Situations like these are a daily occurrence in the South American 6-million-inhabitant metropolis. Especially the World Cup and the upcoming Olympic Games have intensified the conflict between the Brazilian government and the drug cartels ruling the favelas. In fact, the local residents appreciate some of their government’s more recent concessions like the garbage disposal or public transportation. However, what they appreciate even more is the form of personal independency that they managed to preserve over the years. Simply calling the favelas a slum would not do justice to them.
For years now, many of us have been engaged in various discussions and experiments to determine the best way to continuously monitor the pH of our biogas systems. Those of us doing this at home on limited to nonexistent budgets have dreamed of an inexpensive DIY microcontroller based system that we can stick in a port in our tanks and forget about (except for the readings on our smart phones which would alert us when things are going sour, of course!).