Aerobic granulation for future wastewater treatment technology: challenges ahead

Aerobic granules were discovered around 20 years back. These are spherical aggregates of mixed microbial culture, typically around 0.5-3 mm in diameter. Aerobic granule-based wastewater treatment technology has been successfully used on a full-scale for real wastewater treatment. It is argued that the aerobic granule-based technology can potentially replace the traditional activated sludge process. The first of its advantages is that aerobic granule-based wastewater treatment plants can be built within around one quarter of the land occupied by conventional activated sludge-based plants. Additionally, this technology can reduce the operating cost by nearly 25%. Reduction in sludge production and reduction in energy consumption (around 30%) are other benefits of this technology. Granule formation is a relatively slow process. In fact, the time taken for granule formation is a challenge for a full-scale application of this technology. The mechanism behind aerobic granule formation is not fully understood. Thus, further investigation of the molecular mechanism of granule formation would be crucial for the successful commercialization of this technology.