Improvement of Biogas Production Utilizing a Complex Anaerobic Digestion Model and Gradient-Based Optimization

Abstract

Anaerobic digestion (AD) is a promising technology for renewable energy production from organic waste. In order to maximize the produced biogas quantity and quality, this paper deals with the optimization of the AD process in a CSTR bioreactor of a full-scale biogas plant. For this purpose, a novel approach was adopted coupling, a highly complex BioModel for AD simulation, and a gradient-based optimization method. In order to improve AD performance, the dosages of various types of biological additives, the dosages of inorganic additives, and the temperature in the bioreactor were optimized in three different scenarios. The best biogas quality was obtained using multi-objective optimization, where the objective function involves the following two conflicting objectives: the maximization of biogas production and minimization of the needed heating energy. The obtained results show that, potentially, the content of CH4 can be increased by 11%, while the contents of H2, H2S, and NH3 can be reduced by 30%, 20%, and 81% when comparing the simulation results with the experimental data. The obtained results confirm the usefulness of the proposed approach, which can easily be adapted or upgraded for other bioreactor types.

Influence of the Parameters of an Agricultural Biogas Plant on the Amount of Power Generated

“…The chemical composition of the biogas produced in the biogas plant was also checked during the study. The most significant proportion of methane in the biogas studied was 50.8%, at the lower end of the range of methane in biogas reported in the literature [37,48,75]. The carbon dioxide content was as high as 44.3% and was higher than the ranges reported in other publications [48,76].…”

“…The above parameters were measured before the biogas was subjected to the treatment process. These values indicate that the biogas production process in the agricultural biogas plant under investigation should be optimised, e.g., using the solutions described in [37]. The authors will pursue this topic in further studies.…”

“…With the increasing demand for food [31,32], one solution is to increase the unit efficiency of animal production (without increasing the livestock population). Many researchers indicate that to reduce greenhouse gas emissions significantly, one can either reduce animal production (and thus, with ever-increasing demand, reduce the supply of food) [33,34] or, with the shortest possible storage period [35], process animal manure in agricultural biogas plants [36][37][38]. In addition, improper storage of manure increases emissions of CH 4 , N 2 O, CO 2, and NH 3 into the atmosphere and contributes to a significant loss of the nutrients present in this manure [39,40].…”