I’ve had some really interesting feedback on the whole poohcraft thing. To finish off properly – never a bad thing – here’s a roundup:
A badger latrine – try to aim better than this!
What I think is essential is taking a step back from the pooh-hole and taking a wider view. What we’re trying to achieve is:
- Safe disposal of waste
- Preventing spoiling of water sources
- Maintaining near-pristine wilderness areas
- Avoiding trashing of high-use areas
Pablo questioned the burial depth. Here I must hold my hands up – the whole anaerobic, digging deep thing was what I was always taught, not something I’d actively researched – until now. I spent Friday and Saturday evening delving into sewage and soil microbiology but I’m not sure I’ll be changing my dumping habits!
Pablo thought a shallow burial would speed up the composting. Taking a look at composting technology a few things have to be just right to achieve optimal aerobic composting – moisture level, oxygen level, carbon/nitrogen ratio and temperature.
If everything is just right then elimination of harmful pathogens and reduction to harmless compost can be pretty quick (maybe a three months). However to achieve this efficiency, some substantial changes are needed to the way most of use operate. Here’s some science:
- Human faeces contain around 66-80% moisture. For optimal aerobic composting, moisture is needed, but not this much – maybe 50-60%.
- Human faeces have a carbon/nitrogen ration of 5-10 (that is for every part of carbon there’s 5-10 parts nitrogen). Bacteria like a balanced diet and will work optimally at a ratio of 20/1 to 35/1. To get this ration requires the addition of a substantial amount of organic matter (leaves, bark, sawdust). Some estimates place this as high as 486ml of added organic matter per dump. Of course, by adding the organic matter we reduce the moisture and introduce more oxygen, increasing the chances of hitting the sweet-spot for aerobic composting.
- For speediest elimination of pathogens the temperature needs to be elevated. There are bacteria which raise the temperature – think spontaneous combustion in haystacks – but there’s evidence to suggest these bacteria are not found in cooler places such as forests.
I think it may be possible depending on your environment to achieve this. For the cooler temperate wooded environment I’d still hold with my burying a little deeper. The decomposition takes longer but the deeper burial ensures I won’t be sticking my foot in it and hopefully animals will be discouraged from unearthing the brown gold buried below! Of course any alternative viewpoints are welcome.
Ditch your toilet paper
Lightweight hiking guys Hendrik and Joe (always eager to save a few extra grams of toilet paper!) have suggested, quite rightly, the replacement of toilet paper with alternatives from nature. This not only frees you from carrying paper but with careful selection can be more enviro-friendly and helps your carbon/nitrogen ratio of mixed in well!