30 December 2011

Composting to Lighten our Carbon Footprint

There are a variety of ways to calculate your carbon footprint. Online calculators ask you for all kinds of information about your household, flights and car use. On carbonfootprint.com they even ask you about food preferences and how much of your waste is recycled. Composting is mentioned in one of the recycling options. However, I think it deserves more prominence if we want to make decisions about how to tread lighter.


I looked around the Internet to find out how much organic waste people produce on average and I found very little information. One survey reported that “households taking part in the Central Vermont Solid Waste Management District's Bin & Cone Pilot diverted an average of 345kg (760 lbs.) of food scraps per year,” while the Austrialian government reports that Australians generate an estimated 361 kilograms (794 lbs.) of food waste per person per year or approximately  936 kilograms (2059 lbs.) per household per year. The Environmental Protection Agency in the US asserts that North Americans throw away an average of 214 kg. (474 lbs.) of food scraps per family per year.

In summary:

Household Food Waste Generation per Year
Source 1: Central Vermont
345 kg.
Source 2: Australia
936 kg.
Source 3: EPA (USA)
214 kg.

These figures are wildly inconsistent, they come from developed nations and I don’t trust surveys about kitchen waste production. Think about it, if somebody asked you how much your daily compostable kitchen waste weighs, what would you say? So, I decided to find out for myself.

I did what any respectable scientist would do: I weighed our compost before taking it to the compost pile every day for six months (May to November, 2011). Here are the results:

Scoggin Household Food Waste Generation
Average per day
2.64 kg.
Average per week
18.36 kg.
Total for the year
954.80 kg.

Pretty high, no doubt. Six people live in this house, similar to the average Ecuadorian household.  Also, I am vegetarian, and we consume a lot of fresh fruit and vegetables.  Further, our maid composts all leftovers, and they tend to be pretty heavy. When I say that these figures are high, I am not only comparing them to the reported results from other countries, but also to our neighbors who participate in our community composting project. Based on daily observations, my household contributes approximately one third of all compost to the project, even though seven families participate.

Why are these results significant? According to Wikipedia, Ecuadorians emit 3,090 kg. (6,800 lbs.) of carbon per capita per year, considering all sources of carbon emission (compared to 22,182 kg. per American!) Also, each kilogram of food waste emits the equivalent of 6 kilograms of CO2 in a landfill, under anaerobic conditions, and 0 when it is composted in aerobic conditions.

This means that taking into account only CO2 emissions from food waste, my family saves 5728.80 kg. of equivalent CO2 emissions per year, or 955 kg. per person per year. In other words, my family saves 31% of the average CO2 emissions for Ecuadorians only by composting.

Of course the average Ecuadorian household would save considerably less by composting because of the average diet composition and how much food is consumed at home. But even if it turns out to be 20% or even 15%, the effect of composting on greenhouse gas emissions would still be significant.

The fact that my family saves nearly one third of the average CO2 emissions only by composting deserves attention by any authority keen on making this country greener.

13 August 2011

Las Iguanas Landfill

Recently I took a tour of our local landfill, expecting to find a complete disaster of a place like I saw while I lived in Cali, Colombia. Guayaquil’s landfill, however, is better organized and run than most any other local or national government agency! I couldn’t believe it. I am not going to get into specifics about the landfill in this post, but suffice it to say that I was very surprised at what I saw. Everything in the following video is true!

I learned a lot through the visit. For example, here in Guayaquil recycling is strictly prohibited because there are no recycling trucks, so it makes garbage trucks fall behind their schedules and because informal recyclers make a mess of curbside garbage after rummaging through it all and leaving what they can’t use all over the sidewalk. So, everything goes to a single landfill.

The landfill struggles with two big problems on site. First, is the huge quantities of methane that escapes from the garbage. To deal with this properly, tubes are installed to channel the methane out into the atmosphere because otherwise it accumulates underground and becomes quite explosive.

Methane is a greenhouse gas that is 21 times more potent than carbon dioxide. Significant methane production typically begins after approximately one year of disposal and continues from 10 to 60 years.1 Landfills are the largest source of U.S. methane emissions and emitted ... 37% of total U.S. emissions in 1997 (EPA, 1999).

The other major problem is leachate.  This is a liquid produced when rain falls on and moves through garbage and drains off extremely contaminated. It is also produced without rain when organic waste decomposes anaerobically, as you can see whenever you take the garbage out and there is some liquid left at the bottom of your garbage can.

Through a series of pipes and drainage areas made with thick plastic liner, the leachate is channeled to an evaporation pond like the one above where it is supposed to evaporate. Much of the leachate is pumped back up and sprayed over the garbage so that it will evaporate in that process. There is no other way to get rid of it. If it is not collected in this way, it will find its way down into the groundwater and contaminate it at lightening speed. This stuff is so toxic that the guide told me of the hives that broke out all over one worker that accidentally touched it once. This makes me wonder about the composition of the rain that comes out of the clouds formed though its evaporation.

What stayed with me the most is that both of these problems originate either exclusively or mostly from food scraps. Diverting food scraps from landfills would resolve the methane issue completely and reduce leachate production significantly. There are many, many other benefits from doing this that I will look at in depth in later posts.

In “developed” or industrialized countries, food scraps make up approximately 30% of all municipal waste by weight, although in the United States it is much lower at 14.1% as shown in the following figure.

However, in “developing” countries the percentage of landfill made up of food scraps is much higher, making up approximately 60% of all municipal waste. This is true for our local landfill where 56% of the landfill is organic matter.

This makes recycling food scraps a much more significant issue for developing countries like Ecuador. This is one of the reasons that I will now embark on a series of posts about how I have taken steps to contribute to resolving this problem in Guayaquil.

1. http://www.iowadnr.gov/portals/idnr/uploads/waste/ecosec7.pdf

12 June 2011

Our Third Harvest!

I haven't needed to harvest bin 3 until now but it worked out fine because I was able to confirm a hypothesis of mine. I had put too many leaves in to make sure there would be no odors, and that just made everything decompose slower. So, letting it sit longer, I assumed would produce dark, rich humus unlike what we got from previous harvests. We let the first bin sit for 19 weeks, and the second for 20 weeks, while this one had been sitting for 35 weeks since it was filled. It worked! We got loads of perfect humus.

Also, as you will see in the pictures below, we sifted the compost finer this time, which gave us better final results too.

So, the lesson is put fewer leaves in the mix and you won't have to let the compost sit so long. If you put too many leaves in, then let it sit longer. Simple.

Here are some pictures from today's harvest.

24 May 2011

Community Composting One Year On

Our little recycling project has completed its first year of life. It has been the subject of a two-page article in a local newspaper, the topic of a small project for some Master degree students in a local university and the object of two talks to environmental education classes in a local high school. Conversely, it has survived workers stealing the bamboo infraestructure, smear campaigns from neighbors, being associated with an infestation of rats and a long, wet rainy season. After all of this, it seems to be emerging stronger than ever, ready to prosper and grow.

The project languished for about two months when many neighbors associated it with the infestation of rats and as the rains kept the whole place wet and somewhat muddy. During that time, only two families contributed regularly, down from seven during the rest of the year. Then, it occurred to me that instead of fighting their erroneous notion about the rats, it would be better to solve it beyond any doubt and allay their fears.

On the Internet you can find lots of compost projects, but they are all either for one family (in an enclosed bin) or huge, industrial deals inside large areas. Very few are outside, and those are mostly for leaves, cut grass and small branches, with very little kitchen waste. Putting the whole operation within an enclosed area would be too much work and expense. So, I figured that rats only like the fresh stuff and if we could decompose the fresh waste in a closed environment, then they would have no reason to come around. Once it gets hot enough and the waste decomposes beyond recognition, then it can be poured out into the open air bins to be finished.

So, we bought several new garbage bins and drilled holes all around them. The procedure is to fill up one bin with waste and leaves and once it is full (which takes 1 to 3 days), then put the top on it tightly and start filling up the next bin. Once they are all full, then the first one is emptied and it is ready to be filled again. Because there are 7 families participating and we only have 4 bins, each bin stays full for a little over a week until it has to be dumped into the outside compost area. Of course, one week is not quite enough for the kitchen waste to become unrecognizable, so we need more bins. However, during that week, the waste inside each enclosed bin really heats up and the volume is reduced by approximately 30%, so a lot of action takes place in there.

The bins in the back are full and so are waiting their turn to be emptied and filled again.
The grey bin in the foreground is getting filled up.

Here are the 4 spaces for compost.
The second one, where the rake is,  is currently being filled up.

This is how the garden area looks now.

This has convinced some of the sceptical neighbors and they are participating once again! With this resolved, I see no reason the project can’t start growing considerably. For this second year, I would like to double the number of families participating (from 7 to 14) and double the amount of kitchen waste and leaves we recycle this year (from 320 to 640 bins). Further, I would like to consider this as a model method for enclosed housing developments around the city and the country. If this idea comes to fruition, I would like to make an introductory video in Spanish, put it up on youtube, and use it to see if other housing developments would be interested in starting small projects. Of course, this is just an idea, we will have to see how things unfold this coming year.

Soon, I will post news about our third compost harvest, about the little vegetable garden that has been started up with our soil and some amazing statistics that I have been compiling about how much kitchen waste is produced in a typical house around here each week and month.