Structural improvement towards the efficiency of biodigesters in the 21st century: a review of the different designs

Anaerobic biodigesters play a crucial role in the sustainable development of rural areas, managing waste and generating renewable energy. This review evaluates the development and performance of the fixed dome, floating drum, and tubular biodigesters, viz, shows how design improvements and operational strategies impact their efficiency. The original design of these traditional models was found to be restricted by microbial instability caused by climate fluctuations and operational disturbances. In response, modern designs incorporated specific adaptations, such as thermal control and feedstock optimization. The fixed dome model demonstrated improved durability and performance with solar heating and self-mixing capabilities that increase methane production and volatile solids removal. In contrast, floating drum digesters, which are constantly limited by corrosion and inconsistent yields, have been developed to incorporate plastic protective layers, integrated mixing shafts, and <i>in-situ</i> purification to achieve better methane concentrations and improved system efficiency. Affordable and adaptable tubular digesters with modular expansion capabilities, incorporating trench burial and greenhouse enclosures, have been designed to enhance affordability and mitigate the effects of climate change. The modifications increase methane production, process stability, and energy recovery. Biodigester performance and efficiency are fundamentally driven by design. Accordingly, the future adoption of anaerobic biodigesters will depend on locally adaptable and affordable systems supported by practical maintenance frameworks, as well as community awareness and training. Overall, recent design innovations have enabled a shift from climate-sensitive traditional models toward more durable, efficient, and adaptable digesters capable of stabilizing methane yield under variable operating conditions.