Influence of pH and Pre-treatment on Biogas Production in Anaerobic Digestion: A Review

Abstract

Anaerobic Digestion (AD) offers a potential solution to global challenges in renewable energy production and waste management. It is also a promising low-carbon emission technology. However, its efficiency can be limited by various technical factors. This review article addresses these limitations by investigating the main effects of pH and pre-treatment on biogas production and COD removal efficiency. The research methodology involves a comprehensive review of the literature on the effects of different pH ranges and various pre-treatment methods, including thermal, chemical, and enzymatic techniques. The findings revealed that a neutral to slightly alkaline pH range (6.8–8.3) provides optimal conditions because it can balance acidogenesis and methanogenesis, leading to high biogas yield and a COD removal rate of up to 86.34%. In addition, pre-treatment can significantly increase the efficiency of the AD process. For example, thermal alkaline pre-treatment of algal biomass increased methane yield by 229%, and shock wave pre-treatment of algae increased dissolved COD by approximately 70% compared to the control group. The contribution of this study is a consolidated overview of optimal conditions and effective methods for improving AD performance, providing a basis for designing AD systems that are more efficient and stable for sustainable energy and waste management.