Anaerobic digestion has been applied to different organic waste streams, including agricultural waste, industrial waste, municipal solid waste and sewage sludge. This technology has been considered the main option for both treatment and recycling of sewage sludge and it is of great interest from an environmental point of view.
The anaerobic digestion dry (AD) (>20% TS) has been applied at full-scale mainly for OFMSW (Organic Fraction Municipal Solid Waste), whereas systems working with 5-20% TS can be found mostly for residues resulting from farming, agriculture and/or agroindustry. Recently, several research studies have focused on the treatment of sewage sludge by means of high-solids technology.
Although high-solids AD of sewage sludge is gaining attention in some countries like Japan, such interest is not reflected at a European level and efforts remain to be made on this field. The LIFE-ANADRY project seeks to demonstrate that it is possible to broaden the spectra of high-solids AD applicability in Europe beyond its current limits, both in thermophilic operation (55ºC) as well as in mesophilic (35ºC) operation. AD is a technology with important benefits resulting from energy recovery that could be further exploited across EU at a WWTP level.
The addition of an AD process for sludge stabilization could make possible reducing the aeration requirements in the previous aerobic processes and, therefore, major savings could result. All aforementioned aspects are crucial to determine the feasibility of the process prior to its implementation at full-scale, not only from a technical point of view, but also from an economic perspective.
The aim of this project is to explore different theoretical full-scales scenarios by applying modelling tools, including an alternative where a centralized dry AD plant is proposed for the treatment of sewage sludge produced in a concrete area in such a way that a global approach will be obtained of the problem.