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Simplicity versus advanced complexity

After attending a session in anaerobic processes, I was inspired by the presentation of Marcos van Sperling, Brazil. A novel open trickling filter inspired the audience by its simplicity. As it is an open system, nitrification was possible to treat afore anaerobic effluents. However, after that presentation I started thinking of some improvements. For instance, the introduction of some closed zones within this system. As a result, the effluent will go through nitrifying and denitrifying zones, resulting in complete nitrogen removal. Result: a much more complex system, and an increase of operational difficulties. As a consequence, I thought, what is the value of simplicity versus an advanced complex system with slightly better removals? How can you score an improvement in effluent quality versus the complexity of a system?

Tuesday I had coffee with some employees of UNESCO-IHE. A nice group to discuss these ideas. They convinced me relatively easily that it depends on the location where you would like to start such an effluent treatment system. In Africa, where no treatment occurs sometimes (and sometimes the need is not foreseen), simplicity clearly wins from advanced complexity. It is very important that you start with a system that is understood by locals, and does its job very well. After a few years, when the locals see some improvements, they’ll start wondering themselves about how improvements can be applied. However, in European countries this discussion becomes more difficult. Will simplicity still win then?

Today I had the opportunity to ask some leading professionals from America what they would prefer: simplicity or advanced complexity with a higher quality of effluent? Initially simplicity had won the game. However, when we started analyzing the process better and improved the complex system even more, we came to a different conclusion. It is possible to add a denitrification phase (and thus complete nitrogen removal), without extra operational difficulties. It does not require any extra energy, the effluent quality improves and the complexity is only increased by building a trickling filter with open en closed zones. So, why not?

Tessa van den Brand

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