Abstract
Anaerobic digestion producing biogas is a complex process comprising of a population of anaerobic microorganisms at four key stages, hydrolysis, acidogenesis, acetogenesis and methanogenesis. Parameters such as selection of feedstocks, pH, temperature, dry matter content and others significantly influence the process. Anaerobic digestion represents the core of the biogas production process. It could be represented by a centre of the onion diagram – “reactor”. Anaerobic digestion directly influences the biogas production process (second layer of the onion), and further its supply network (third layer), the company (fourth layer) and finally material, energy and waste treatment system of the company (fifth layer). This contribution introduces a synthesis approach based on onion diagram applied to biogas production systems. Proposed approach consists of the following steps where the hierarchy/dependencies are considered between the onion layers: i) reaction layer using the models for anaerobic digestion, ii) process layer by optimising the biogas production process, iii) supply network layer by optimising the whole supply network of biogas production, iv) company layer by the synthesis of biogas production together with the surroundings (farm, food-processing industry, etc.), and v) integrated company layer which includes improved energy and mass integration and treatment of water, waste and emissions. A similar approach could also be applied in other fields, such as in wastewater treatment processes.
