Thursday, 5 June 2014

Turning Food Waste into Compost in High-Rise Apartments

5 June 2014
In Singapore, more than 90% of the populations live in high-rise buildings.  Some might have luxury of balconies,  most just have common corridors for planting some plants and flowers in pots.  Not many have backyards that could be used to make compost which usually emits foul smell.  Many resorted to buying  pallet fertilisers from the shelves which can cost them a bomb over a longer period.

What is compost?

It is an organic fertiliser made from waste fruit peels,  skins,  vegetables and other organic foods.  They are usually left to decompose for a period of about two to three weeks until they are turned into partly a soil enriched with organic fertilising elements. 

How Compost was made?

Many in the net taught us how to make compost at home; some are suitable for high-rise buildings while others are not. Some used compost bins and some used earthenware to keep and make the compost. What they normally teach us is either to keep the waste in the bins or earthenware together with some dry leaves. These bins/earthenware might give out odours or scents and other rotten smell filling the whole apartment. 

What is the better method? 

Instead of bins and earthenware,  the better method would be to use plastic bag which every household will have plenty when they shop at the Supermarkets.  Instead of keeping the waste together with dry leaves,  one must treat the waste such that it will not give out lots of rotten smell.   

Preparing the compost 

1. Drying the waste 

A good method is just putting the waste under the sun. This will unfortunately attract a lot of small food flies and sometimes,  big flies which some may have strong objections.  However,  one can cover the waste with fine net mesh to keep away the flies as shown.   

It is always good to cut the waste into small pieces for easy spreading and for drying under the sun.

The other method is to fry the waste on a frying pan so that the heat will not only dry up the waste for safe keeping in the plastic bags,  it will also kill  the bacteria inside the waste.  

2.     Grinding the waste (optional) 

It would speed up the compost making if the waste is grounded every time for storage.  It is not quite necessary if one is prepared to keep the waste for a longer period than 3 weeks and not too fussy about the smell that may be emitted from the compost.   One could further fry the grounded waste to get rid of more moisture.

3.  Storage  

The success of the compost making will depend on how one can cultivate the anaerobic bacteria that will consume the waste and turn the waste into soil enriched with organic fertilising elements.  This is where plastic bags will come in handy as one can easily mark the plastic bags to keep track of the storage period as well as ensuring that there will be little exchange of oxygen that will kill the anaerobic bacteria.  

1.     Find a good plastic bag.  The shopping plastic bags are so thin that they would usually have small holes here and there.  To plug these holes,  inflate the plastic bag by blowing air into it and plug up the holes if any with masking tape. 

2.     Put the dry waste and spread it across the bag as a layer,  then cover it with 2 layers of ordinary soil. Active soil with some anaerobic bacteria in it will populate and digest the waste much faster than those inactive soil, idled for some period. 

3.     Mark the plastic bag with dates and keep in storage until 2 to 3 weeks later. Additional layer of same proportion of waste can be added to the plastic bag until it is full.

Precautions in Handling Compost

There were reports that some farmers in Australia and New Zealand were killed by legionnaire bacteria when they handled the compost with their bare hands and did not wash their hands afterwards.   

It is good to bear in mind that there would be many different type of bacteria in the soil and compost.  Legionnaire bacteria are one of such bacteria that could populate well under anaerobic condition especially when the waste is still wet before storage.   Legionnaire bacteria are commonly found in air conditioning cooling towers and also air conditioning condensate pipes and water storage if some part of the water is kept under an anaerobic condition. 

It is good to wear gloves as well as breathing mask when handling the compost as bacteria could fly around when the compost are being churned and mixed.  It is always advisable to wash the hands with soap and clean water each time after handing the compost.   Let the soil expose to the sun for a few day before handling them with the bare hands.

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