Waste stabilization ponds

Well, this week I’ve been in Belo Horizonte, the capital of the state of Minas Gerais in Brazil, at the International Water Association’s international specialist conference on waste stabilization ponds − a low-cost but highly efficient way to treat wastewater (details here). What a week! Very good conference, very good crowd of people (some of whom I only meet at these events, so it’s good to catch up with them), and excellent Brazilian food! Wastewater treatment is part of sanitation − if you have low-cost sewerage, you need low-cost wastewater treatment, and waste stabilization ponds are the best way to treat wastewater at the least cost. You can collect the biogas from anaerobic ponds and generate electricity (and maybe earn some carbon credits). It’s also possible, although more difficult and more expensive, to harvest the algae from high-rate algal ponds and make algal biodiesel − but this is likely to take a decade or two before it’s commercially viable.