Contribution to the development of a "low cost" process for sewage sludge stabilization.

The quantity of sewage sludge (SS) requiring disposal in the EU is increasing. Sludge post-treatment operations, such as stabilization, dewatering, drying, and sustainable disposal options, have become a global concern. Costs associated with these operations are exorbitant. Innovations targeting the management of sludge at minimal cost remains a challenge. Integrating microalgae biomass production with SS stabilization process is a promising approach for the implementation of a “low cost” technology. Being photosynthetic microorganisms, microalgae can eliminate the CO2 emission, lower the need for mechanical aeration by providing oxygen via photosynthesis, scavenge resources (C, N and P), remove pathogens microorganisms, and convert solar energy into valuable biomass: a potential biofertilizer called Microalgae-Bacteria Flocs (MAB-Flocs). Thus, a general trends in changes of physicochemical properties of stable sludge, influencing SS dewatering and drying