Anaerobic digestion is a waste stabilisation process that takes place in the absence of oxygen. One of the benefits of this process is the possibility of energy recovery. This is due to the fact that a number of coupled metabolic reactions take place within the anaerobic digesters and these give rise to a stabilised digestate, as well as a biogas mainly composed of methane (65-70%) and carbon dioxide (35-30%) (5). An increasingly developed society has resulted in an increase in the generation of agro-food waste. This waste has a high organic load, which must be stabilised in order to neutralise its contaminating potential. Anaerobic digestion is one way of stabilising this waste.
In recent years, the implementation of anaerobic digestion for the treatment of this type of organic waste has grown substantially, due to its numerous benefits(3)(4).
However, owing to the complexity of the processes that take place within anaerobic digesters, co-digestion of sludge and agro-food waste must be carried out in a controlled manner.
In order to carry out controlled dosing, it is first necessary to undertake physicochemical characterisation of the waste, determine its maximum biogas generation potential (BMP) and the maximum doses accepted by the system at a given time. The latter depends to a large extent on the stability of the digestate.
Anaerobic digestion has a number of drawbacks, which to a large degree are associated with long start-up periods, initial stabilisation and vulnerability to variations such as temperature, mixing and organic loading. There is also a wide variety of inhibiting substances, which are the primary cause of destabilisation in anaerobic digestion(2).
Following this line of treating organic waste in anaerobic digestion, MARE (Medio Ambiente, Agua, Residuos y Energía), in conjunction with Aguas de Valencia (Global Omnium) and Empresa General Valencia del Agua (EGEVASA), are carrying out the LIFE ECOdigestion (13ENV/ ES/000377) project. The Project has the objective of automating the combined dosing of biological sludge and waste with a high organic load from the agro-food industry.
Published in: FuturENVIRO #41 June 2017