The next time you go to scrape your leftover food scraps into the bin after a meal, it’s worth having a think about the consequences of this all-too-common ritual – and how we might be able to make a change for the benefit of the environment. Whether it’s investing in a composting bin for recycling food waste, using leftovers for lunches, or cooking smaller quantities, here’s a few things to think about.
Whether you’re a global warming warrior or a climate change sceptic, no one can deny that our human presence on earth is leaving a less than desirable footprint. Landfills are overflowing and chemical-laden industrial and farming practices are polluting our water systems. Fertile topsoil, in which 95 percent of our food is grown, is disappearing way faster than it’s being replenished, and bird and insect populations are decreasing.
Regardless of what lies ahead with the climate, we need to be living a more environment- and future-friendly existence. While it’s easy to blame rising populations, poor governance or unethical business decisions, there is one very easy and effective way we can all make a difference on an individual basis.
The menace of methane
First, let’s take a look at the bigger picture of what’s going on in the air around us. While many may be familiar with the most prolific of the greenhouse gases, carbon dioxide, there are a number of other nasties out there that are coming under the microscope. The most notable of these is methane (chemical formula: CH4).
Since the Industrial Revolution, methane concentrations in the atmosphere have increased by over 150 percent. As a gas that is involved in the ground-level formation of the air pollutant ozone, as well as having exceptional heat-absorbing capabilities (84 times more potent than carbon dioxide over a 20-year period!), methane could exacerbate extreme weather conditions in the short term and increase the risk of respiratory health issues.
While much of the methane in the atmosphere comes from natural sources such as wetlands and volcanoes, scientists now believe that more than 60 percent is directly attributable to human activities. The highest contributor to this figure is fossil fuels, particularly leakages during the production and distribution of natural gas, a fossil fuel that consists primarily of methane. Other large sources of methane are the gaseous bodily functions of ruminants (cattle, sheep, goats and so on) and the methane-producing bacteria present in waterlogged rice paddies and landfills. The consumeristic attitude that is causing our landfill sites to overflow is also causing another problem: biodegradable material that is left to rot, in the absence of oxygen, produces methane.
How we can help
That’s where we enter the picture. Even though technology is being developed to siphon off some of these landfill emissions for use as fuel for heating and cooking, a much greater benefit could be achieved by not sending our organic waste to landfill in the first place.
By recycling food scraps back into the ground via a composting process, we can not only reduce landfill emissions but actually draw down carbon from the air by using the compost to grow our own plants and veggies. Plants absorb carbon during photosynthesis, a process that produces simple sugars and other related compounds that then feed specific groups of microorganisms in the soil, namely bacteria and fungi. These microorganisms use this carbon-rich food source to multiply, and they can then remain unchanged in the soil for hundreds of years, thereby locking up large quantities of carbon. Soil regeneration experiments have resulted in as much as 20 tonnes of carbon per hectare being sequestered annually; this suggests a huge potential for balancing atmospheric carbon levels naturally.
A composting guide
There are many ways to get involved with this regenerative process.
#1 Aerobic composting
If you have enough space, you can create a compost pile in the garden; otherwise, use a compost bin. For this aerobic form of composting you need to add nitrogen-rich food scraps (no meat, dairy or oils) and carbon scraps such as newspaper, cardboard and dried leaves – preferably in a ratio that favours slightly more carbon. Keep the mix moist but not soaking wet, and adjust as needed by adding more carbon or more water. Turn once a week.
#2 Bokashi composting
Named after the Japanese word for fermented organic material, Bokashi composting is an anaerobic fermentation process. Your food scraps (which in this instance can contain meat, dairy and oil) and carbon scraps are mixed in any ratio with a microbe-inoculated medium (sometimes known as Bokashi bran or powder) and compressed into a bucket. The resulting liquid (known as leachate) is drawn off every second day. Once the bucket is full, the scraps are left for two weeks to ferment, as you continue to draw off the leachate; after this, they can be buried in the ground or layered with soil in a bigger bucket until fully broken down. Tip: Don’t plant anything in the Bokashi area for at least two weeks as it is very acidic.
This is a great system to use if you have children. Food and carbon scraps are fed to special composting worms that are kept in a wormery. These industrious creatures accelerate the aerobic decomposition process by tunnelling and eating their way through the waste, turning it into a wonderful compost that is further enriched by the worm’s own excrement.
If making your own compost isn’t an option, perhaps investigate the possibility of starting a community garden and composting system, or, if you can find a composting neighbour, pass your scraps to them to put to good use. Whichever way you choose to participate, there’s the feel-good factor in knowing you are giving something back to nature and becoming part of the solution rather than being part of the problem.
RESOURCES IN HONG KONG
Hong Kong Composting Guides and Methods: hkcomposting.com | greenqueen.com.hk
Compost Bins: ubuy.hk | greenearthsociety.com
Bokashi Food Waste Recycling System: greenersaction.shopunch.com
Community Gardens: lcsd.gov.hk/en/green/garden/index.html