rich particles that can be used to fertilise plants, says Dr Victor Chang, deputy director of Residues & Resource Reclamation Centre at Nanyang Technological University (NTU). The process can take three months or longer.

Dr Chang says: "To ensure that the composting micro-organisms flourish and emit enough heat, it is important to get the right balance of carbon, nitrogen, and moisture in the compost bin."

  • Make your own compost


    1. A plastic container (you can start with a 5-litre container) with holes drilled into its sides and bottom. Make sure the container is clean and dry. You can cut off the top of the container so you can put in waste more easily. Put the top back on after adding the waste.

    2. Materials with carbon content, usually called "browns", such as dry leaves and sugarcane pulp. Cut into small pieces to allow micro-organisms to break them down more easily.

    3. Materials which contain nitrogen, including nutrient-rich black soil, chicken manure and "greens" or raw food scraps such as fruit peels, discarded vegetable parts and soya bean dregs. Avoid oily and cooked food as well as sour-ish food such as lemon and lime. Cut them into small pieces.

    4. Coffee grounds


    1. Put a compact layer of about 3cm of dry leaves or grass at the bottom of the container. Compress the layer by pressing it down with your gloved hands or a tool.

    2. Add the "browns". Before adding, however, make sure these are damp, but not so wet that water is dripping out of the holes at the bottom of the container. If they are too dry, soak them in water - for instance, water that has been used to wash rice - for about a minute. Compress the layer till it is about 3cm thick.

    3. Cover with another compact layer - about 1cm thick - of nitrogen-rich materials or "greens". Compacting helps the heat to build up more easily.

    4. Alternate between the layers until the container is about 80 per cent full.

    5. Put a final layer of coffee grounds to absorb any unpleasant odour and cover the container with the lid.

    6. Put a plastic bag over the container to keep the heat and moisture in.

    7. After two weeks, pour the contents of the container onto a big plate and turn and aerate them with a spade. If the materials are too dry, add some rice water. If they are too wet, add some dry leaves.

    8. Repeat once every week for the next three months.

    9. The compost is done when you do not see any more food and other waste in it and it has turned dark brown, with a tinge of black. It should feel soft and spongy, and not sticky, and there should be no foul odour.

When this is out of balance, it may attract pests or emit a bad odour.

Some like Ms Rheaume use worms to speed up the process.

The worms feed on the waste and their "poo", or vermicompost, is then used to fertilise plants. It takes one to three months to create compost this way.

There are several other groups that focus on composting.

Singapore Worm Composting is an online platform started by four students from NTU as an entrepreneurship project in 2010.

They bought a composting system called Can-O-Worms in bulk from Australia - each comes with three vertical trays and uses worms and uncooked vegetable and fruit scraps for composting - and started a company to sell them.

Six months later, after the project ended, two of the students decided to continue the business.

One of them, secondary school teacher Chuah Chongxian, 27, says: "Schools, individuals and companies were buying from us."

They took about a year to break even and now sell more than 100 bins a year. Each bin costs about $280 and comes with 500g of worms.

The Facebook page and website, Composting in Singapore, was started in 2010 by Mr Joseph Solomon and his wife, Sarah, after they completed a user-experience design project on composting while they were undergraduates at the National University of Singapore.

Mrs Solomon says: "We wanted to share our experience on how easy it is to compost even in space- strapped, high-rise apartments."

A year later, they registered the company Kainosis Sustainability Development Consultancy to offer sustainability-related consultancy services, including agriculture and aquaponics, to schools, companies and communities.

"When we started, there was a general belief that composting and food waste recycling could be done only on a large-scale basis by large organisations," says Mrs Solomon.

"But in recent years, we have started to see a greater demand for our composting workshops and speaking engagements from a wider demographic, such as government institutions, schools, corporates and grassroots communities."

She says this could be due to greater awareness about sustainable and environment-friendly living, which is being promoted by many local organisations, such as the National Environment Agency, through events and initiatives.

For Ms Rheaume, there is something primal about making her own compost.

She says: "Living in a concrete jungle, on the 15th floor of a condominium, I hardly get to touch soil. But with my own compost, I get to smell earth every day."

Mr Faiz Zohri showing a young visitor at the Singapore Really Really Free Market the free Malayan blue worms (above) he gives away. ST PHOTO: NG SOR LUAN

Worms - for free

People usually give out books, clothes and CDs at the Singapore Really Really Free Market, a free-for-all flea market held once every two months. But landscape architect Faiz Zohri, 32, hands out wriggly worms instead.

These are Malayan blue worms, composting worms that have helped transform his household food and other waste into nutrientrich fertilisers or compost, which he uses on the plants at home.

The worms are gifted to people, together with the soil-like "vermicompost" - their droppings after they help break down the waste.

Mr Faiz first learnt about composting during a visit to a farm in Indonesia. He saw that farmers there avoided commercial fertilisers and, instead, used food and other organic waste as fertilisers.

In 2015, he started composting part of his food waste in a 40cm by 30cm storage box in the three- room HDB flat he shares with a friend.

His first attempt ended a few days later. The decaying food waste attracted ants and flies and he had to throw it away and start afresh.

He says: "I realised I had added too much food waste too quickly and the air flow was not good."

So, he drilled holes to the box's sides and bottom. He had to throw part of the waste away a few times due to maggot and ant attacks.

It took him about a year to get the hang of things.

He says: "Composting is like cooking. You need to experiment and see what works. If your compost is too wet, you need to add more dry materials and vice versa.

"Over time, you find that some waste like watermelon peels decay very fast and can attract ants, so you have to make sure you don't add too much of them."

In September that year, he attended a two-week course in permaculture, a sustainable form of agriculture, at Bumi Langit Institute in Yogyakarta.

Back home, he decided to put his knowledge into practice and try composting with worms. He says: "With the worms, it just takes me one month to get the vermicompost, compared with the three to five months without the worms."

Thanks to composting, he has reduced 70 per cent of his household food waste and about 20 to 30 per cent of his paper waste. He now has three bins that produce half a bin of vermicompost a month.

The best part of worm composting is sharing with others.

"The people I meet often tell me that they have read about worm composting, but do not know where to get the worms.

"I am happy I can help them get started and, at the same time, get rid of my extra compost."

Pre-schoolers and their teachers and principal, Ms Tham Kum Fong, at Singapore Hokkien Huay Kuan Pre-school with the food waste they collected for their compost bin (above). PHOTO: AZIZ HUSSIN FOR THE STRAITS TIMES

Getting the young involved

Once every school term, pre-schoolers at Singapore Hokkien Huay Kuan Pre-school in Upper East Coast take along a plastic bag full of raw food trash to school.

These are orange and apple peels, vegetable scraps and egg shells that they have collected in their homes.

In school, under their teachers' guidance, they glove up and help to fill a compost bin - scooping in a layer of soil first before throwing in the food waste they have collected.

They repeat the process till the bin is two-thirds full. It takes about eight weeks for the compost to form.

The pre-school's principal Tham Kum Fong says: "After about a week or so, the teachers open up the box to let the children feel the heat coming out. They also take the children to the bin every now and then so that they can see the food waste slowly disappearing."

When all the scraps are gone and the compost is done, the children help to scoop it into pails and use it to fertilise the plants in the school's garden, which is part of the National Parks Board's Community In Bloom programme.

Ms Tham says: "In the process, children learn that food waste is not totally useless, but can be used as fertilisers for plants. They become more aware about re-using waste and saving the earth."

Lawyer Cheryl Kong, 38, whose five-year-old attends the pre- school, appreciates the school's effort. She says: "Whenever the food collection date nears, my daughter will remind me to collect scraps at home. She finds it amazing to see the waste transform into something useful."

Meanwhile, composting is not new to schools such as St Anthony's Primary in Bukit Batok.

It has had a compost bin in its garden since 2008. This is filled with dead leaves and weeds picked up by pupils from its science and environment club. The pupils also help to use the compost to fertilise the school's garden.

Ms Lina Sim, the school's science level head, says the pupils enjoy being engaged in such hands-on activities. She adds that teachers also use the compost bin as a learning aid to explain to pupils concepts in textbooks such as decomposition.

Another school, St Joseph's Institution International in Thomson Road, plans to start a similar composting programme in its garden for high-school students.

The school has bought a compost bin and one of its teachers, who is good with carpentry, will build a wooden compost box in the school's garden. It will start by composting plant debris, which is now being trashed.

Chemistry teacher and gardening enthusiast Charlie McBride says: "It makes sense to recycle plant debris instead of throwing it away. The compost also gives good soil and is not difficult to make. Every good garden should have a compost pit."

Gardeners Kong Wah Beng (with hat) and Chen Shih Tse are composting enthusiasts at the Toh Yi Community Garden. PHOTO: TIFFANY GOH FOR THE STRAITS TIMES

Sharing knowledge with others

Dead leaves, vegetable scraps and fruit peels around the Toh Yi neighbourhood in Upper Bukit Timah are given a new life at its community garden. They are converted into compost and used to fertilise the garden's plants.

One of the people to start composting in the garden, which opened in 2014 and is part of the National Parks Board's Community In Bloom programme, is freelance photographer Chen Shih Tse, 63.

He says: "I heard that compost can help improve soil quality and make plants grow better."

He pored through books about composting and found that the materials he needed could mostly be found around him.

He collected dead leaves from the neighbourhood, vegetable scraps and fruit peels from his home, as well as coffee grounds, sugar cane and soya pulp from hawker stalls.

His compost bin was a plastic container picked up from his block's void deck. The only thing he bought, to speed up decomposition, was chicken manure from a local farm. A 20kg bag cost him about $5.

It took him about two trials to get the compost right. Both times, he had added too much chicken manure, resulting in a smelly and sticky compost.

Last year, together with two other gardeners - Mr Chien Choo Nyan, 67, and Mr Jason Ong, 58 - he decided to compost on a bigger scale and share his knowledge with other gardeners and residents.

They converted a 60-litre barrel into a compost bin, drilling holes into its sides and adding a door on top. They put it on a steel structure with wheels so that it can be rotated easily at regular intervals to aerate the compost pile to speed up decomposition.

Meanwhile, other gardeners in the community garden had also started another form of composting - using worms.

Mr Derrick Lim, 40, whose mother is the secretary of the Toh Yi Community Garden committee, donated some composting worms and two compost bins.

One of the gardeners, Mr Kong Wah Beng, 64, a part-time associate training consultant, volunteered to take over the bins, though he had zero knowledge about composting.

The worms escaped three or four times and he had to spend hours using a satay stick to take them back to the bin.

He found that overfeeding them with discarded fruit collected from wet markets had led to excessive heat, which the worms dislike, causing them to escape.

Ants also almost wiped out his worms thrice. To prevent them from doing so again, he now puts the stands of his two bins in containers of oil.

Mr Kong has been sharing his knowledge about worm composting with other gardeners, as well as the public, at events such as the Singapore Garden Festival.

He is also helping landscape design and horticulture students at Ngee Ann Polytechnic to build a worm compost box for a project.

Being able to share his knowledge with others is the best part of his composting journey so far, he says.

"I am also happy that more people get to know about Toh Yi Community Garden as a result."

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A version of this article appeared in the print edition of The Straits Times on January 21, 2017, with the headline More composting to turn food scraps into fertiliser. Subscribe