April 22, 2009

Celebrating Earth Day on the Loo

In honor of Earth Day, I’d like to introduce you to our new best friend (on the left).


Anyone know what it is? Anyone? Bueller? Anyone?

It’s a Bio-Digestor!!!!

We’re so excited about this we could just… well…. pee!! And with this, we'll finally no longer have to do it behind the bananeiras.

So what is a bio-digestor you ask? Well, it digests biological stuff. At least at the end stages of that stuff.

In carving out our little spot of paradise (petulant, bratty and trying as it can be), we have done our best to keep it as sustainable and low-impact as possible. Not too hard so far, given that we don’t even have electricity.

But a suitable arrangement for our plumbing and septic had us a bit flummoxed for a while. The traditional way on the roça is either the afore mentioned bananeiras, or if you’re lucky enough to have running water and a porcelain vaso, you build a septic leech field. Well, behind our house and a level down is a large swamp. A beautiful one actually, full of lilies and cattails and birds. It is home to all sorts of animals and plays a very important role in the ecosystem, one that we didn’t want to upset with possible contamination from a nearby septic field.

Enter the bio-digestor. This little beast can handle organic waste of up to 600 liters. After it does its digesting job, it releases from one end water that is tested 99% pure. And from the other end, into a small casement box the effluent gathers which once every 4-6 months needs to be cleaned out. It comes as dry as ash, clean and uncontaminated and can be buried or sprinkled about as fertilizer. Cool, hugh!?

(Here's C with his internet instructions trying to work out with Vicente how to install it.)


But wait, there is more…

Do you know what makes this grand process work? You’ll never guess….

Soda bottles.

Yes indeed! The bio-digestor runs on PET plastic! We were totally blown away when the guy in the store opened up the top to give us a tour and out tumbled chopped up Sprite and Coke bottles. We though they were just in there for packing material, but no! They are actually the filter that enables the anaerobic process to take place. Don’t ask me how, I haven’t quiet figured it out. It’s a design invented by some clever Brazilians (they are very good at coming up with ways to reuse PET plastic) and I think patented as well.

Up until now, bio-digestors have been mainly used for recycling livestock waste. But there are a number of efforts being made, especially in areas where poverty and sanitation are real issues, to bring them into residential/community use. Many bio-digestor designs allow for the methane gas they produce to be reclaimed and used for heating, electricity and cooking gas! How cool is that?

We’re very excited about our newest addition. I was really hoping that we’d have it installed and ready to be inaugurated by Earth Day, but alas, as usual, things are moving slowly. So for the time being, we’re still roughing it in the great outdoors.


Ballerina Girl said...

How cool is this machine!
I hope it is up and running and becomes a great inspiration for many more communities. I think it is a great idea!


markuza said...

wow- never heard of such a beast. Very cool. My guess is that the PET chips provide surface area for bacteria to live on, kind of like all the crazy folds in our intestines.

Danielle said...

Wow, this is pretty great. :) If we weren't renting an apartment, I'd definitely look into it!

I have a friend who's an environmental engineer, and I sent her the article to see if she knows anything about the reason for the plastic bottles. :)

lovelydharma said...

Cool, thanks Danielle. I'll be interested to hear what she says.

Kuza, I think you're right. I remember hearing the guy in the store say something about surface area.

BG - I googled them and found an article about a slum in Kenya where they went from having an open sewer, to having toilets AND heat, hot water and cooking gas all from the reclaimed methane. It's a very cool idea!

el joy said...

Awww, a baby digester! I agree with markuza--the PET pieces maximize surface area for biofilms. It’s the same idea in raw surface water treatment using slow sand filters, where fine sand provides surface area for biofilm... and also in wastewater treatment using constructed wetlands (a prettier eco-alternative to septic leech fields), where plants like cattails and bulrushes are home to biofilms. The 11 digesters at the wastewater treatment plant where I work digest millions of gallons per day of wastewater, livestock dairy/blood, food waste, etc. and produce enough biogas for heat/electricity to run the entire plant and sell to the gas/electric company. Municipal digesters have been around for so long, it’s awesome (and about time) that point-of-use digesters are more available for developing communities. I’m excited to read more about your biodigester experience! :D

lovelydharma said...

Hey El Joy! THank you so much for the info. Wow - are you in the US? What an awesome self contained set up - generating it's own electricity. See, it's things like this that give me hope for the planet!

I knew that the swamp below our house could act as a filter, but the swamp drains into a stream that our next neighbor down in the valley uses as his water source, so we were worried about contaminating him. When the environmental laws are enforced in Brazil, they are REALLY enforced, so we have to be very careful in our choices - no that we don't want to be.
We're very excited about our baby digestor!

We now will just have to train guests not to throw TP in the pot!

el joy said...

No worries, I'm happy to geek out about wastewater treatment any time! I live in the Bay Area, and learning about small-scale digesters in places like Brazil and Kenya also gives me hope for the planet :). I'm also happy to learn that Brazil strictly enforces environmental laws like the US, which would never allow using a natural (vs. constructed) wetland for wastewater treatment. About no TP in the pot, it's funny because I sometimes have to tell my guests (who grew up in areas lacking sound plumbing and sewage systems)to throw their soiled paper in the toilet not the trash. Since you're not digesting your toilet paper, how will you dispose of it... composting?


lovelydharma said...

Oi Elena!
You're too funny about geeking out on water treatment! Love it. A friend of mine's sister is an environmental engineer here in Brasil, working on sewage treatment. I will have to ask her if biodigesters are being used in large scale treatment plants here.

And far as the TP goes, well... we're considering various options. We will certainly build a compost bin for food scraps, but I never considered putting soiled tp in there. Is that safe if we reuse it for fertilizer? Because we don't have electricity and don't have any time line for getting it (many rural areas are still without, and the cost to run it is over 30 grand, so we can't do it ourselves and have to wait for a government program to get around to it.)

So hot water and cooking is for the time being going to be done with a traditional wood burning stove. There is a system where you run water through pipes through the stove and then to a reserve box for taking hot showers (it's Brazil yeah, but cold where we are). You can see a pic on the post "Rural Dreamers" of our neighbor's stove.

Anyway, not exactly carbon friendly, but our neighbors end up burning everything that isn't compostable in their stove - except for plastic and glass and metal which get's hauled in to be recycled once a month.

Solar isn't an option because the structure of the house we are rebuilding doesn't have the distance between the roof and the reserves that is necessary for solar panels to work. - i.e. no attic space.

Anyway, it's a give and take, and the stove will be there to get us started, but hopefully it won't be something that we use constantly or until and we can come up with better options...

Evelyn said...

I love the amazing environmentally friendly inventions out of Brazil! How cool is your digestor?! Love the way you all are living there!

el joy said...

Sweet, I'd love to hear what your friend's sister says about environmental engineering in Brasil!

Combining food/yard and fecal wastes for compost is scientifically controversial. Some studies prove that green-black waste or black-only waste compost is safe for horticulture, while others prove otherwise. Of course, these results varied because of different methodologies, so obviously the safety of green-black waste composting depends on the usual factors such as temperature, moisture, aeration, C:N, etc. In my opinion, a pile that is properly and thoroughly composted will ensure high temperatures that deactivate harmful microbes to safe levels. I see soiled TP (preferably recycled/unbleached) as a nutrient/carbon-rich source for friendly microbe activity in compost. Others may see it as a "no-no" for composting (e.g. http://www.compostthis.co.uk/item/toilet-tissue). Your compost, your call!

Chemical->mechanical->electrical (see: http://www.anaerobic-digestion.com/html/electricity_from_methane_diges.php). Your baby digester (or digester twins or triplets, ask your neighbors to invest:) might produce enough methane for a small generator, and waste heat from this system could be used to heat water for showers, while avoiding the health and environmental impacts of burning wood. Just an idea... you'd have to consult a mechanical engineer for the details, maybe your friend's sister is also a mech. e.?

Boa Sorte!

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Anonymous said...

I really love your post. I am getting ready to go back to Brasil (pra BH) after living in the US for 8 years and it is very cool to see all these environment friendly ideas.


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