This type of system can be operated under configurations with low or even negative energy demand, since it does not require power for aeration and is able to partially recover energy from the organic matter in the form of methane. In addition, the organisms that anaerobically degrade the organic material have low cellular activity and thus produce much less sludge than aerobic systems.

The CALAGUA group opts to study efficient technologies for the valorisation of organic wastes from different origins, such as urban wastewater, industrial wastewater, solid urban waste, algal biomass, etc. According to the type of waste, CALAGUA evaluates the viability of different anaerobic treatment systems such as mesophilic or thermophilic digesters, anaerobic membrane bioreactors (AnMBR) or different combinations of anaerobic systems that can transform existing WWTPs into producers of nutrients, recycled water and energy.