A Review of the Chemistry of Anaerobic Digestion: Methods of Accelerating and Optimizing Process Efficiency

Abstract

The anaerobic digestion technology has been in existence for centuries and its underlying theory established for decades. It is considered a useful technology for the generation of renewable energy, and provides means to alleviate problems associated with low access to energy. However, a great deal of current research is targeted towards the optimization of this technology under diverse digestion process conditions. This review presents an in-depth analysis of the chemistry of anaerobic digestion and discusses how process chemistry can be used to optimize system performance through identification of methods that can accelerate syntrophic interactions of different microorganisms for improved methanogenic reactions. Recent advances in addition to old research are discussed in order to offer a general but comprehensive synopsis of accumulated knowledge in the theory of anaerobic digestion, as well as an overview of previous research and future directions and opportunities of the AD technology. Achieving a sustainable energy system requires comprehensive reforms in not just economic, social and policy aspects, but also in all technical aspects, which represents one of the most crucial future investments for anaerobic digestion systems.

Advancement in biogas production from the solid waste by optimizing the anaerobic digestion

“…The above reaction shows methane production will be maximized under reducing conditions, while in aerobic condition formation of CO 2 in the form of byproduct was also observed [4,16]. In general, the overall reaction can be written as in reaction Eq.…”

“…Thin slurry feedstock digester was considered to be more efficient, because it provides more surface area for the interaction between the microorganism and organic material. This enhanced the efficiency of microorganism in formation of the biogas [16,62,95].…”

“…The anaerobic transformation of organic material can be defined as given in the reaction Eq. R1 [16].…”

“…There are four major steps identified for the anaerobic digestion. These steps are (1) hydrolysis, (2) acidogenesis, (3) acetogenesis, and (4) methanogenesis [16]. The mechanisms of the anaerobic digestion process for these organic materials are described in Fig.…”

“…Since biogas is the mixture of gases, few of them are flammable (CH 4 and H 2 ) and the rest non-flammable. Hence, biogas requires treatment to improve its quality so that it can be utilized as a good energy source [16,37,100]. H 2 S is a poisonous gas generated through sulfate available in solid waste in a small amount along with biogas.…”