Acerca de jens

Jens is a Dutch/German biochemical engineer living in Barcelona since 2008. After a quick start in the petrochemical industry (in Greece, Malaysia and the UK), he soon changed course to renewables (mainly biogas and international carbon credit origination), and is now primarily focusing on 2nd generation biofuels from (bio)residues. Due to growing concerns about the current urban food supply chain, he also started to experiment ( with hydro/aero/aquaponics as a form of urban farming. Besides all this, he also enjoys sailing, (scuba)diving, hiking, and cooking :)

1st Bokashi Batch

Hey guys, my bokashi system is more or less operational by now. After two weeks fermenting the papers in plastic bags, I laid them in the sun to dry. There were some air pockets in the plastic bags, which resulted in a few colorful fungi at some spots of the paper (I think Nestor had the same situation).


For the composting tank I found this 8L bucket (including airtight lid), a strainer with a slightly smaller diameter, and plastic drain valve.IMG_1447 As you can see in the picture I already cut off the handle from the strainer, and dented the grid so it fits in a stable manner at the bottom of the the tank.2014-06-01_13-05-26_515Subsequently I made a whole at the bottom and screwed in the valve (optionally you can use some Teflon tape on the thread to make sure there are no leaks).2014-06-07_12-19-57_849So this what my ‘final product’ looks like. Time to start filling it up!

paper Bokashi

Again I missed another gathering (a bit busy these days). However, my bacteria are still up and running!! I didn’t take a picture of the serum with milk after two weeks, but basically it was a slightly cloudy liquid with big white cheese floating on top. Yesterday I separated the serum and added some molasses. As a carrier, I found some brown wrapping paper, which I drowned in the serum. Subsequently I put these wet papers (about 6 layers) in a plastic bag, sealed it, and now it should ferment another two weeks.2014-05-13_09-08-34_273

Since ‘tortilla’ is made in our kitchen on a weekly basis, I though the remaining egg shells could serve as a good calcium source (also mentioned by Mathew some weeks ago). To speed-up the degradation rate, I dry and grind them by using a (very) basic pepper mill, which works pretty well.2014-04-14_15-21-37_348

After a while I realised it’s quite labour intensive, so I’m wondering how many egg shells you need before you see a significant calcium increase in your compost.

1st step towards a lactobacillus culture

After 12 days in a cool and dark place, my first serum ever made looks like this: 2014-04-22_23-05-28_66 Basically at the bottom some sediment, the serum (dissolved starch) in the middle, and on top a layer of some scum. So this is the result of washing one part of rice with one part of water, and leaving about one part of head-space (with air). After some shaking I drained the (kind of milky) water, kept it in these two jars, and made some nice ‘nasi campur’ of the rice :)

more on day#2

Indeed a super interesting talk by Mathew! A few things I found regarding the ‘farms’ he mentioned: The rooftop greenhouse in Montreal: pretty impressive! And this self sustaining place in Chicago making veggies, beer, fish, and tea:
Having seen the “back yard” of the IAAC, I’d like to brainstorm a bit about some vertical systems mounted to (one of) these walls. However, I guess the rooftop should have the first priority. (something to discuss with Hernani and the group). This weekend I tried the “wood tie”: Restricting the flow works very well!

Opening the “valve” again takes much longer. So I was wondering how to calibrate it.