The main advantage of wet anaerobic digestion is that it allows for the optimal mixing and thus high biogas production. There are good reasons to process dry biomass in a wet digester. Possibility to use heat in a nearby facility.Space available for the plant construction (at least 600 m² just for digesters).Sufficient substrate (at least 2,000 tonnes of manure).In many cases, large quantities of structure material is required (a lot of digester space is consumed for structure material).In many cases, lower methane yields compared to wet AD systems.In discontinuous systems, the microbial process has to start for each batch.Need to manage the variation of biogas and heat production.Special technologies for loading and unloading of the digester are necessary.Use of various substrates per unit of digesters.Less complex system compared to wet AD systems.Production of land-applied solid digestate similar to manure.Less critical equipment (pumps, agitation systems, feeding equipment).Management of several digesters simultaneously.Possibility of mobile biogas plants (containers).Very tolerant system for contaminants (sand, fibres, large particles, etc.).Dry matter / total solids 20-40% compared to 20% maximum for wet digestion.Dry anaerobic digestion systems allow the use of substrates with a high content of crop residues, household waste and livestock manure. In fact, a wet anaerobic digestion plant is quite limited for the treatment of dry matter-based substrate. Several digesters will operate in parallel and allow a constant production of biogas over time.ĭry anaerobic digestion is an alternative solution to wet anaerobic digestion in order to optimize the value of manure. Dry digestion is called discontinuous because biogas production is sequenced with loading and unloading phases. What is Dry Anaerobic Digestion?ĭry Digestion in full-scale application can be performed in a continuous or discontinuous system. The choice whether to use dry or wet digestion for the fermentation of the organic depends on dry matter content. Dry anaerobic digestion systems for organic matter with consistency of 20–>40% dry matter or more.Wet anaerobic digestion systems, which use organic material with consistency of 10–20% dry matter or less.There are two main types of anaerobic digestion processes for treatment of biodegradable wastes: Appropriate conditions such as temperature, pH, N balance, etc.Continuous process of feeding the digester with organic matter and removing the processed matter.Methanogenic phase, in which fatty acids decompose to become methane.Ī stable anaerobic fermentation process meets the following requirements:.Hydrolysis phase: Transformation of organic matter into CO2, hydrogen and fatty acids.Biogas consists mainly of methane (CH4) and carbon dioxide (CO2).Īnaerobic fermentation process to produce biogas production occurs in two phases ( HoSt):
Digested organics series#
Anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material in the absence of oxygen.
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